Interfacial Area Research Articles

Influence of the Complex Interface between Transport and Catalyst Layer on Water Electrolysis Performance

The interface design between anode catalyst layer (ACL) and porous transport layer (PTL) significantly influences the performance of proton exchange membrane water electrolyzers. Lately, the influence of the ACL/PTL interface on performance is more intensively investigated, including modeling approaches. Contrary to other models that apply through-plane resolved modeling, in-plane models better characterize the ACL/PTL interface. These models separate the interface into three domains: in an open pore area (P), under a contacted solid of the PTL (S), and the interfacial point between the pore and solid (S│P). In our work, we focused on the behavior of the model in the kinetic region, in which no two-phase behavior is to be expected. Consequently, we apply a one-phase model as the main model and a simple two-phase model for comparison. We find that for most reference samples, the one-phase model well describes polarization behavior. However, for samples with larger interfacial contact area, a two-phase model might explain the found effect better even for very low current densities. Finally, we show that the one-phase model and the simple two-phase model can be used to study the general behavior of different solid to pore ratios to guide electrode development in the future.

Robust natural graphite-based bulk graphites with nanodiamond-containing fibrous nanofiller as reinforcement by electrohydrodynamic processing

One-dimensional (1D) structures, such as carbon nanotubes and carbon fibers, used as reinforcements in advanced carbon materials, have been greatly appreciated but facing with some significant challenges of dispersion and interfacial bonding. We utilized electrospinning technology to create a new 1D nanofiller. This material is a superfine fiber composed of polyacrylonitrile (PAN) with a high nanodiamond (ND) content of 75 %, which is referred to as PDNF. During the preparation process, these nanofillers were blended with natural flake graphite (NFG) through electro-spraying. The as-prepared mixture served as the precursor powder sintered into NFG-based high-strength bulk graphite (HPG). During spark plasma sintering at 1800 °C, fibrous PDNF undergoes a phase transformation of diamond to graphite, with onion carbon pinning into and markedly reducing cleavage along the (002) plane of NFG, foundational to the high strength of NFG-based HPG. The PDNF's fiber-like structure and NFG's flake structure greatly increase the interfacial area between the matrix and reinforcement. Furthermore, the PDNF excels at blunting and deflecting cracks, thus bolstering the NFG-based HPG's overall resistance to crack propagation. The density, Young's modulus, and flexural strength of the as-prepared NFG-based HPG achieve 1.65 g/cm3, 17.4 GPa, and 145 MPa, respectively. Most importantly, this process can be a general approach for other high-performance composite materials.

Droplet evaporation on curved surfaces: transients of internal and external transport phenomena

We explore the transient evolution of thermo-fluid-dynamics of evaporating sessile droplets over curved substrates in the liquid and gaseous domains. A computational model using the Arbitrary Lagrangian-Eulerian framework is adopted. The governing equations in both liquid and gaseous domains are solved in a fully coupled manner, considering coupled effects of evaporative cooling and heat advection due to bulk fluid motion. This bulk motion in the liquid domain is caused by natural advection due to thermal actuations such as thermal Marangoni flow and buoyancy-driven convection. For the gaseous domain, the additional effects of solutal convection (due to vapour-concentration variation), Stefan flow and interfacial viscous stresses are also considered. To depict a generalized role of substrate curvature, both concave and convex surfaces with curvatures over a wide range are studied. The surface wettability effects are also explored by varying the true contact angle of the droplets. Computational predictions on evaporation rate and internal flow field are validated against experimental results from literature. The interplay of wetting state and substrate curvature is noted to substantially affect the evaporation process and its thermo-fluidics. The convex curvature significantly augments internal advection while the same is weakened over concave substrates due to altered mass loss rate. Consequently, the duration of multi-vortex Marangoni flows in the development stages of evaporation and the advection in the external gaseous domain is markedly different for different curvatures. Further, on superhydrophobic curved surfaces, the effects of re-distributed evaporative fluxes play a major role. In such cases, the reduced mass flux over a large interfacial area near the periphery expedites the stable state Marangoni and external flow features.

THE EFFECT OF FRICTION TIME VARIATIONS ON DISSIMILAR MATERIAL WELDING JOINTS AND HARDNESS VALUE USING A BAR-PLATE ROTARY FRICTION WELDING MACHINE

This research aims to determine the effect of variations in friction time on welded joints of dissimilar materials and hardness values. The method used is the friction welding method. One of the materials widely used in industrial products is mild steel AISI 1037 and stainless steel 304. One of the tools used is a bar-plate upright rotary friction welding machine. The parameters used are friction time variations of 25-35 seconds, 55-65 seconds and 115-125 seconds with a rotational speed of 2,484 rpm, friction pressure of 0.5 MPa, forging pressure of 0.7 MPa, forging time of 10 seconds. From the results of the connection several tests were carried out, namely liquid penetrant , macro observation and hardness test. The results of liquid penetrant testing and macro observations showed no influence on the welding area. The results of hardness testing have an influence on the hardness value. In the interface area, the friction time variation of 120 seconds has the highest hardness value of 161.67 VHN. The lowest hardness value in the interface area with a friction time variation of 30 seconds is 152.90 VHN. Where the longer the friction time, the hardness value also increases.

Impact of fiber diameter on mechanical and water absorption properties of short bamboo fiber-reinforced polyester composites

Abstract This study aims to investigate the effect of fiber diameter on the mechanical and water absorption characteristics of short bamboo fiber-reinforced polyester composites. Three different fiber sizes (180–250 µm, 250–500 µm, and 700–1000 µm) were used to prepare composites with varying fiber loadings of 10 wt.%, 20 wt.%, and 30 wt.%. The fabricated composites were cut to standard dimensions, and tension tests, impact tests, and water absorption tests were performed. Reproducible results were obtained, revealing that using fibers of smaller diameter (180–250 µm) increased the tensile strength of the composite by 20 % compared to composites with larger diameter fibers (700–1000 µm), while the tensile modulus showed a 22 % enhancement with decreasing fiber diameter. Composites with larger diameter fibers exhibited more defects (voids and matrix detachment), as revealed by SEM analysis of fractured surfaces. The impact strength of composites with a diameter size of 700–1000 µm increased by 33 % compared to composites reinforced with the smallest fiber diameter. Water absorption of the composites was also studied by long-term immersion in water, showing that water intake was high initially, reaching a saturation point after a certain time interval. The absorbed water values indicated that composites with the smallest diameter (180–250 µm) showed maximum water intake due to the creation of more water intake sites (increased interfacial area), while composites with the largest diameter fibers (700–1000 µm) exhibited the least water absorption as the interaction region between fibers and matrix was reduced.

Finite size effects and optimization of the calculation of the surface tension in surfactant mixtures at liquid/vapour interfaces

The surface tension of monolayers with mixtures of anionic and nonionic surfactant at the liquid/vapour interface is studied. Previous works have observed that calculations of the surface tension of simple fluids show artificial oscillations for small interfacial areas, indicating that the surface tension data fluctuate due to the finite size effects and periodic boundary conditions. In the case of simulations of monolayers composed of surfactant mixtures, the surface tension not only oscillates for small areas but can also give non-physical data, such as negative values. Analysis of the monolayers with different surfactant mixtures, ionic (DTAB, CTAB, SDS) and nonionic (SB3-12), was done for density profiles, parameters of order and pair correlation functions for small and large box areas and all of them present similar behaviour. The fluctuations and the non-physical values of the surface tension are corrected when boxes with large interfacial areas are considered. The results indicate that in order to obtain reliable values of the surface tension, in computer simulations, it is important to choose not only the correct force field but also the appropriate size of the simulation box.

Effect of viscosity on bubble spreading on flat solid surfaces

The behavior and dynamics of bubble spreading has a great impact on interfacial contact area and time, which is significant for the heat/mass transfer or separation efficiency. In this work, the dynamical behavior of bubble spreading especially the three-phase contact line (TPL) on solid flat surfaces in low viscous liquids was investigated. The results show that the final length of TPL on homogeneous solid surfaces tend to decrease with the increasing liquid viscosity. For heterogenous solid surfaces, TPL motion on non-stick coal surface is basically the same as that on homogeneous solid surfaces, whereas that on anthracite surface shows an anomalous morphology. By applying the power-law model, the fast and slow spreading stages of bubble on homogeneous surfaces show the universal exponent of b = 1/2 and b = 1/10, respectively. While the exponent for bubble spreading on heterogeneous surface is complicated due to the special surface physico-chemical properties.

Oil-Water Two-Phase Flow with Three Different Crude Oils: Flow Structure, Droplet Size and Viscosity

The study focuses on the flow patterns and pressure drop characteristics of three crude oils and water in a horizontal pipe. The experimental results showed that the transformation boundary of the flow pattern and phase inversion water fraction were related to the flow parameters. Comparing the three oils, it was found that the viscosity and composition of the oil also significantly influence the flow performance, which can be explained by the adsorption properties of the asphaltenes at the oil-water interface. In particular, the droplet size in water-in-oil dispersion flow was observed and measured. It showed that the water droplet size decreased with the increase of oil viscosity, the decrease of water content, the drop of temperature, and the growth of mixing velocity, probably due to higher shear stress and lower frequency of collision and coalescence between droplets. The apparent viscosity of water-in-oil emulsions was calculated by the rheological model, and the qualitative relation between flow parameters and interfacial area concentration on apparent viscosity was obtained. Taking the influence of interfacial area concentration into consideration, a simple and accurate viscosity model was established based on dimensional analysis, which is of great significance for process design in gathering and transportation systems.

A numerical study of thermal shrinkage influence on the impact dynamics of alumina droplets thermally sprayed on flat, grit-blasted and laser treated surfaces

Thermal spray splat morphology and its microstructure are of significance to the coating resulting properties. Depending on the material, the changes in density as the droplet solidifies during splat development and solidification could have a substantial role in the particle deformation dynamics, formation of porosity and subsequent adhesion to the flat or rough target surface.In the current study, the effect of shrinkage on the final splat shape is numerically investigated for collisions occurring under several high-speed impact conditions using the Volume-of-Fluid (VOF) method on real surface topography. This influence is also studied for the interaction of two successive impacting particles. The developed models study the splat impact, development and dynamics of heat transfer on flat, laser-patterned, grit-blasted surfaces and numerically designed features. The results of droplet material variable density cases are compared with those assuming constant density. Experimentally obtained single splat depositions are also used to validate the developed models and obtained numerical results.Findings show that micro substrate surface features lead to splat stretching, porosity and limited finger creation subsequent to improved solidification through interfacial contact area increase. Macro surface characteristics, however, lead to splashing and separation from the substrate surface driven by fluid instabilities. Irrespective of the interface topography, shrinkage processes reduce droplet spreading and accentuate splat feature discontinuities such as porosity.

Synthesis and characterization of Al2O3-methanol nanofluid and its usage in bubble column for an improved mass transfer rate

Methanol-based physical absorption, known for its effective CO2 capture ability, has been employed in acid gas removal (AGR) unit. However, the high energy consumption associated cooling methanol and acid gas hampers its widespread adoption. To address this challenge, numerous studies have explored the use of nanoparticles to enhance the CO2 absorption at room temperature, thereby reducing the energy requirements. In this study, the objective is to synthesize and characterize the Al2O3-methanol nanofluid and investigate its application in a bubble column for improved mass transfer rates during CO2 absorption. The methanol based Al2O3 nanofluid was prepared using the two-step method with ultrasonication technology and CO2 absorption in the resultant product was investigated. Initially, 0.001 vol%, 0.01 vol % and 0.1 vol% Al2O3 nanoparticles was added to methanol solution and to mixture them well via ultrasonication technology. The static settlement method and zeta potential analysis were utilized to characterize the stability of the as-prepared nanofluid. Both impact of sonication power and time on the stability of nanofluid were discussed as well. Then, numerical simulations was employed to investigate the mass transfer coefficient for CO2 absorption and the numerical uncertainty was carefully analyzed to verify the reliability of the numerical method. It revealed a 7.3%, 29.2% and 60.7% enhancement in mass transfer coefficient during CO2 absorption for 0.001 vol%, 0.01 vol% and 0.1 vol% nanoparticles under room temperature, respectively. The visualized reason for this improvement was related to the enhanced bubble breakup and coalescence after adding nanoparticles to methanol. The expanded interfacial area between gas and liquid plays a vital role in the mechanism of this improvement.

Experimental research and estimation model of gasoline evaporative emissions from vehicles in China

Evaporative emission is an important source of vehicle pollutant emission and volatile organic compounds (VOCs), causing serious environmental pollution. Carbon canisters are used to store fuel vapor in evaporative emission control (EVAP) system, but canisters are prone to saturation, leading to the direct release of fuel vapor into the atmosphere. Therefore, accurate estimation of fuel vapor generation is crucial for EVAP system. Gasoline evaporation rate is mainly influenced by vapor-liquid interface area, gasoline saturated vapor pressure, filling level and temperature. The quantitative relation between different parameters and gasoline evaporation rate has rarely been reported, and a gasoline evaporative emission estimation model suitable for China needs to be proposed urgently. In this study, gasoline evaporative emission tests have been carried out in VT-SHED, and the effects of vapor-liquid interface area, filling level and temperature on gasoline evaporative emissions have been analyzed under the premise of consistent gasoline temperature and ambient temperature. Some valuable conclusions are obtained. The results show that different from expectation, gasoline evaporative emissions are not positively correlated with the vapor-liquid interface area. There is an approximately exponential relationship between the headspace volume and gasoline evaporative emissions. The widely used Reddy equation and Hata equation underestimate the gasoline vapor generation in China. Based on China VI test program and gasoline, accurate estimation of mass transfer coefficient has been conducted, and a new semi-empirical estimation model for vapor generation has been proposed. The model can accurately estimate the fuel evaporation of vehicles in China, providing guidance for the matching and optimization of EVAP system.

Abstract 1503: Melanoma-derived lymphatic extracellular vesicles suppress dendritic cell differentiation and maturation in the sentinel lymph node

Abstract Spread to regional lymph nodes is the most common site of metastasis from melanoma and almost all solid tumors. Lymphatic metastases begin in the first lymph nodes draining from the primary tumor, i.e., the sentinel lymph nodes (SLN), preceded by the development of the premetastatic niche (PMN) initiated by primary cutaneous melanoma. Melanoma mediators are known to play a critical role in developing the PMN through the immune subversion in SLN. The DCs are a vital component of LN immunity that directly relates to eliciting T-cell functions. Our multiplex immunofluorescence (MxIF) analysis of SLNs indicates significantly decreased levels of DCs and cytotoxic-T cells in both core and interface areas of tumors in recurred patients treated with immunotherapy compared to non-recurred melanoma patients. The goal of this study is to determine whether the lymphatic extracellular vesicles (L-EVs) of melanoma patients regulate DC tolerization in SLN in order to stimulate the development of PMN. To identify whether L-EVs stimulate DC suppression, we extracted L-EVs from the lymphatic fluid of patients with melanoma downstream of primary cutaneous melanomas, compared it with controls (non-malignant post-operative fluid collected from the lymph node dissection field, and evaluated their effect on DC maturation by challenging these L-EVs in monocytic (CD14+) and hematopoietic stem cells (CD34+) cells. We found that L-EVs derived from melanoma patients suppress differentiation of CD11c+HLA-DR+ DCs and their maturation (defined by CD83 and CD86) compared to control L-EVs in CD14+ based DC maturation assay. We also found a reduction of conventional type 1 DC (cDC1) in CD34+-based DC maturation assay those challenged with patients’ L-EVs compared to control. To understand the mechanism of DC suppression in patients' L-EVs, we also conducted a total RNA sequencing analysis of subsets of DCs from maturation experiments to evaluate differently regulated transcriptomic profiles. The gene ontology analysis indicates that patient-derived L-EVs interfere with tRNA processing, oncostatin M & IL-10 signaling, and other immunoregulatory pathways to alter the hematopoietic cell lineage pathways in the DC maturation. Furthermore, the proteomic analysis of L-EVs also indicated several differentially regulated cargo-identified proteins in patient L-EVs, which are associated with immunomodulation, including regulation of DC function compared to control L-EVs. In conclusion, our study revealed that the patient's L-EVs carry differential proteomic cargoes secreted by cutaneous melanoma, which may be involved in regulating DC differentiation and maturation to diminish their functions and support the developing PMN in SLN. Citation Format: Shankar Suman, Wendy K. Nevala, James W. Jakub, Ray Guo, Alexey A. Leontovich, Raymond M. Moore, Chathu L. Atherton, Liyi Geng, Jeffrey E. Johnson, Sarah A. McLaughlin, Svetomir N. Markovic. Melanoma-derived lymphatic extracellular vesicles suppress dendritic cell differentiation and maturation in the sentinel lymph node [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1503.

Influences of hybrid fiber-reinforcement using wollastonite and cellulose nanofibers on strength and microstructure characterization of ultra-high-performance mortar

This paper presents the effect of incorporating wollastonite microfibers and cellulose nanofibers on mechanical properties and microstructure of ultra-high-performance mortar (UHPM). Cellulose nanofibers of 0.005%, 0.015%, and 0.030% are combined with 4.8% wollastonite microfiber by weight of binder, which consists of 10% silica fume and 90% cement. Compressive and flexural strengths of the UHPM specimens are measured at 7 days. The microstructure is characterized in terms of SEM/EDX, XRD, FTIR, and nanoindentation. The results show the effectiveness of the fiber hybridization in enhancing the compressive and flexural strength of ultra-high-performance mortar with the improvement in flexural toughness and fracture energy by as much as 10% than control mortar. Moreover, hybrid fiber-reinforcement based on the microstructural analysis provided more synergic effect and uniform distribution of the fibers, thus developing an efficient micro crack bridging mechanism as well as resulting in enhanced toughening properties and an increased load carrying capacity. Additionally, the combination of wollastonite microfibers and cellulose nanofibers promoted the hydration reaction products and contributed a denser matrix between the fibers and cement matrix, resulting in an increase of the microstructure and interface area between the fibers and cement matrix. Nano indentation analysis also confirmed the increase of UHD C-S-H from 65% to 84% and lower percentage of anhydrous phase in ultra-high-performance matrix after combining wollastonite microfibers and cellulose nanofibers.

Skew scattering dominated anomalous Hall effect in Si/Ni multilayers containing varying number of bilayers

A systematic study of the skew scattering dominated anomalous Hall effect (AHE) in Si/Ni multilayers has been carried out on several samples containing different number of bilayers. The investigation is performed by preparing a series of Si10Å/Ni30ÅN multilayers. When the number of bilayers (N) is decreased, structural analysis showed that the size of Ni nanocrystallites and the distance between them decreases whereas their count rises. As a result, the saturation magnetization lowers with N. Furthermore, the perpendicular magnetic anisotropy of the multilayers improves as N is reduced. The saturated AHE resistance (RHSA) is also found to decrease as N increases due to the decreases of the Si/Ni interface area and scattering effect from the Ni nanocrystallites. A maximum of about 28 times enhancement in RHSA is observed for the sample with N = 1 when compared with that for N = 24. It is seen that the skew scattering is the dominant mechanism which is responsible for the AHE in the Si/Ni multilayers.

Microstructure and Properties of Al-Cu-Fe-Ce Quasicrystalline-Reinforced 6061 Aluminum Matrix Composites after Aging

Al-Cu-Fe-Ce quasicrystalline-reinforced 6061 aluminum matrix composites were prepared through hot press sintering and treated with a solid solution and aging treatments. The influence of the solid solution and aging treatments on the microstructure and mechanical properties of the composites was investigated by XRD, EDS, SEM, and TEM. The results show that using Al-Cu-Fe-Ce quasicrystalline intermediate alloy as the reinforcing phase increases the interfacial areas of the composites and enhances the grain boundary strengthening effect, which is conducive to the improvement of the mechanical properties of the composites. And through the solid solution and aging treatment, the β phase and the Al2CuMg phase belonging to the orthorhombic crystal system, as well as the β″ phase and a small amount of the β′ precipitated phase, were formed in aluminum matrix composites, and these precipitated phases all existed in the composites in a fine and uniform distribution, which ensured the consistency of the mechanical properties of the materials and improved the mechanical properties of the composites. Meanwhile, the deficiency of quasicrystalline particle-reinforced 6061 aluminum matrix composites in age-hardening was solved and the age-hardening capability of the composites was further developed. This method provides a feasible process route for the preparation of high-performance aluminum matrix composites. The application of this process is expected to improve the mechanical properties and durability of this composite and offer a more reliable option for the application of aluminum matrix composites in aerospace, transportation, and other fields.

Two-group drift-flux model for dispersed gas-liquid flows in annuli

Interfacial area concentration (IAC) plays a vital role in mass, momentum, and heat transfers between gas and liquid phases in two-phase flows. The IAC of group-one bubbles, including spherical and distorted bubbles, differs from the IAC of group-two bubbles, including cap, slug and churn-turbulent bubbles. The two-group interfacial area transport equation (IATE) can be used as a mechanistic model to obtain the IAC of each group. The equation demands the two-group gas velocity fields, leading to the need to solve an extra momentum equation, which is complicated. The two-group drift-flux model can prevent this complexity by providing two-group gas velocities without introducing the extra momentum equation. Despite the importance of gas-liquid flows in annuli, the drift-flux model for gas-liquid flows is not well-developed like it is for pipe flows. The main objective of this study is to develop a two-group drift-flux model for dispersed vertical flows in annuli. The two-group drift-flux model provides the flow characteristics of group-one and group-two bubbles, such as void fractions and velocities, which strongly affect the prediction of the available interfacial area concentration of the group-one and group-two bubbles for heat and mass transfer. Hence, after comprehensively investigating the available experimental data, this study first improves a one-group drift-flux model for dispersed gas and low-viscosity liquid upward flows in annuli and proposes a new two-group drift-flux model. Then, the models are evaluated using the respective group experimental data. The consistency between one-group and two-group drift-flux models is also investigated. This consistency helps to reduce the two gas momentum equations to one gas mixture momentum equation. The results of the comparison between model predictions and experimental data are satisfactory.

Enhancing carbon fiber reinforced aluminum laminates with cellulose paper interlayers: experimental characterization of tensile, flexural, and interlaminar fracture toughness

ABSTRACT The mechanical properties of fiber metal laminates (FML) are influenced by several various factors. Interface adhesion plays a particularly crucial role in interlaminar strength. Enhancing the interlaminar strength of carbon fiber reinforced aluminum laminate (CARALL) composites present a persistent challenge due to inherent weaknesses between metal and composite elements. Therefore, this study focuses on improving the interlaminar performance of CARALL composites by introducing cellulose paper interlayer at the metal/composite interface. The cellulose paper interlayer offers the advantage of being cost-effective and sustainable. Cellulose paper-interleaved CARALL composites were fabricated by vacuum bagging method and exhibited noteworthy improvements in mechanical properties. Comparative analysis with pristine samples revealed substantial enhancements, including a 15% increase in tensile strength, a remarkable 42% improvement in flexural strength, and a significant enhancement in mode-I fracture toughness by 65%. Furthermore, the cellulose paper interleaving played a crucial role in stabilizing fracture formation at the fiber-matrix interface, with mode II fracture toughness witnessing a 3% increase. Visual examination revealed the underlying toughening processes occurring in the interfacial area. This innovative approach of interleaving laminated composites with cellulose paper emerges as a sustainable and effective strategy, demonstrating the potential to fortify and toughen the interlaminar zones of CARALL composites.

Glass Transition Temperature and Mechanical Properties of Poly(Ethylene Carbonate)/Organoclay Composites

Poly(ethylene carbonate) (PEC) is a form of aliphatic polycarbonate, a biodegradable polymer made via the copolymerization of carbon dioxide and epoxides. The poor thermal stability and mechanical properties of these aliphatic carbonates are attributed to the carbon structure's flexibility, which restricts their applications. By combining PEC with organoclay CP180, this study addressed the weaknesses of PEC with organoclay addition. A physical blending technique was employed to generate PEC/organoclay composites with a 10-50 wt.% ratio of organoclay. The blended material's thermal characteristics were analyzed using differential scanning calorimetry (DSC), and the mechanical characteristics were measured using a universal tensile machine. The Field Emission Scanning Electron Microscopy (FESEM) analysis determined the blends' morphology. Before the torque value for all curves grew with the addition of CP180 material to the PEC matrix, it became constant. It reached a high value due to the shear-thickening behavior of the PEC matrix with organoclay addition. Tg of PEC increased by more than 7°C by 40 wt.% organoclay addition, as evident in the hindrance of PEC flexibility, significantly increased the toughness of this PEC. From the FESEM images, the formation of large silicate starts to aggregate effectively, lowering the interfacial area between organoclay and PEC as the clay content continues to rise, as shown by 50 wt.% organoclay addition.

Recommendations for the specialist further training of nursing personnel on intensive care units in the treatment of abdominal aortic aneurysms: results of a modified Delphi procedure with experts

The medical development in the previous 15 years and the changes in treatment reality of the comprehensive elective treatment of abdominal aortic aneurysms necessitate a re-evaluation of the quality assurance guidelines of the Federal Joint Committee in Germany (QBAA-RL). In the current version this requires a specialist further training quota for nursing personnel in intensive care wards of 50%. The quota was determined in 2008 based on expert opinions, although a direct empirical evidence base for this does not exist. Representatives from the fields of patient representation, physicians, nursing personnel and other relevant interface areas were invited to participate in a modified Delphi procedure. Following a comprehensive narrative literature search, a survey and focus group discussions with national and international experts, a total of three anonymized online-based voting rounds were carried out for which previously determined key statements were assessed with a 4‑point Likert scale (totally disagree up to totally agree). In addition, the expert panel had also defined a recommendation for a minimum quota for the specialist training of nursing personnel on intensive care wards in the treatment of abdominal aortic aneurysms, whereby an a priori agreement of 80% of the participants was defined as the consensus limit. Overall, 37 experts participated in the discussions and three successive voting rounds (participation rate 89%). The panel confirmed the necessity of a re-evaluation of the guideline recommendations and recommended the introduction of a shift-related minimum quota of 30% of the full-time equivalent of nursing personnel on intensive care wards and the introduction of structured promotional programs for long-term elevation of the quota. In this national Delphi procedure with medical and nursing experts as well as representatives of patients, the fundamental benefits and needs of professional specialist qualifications in the field of intensive care medicine were confirmed. The corresponding minimum quota for specialist further training of intensive care nursing personnel should generally apply without limitations to specific groups. The expert panel stipulates a shift-related minimum quota for intensive care nursing personnel with specialist training of 30% of the nursing personnel on intensive care wards and the obligatory introduction of structured and transparent promotion programs for the long-term enhancement.

Dumbbell-shaped polymeric nanoparticles with one-side anchored Pd-clusters for efficient catalytic hydrogenation at biphasic interfaces

Pickering interfacial catalysts incorporated with amphiphilic architecture significantly expand the sustainability of green catalysis systems. In this work, we present precise and well-designed dumbbell-shaped Janus-structured polymeric nanoparticles with one-side anchored palladium clusters (DB-JPP-Pd) as Pickering interfacial catalyst for static hydrogenations. The large wettability difference of each lobe renders the prominent amphiphilicity of the dumbbell-shaped DB-JPP-Pd. The amphiphilic Janus catalyst displays excellent interfacial activity and extensively reduces the interfacial tension from 34.06 ± 0.13 to 20.54 ± 0.31 mN/m, promoting the formation of a more stable Pickering emulsion than that of the bulk PS-Pd catalyst, which can continuously provide a large interfacial area and shorten the molecular mass transfer distance during the reaction process. As a result, the DB-JPP-Pd catalyzed nitroarene reduction reaction exhibits a normalized reaction rate constant (knor) of 3.39 min−1⋅g−1⋅L under static conditions, which is 56.5 times higher than that of bulk PS-Pd. The constructed Pickering interfacial catalysis (PIC) system converts all the nitrobenzene into aniline within three minutes and possesses excellent selectivity in hydrogenations of different nitro aromatics. In addition, the emulsion catalytic system was conveniently recycled for ten consecutive runs. Hence, this unique amphiphilic dumbbell-shaped catalyst effectively develops an efficient static biphasic catalysis system.