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Dilute Pd-in-Au alloys are valuable materials for selectively hydrogenating alkynes and isomerizing alkenes. By diluting Pd in a Au host, the selectivity toward semihydrogenated alkene isomers can be significantly enhanced and the unfavorable overhydrogenation to alkanes is suppressed. However, a detailed mechanistic study on the origin of the enhanced alkene selectivity over dilute alloy catalysts is still missing. Here, we combine experiment and theory to unravel the reaction mechanism, identifying rate-limiting and selectivity-controlling steps in 1-hexene hydrogenation over dilute Pd-in-Au catalysts. Using isotope-exchange hydrogenation experiments, we show that 1-hexene and hydrogen over a bimetallic Pd4Au96 in silica catalyst preferentially form 1-hexene isomers, (trans and cis) 2- and 3-hexene and only a small amounts of hexane. The reaction is consistent with a Horiuti-Polanyi mechanism, similar to a monometallic Pd nanoparticle catalyst. Computation of the free-energy profiles for 1-hexene hydrogenation and isomerization over a single Pd atom in a Au surface using first principles calculations indicated that the isomerization of 1-hexene to 2-hexene is energetically favorable due to the relatively large barrier for H2 dissociation preventing hydrogenation to n-hexane. Microkinetic modeling established that H2 dissociation on the single-atom Pd sites and H spillover from these sites onto the Au host are rate-limiting and key in steering the selectivity of dilute Pd-in-Au alloys toward the hexene isomers. The mechanistic insights from this study contribute to the rational design of optimized dilute alloy catalysts for selective alkene isomerization.

Designing compatible electrode–electrolyte interfaces is critical to achieve high and consistent performance and life span in next-generation rechargeable lithium batteries. In the study of nanoscopic interfaces, ab initio molecular dynamics (AIMD) simulations allow for a highly accurate description of interface dynamics and reactions. However, due to the high computational cost, simulations are limited in the size and time domains and therefore merit the need for a new interpretational approach that can deduce the long-term reactivity from such short yet highly accurate simulations. In this study, this is established by means of bond length distribution analysis through which the reactivity of key solid polymer electrolyte (SPE) polymer functional groups in contact with key electrode materials (graphite, silicon, lithium) and the influence of the electric field and temperature was successfully determined. Bond length distributions were found to respond to environmental changes and relate to the long-term reactivity in which the strength of electrode surface interactions and the accessibility of functional groups were found to be critical factors. Furthermore, the balancing of the SPE polymer mobility and functional group–electrode surface attraction, respectively, kinetic and thermodynamic properties, further suggests a selective spatial orientation of functional groups when exposed to an electric field, which could have great implications for low-temperature and high-current-density environments. The obtained knowledge on how reactive key SPE polymer functional groups are and also how their reactivity changes in terms of the electric field orientation effect could provide new insights for designing new stable SPE polymers.

Hypothesis Imbibition of a fluid into a porous material involves the invasion of a wetting fluid in the pore space through piston-like displacement, film and corner flow, snap-off and pore bypassing. These processes have been studied extensively in two-dimensional (2D) porous systems; however, their relevance to three-dimensional (3D) natural porous media is poorly understood. Here, we investigate these pore-scale processes in a natural rock sample using time-resolved 3D (i.e., four-dimensional or 4D) X-ray imaging. Experiments We performed a capillary-controlled drainage-imbibition experiment on an initially brine-saturated carbonate rock sample. The sample was imaged continuously during imbibition using 4D X-ray imaging to visualize and analyze fluid displacement and snap-off processes at the pore-scale. Findings We discover a new type of snap-off that occurs in pores, resulting in the entrapment of a small portion of the non-wetting phase in pore corners. This contrasts with previously-observed snap-off in throats which traps the non-wetting phase in pore centers. We relate the new type of pore-snap-off to the pinning of fluid-fluid interfaces at rough surfaces, creating contact angles close to 90°. Subsequently, we provide correlations for displacement events as a function of pore-throat geometry. Our findings indicate that having a small throat does not necessarily favor snap-off: the key criterion is the throat radius in relation to the pore radius involved in a displacement event, captured by the aspect ratio.

The interaction of water with oriented NiO films is studied by using a combination of photoelectron spectroscopy with in situ sample preparation and electrochemical measurements in the stability window of water. In contrast to NiO(100), room temperature water exposure induces a downward band bending on the (110)- and (111)-oriented films, indicating a more positive surface charge. The surface charge is assigned to a dissociative adsorption of water accompanied by a removal of oxygen, which corresponds to a preferential adsorption of protons. Photoelectron spectroscopy suggests that the nonstoichiometric adsorption is related to the presence of adsorbed oxygen species prior to water exposure. For the NiO(110) surface, the stability of adsorbed bridging oxygen dimers is confirmed by density functional theory calculations. The preferential adsorption of protons, which requires interaction of two water molecules with the oxygen dimers, explains that water acts as an electron donor on many oxide surfaces. The different adsorption behavior is consistent with a lower electrochemical activity of the (110)- and (111)-oriented surfaces toward hydrogen adsorption due to an effective reduction of Lewis base sites.

Bimetallic nanoparticles (BMNPs) are frontrunners in various fields including heterogeneous catalysis, medicinal applications, and medical imaging. Tailoring their properties requires adequate control over their structure and composition, which still presents a non-trivial endeavor. We present a flexible strategy to deposit phase-controlled BMNPs by vapor-phase “titration” of a secondary metal to a pre-deposited monometallic nanoparticle (NP) host. The strategy is exemplified for archetypal Pt–Sn BMNPs but transferrable to other BMNPs which alloy noble and non-noble metals. When exposing Pt NPs on a SiO2 support to discrete TDMASn (tetrakis(dimethylamino)tin) vapor pulses from 150 to 300 °C, TDMASn selectively decomposes on Pt NPs. This leads to saturated infiltration of Sn into Pt NPs through reactive solid-state diffusion, resulting in the formation of Pt–Sn BMNPs with phase/composition control via the substrate temperature. An additional H2 pulse after each TDMASn pulse removes the surface ligands and excess Sn on the surface as SnH4, preserving the small sizes of the pre-deposited Pt NPs. This approach provides a single-step, selective “vapor-phase conversion” of Pt NPs into PtxSny BMNPs with great potential for catalysis. Hereto, a proof of concept is provided by converting wet impregnated Pt NPs into Pt–Sn BMNPs on high surface area supports.

Semiconductor superstructures made from assembled and epitaxially connected colloidal nanocrystals (NCs) hold promise for crystalline solids with atomic and nanoscale periodicity, whereby the band structure can be tuned by the geometry. The formation of especially the honeycomb superstructure on a liquid substrate is far from understood and suffers from weak replicability. Here, we introduce 1,4-butanediol as an unreactive substrate component, which is mixed with reactive ethylene glycol to tune for optimal reactivity. It shows us that the honeycomb superlattice has a NC precursor state before oriented attachment occurs, in the form of a self-assembled hexagonal bilayer. We propose that the difference between the formation of the square or honeycomb superstructure occurs during the self-assembly phase. To form a honeycomb superstructure, it is crucial to stabilize the hexagonal bilayer in the presence of solvent-mediated repulsion. In contrast, a square superstructure benefits from the contraction of a hexagonal monolayer due to the absence of a solvent. A second experiment shows the very last stage of the process, where the increasing alignment of NCs is quantified using selected-area electron diffraction (SAED). The combination of transmission electron microscopy (TEM), SAED, and tomography used in these experiments shows that the (100)/(100) facet-to-facet attraction is the main driving force for NC alignment and attachment. These findings are validated by coarse-grained molecular dynamic simulations, where we show that an optimal NC repulsion is crucial to create the honeycomb superstructure.

This paper summarizes the submissions to a recently announced contact-mechanics modeling challenge. The task was to solve a typical, albeit mathematically fully defined problem on the adhesion between nominally flat surfaces. The surface topography of the rough, rigid substrate, the elastic properties of the indenter, as well as the short-range adhesion between indenter and substrate, were specified so that diverse quantities of interest, e.g., the distribution of interfacial stresses at a given load or the mean gap as a function of load, could be computed and compared to a reference solution. Many different solution strategies were pursued, ranging from traditional asperity-based models via Persson theory and brute-force computational approaches, to real-laboratory experiments and all-atom molecular dynamics simulations of a model, in which the original assignment was scaled down to the atomistic scale. While each submission contained satisfying answers for at least a subset of the posed questions, efficiency, versatility, and accuracy differed between methods, the more precise methods being, in general, computationally more complex. The aim of this paper is to provide both theorists and experimentalists with benchmarks to decide which method is the most appropriate for a particular application and to gauge the errors associated with each one.

Using large gas cluster ion beams (Ar1000-5000 + ), it is possible to desorb and transfer non-volatile and active biomolecules (e.g. lysozymes, 14 kDa) for nanofabrication or mass spectrometry. Depending on the cluster and target characteristics, the collision may induce fragmentation and/or denaturation of the proteins. To clarify the Ar cluster-induced desorption mechanisms of proteins, molecular dynamics (MD) simulations were performed using reactive force fields (ReaxFF). First, lysozymes were adsorbed and relaxed on a gold surface with a (543) orientation and then bombarded by Ar clusters at 45◦ angle. The simulations consider different cluster sizes (from 1000 to 5000 atoms) and kinetic energies (from 1 to 10 eV/atom), investigating how these parameters affect desorption, and the concomitant chemical reactions and/or protein unfolding events. Three different surfaces were modelled: one single lysozyme adsorbed on gold, a lysozyme monolayer and a bilayer. The simulations show a correlation between the lysozyme fragmentation and the cluster energy per atom (E/n) but also an additional effect of the cluster size for a given E/n. The structure of the organic target influences the emission, which becomes softer when the amount of organic material increases. In the lysozyme bilayer, non-covalent aggregates were desorbed with relatively limited protein denaturation.

The crystalline texture of arrays of low diameter Co nanowires (NWs) synthesized by electrodeposition using electrolytes with different acidities (pH in the range 2.0–6.6) was studied by the switching field distribution (SFD) and first order reversal curve (FORC) diagrams. Particularly, the SFD determined as the derivative d M / d H of the descending part of the major hysteresis loop has proven to be a reliable and powerful method for the identification of different crystalline textures in the NWs and the quantification of their corresponding texture percentages. The presence of the face centered cubic-like texture at low pH values and hexagonal close packed textures with the c-axis perpendicular and parallel to the NWs axis at higher pH values have been identified by performing multiple Gaussian fits to the SFD by virtue of their different magnetic behavior observed during reversal of the magnetization. The field position and size of each curve in the multiple Gaussian fit provide information about the corresponding magnetic contribution and volumetric texture percentage of each crystalline texture in the NWs, respectively. The analysis of the SFD has been complemented and validated with FORC diagram measurements, showing that the width of the coercive field distribution is in good agreement with the width of the SFD. Also, it has been found that the different branches observed in the FORC diagrams along the interaction axis provide further insight on the interaction between magnetocrystalline fields. This work provides a novel methodology for the use of magnetometry as a reliable technique for the study of the interplay between the microstructure and magnetic behavior of arrays of NWs.

We investigate the behavior of small water droplets impacting fabrics of different roughness and coating type in a range of impacting conditions, and compare it to measurements of static and roll-off angles. Fabrics with low roughness display lower static contact angle, no roll-off, a slightly slower retraction rate for impacting droplets, a narrower Weber number (We) range in which rebound occurs, and a limited maximum rebound at intermediate We. Rougher fabrics exhibit slightly higher static contact angles, lower roll-off angles, a slightly faster retraction rate for impacting droplets, and a larger We range for rebound; additionally, the restitution of kinetic energy upon rebound is proportional to 1/We, indicating a near-to-constant rebound height independent of the impact velocity. As regards coating type, roll-off angle, We range for rebound, and to a lesser extent restitution coefficient, depend on coating type, with the more environmentally-friendly wax-based coating being superior to silicone and perfluorobutyl-based ones in both drop impact and roll-off experiments. Our results thus provide hope that perfluorinated coatings can be eliminated in standard textiles, and provide an extensive view of how roughness, coating and impact conditions control the fate of small droplets falling on textiles.

Methylated carbohydrates are important from both biological and technical perspectives. Specifically, methylcellulose is an interesting cellulose derivative that has applications in foods, materials, cosmetics, and many other fields. While the molecular dynamics simulation technique has the potential for both advancing the fundamental understanding of this polymer and aiding in the development of specific applications, a general drawback is the lack of experimentally validated interaction potentials for the methylated moieties. In the present study, simulations using the GROMOS 56 carbohydrate force field are compared to NMR spin–spin coupling constants related to the conformation of the exocyclic torsion angle ω in d-glucopyranose and derivatives containing a 6-O-methyl substituent and a 13C-isotopologue thereof. A 3JCC Karplus-type relationship is proposed for the C5–C6–O6–CMe torsion angle. Moreover, solvation free energies are compared to experimental data for small model compounds. Alkylation in the form of 6-O-methylation affects exocyclic torsion only marginally. Computed solvation free energies between nonmethylated and methylated molecules were internally consistent, which validates the application of these interaction potentials for more specialized purposes.

The unique properties of yolk-shell or rattle-type particles make them promising candidates for applications ranging from switchable photonic crystals, to catalysts, to sensors. To realize many of these applications it is important to gain control over the dynamics of the core particle independently of the shell. Hypothesis: The core particle may be manipulated by an AC electric field with rich frequency-dependent behavior. Experiments: Here, we explore the frequency-dependent dynamic electrophoretic mobility of a charged core particle within a charged, porous shell in AC electric fields both experimentally using liquid-phase electron microscopy and numerically via the finite-element method. These calculations solve the Poisson-Nernst-Planck-Stokes equations, where the core particle moves according to the hydrodynamic and electric forces acting on it. Findings: In experiments the core exhibited three frequency-dependent regimes of field-driven motion: (i) parallel to the field, (ii) diffusive in a plane orthogonal to the field, and (iii) unbiased random motion. The transitions between the three observed regimes can be explained by the level of matching between the time required to establish ionic gradients in the shell and the period of the AC field. We further investigated the effect of shell porosity, ionic strength, and inner-shell radius. The former strongly impacted the core's behavior by attenuating the field inside the shell. Our results provide physical understanding on how the behavior of yolk-shell particles may be tuned, thereby enhancing their potential for use as building blocks for switchable photonic crystals.

Supported nanoparticulate Au/Ti-SiO2 catalysts are a promising candidate for selective epoxidation of propene with H2/O2 mixtures. Here, we demonstrate that by altering the acidity of the surface titanol groups in Au/Ti-SiO2, the selectivity of these catalysts in propene oxidation can be controlled. That is, Au/Ti-SiO2 prepared using an alkali base during gold deposition shows basic properties due to the formation of Ti-ONa groups. The catalysts that contained Na+ and neutralized acid sites demonstrate high selectivity toward propene oxide. On the contrary, when the acidity of the Ti-OH groups is preserved by using NH4OH as a base during gold deposition, the catalyst is highly selective toward propanal at a similar propene conversion. This difference in selectivity is explained by the isomerization of initially formed propene oxide into propanal over acidic Ti-OH groups as we demonstrated using stacked bed experiments, where the Ti-support was exposed to propene oxide. When Na+ was present, no isomerization was observed, while without Na+ present, propene oxide was isomerized to propanal. In short, we demonstrate the crucial role of Na+ and acidic Ti-sites in steering the selectivity in gold-catalyzed propene epoxidation.

We studied the stability and folding and unfolding kinetics of the tryptophan zipper, containing different double thioamide subsitutions. Conformation change was triggered by photoisomerization of an integrated AMPP photoswitch in the turn region of the hairpin, and transient spectra were recorded in the deep UV and the mid-IR, covering the time window of the (un)folding transition from picoseconds to tens of microseconds. Thio-substitution of inward-pointing backbone carbonyls was found to strongly destabilize the β-hairpin structures, whereas molecules with two outward pointing thio-carbonyls showed similar or enhanced stability with respect to the unsubstituted sequence, which we attribute to stronger interstrand hydrogen bonding. Thiolation of the two Trp residues closest to the turn can even prevent the opening of the hairpin after cis-trans isomerization of the switch. The circular dichroism due to the two thioamide ππ* transitions is spectrally well-separated from the aromatic tryptophan signal. It changes upon photoswitching, reflecting a local change in coupling and geometry.

Here we report on carbon monoxide-photoreleasable compounds (photoCORMs) that combine heptamethine cyanine and flavonol chromophores and are activated upon irradiation with near-infrared light. Excellent CO-release yields and uncaging cross sections in aqueous solutions, enhanced water solubilities thanks to polar substituents or a host-guest approach using cucurbit[7]uril are demonstrated. The hybrids display outstanding biocompatibility and diverse, structure-dependent cell penetrability and internalization.

Hypothesis: Colloidal molecules with anisotropic shapes and interactions are powerful model systems for deciphering the behavior of real molecules and building units for creating materials with designed properties. While many strategies for their assembly have been developed, they typically yield a broad distribution or are limited to a specific type. We hypothesize that the shape and relative sizes of colloidal particles can be exploited to efficiently direct their assembly into colloidal molecules of desired valence. Experiments: We exploit electrostatic self-assembly of negatively charged spheres made from either polystyrene or silica onto positively charged hematite cubes. We thoroughly analyze the role of the shape and size ratio of particles on the cluster size and yield of colloidal molecules. Findings: Using a combination of experiments and simulations, we demonstrate that cubic particle shape is crucial to generate high yields of distinct colloidal molecules over a wide variety of size ratios. We find that electrostatic repulsion between the satellite spheres is important to leverage the templating effect of the cubes, leading the spheres to preferentially assemble on the facets rather than the edges and corners of the cube. The sixfold symmetry of cubes favors the assembly of molecules with six, four, and two satellite spheres at appropriate size ratios and interaction strength. Furthermore, we reveal that our protocol is not affected by the specific choice of the material of the colloidal particles. Finally, we show that the permanent magnetic dipole moment of the hematite cubes can be utilized to separate colloidal molecules from non-assembled satellite particles. Our simple and effective strategy might be extended to other templating particle shapes, thereby greatly expanding the library of colloidal molecules that can be achieved with high yield and purity.

This systematic review and meta-analysis aimed to evaluate the effect of Er:YAG laser etching on shear bond strength (SBS) of brackets bonded to the enamel and compare to the phosphoric acid (contr...

The enhancing effect of extraframework Al (EFAl) species on the acidity of bridging hydroxyl groups in a steam-calcined faujasite zeolite (ultrastabilized Y, USY) was investigated by in situ monitoring the H/D exchange reaction between benzene and deuterated zeolites by 1H MAS NMR spectroscopy. This exchange reaction involves Brønsted acid sites (BAS) located in sodalite cages and supercages. In a reference faujasite zeolite free from EFAl, both populations of BAS are equally and relatively slowly reactive toward C6H6. In USY, in stark contrast, the H/D exchange of sodalite hydroxyl groups is significantly faster than that of hydroxyl groups located in the faujasite supercages, even though benzene has only access to the supercages. This evidences selective enhancement of BAS near Lewis acidic EFAl species, which according to the NMR findings are located in the faujasite sodalite cages.

The objective of this review was to collect information on available additive manufacturing technologies used for the fabrication of either single crowns or fixed-dental prosthesis (FDP) with a foc...

The United Nations’ Sustainable Development Goals have sparked growing interest in biosurfactants from many surfactant-loaded industries including those utilizing froth flotation for mineral separation. However, the interaction of biosurfactants with mineral surfaces is currently poorly understood. We bridge this gap by studying adsorption of a yeast-derived bola acidic sophorolipid (ASL) biosurfactant on djurleite (Cu1.94S). The methods used include Hallimond flotation, contact angle, adsorption isotherm, zeta potential, leaching measurements, and X-ray photoelectron spectroscopy (XPS). To facilitate the interpretation of the adsorption results, we characterize the activity of ASL at the air-water interface and measure its critical micelle concentration (CMC) at different pH using static surface tension. We find ASL to be a multifunctional surfactant with an unusual, pH-sensitive interfacial behavior. At the air-water interface, ASL is most active at pH 8, while its CMC goes through minimum as low as 40 μM at pH 7. The surfactant adsorption at the djurleite-water interface makes the sulfide surface hydrophilic at acidic pH and hydrophobic at neutral and basic pH. In addition, ASL has strong affinity to copper sulfide and demonstrates metal leaching properties. Finally, ASL demonstrates detergency properties. We offer a mechanistic interpretation of these findings. Our results provide a basis for the application of acidic glycolipids in froth flotation and have implications for their application in ion separation using hydrometallurgical routes, as well as for the chemical stability of metal sulfides in environmental systems. © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The cervical area of teeth is the most unpredictable region for durable adhesive bonding. This study evaluated the adhesion potential of resin cement to coronal and cervical/root structures with a ...

We report a method of glycosylated enzymes' surface immobilisation and stabilisation. The enzyme is immobilised at the surface of silica nanoparticles through the reversible covalent binding of vicinal diols of the enzyme glycans with a surface-attached boronate derivative. A soft organosilica layer of controlled thickness is grown at the silica surface, entrapping the enzyme and thus avoiding enzyme leaching. We demonstrate that this approach results not only in high and durable activity retention but also enzyme stabilisation.

We designed and synthesized two resorcin[4]arene scaffolds with four phosphate binding groups. The ligands effectively bind in at least a tridentate fashion at low surface coverage. The superior binding affinity is demonstrated using solution NMR spectroscopy and exceeds that of single phosphonates., Chemical Communications, 57 (38), ISSN:1359-7345, ISSN:1364-548X

Made available in DSpace on 2022-05-01T08:45:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Evaluate the influence of cleaning protocols on vitrification patterns, contact angles, and bond strength between zirconia and resin cement. 48 zirconia discs were sectioned, polished, and sintered (15 × 2 mm). The discs were randomized into four groups according to the zirconia cleaning protocol (n = 12), following: CJ (positive control)-sandblasted with 30-µm particles of alumina coated by silica (Cojet/3M); AV (negative control)-cleaning with alcohol + vitrification (glaze); PV-37% phosphoric acid + vitrification; and HFV-10% hydrofluoric acid + vitrification. Next, the surfaces were conditioned with hydrofluoric acid and then silanized. The samples from the CJ treatment group were silanized to proceed with the cementation stage. Resin cement cylinders were built on 10 specimens from each group (ϕ = 3mm, height = 5mm), following the manufacturer’s instructions, and next they were subjected to thermocycling (5000 cycles at 5 °C and 55 °C for 30 s) followed by the shear test (1 mm/min) and failure analysis. Two discs of each group were subjected to contact angle evaluation and surface analysis under SEM. One-way ANOVA (α = 0.05) and Tukey’s test (p < 0.05) were used to analyze the data (MPa). Weibull analysis was performed to evaluate the shear bond strength test data. Our results revealed that the shear bond strength varied among our experimental groups (p < 0.0001). AV=9.5 (0.5)B presented lower bond strength than CJ=10.8 (0.2)A, PV=10.9 (0.2)A, and HFV=10.9 (0.3)A experimental groups. The predominant mode of failure was the adhesive between the resin cement and glaze. Surface treatments have influenced the contact angles (p < 0.0001), following: CJ=41.6 (0.9)C; AV=52.1 (0.7)A; PV=46.8 (0.5)B; and HFV=46.0 (0.9)B. Zirconia cleaning protocols using 37% phosphoric acid or 10% HF followed by glaze application demonstrated to modify the ceramic surface and to increase the bond strength to resin cement after its etching with HF followed by silanization. Department of Dentistry Federal University of Juiz de Fora Faculty of Dentistry Federal University of Pelotas Department of Dental Materials and Prosthesis Institute of Science and Technology Univ Estadual Paulista–UNESP Institute of Science and Technology Universidade Estadual Paulista–UNESP Division of Dental Biomaterials Unit Clinic for Reconstructive Dentistry Center for Dental and Oral Medicine University of Zurich Department of Dentistry Division of Prosthodontics Federal University of Rio Grande do Norte (UFRN) Department of Dentistry Federal University of Rio Grande do Norte (UFRN) Department of Dental Materials and Prosthesis Institute of Science and Technology Univ Estadual Paulista–UNESP Institute of Science and Technology Universidade Estadual Paulista–UNESP

Picosecond optical and X-ray absorption spectroscopies with time- dependent density functional theory revealed the reaction pathways, electronic and structural conformations of Ir–Co hydrogen evolution photocatalysts. The dyad bearing 2-phenylpyridine ancillary ligands produced more photoreduced Co(II) than its 2-phenylisoquinoline analogue. These findings are important for designs of earth- abundant photosensitizers for photocatalytic applications.

This study evaluated the tensile strength of three aesthetic abutment materials at two different angulations (0 and 15°) to Ti-base and monolithic zirconia crowns. Prefabricated polyvinylidene difl...

Oxidized single walled carbon nanohorns (ox-SWCNH) were electrodeposited onto gold microelectrode arrays in conjunction with poly(3,4-ethylenedioxythiophene) (PEDOT) and polystirenesulfonate (PSS), and the properties of the new composite material for neural recording and stimulation were assessed. PEDOT/ox-SWCNH composites were compared with films prepared with one of the most notorious carbonaceous material in this field, the oxidized multi-walled Carbon Nanotubes (ox-MWCNT). The PEDOT/ox-SWCNH exhibited superior charge transfer capability, reflecting greater electroactive surface, as confirmed by SEM and EIS characterizations. As a consequence, a charge injection limit of 11.6mC/cm⁠2 was observed for the new composite, which is higher than the one of PEDOT/ox-MWCNT (8.7mC/cm⁠2). Having confirmed comparable neural recording performance, the PEDOT/ ox-SWCNH composite results very promising for improving therapeutic electrical stimulation in the central and peripheral nervous systems.

Understanding the relationship between colloidal building block shape and self-assembled material structure is important for the development of novel materials by self-assembly. In this regard, colloidal superballs are unique building blocks because their shape can smoothly transition between spherical and cubic. Assembly of colloidal superballs under spherical confinement results in macroscopic clusters with ordered internal structure. By utilizing Small Angle X-Ray Scattering (SAXS), we probe the internal structure of colloidal superball dispersion droplets during confinement. We observe and identify four distinct drying regimes that arise during compression via evaporating droplets, and we track the development of the assembled macrostructure. As the superballs assemble, we found that they arrange into the predicted paracrystalline, rhombohedral C1-lattice that varies by the constituent superballs' shape. This provides insights in the behavior between confinement and particle shape that can be applied in the development of new functional materials., 14 pages, 5 figures, supporting info, accepted for publication in JCISOpen

A method to obtain full mass over charge (m/z), time-resolved quadruple mass spectrometry (QMS) spectra of an atomic layer deposition (ALD) cycle is proposed. This method allows one to circumvent the limitations of traditional approaches for obtaining QMS information in ALD as all m/z values can be simultaneously screened for the formation of reaction products in an efficient way. As a proof of concept, this method was applied to the trimethylaluminum (TMA)-water process. This process has been studied extensively over the past decades. Besides the expected formation of CH4, formation of gaseous HOAl(CH3)2 during the water pulse is observed, revealing a secondary reaction pathway for the water. The reaction energy and Gibbs free energy for different reactions are investigated computationally using density functional theory calculations and confirm that the secondary reaction pathway is thermodynamically allowed for certain surface conditions.

Hypothesis The shape of colloidal particles affects the structure of colloidal dispersions. The effect of the cube shape on the thermodynamics of colloidal cube dispersions has not yet been studied experimentally. Static light scattering measurements on colloidal cubic silica shells at finite concentrations allows us to measure the structure factor of colloidal cube fluids and to test theoretical predictions for the equation of state of hard convex superballs. Experiments Hollow silica nanocubes of varying concentrations in N,N,-dimethylformamide were studied with static light scattering. The structure factor was extracted from the scattering curves using experimental form factors. From this experimental structure factor, the specific density of the particles, and the osmotic compressibility were obtained. This osmotic compressibility was then compared to a theoretical equation of state of hard superballs. Findings The first experimental structure factors of a stable cube fluid are presented. The osmotic compressibility of the cube fluid can be described by the equation of state of a hard superball fluid, showing that silica cubes in N,N,-dimethylformamide with LiCl effectively interact as hard particles.