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Although architected materials based on truss networks have been shown to possess advantageous or extreme mechanical properties, those can be highly affected by tolerances and uncertainties in the manufacturing process, which are usually neglected during the design phase. Deterministic computational tools typically design structures with the assumption of perfect, defect-free architectures, while experiments have confirmed the inevitable presence of imperfections and their possibly detrimental impact on the effective properties. Information about the nature and expected magnitude of geometric defects that emerge from the additive manufacturing processes would allow for new designs that aim to mitigate (or at least account for) the effects of defects and to reduce the uncertainty in the effective properties. To this end, we here investigate the effects of four most commonly found types of geometric imperfections in trusses, applied to eleven representative truss topologies in two and three dimensions. Through our study, we (i) quantify the impact of imperfections on the effective stiffness through computational homogenization, (ii) examine the sensitivity of the various truss topologies with respect to those imperfections, (iii) demonstrate the applicability of the model through experiments on 3D-printed trusses, and (iv) present a machine learning framework to predict the presence of defects in a given truss architecture based merely on its mechanical response.

We used coarse-grain molecular dynamics simulations to screen all possible histidine-bearing tetrapeptide sequences, finding novel peptide sequences with pH-tunable assembly properties. These tetrapeptides could be used for various biological applications, such as triggered delivery of bioactive molecules., Division of Civil, Mechanical and Manufacturing Innovation; Office of Naval Research

Damage that affects large volumes of skeletal muscle tissue can severely impact health, mobility, and quality-of-life. Efforts to restore muscle function by implanting tissue engineered muscle grafts at the site of damage have demonstrated limited restoration of force production. Various forms of mechanical and biochemical stimulation have been shown to have a potentially beneficial impact on graft maturation, vascularization, and innervation. However, these approaches yield unpredictable and incomplete recovery of functional mobility. Here we show that targeted actuation of implanted grafts, via non-invasive transcutaneous light stimulation of optogenetic engineered muscle, restores motor function to levels similar to healthy mice 2 weeks post-injury. Furthermore, we conduct phosphoproteomic analysis of actuated engineered muscle in vivo and in vitro to show that repeated muscle contraction alters signaling pathways that play key roles in skeletal muscle contractility, adaptation to injury, neurite growth, neuromuscular synapse formation, angiogenesis, and cytoskeletal remodeling. Our study uncovers changes in phosphorylation of several proteins previously unreported in the context of muscle contraction, revealing promising mechanisms for leveraging actuated muscle grafts to restore mobility after volumetric muscle loss.

This paper discusses the little-known fact that Donnan’s equilibrium criteria established over 100 years ago neglected the coupling between ion concentrations and the osmotic pressure. Such coupling can be treated based on general thermodynamic considerations including the solvent equilibrium, leading to a membrane potential that consists of not only the classical Donnan potential term but also an additional term due to the osmotic pressure, and the existence of a membrane potential even when the impermeable species are not charged. This coupled treatment conflicts with the well-established Poisson–Boltzmann equation and Nernst–Planck equation, but is consistent with the extension of these equations including the solvent effects by Freise and Schlogl, enables us to view the electrical double layer equilibrium as Donnan equilibrium.

Novel arrays of Nb2O5-based ceramic nanostructures of various sizes (9–210 nm) and morphologies (dots, goblets, rods) aligned on substrates are fabricated via the anodizing of a thin Nb film through the initially formed porous anodic alumina (PAA) film in 1.5 M selenic acid (H2SeO4) – a new aqueous electrolyte generating extraordinarily thinner PAA pores than any other solutions. Accordingly, the nanostructures formed in the selenic acid are 1.3-fold thinner and better self-ordered than their counterparts formed from the same Al/Nb precursor bilayer in a reference oxalic-acid electrolyte. The nanostructures have a dual (core/shell) composition: the inner material (the core) is stoichiometric Nb2O5, whereas the outer layer (the shell) is a few nm-thick substoichiometric NbOx mixed with Al2O3. The composite-ceramic nanoarrays grow doped with selenium species such as selenate (SeO42−) and selenide (Se2−) anions originating from the electrolyte and migrating inward under the high electric field. The incorporated Se species do not contribute to photoluminescence emission nor hinder the Raman signal from the nanoarrays, which makes them highly promising as Nb2O5-based SERS biosensing substrates. The planar PAA-inbuilt Se-doped Nb2O5–Al2O3 nanostructured ceramic film performs like a high-k low-loss low-leakage-current dielectric promising for on-chip integration. More potential applications of the Se-doped ceramic nanoarrays developed here include biomedical antibacterial coatings, advanced superhydrophobic surfaces, gas-sensing, and catalytic layers.

A new isopolyoxotungstate has been characterised, thirty years since the first spectroscopic evidence of its existence. The heptatungstate [W7O24H]5-, containing a {W5} lacunary Lindqvist unit fused to a ditungstate fragment, has significant stability and is only the third isopolytungstate structure to be obtained from non-aqueous systems.

Understanding biological interactions at a molecular level grants valuable information relevant to improving medical treatments and outcomes. Among the suite of technologies available, Atomic Force Microscopy (AFM) is unique in its ability to quantitatively probe forces and receptor–ligand interactions in real-time. The ability to assess the formation of supramolecular bonds and intermediates in real-time on surfaces and living cells generates important information relevant to understanding biological phenomena. Combining AFM with fluorescence-based techniques allows for an unprecedented level of insight not only concerning the formation and rupture of bonds, but understanding medically relevant interactions at a molecular level. As the ability of AFM to probe cells and more complex models improves, being able to assess binding kinetics, chemical topographies, and garner spectroscopic information will likely become key to developing further improvements in fields such as cancer, nanomaterials, and virology. The rapid response to the COVID-19 crisis, producing information regarding not just receptor affinities, but also strain-dependent efficacy of neutralizing nanobodies, demonstrates just how viable and integral to the pre-clinical development of information AFM techniques are in this era of medicine.

Biolayer interferometry (BLI) and circular dichroism (CD) spectroscopy were used to investigate the interaction between previously reported i-motif DNA (i-DNA) ligands and folded or unfolded i-DNA in acidic (pH 5.5) and near-neutral (pH 6.5) conditions. We observed that although several ligands, in particular macrocyclic bis-acridine (BisA) and pyridostatin (PDS), showed good affinities for the telomeric i-motif forming sequence, none of the ligands displayed selective interactions with the i-DNA structure nor was able to promote its formation.

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.

Reported here is the first FeII based supramolecular cage with pyridyl-hydrazone ligand scaffolds that exhibits temperature induced spin crossover behaviour. Density functional theory calculations were employed to investigate the cause of the occurrence of this phenomenon based on the ligand structure. These results indicate that the reported low-spin cages with pyridyl-imine sites could be reconsidered for spin crossover by carefully manipulating the functional groups in the ligand system.

We present a thought-provoking development in chiral resolution. Using a resolving agent of a given handedness, L-proline, we show that both R- and S-enantiomers of mandelic acid can be resolved from a racemic mixture simply by varying the stoichiometry. We are the first to report this specific feature, achieved by the existence of stoichiometrically diverse cocrystal systems between R- and S-mandelic acid and L-proline.

Uniform flexible carbon nitride coatings have been synthesized by means of annealing of films, fabricated from soluble triazine-based polymeric precursors. The coatings exhibit fascinating electrochemical stability and drastically increase the capacitance of coated carbon cloth electrodes. Following the analogue with turbostratic carbons, typically produced by means of polymeric precursors pyrolysis, we demonstrate that annealing of dried nitrogen-rich polymeric films results in coatings, composed by nearly equal atomic quantities of carbon and nitrogen, according to elemental analysis, and exhibiting noticeable mechanical robustness. X-ray difffraction patterns and infrared spectra of the materials allow to characterize them as partially amorphous carbon nitride with presumably heptazinic structure. Annealed films exhibit extrinsic semiconducting behavior with optical bandgaps in the range from 1.71 to 1.99 eV and fairly good conductivity. The outstanding long-term electrochemical stability of annealed films makes them competitive with pyrolytic carbon, while much lower annealing temperatures allow preparation of nanocomposites with various particles. The precursor polymers were obtained by self-condensation of 2-amino-4,6-dichloro-1,3,5-triazine and condensation of cyanuric chloride with 5-aminotetrazole and 3-amino-1,2,4-triazole-5-carboxylic acid, respectively, in N,N-dimethylacetamide. The polymers contain mainly C–N skeletal bonds and can therefore be viewed as “extension” of typical carbon nitride precursors, like melamine or dicyandiamide, to polymeric structure.

This study aimed to assess the characteristics, including morphology, physicochemical properties, and antibacterial properties, of silver nanocolloids obtained by D-glucose reduction. Silver nanoparticles were synthesized in accordance with the principles of green chemistry using D-glucose as a reductor. The obtained nanostructures were characterized by UV–vis spectroscopy, transmission electron microscopy, and dynamic light scattering. Stability tests performed after 1 month of storage revealed that the colloids prepared with and without polyvinylpyrrolidone as a stabilizer had the same properties. Distribution of the nanoparticles was tested using inductively coupled plasma mass spectrometry by doping the silver colloids into a natural soap mass. The antibacterial activity of the soap containing silver nanoparticles was tested on dirty hands. The antibacterial activity test demonstrated that the novel green soap materials improved with D-glucose-reduced silver nanoparticles possessed better antibacterial properties than a pure soap, and thus, they could be recommended for quotidian use by dermatological patients.

Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

The tools of sol–gel chemistry allow synthesizing a plethora of functional materials in a controlled bottom-up fashion. In the field of heterogeneous catalysis, scientists utilize sol–gel routes to design solids with tailored composition, texture, surface chemistry, morphology, dispersion, etc. A field of investigation which shows great promises is that of hybrid heterogeneous catalysts. Examples are flourishing to show that catalysts featuring a combination of inorganic and organic components often display improved activity, selectivity, or even chemical stability as compared to the purely inorganic counterparts. Yet, classic sol–gel methods face some well-known limitations—related to the different reactivity of the precursors and to the high surface tension of water—which complicate the tasks of chemists, specifically for the synthesis of hybrid catalysts. Non-hydrolytic sol–gel (NHSG) chemistry appears as a pertinent alternative. Being realized in the absence of water, NHSG routes allow reaching an excellent control over the solid properties and on the distribution of the organic and inorganic components at the nano- and microscales. In this review, we briefly recapitulate the main types of non-hydrolytic sol–gel routes and we present the modified protocols to hybrid materials. Then, we present an overview of the non-hydrolytic sol–gel approaches that have been proposed to synthesize hybrid heterogeneous catalysts. For both Class I and Class II hybrids, we discuss how the NHSG technique has allowed tailoring the key properties that command catalytic performance. From this panorama, we argue that NHSG has a prominent role to play for the development of advanced hybrid heterogeneous catalysts.

A complex Al/Cu magnetic pulse welding interface is systematically investigated using experimental characterizations and numerical simulations. A Coupled electromagnetic-mechanical simulation is proposed to compute the impact velocity and impact angle along the entire interface. This model allows to further understand the formation mechanism of various interface characteristics during MPW. The results revealed that the impact velocity gradually decreases in conjunction with the gradual increase of the impact angle. These simulations elucidate the experimentally observed successive interface morphologies, i.e., the unwelded zone, vortex zone, intermediate (IM) layers and wavy interface. Microstructural characterizations show that the IM layers are formed by mechanical mixing combined with melting and are characterized by highly heterogeneous porous zone with random sizes and distributions of void. Subsequently, an Eulerian simulation is proposed to investigate the thermomechanical effects during the wave formation which vastly influence the joint quality. The predicted wavy morphologies, temperature distribution and average equivalent plastic strain along the interface provided a better understanding on the formation steps of the experimentally observed wave morphologies. The actual kinematics during wave generation revealed that the wave was formed with repeated deformation of the interface material. The wave amplitude increases with increasing jetting angle; while the wavelength increases with increasing collision point velocity. The ratio between collision point velocity and impact velocity is found to be the most suitable parameter for explaining the influence of the collision parameters on the wavelength. These results indicate that the combination of the Coupled electromagnetic-mechanical simulation and Eulerian simulation can help us investigate the governing mechanisms of complex interface morphologies and further used to optimize the processing parameters du

Twining is an important deformation mode in magnesium. In a deformed magnesium sample, an extension twin crystal, i.e., {101̅2} twin, can form inside a {101̅2} primary twin, which is named {101̅2}– {101̅2} secondary twin. These secondary twins often appear at the intersection of two primary twins, and form primary–secondary twin pairs. Experimental observations show that the most frequently observed primary–secondary twin pairs have a unique misorientation, i.e., twin variant selection exists. Such variant selection of the primary-secondary twin pairs is studied in this work. The crystallographic analysis reveals that the twin planes of the primary and secondary twins that form a twin pair have coincident intersection lines with the boundary where the twin pair adjoins. An analytical calculation method based on Eshelby’s inclusion theory is developed, and the calculation results show that only for this unique misorientation, the stress fields concentrated at the rims of the primary and the secondary twins are mutually favoured. The analysis is further extended to the incoming–outgoing twin pairs across ordinary grain boundaries, and compared with the commonly used geometrical compatibility factor m'. It is found that m' only gives good prediction for twin transmission when the shear stress component on the twin plane along the twin shear direction of the incoming twin is the major contributor to the resolved shear stress of the outgoing twin. When other stress components play a dominant role, m' becomes ineffective in prediction, which is the case for the primary-secondary twin pairs

The solar spectral converters mainly involve the energy transfer between two codoped ions. Here, we report a series of Ce3+, Cr3+, Ln3+ (Ln = Yb, Nd, Er) tridoped Gd3Sc2Ga3O12 (GSGO) phosphors with improved absorption and increasing near infrared (NIR) emission. We observed the multiple energy transfer behaviors of Cr3+→Ln3+, Ce3+→Ln3+, Ce3+→Cr3+, and Ce3+→Cr3+→Ln3+ in GSGO matrix. When Ce3+ is introduced into the GSGO:Cr3+,Ln3+ phosphors, the energy transfer of Ce3+→Cr3+→Ln3+ has been realized by utilizing the energy transfer bridge of the Cr3+ ion. Consequently, GSGO:Ce3+,Cr3+,Ln3+ can absorb almost all ultraviolet and visible (UV–Vis) light and produce strong NIR light thanks to the synergistic effect of Ce3+→Cr3+→Ln3+, improving the photovoltaic conversion efficiency of c-Si solar cells. Our results show that the prepared GSGO:Ce3+,Cr3+,Ln3+ have the potential application in the solar spectral material for c-Si solar cells. Meanwhile, the strategy of multiple energy transfers gives a new way to design the spectral conversion materials with wider absorption for c-Si solar cells.

Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

A comparative study to investigate the influences of single component fluxes on the depth-to-width ratio (DWR) of oxygen free copper was carried out with novel variants of tungsten inert gas (TIG) welding namely Activated TIG (A-TIG), Flux Bounded TIG (FB-TIG) and Flux Zoned TIG (FB-TIG) processes. The experiments to identify the fluxes delivering the higher DWRs in A-TIG welding among thirteen distinct fluxes were followed by the trials with FB-TIG and FZ-TIG employing those identified DWR fluxes. The fluxes which outperformed with all the techniques were MoO3 & MgO. Reversed Marangoni and arc constriction mechanisms were perceived to be opt for such an increase in DWR. Metallurgical characterization of the weldment indicated distinct grain morphologies and certain defects as well in the weld zones. The FZ-TIG welding is postulated to surpass all the techniques in terms of bringing about the upmost weld penetration., BY-NC-ND licens

Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

Friction stir processing (FSP), an adaption of the solid-state joining process friction stir welding (FSW), is now a widely recognized severe plastic deformation (SPD) technique. It induces microstructural refinement in the metallic materials which enhances their formability and other mechanical properties. Dynamic recrystallization occurs during the stirring phase which leads to reduction in the grain size and texture modification. Breaking up of the intermetallics and precipitates with their homogeneous distribution in the matrix is also accompanied. This further improves the material's ability to attain maximum ductility during plastic deformation at higher temperatures, resulting in very large uniform elongations (>200%) termed as ‘superplasticity’. Optimization of FSP parameters activates superplastic behaviour in different magnesium alloys at low temperatures and high strain rates. It has become the focal point of the recent researches owing to its huge potential in the light-weight structural applications. In addition to the essential aspects of superplasticity, this article highlights the major explorations in the area of superplasticity of magnesium alloys using FSP method and it's recently developed variants., CC BY license

A novel material processing approach using the bobbin tool technique called bobbin tool friction stir processing (BTFSP) was developed to simultaneously fabricate two-side composites. The feasibility of simultaneous fabrication of composites on the top and bottom sides of the workpiece using B4C reinforcement particles into Al 6061 alloy was successfully studied in the present paper. Excellent dispersion of the B4C particles obtained at the bottom side of the workpiece by this technique. The metallurgical investigation of Al 6061/B4C double side composites was carried out using optical and scanning electron microscopy. The mechanical properties include sliding wear behavior, and microhardness of the fabricated composites was studied in detail. The results indicated a more uniform distribution of B4C particles with 3 passes. The grain refinement and homogeneous distribution of the B4C significantly improved microhardness and wear properties of the fabricated composites compared to as-received Al., CC BY license

Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

We describe the preparation of densely functionalised 1,1-silylborylated trisubstituted alkenes, via a boron-Wittig reaction, between LiC(Bpin)(2)(SiMe3) and aliphatic or aromatic aldehydes. The condensation of diborylsilylmethide lithium salts with alpha,beta-unsaturated aldehydes provides a direct pathway to synthesize 1,1-silylborylated conjugated dienes and diynes.

A novel endohedral metallofullerene (mono-EMF), Th@D-5h(6)-C-80, has been successfully synthesized and fully characterized by mass spectrometry, single crystal X-ray diffraction, UV-vis-NIR and Raman spectroscopy and cyclic voltammetry. Single crystal XRD analysis unambiguously assigned the fullerene cage as D-5h(6)-C-80, the first example in which the highly symmetric cage is stabilized by a single metal ion. The combined experimental and theoretical studies further reveal that the D-5h(6)-C-80 cage, known only for its stabilization by 6-electron transfer, is stabilized by the 4-electron transfer from the encapsulated Th ion for the first time.

Any attempt to facilitate a new generation of C-B bonds represents a useful tool in organic synthesis. In addition, if that approach highlights the nucleophilic character of boryl moieties in the absence of transition metal complexes, the challenge to create new reactive platforms becomes an opportunity. We have been deeply involved in the experimental and theoretical validation of C-B bond formation by means of alkoxide activation of tetra-alkoxy diboron reagents and here is presented a convenient guide to understand the concept and the applications.

We present a comparative study of two Lu-based oxide ceramics doped with Yb3+ ions, namely Yb:Lu3Al5O12 (garnet) and Yb:Lu2O3 (sesquioxide), promising for thin-disk lasers. The ceramics are fabricated using nano-powders of 3.6 at.% Yb:Lu2O3 and Al2O3 produced by laser ablation: Yb:Lu3Al5O12 - by vacuum sintering at 1800 degrees C for 5 h with the addition of 1 wt% TEOS as a sintering aid, and Yb:Lu2O3 - by vacuum pre-sintering at 1250 degrees C for 2 h followed by Hot Isostatic Pressing at 1400 degrees C for 2 h under Ar gas pressure of 207 MPa. The comparison includes the structure, Raman spectra, transmission, optical spectroscopy and laser operation. The crystal-field splitting of Yb3+ multiplets is revealed for Lu3Al5O12. A continuous-wave (CW) Yb:Lu3Al5O12 ceramic microchip laser generates 5.65 W at 1031.1 nm with a slope efficiency of 67.2%. In the quasi-CW regime, the peak power is scaled up to 8.83 W. The power scaling for the Yb:Lu2O3 ceramic laser is limited by losses originating from residual coloration and inferior thermal behavior.

We develop an optical image tracking technique for the simultaneous observation of a wide area in proximity to the electrode, and study the growth of bubbles during hydrogen gas evolution in alkaline water electrolysis. Using a diffusion model we can successfully extract the concentration profile of dissolved hydrogen gas as a function of distance from the electrode. The obtained concentrations agree well with the values by the electrochemical method.

The aim of the present study is to extend the knowledge about the formation and thermal stability of vacancy-type defects in tungsten under neutron irradiation, thereby mimicking the temperature and neutron flux expected in the ITER divertor. Neutron irradiation of single crystal tungsten, W(100), in the temperature range 600-1200 °C is performed up to 0.12 dpa. Positron annihilation spectroscopy is employed to detect the presence of open volume defects, while hardness tests are applied to relate the irradiation-induced defects with the modification of mechanical properties. Rationalization of the experimental results is enhanced by the application of a kinetic Monte Carlo simulation tool, applied to model the microstructural evolution under the neutron irradiation process. The relation between radiation microstructure and hardness is explained via a dispersed barrier model.

A new strategy is developed to design multi-drug solid forms. Using an inorganic salt as the glue sticking together two different APIs in a “drug-bridge-drug” approach, we successfully created and characterized three different ternary ionic cocrystals (TICCs). The link between binary and ternary ICCs and the importance of reaction stoichiometry was investigated using ternary solid-state phase diagrams. In addition, we highlighted the crucial role of water for the stability of these systems, as well as the impact on solubility compared to the respective parent compounds. We expect the strategy presented here to be applicable to a large series of drug combinations, opening up a promising new way of building multi-drug systems.

This paper deals with the evaluation of several homogenization methods for short fiber-reinforced composites (SFRC) in isothermal linear elasticity. In order to have an unbiased assessment, only full-field finite element (FE) versions of the methods are developed and studied, no analytical mean-field models are considered. Firstly, the FE homogenization of unidirectional (UD) SFRC is performed using two computational models: representative volume elements (RVE) and unit cells, and comparing their predictions. Secondly, for the homogenization of misaligned SFRC, a model RVE seen as an aggregate of UD pseudo-grains (PG) is homogenized in two steps. In the first step, the effective response of PGs is obtained by FE analysis on UD unit cells. The second step is performed with one of three homogenization schemes: Voigt, Reuss and a FE-based version of the Mori-Tanaka (MT) model. The latter is equivalent to a direct MT homogenization of the RVE. The actual SFRC microstructure is 3D, but because of limited computer resources, the current article is restricted to 2D analyses, which nevertheless provide some guidance. A parametric study is conducted using several fiber volume fractions and orientation tensor components. Both the effective properties of RVEs and the mean strains inside individual fibers are assessed against reference results obtained by direct FE homogenization of the actual RVEs.

Experimental and numerical approaches are used to investigate the effect of impact location and different external patch configurations on the low-velocity impact behaviors of repaired CFRP laminates. Various external patches with different thicknesses (number of layers) and stacking sequences are considered and those patches are used to repair single side of the damaged laminate plates to improve the impact-resistance. To predict the damage initiation and progression of the repaired CFRP laminates under impact loading, a continuum damage mechanics (CDM) model that combines 3D Hashin damage criteria and cohesive zone model (CZM) is proposed. The corresponding drop-weight impact tests are conducted to experimentally obtain the impact response such as impact force and energy. Numerical impact simulations have been performed to study the effect of impact location during the low-velocity impact behaviors of repaired structures. Parametric studies of patch thickness and stacking sequence are also carried out using the low-velocity impact simulation to analyze their effect on the impact-resistance. Finally, this study provides an optimization cafeteria to identify the important design parameter to perform external patch repair based on the simulation results.

Herein, aminoquinolate diarylboron complexes are utilized as photocatalysts in dual Ni/photoredox catalyzed carbon-oxygen construction reactions.Viathis unified metallaphotoredox platform, diverse (hetero)aryl halides can be conveniently coupled with acids, alcohols and water. This method features operational simplicity, broad substrate scope and good compatibility with functional groups.

© The Royal Society of Chemistry 2020. In the early 1990s chiral P-thiother ligands emerged as promising ligands in the field of asymmetric catalysis, with the development of many P-thioether ligand families. However, only a few of them have shown a broad reaction and substrate scope. So, compared with other heterodonor ligands such as the widely studied P-N ligands, their impact in asymmetric catalysis was not realised until recently. This has been mainly attributed to the difficulty of controlling the configuration at the sulfur atom when coordinated to the metal. More recently, it has been found that this problem could be solved by a rigorous choice of the ligand scaffold, a process usually aided by mechanistic studies. This allowed the recent discovery of new P-thioether ligand families with a broader versatility, both in reactions and in substrate/reagent scope. This feature article aims to highlight those new P-thioether ligand libraries and the relationship between the structure and catalytic performance.

We report the high pressure synthesis of a layered perovskite Ca₂GeO₄ which is found to have the Ruddlesden–Popper structure with I41/acd symmetry. Consonant with our recent predictions [Ablitt et al., npj Comput. Mater., 2017, 3, 44], the phase displays pronounced uniaxial negative thermal expansion over a large temperature range. Negative thermal expansion that persists over a large temperature range is very unusual in the perovskite structure, and its occurrence in this instance can be understood to arise due to both soft lattice vibrations associated with a phase competition and the unusually compliant nature of this structure, which effectively couples thermal expansion in the layer plane to lattice contractions perpendicular to the layering direction via a “corkscrew” mechanism.

We developed a novel software for large-scale electromagnetic field analyses of coils wound with coated conductors based on current-vector-potential formulation with thin-strip approximation. Although this formulation was effective for obtaining the precise solutions of the electromagnetic field, the strong nonlinear property of superconducting materials frequently led to highly ill-conditioned linear systems of equations, which were difficult to solve efficiently. Moreover, the memory consumption and computation time required for the analyses rapidly increased with the size of the analysis due to dense matrix operations. In our software, the first difficulty was addressed by a novel preconditioning technique based on the algebraic multigrid method. Algebraic multigrid preconditioning enabled us to efficiently and stably solve the ill-conditioned linear systems of equations encountered in our analyses. It also improved the robustness of the analyses containing multifilament-coated conductors. As regards the second difficulty, the hierarchical matrices representation drastically reduced the memory consumption related to the dense matrices, as well as computation time. Meanwhile, our implementation of the hierarchical matrices representation was quite compatible with parallel computations on distributed memory computers. Finally, we presented some practical examples of large-scale analyses, which became possible by using the new software. For instance, the analysis of a cosine-theta dipole magnet whose number of degrees of freedom was more than 1.5 million was successfully completed in 78 h by 56 parallel processes and with a total memory consumption of 177 GB.

A single pancake coil wound with a copper-plated multifilament coated conductor, with four filaments, was put in a cusp magnetic field, and the magnetic field was measured near the coil at 30 K. A similar experiment was performed by using another reference single pancake coil wound with a monofilament coated conductor. Numerical electromagnetic field analyses of these coils were carried out, and the calculated shielding current-induced fields (SCIFs) were compared with the measured ones in both coils. The temporal behaviour of the calculated SCIF in the coil wound with the four-filament coated conductor was also compared with a series of exponential components, in which a coupling time constant extrapolated from short sample experiments was used as the time constant of the primary component. Current distributions in the coated conductors wound into the pancake coils were visualised. In particular, the temporal behaviours of the current distributions in the four-filament coated conductor and their influence on the SCIF were discussed.

In this paper, we propose an analytical electromagnetic modelling and an electromechanical coupling of the 1-turn bulk coil with a cut, made of conducting steel or copper alloys, and used in the electro-magnetic forming technology. The electromagnetic part of the work is the one created beyond the state of the art. Such analytical models that can quickly solve for key process parameters are extremely desirable but must be completed with a mechanical model able to calculate in the end the deformation. An existing mechanical model to calculate the deformation is used and coupled to our electromagnetic model. First, the basic electromagnetic theory will be summarised and then the One-Dimensional (1-D) axi-symmetrical approximation discussed (part 2). The goal is to be able to determine the magnetic vector potential A diffusion, that will quickly lead to all the parameters needed to characterize, qualify, feed and optimize the use of the coil (ex.: magnetic flux density, equivalent inductance, force coefficients, …). Then the pseudo-harmonic solution of the 1D-problem is expanded with the help of Bessel basis functions, including some specific limit conditions and constraints (part 3). The results are compared to numerical 2-D and 3-D computations, performed, thanks to the Finite Element Method, onto some test cases without and with a tube to deform. The proposed model does not only give the numerical value of each parameter, but it provides analytical formulae, with explicit dependences upon some key geometrical and physical variables (ex.: changeable air-gap between the coil and the tube linked to the deformation). The use of a pseudo harmonic working condition will be justified by comparing it to the transient working condition for which the model is improved. Experimental measurements will be carried out with and without a tube but with no deformation (part 4). The results are close and coherent and useful when sizing the coil with respect to performance criteria an

Experimental and numerical approaches are used to investigate the effect of impact location and different external patch configurations on the low-velocity impact behaviors of repaired CFRP laminates. Various external patches with different thicknesses (number of layers) and stacking sequences are considered and those patches are used to repair single side of the damaged laminate plates to improve the impact-resistance. To predict the damage initiation and progression of the repaired CFRP laminates under impact loading, a continuum damage mechanics (CDM) model that combines 3D Hashin damage criteria and cohesive zone model (CZM) is proposed. The corresponding drop-weight impact tests are conducted to experimentally obtain the impact response such as impact force and energy. Numerical impact simulations have been performed to study the effect of impact location during the low-velocity impact behaviors of repaired structures. Parametric studies of patch thickness and stacking sequence are also carried out using the low-velocity impact simulation to analyze their effect on the impact-resistance. Finally, this study provides an optimization cafeteria to identify the important design parameter to perform external patch repair based on the simulation results.

Single and multiple track-ballast impacts are investigated for the CFRP laminates used in train carbodies. Numerical simulations have been performed to study the damage behaviors of CFRP laminates during ballast impacts and compressions after ballast impact (CABI). Intralaminar and interlaminar damages are successfully predicted using continuum damage mechanics and cohesive zone model, respectively. It reveals that, for a high-speed ballast impact, delamination occurs during the damage initiation and appears at several interfaces nearby the impacted side of the specimen. After that, fiber breakage and matrix cracking appear, while delamination continuously extends until the failure. Repeated ballast impacts on the same site and different sites of specimens show significant increase of delamination while indicating less intralaminar damage. Furthermore, CABI simulations show that, the residual compression strength decreases in a nonlinear manner with the increase of impact energy. To bear the same impact energy, less detrimental effect is caused when one impact is replaced by two or more impacts.

A novel approach for fabricating one, two, and three-dimensional hybrid ZnO and Cu2O nanostructures has been developed. We have controlled the thickness of hybrid ZnO nanosheets to reach nanoscale at room temperature. The ability of engineering hybrid ZnO nanowires in few minutes is demonstrated. Moreover, supposed mechanism has been suggested and supported by the in situ SEM analysis for a series of picked samples during the reaction. The morphology transition of Cu2O nanoparticles to hierarchical nanowires and nano-flowers is highlighted as experimental evidences for Abdelmohsen theory for morphology transition engineering (ATMTE). In addition, the ability of multi-walled carbon nanotubes (MWCNTs) to act as a structural directing material for engineering nanowires is introduced. A hypothesis for engineering of micro and nanostructures (HEMNS) that may be applied for nearly all solid materials is demonstrated. Finally, the possibility of engineering Zn-oxidene and thin films are introduced.

Cellular membrane lateral organization, in particular the assembly of lipids in domains, is difficult to evaluate at high resolution. Here, we used atomic force microscopy (AFM) to investigate at high-resolution lipid membranes containing variable amounts of sphingomyelin (SM) and cholesterol (Chol), two abundant membrane lipids. To this end, we developed new AFM tip functionalization strategies to specifically probe SM and Chol. Multiparametric AFM imaging allowed us to highlight the lateral submicrometric organization of these two lipids within lipid bilayers through the simultaneous topographic evidence of different phase regimes together with the extraction of their nanomechanical properties and the specific detection of lipid moieties by functionalized AFM probes. The combination of AFM topography and nanomechanical mapping with specific probes for molecular recognition of lipids represents a novel approach to identify lipid-enriched domains in supported bilayers and offers a unique perspective to directly observe lipid assemblies in living cells.

Chiral resolution of racemic etiracetam was achieved via co-crystallization with ZnCl2. Depending on the amount of ZnCl2 either a stable racemic compound or a stable conglomerate can be obtained. Excess ZnCl2 triggers the quantitative conversion of the racemate into the conglomerate solid; this unprecedented behaviour was investigated through a racetam/ZnCl2/solvent phase diagram.

1,2,3-Triborated compounds can be prepared by simple nucleophilic borylation of 1,3-dienes, without the assistance of metal catalysts. Selective functionalisation of the internal C-B bond of the 1,2,3-triborated compounds, through cross-coupling with aryl iodides, highlights the powerful methodology toward polyfunctionalisation.

Este trabajo estudia la aplicación del proceso de templado químico en porcelánicos hechos en España. El proceso de templado químico es largamente aplicado a vidrios y tiene por finalidad principal incrementar la resistencia mecánica de estos materiales. Para lograr este objetivo, fueron seleccionados 3 porcelánicos hechos en España de diferentes suministradores. Las piezas industriales fueron cortadas en probetas pequeñas con dimensiones de 70×17×9mm de longitud, anchura y espesor, respectivamente. A continuación estas fueron sometidas a un tratamiento químico de intercambio iónico, también conocido por templado químico. El tipo de porcelánico, la temperatura y el tiempo del tratamiento químico fueron variados según un diseño factorial. Los resultados mostraron un incremento del ?55% en la resistencia a la rotura de uno de los materiales porcelánicos. Además, el estudio estadístico desarrollado mostró que el tipo de porcelánico y la temperatura del tratamiento químico fueron las variables que influyeron en la resistencia mecánica a flexión de los porcelánicos

Ground tire rubber from car and truck was modified using microwave irradiation at variable time. The irradiated ground tire rubber was used as filler in composites based on natural rubber. The composites, with high content of ground tire rubber, were prepared using an internal batch mixer and subsequently cross-linked at 160℃. The influence of the ground tire rubber source (car/truck) and irradiation time on structure, physico-mechanical behaviour, thermal properties and morphology of natural rubber/ground tire rubber composites was studied. The interfacial interactions between ground tire rubber and natural rubber as function of ground tire rubber source and irradiation time were evaluated by Fourier transform infrared spectroscopy, thermogravimetric analysis, tensile tests, swelling measurements and scanning electron microscopy. The results showed that irradiation of ground tire rubber slightly enhanced tensile properties and cross-link density of natural rubber/ground tire rubber composites. This effect was more evident in the case of ground tire rubbertruck because of its higher content of natural rubber and was reflected in changes in the interfacial adhesion, which were confirmed by the results of Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy analysis.

© 2018 Society of Plastics Engineers Thermal dissipation is a critical aspect for the performance and lifetime of electronic devices. In this work, novel composites based on a cycloaliphatic epoxy matrix and BN fillers, obtained by cationic curing of mixtures of 3,4-epoxy cyclohexylmethyl 3,4-epoxy cyclohexane carboxylate (ECC) with several amounts of hexagonal boron nitride (BN) were prepared and characterized. As cationic initiator a commercial benzylanilinium salt was used, which by addition of triethanolamine, exhibited an excellent latent character and storage stability. The effect of the formulation composition was studied by calorimetry and rheological measurements. The variation of thermal conductivity, thermal stability, thermal expansion coefficient, and thermomechanical and mechanical properties of the composites with the load of BN filler (ranging from 10 to 40 wt%) was evaluated. An improvement of an 800% (1.04 W/m·K) in thermal conductivity was reached in materials with glass transition temperatures >200°C without any loss in electrical insulation. POLYM. COMPOS., 39:E1760–E1769, 2018. © 2018 Society of Plastics Engineers.