High Local Concentrations Research Articles

The student experience during a rural clerkship in Brazil.

Universities have the ability to bring science and comprehensive care to remote regions. This can be done through the creation of rural clerkships during the training of health professionals. Report of students' experiences during their rural clerkships in Brazil. Rural clerkships made contact possible between students from different areas of health, such as medicine, nutrition, psychology, social assistance, and nursing. This multidisciplinary team expanded the possibilities of care in the region, which often suffers from a shortage of healthcare professionals. Students noticed that the use of management and treatment guided by evidence-based medicine was more common in their university than in rural facilities. The relationship between students and local health professionals provided discussions and application of new scientific evidence and updates. Due to the greater number of students and residents of the multi-professional health team, it was possible to initiate health education, integrated case discussions, and territorialization projects. Areas with untreated sewage and a high local concentration of scorpions were identified, which allowed a targeted intervention. The students noticed the numerous differences between the tertiary care they were used to at medical school and the access to health and resources in a rural area. Collaboration between educational institutions and rural areas with scarce resources makes it possible to exchange knowledge between students and local professionals. In addition, these rural clerkships expand the possibilities for care for local patients and make it possible to carry out projects related to health education.

Tailored Solvation and Interface Structures by Tetrahydrofuran-Derived Electrolyte Facilitates Ultralow Temperature Lithium Metal Battery Operations.

Ineffectiveness of Li-ion batteries (LIBs) in cold climates hinders electronics to work in various conditions including frigid environments, despite high demands. Given that intrinsic properties of LIB materials cause this problem, optimized cell chemistries ultimately are required for low-temperature usage. In this study, Li-metal batteries (LMBs) composed of a Li-metal anode (LMA) stabilized by a localized high-concentration electrolyte (LHCE) are found to significantly enhance low-temperature performance. The LHCE allows the LMA to have compact and regular deposition and excellent plating/stripping efficiency at sub-zero temperatures. The LHCE produces an inorganic-rich solid-electrolyte interphase with larger amounts of Li2 O/LiF interfaces, dominance of ion aggregates in Li+ solvation, and enhanced Li+ transport, which can greatly improve the LMA stability. LMB full cells based on LiNi0.8 Co0.1 Mn0.1 O2 cathodes with the tailored electrolyte show high retentions of 75 and 64 % at -20 and -40 °C, respectively. Furthermore, the LMB configuration retains its charge-discharge capability even at -60 °C.

Dual-Salt Localized High-Concentration Electrolyte for Long Cycle Life Silicon-Based Lithium-Ion Batteries.

Silicon-based materials are considered the most promising anodes for next-generation lithium-ion batteries (LIBs) owing to their high specific capacity. However, poor interfacial stability due to enormous volume changes severely restricts their mass application in LIBs. Here, we design a fluoroethylene carbonate (FEC)-containing dual-salt (LiFSI-LiPF6) ether-based localized high-concentration electrolyte (D-LHCE-F) for enhancing the interfacial stability of silicon-based electrodes. It is revealed that the dominating LiFSI salt of superior chemical and thermal stability prevents the formation of corrosive HF, while the addition of FEC improves the interface stability by promoting the formation of protective LiF-rich SEI and increasing the flexibility of the interface. This robust and flexible SEI layer can adapt to substantial variations in the volume of silicon electrodes while preserving the integrity of the interface. The SiOx/C electrode using the unique D-LHCE-F retains up to 78.5% of its initial capacity after 500 cycles at 0.5C, well surpassing that of the control electrolyte (3.4% capacity retention). More notably, the cycle life of the SiOx/C||NCM90 (LiNi0.9Co0.05Mn0.05O2) full batteries is effectively enhanced thanks to the stabilized electrode/electrolyte interfaces. The key findings of this work offer crucial knowledge for rationally designing electrolyte chemistry to enable the practical application of high-energy-density LIBs adopting silicon-based anodes.

Stable electrode/electrolyte interfaces regulated by dual-salt and localized high-concentration strategies for high-voltage lithium metal batteries.

High-voltage lithium metal batteries (LMBs) have faced application obstacles derived from the unstable interfacial layers on both the cathode and anode sides. Herein, a dual-salt localized high-concentration electrolyte (LHCE) is optimized to modify the anion-derived inorganic-rich interfacial layers with conductive inorganic and robust organic components.

Concise nanotherapeutic modality for cancer involving graphene oxide dots in conjunction with ascorbic acid.

Cancer cells tend to have higher intracellular reactive oxygen species (ROS) levels and are more vulnerable to ROS-generating therapies such as ascorbic acid (H2Asc) therapy, whose potency has been explored by several clinical trials. However, its efficiency is restricted by the requirement of pharmacologically high local H2Asc concentrations. Here, we show that nitrogen-doped graphene oxide dots (NGODs), which are highly crystalline and biocompatible, can serve as a catalytic medium for improving H2Asc cancer therapy at orally achievable physiological H2Asc concentrations. NGODs catalyze H2Asc oxidation for H2O2 and dehydroascorbic acid generation to disrupt cancer cells by consuming intracellular glutathione (GSH) and inducing ROS damage. This is the first study to demonstrate the direct consumption of GSH using a carbon-based nano-catalyst (NGODs), which further expedites tumor killing. In addition, as in our previous study, NGODs can also serve as a highly efficient photosensitizer for photodynamic therapy. Under illumination, NGODs produce a considerable amount of H2O2 in the presence of physiological levels of H2Asc as a hole scavenger and further enhance the therapeutic efficiency. Thus, a concise nanotherapeutic modality could be achieved through the conjunction of multifunctional NGODs and H2Asc to selectively eliminate deep-seated and superficial tumors simultaneously (under 65% of normal cell viability, it kills almost all cancer cells). Note that this level of therapeutic versatility generally requires multiple components and complex manufacturing processes that run into difficulties with FDA regulations and clinical applications. In this study, the concise NGOD-H2Asc nanotherapeutic modality has demonstrated its great potential in cancer therapy.

Towards a realistic prediction of catalyst durability from liquid half-cell tests.

Liquid half-cell measurements provide a convenient laboratory method for determining relevant parameters of electro-catalysts applied in e.g. polymer electrolyte membrane fuel cells. While these measurements may be effective in certain contexts, their applicability to real-world systems, such as single-cells in a membrane electrode assembly (MEA) configuration, is not always clear. This is particularly true when assessing the stability of these systems through accelerated stress tests (ASTs). Due to different electrode compositions and operating conditions, nanoscale degradation proceeds differently. Nevertheless, given the high demands of MEA measurements in terms of time, testing equipment complexity, and amount of catalyst material, application-relevant predictions of catalyst durability from liquid half-cell tests are highly desirable. This study combines electrochemical and nanoparticle analysis based on transmission electron microscopy to conduct a typical voltage cycling AST for rotating disc electrode (RDE) measurements, showing that the loss of the electrochemically active surface area (ECSA) of the used Pt/Vulcan catalyst is strongly enhanced at 80 °C compared to room temperature, which goes along with increased nanoparticle coarsening. Additionally, a high ionomer/carbon mass ratio (I/C = 0.7) accelerates the ECSA loss, and further investigations of its influence suggest a combination of several factors, including the high local proton concentration and the presence of adsorbing anions. At the same temperature (80 °C) and I/C ratio (0.7), the ECSA loss vs. AST cycle number of the Pt/Vulcan catalyst is essentially identical for a voltage cycling AST conducted in either an RDE half-cell or an MEA configuration, suggesting that liquid electrolyte half-cell based ASTs can provide application-relevant results. Thus, our study points out a way for predicting the stability of electro-catalysts in MEAs based on RDE experiments that require less specialized equipment and only μg-quantities of catalysts.

Observation of filaments in mega-ampere dense plasma focus within pure deuterium by means of simultaneous schlieren and interferometry diagnostics

Fifteen-frames interferometric diagnostics at the PF-1000 facility was enhanced by adding four frames of the schlieren diagnostics and by splitting of four channels in the optical delay line. This setup enabled the visualization of gradients in the plasma density perpendicular to the direction of the diagnostic laser beam, and their relationship with larger structures visualized by using laser interferometry. The schlieren pictures showed filamentary structures of submillimeter 200–300 μm diameter in shots performed with pure deuterium filling. Filaments were observed in a thin (millimeter-thick) lateral-boundary layer, in lobules, and in internal fast transforming regions of the dense plasma column. Their high-density gradients and location in the regions of recorded (or inferred) currents indicated local concentrations of the magnetic field and current distribution. Millimeter- and submillimeter-size sources of fast charged particles, which were identified in the recorded ion pinhole pictures, have been conjectured to be a manifestation of high local concentrations of the magnetic energy.

Localized high-concentration electrolyte enabled by a novel ester diluent for lithium metal batteries.

To achieve stable Li anode cycling with a high-voltage cathode and high efficiency, a novel ester diluent-based localized high-concentration electrolyte (LHCE) was successfully applied. The oxidation resistance of the high-concentration electrolyte is retained after dilution. More than 99.5% Coulombic efficiency is achieved in Li||Cu cells owing to the optimized physical properties, and the robust SEI film enables superior long-term operation with a high-voltage cathode. This strategy verifies the effectiveness of developing ester diluents for LHCEs applied in lithium metal batteries.

Multi-constraint molecular generation using sparsely labelled training data for localized high-concentration electrolyte diluent screening

We use a mixture of incomplete-labelled molecule property databases to conditionally generate new molecules with multiple property co-constraints.

Assessment of the depressurisation and mixing effects of two spray systems in the PANDA facility, part II – Simulations using GOTHIC8.3(QA)

The spray safety system is one of the most effective solutions to limit the pressure and temperature rise in the containment of a nuclear power plant during a design basis accident. However, its actuation under severe accident conditions may have either a positive effect on the hydrogen risk by mixing the containment atmosphere and avoiding high H2 local concentrations or a negative impact by condensing the steam and de-inerting the atmosphere. The experiments performed during the OECD/NEA HYMERES-2 Project aimed to extend the experimental database dedicated to assessing the capabilities of the codes used to optimise the operation of the safety systems. Specifically, the H2P5 series consisted of two experiments that compared the activation of a central full cone spraying nozzle (H2P5_2) with nine smaller spraying nozzles, eight equally distributed at 0.5 m from the metallic walls of PANDA (H2P5_1). The ninth nozzle was positioned in the vessel vertical axis for the latter configuration. These experiments created a demanding scenario for the computational codes, which need to consider three different fields: three components of the gas phase (air, helium, and steam), the dispersed liquid (droplets), and the continuous liquid accumulated on the walls and at the bottom of the PANDA vessel during the test. Furthermore, the proximity of the nozzles to the walls in H2P5_1 requires considering the strong interaction of the fluid with these metallic structures.In this work, the GOTHIC 3D models were able to qualitatively represent all the relevant phase change phenomena affecting the cooling effect of the spray and provided a reasonable qualitative representation of the depressurization behaviour observed during the experiments. However, the code overestimated the steam condensation on droplets. To achieve quantitative agreement between the experiments and computer models it was necessary to enhance the spatial distribution of the droplets (to compensate for anomalies due to a conical injection in a relatively coarse cartesian mesh) and to diminish the steam condensation on the droplets by decreasing the spray mass flow rate. Regarding the helium mixing, the simulations revealed a potential explanation for the faster mixing observed in the single nozzle (H2P5_2) experiment. Furthermore, the droplet diameter showed to be the parameter inducing the most significant variations in the mixing.

Design, development and evaluation of Resveratrol transdermal patches for breast cancer therapy

Resveratrol (RVT) is a polyphenolic phytoestrogen which has shown antiproliferative activity in breast cancer. However, its low bioavailability and short half-life have restricted its use. The current study aimed to develop transdermal patches of RVT and evaluate its site-specific delivery for breast cancer therapy. Different penetration enhancers were screened using a computational tool, quantitative structure propery relationship (QSPR). The best permeation of RVT was observed in a patch comprising hydroxypropyl methylcellulose (HPMC) E15LV: HPMC-K4M: polyvinyl pyrrolidone (PVP) K30 in the ratio of 3:1:2 as release controlling polymers with Glycerol:Capryol 90 (4:1) as penetration enhancer and plasticizer. To assess the localized delivery of RVT, the patch was applied to the breast of female rats. Higher breast tissue disposition with lower systemic concentration was observed compared to oral administration, demonstrated by increased AUC and MRT. Further, the optimized RVT patches were tested in 7,12-Dimethylbenz[a]anthracene (DMBA) induced rat mammary cancer. Compared to oral RVT, the application of RVT tansdermal patches significantly reduced the tumor volume and serum CA 15–3, a cancer biomarker. Thus, the RVT transdermal patch may be a viable approach for ensuring high local concentration of drug for site-specific delivery in breast cancer therapy.

Dynamic Behavior of Additively Manufactured FeCoCrNi High Entropy Alloy

Additively manufactured face-centered-cubic high entropy alloys have a combination of high strength and good ductility, and are promising impact-resistant structural materials. However, the dynamic behavior of additively manufactured face-centered-cubic high entropy alloys is seldomly reported. In this study, FeCoCrNi high entropy alloy was fabricated, using the laser beam powder bed fusion technique, and dynamic tests were performed by means of a Split Hopkinson Pressure Bar. The high entropy alloy showed a more excellent combination of yield stress and toughness at high strain rates, than previously reported alloys. This was attributed to the dislocation cell structure of the additively manufactured FeCoCrNi HEA, which provided high local stress concentration, leading to the formation of microbands and deformation twins. The high entropy alloy showed higher strain rate sensitivity than the cast counterpart, at both quasi-static and strain rates over 3000 s−1. Interestingly, the yield stress kept stable at a strain rate from 1000 s−1 to 3000 s−1, showed a steep decrease of strain rate sensitivity and a four-fold increase in activation volume, implying a transition in deformation mechanism to collective dislocation nucleation.

From Protein Film Electrochemistry to Nanoconfined Enzyme Cascades and the Electrochemical Leaf.

Protein film electrochemistry (PFE) has given unrivalled insight into the properties of redox proteins and many electron-transferring enzymes, allowing investigations of otherwise ill-defined or intractable topics such as unstable Fe-S centers and the catalytic bias of enzymes. Many enzymes have been established to be reversible electrocatalysts when attached to an electrode, and further investigations have revealed how unusual dependences of catalytic rates on electrode potential have stark similarities with electronics. A special case, the reversible electrochemistry of a photosynthetic enzyme, ferredoxin-NADP+ reductase (FNR), loaded at very high concentrations in the 3D nanopores of a conducting metal oxide layer, is leading to a new technology that brings PFE to myriad enzymes of other classes, the activities of which become controlled by the primary electron exchange. This extension is possible because FNR-based recycling of NADP(H) can be coupled to a dehydrogenase, and thence to other enzymes linked in tandem by the tight channelling of cofactors and intermediates within the nanopores of the material. The earlier interpretations of catalytic wave-shapes and various analogies with electronics are thus extended to initiate a field perhaps aptly named "cascade-tronics", in which the flow of reactions along an enzyme cascade is monitored and controlled through an electrochemical analyzer. Unlike in photosynthesis where FNR transduces electron transfer and hydride transfer through the unidirectional recycling of NADPH, the "electrochemical leaf" (e-Leaf) can be used to drive reactions in both oxidizing and reducing directions. The e-Leaf offers a natural way to study how enzymes are affected by nanoconfinement and crowding, mimicking the physical conditions under which enzyme cascades operate in living cells. The reactions of the trapped enzymes, often at very high local concentration, are thus studied electrochemically, exploiting the potential domain to control rates and direction and the current-rate analogy to derive kinetic data. Localized NADP(H) recycling is very efficient, resulting in very high cofactor turnover numbers and new opportunities for controlling and exploiting biocatalysis.

The Anion-Dominated Dynamic Coordination Field in the Electrolytes for High-Performance Lithium Metal Batteries

Electrolyte plays a dominant role in solving the various challenges of Li-metal batteries (LMBs). The complex competition coordination and diversity of the anion coordination clusters in electrolytes are still unclear. In this paper, an anion-dominated dynamic coordination field (ADCF) theory is proposed to reasonably explain the coordination behavior in the high-concentration, localized high-concentration, and weak-ionization localized high-concentration electrolytes, which is based on specific characterizations and theoretical calculations. The novel model selects the anions as the center of the whole molecular groups/clusters, while the Li+ acts as the counterion or carrier, which can promote the dynamic and elastic movement of the whole cluster. The specific coordination clusters could remarkably enhance the interaction between TFSI− and Li+, and make the counterion composition of Li+ increase. The confinement effect of the coordination field provides a difficult ionization atmosphere for the Li+, and enables clusters to preferentially adsorb on the Li surface, and construct a specific solid electrolyte interphase (SEI). Furthermore, the electrode/electrolyte interface kinetics and the growth of lithium dendrites are systematically investigated. These new viewpoints of coordination behavior provide inclusive strategies in the electrolyte design, and promote further research of the charge transfer or solution behavior.

Stress relaxation behavior of 3D printed silicone rubber foams with different topologies under uniaxial compressive load

3D printed elastomeric foams present good potential for mechanical application and their stress relaxation behaviors are critical for engineering performance. In this work, polydimethylsiloxane (PDMS) foams with simple tetragonal (ST) and face-centered tetragonal (FCT) structures were printed and present different stress relaxation behaviors. The ST foam had a similar stress relaxation rate to that of the stochastic foam (15–16%), whereas the FCT foam had a lower stress relaxation rate (10%). The ST foam had high local stress concentrations under compression, because it deformed by uniaxial buckling deformation, leading to high stress relaxation of the PDMS matrix. In contrast, the stress distribution was more uniform in the FCT foam due to its bending deformation under compression. Thus, the compressive deformation mechanism of the printed topology greatly affects the stress relaxation properties. This finding provides an important guide for the design of elastomeric foams with low stress relaxation for high performance applications.

Microbial biofilms are shaped by the constant dialogue between biological and physical forces in the extracellular matrix.

Microbial biofilms are shaped by the constant dialogue between biological and physical forces in the extracellular matrix.

Deciphering the mechanism of concentrated electrolyte for lithium metal anode via cryogenic electron microscopy

Increasing electrolyte concentration is a typical strategy to boost the stability of lithium (Li) metal anode, yet the fundamental mechanism remains a mystery. By virtue of comprehensive characterization of solid electrolyte interphase (SEI) via cryogenic electron microscopy (Cryo-EM), we revealed the effects of solvation structure in ether-based electrolytes on SEI formation as well as electrochemical performance. The SEI formed in the low-concentration electrolyte (LCE) adopts a Mosaic-type structure with randomly distributed Li2CO3, which leads to uneven Li deposition and poor cycle stability. The high-concentration electrolyte (HCE) with few free solvent molecules generates an amorphous monolayer SEI, contributing to significantly improved Coulombic efficiency and cycle stability. The addition of non-solvating diluent enables uniform Li deposition on Cu foils in the prepared local high-concentration electrolyte (LHCE), and brings about further enhancement in reversibility and stability. It is correlated with the dual-layer but thinner SEI consisting of an inner amorphous layer and an outer layer made up of mainly crystalline Li2S2O7 with high Li+ conductivity. This work points out the necessity to optimize the SEI structure as well as the solvation structure by altering the salt-to-solvent ratio or adding diluent to modify the viscosity and conductivity of electrolyte system.

Successful treatment of invasive tracheobronchial pulmonary aspergillosis with venovenous extracorporeal membrane oxygenation and combined systemic, intratracheal instillation of liposomal amphotericin B: a case report

BackgroundInvasive pulmonary Aspergillus and invasive bronchial aspergillosis is a life-threatening opportunistic fungal infection that predominantly affects immunocompromised hosts. A case series and review found that the mortality rate of invasive bronchial aspergillosis is high, at about 40%, and 23.7% of invasive bronchial aspergillosis patients require mechanical ventilator management. There are few reports of life-saving cases with venovenous extracorporeal membrane oxygenation as rescue therapy in invasive pulmonary Aspergillus and invasive bronchial aspergillosis. Here, we report a case of invasive bronchial aspergillosis and invasive pulmonary Aspergillus that was successfully treated with venovenous extracorporeal membrane oxygenation, and combined systemic and intratracheal instillation of liposomal amphotericin B.Case presentationWe present the case of a 61-year-old Japanese man with invasive tracheobronchial-pulmonary aspergillosis while receiving chemotherapy for malignant lymphoma. Bronchoscopy revealed trachea covered with pseudomembranous necrotizing tissue, the culture revealed Aspergillus fumigatus, and the histological findings of pseudomembranous revealed fungal hyphae. The patient required venovenous extracorporeal membrane oxygenation because of respiratory failure for atelectasis and obstructive pneumoniae. While continuing systemic administration of liposomal amphotericin B, intratracheal instillation liposomal amphotericin B was performed by bronchoscopy three times a week. Although the respiratory conditions improved and the patient was discontinued on venovenous extracorporeal membrane oxygenation, he ultimately died of recurrence of malignant lymphoma.ConclusionIntratracheal instillation of liposomal amphotericin B is safe, and liposomal amphotericin B instillation allowed a targeted high local drug concentration, which led to improvement in the invasive bronchial aspergillosis. In addition, since the patient was supported with venovenous extracorporeal membrane oxygenation, we were able to perform safe bronchoscopic debridement of airway lesions and intratracheal instillation of liposomal amphotericin B.

Molecular insight into nano-heterogeneity of localized high-concentration electrolyte: Correlation with lithium dynamics and solid-electrolyte interphase formation

Localized high-concentration electrolytes (LHCEs) have attracted extensive attention in light of their excellent characteristic that inherits the advantages of high-concentration counterparts and minimize their shortcomings. However, the fundamental mechanisms of nano-heterogeneity influencing the LHCE properties are still not well understood. Herein, a systematic comparison combining theoretical and experimental methods is performed to clarify the fundamental correlation between electrolyte microstructure and properties. The unique microstructure in the LHCE of high-concentration clusters surrounded by a nonsolvating diluent enables the hopping diffusion of Li+ through the anion ligand layers, which is responsible for the high transference number and fast diffusion of Li+. In addition, the anion coordinated with multiple Li+ undergoes defluorination reactions and contributes, with the diluent decomposition, to the formation of a stable and robust “LiF-rich” solid electrolyte interphase (SEI) layer on the Li metal, which is responsible for the enhanced cycling stability. These fundamental insights highlight the correlation of microstructural and dynamic heterogeneities of electrolytes with SEI formation, which should be considered in the rational design of next-generation improved electrolytes.

Room-Temperature Pseudo-Solid-State Iron Fluoride Conversion Battery with High Ionic Conductivity.

Li-metal batteries (LMBs) employing conversion cathode materials (e.g., FeF3) are a promising way to prepare inexpensive, environmentally friendly batteries with high energy density. Pseudo-solid-state ionogel separators harness the energy density and safety advantages of solid-state LMBs, while alleviating key drawbacks (e.g., poor ionic conductivity and high interfacial resistance). In this work, a pseudo-solid-state conversion battery (Li-FeF3) is presented that achieves stable, high rate (1.0 mA cm-2) cycling at room temperature. The batteries described herein contain gel-infiltrated FeF3 cathodes prepared by exchanging the ionic liquid in a polymer ionogel with a localized high-concentration electrolyte (LHCE). The LHCE gel merges the benefits of a flexible separator (e.g., adaptation to conversion-related volume changes) with the excellent chemical stability and high ionic conductivity (∼2 mS cm-1 at 25 °C) of an LHCE. The latter property is in contrast to previous solid-state iron fluoride batteries, where poor ionic conductivities necessitated elevated temperatures to realize practical power levels. The stable, room-temperature Li-FeF3 cycling performance obtained with the LHCE gel at high current densities paves the way for exploring a range of architectures including flexible, three-dimensional, and custom shape batteries.