Isotropic Orientation Research Articles

Characterization of surface orientation and tenderness of sous vide processed edible offal and psoas muscle from Dohne Merino sheep

The microstructural orientation and tenderness of edible offal and the psoas minor muscle from Dohne Merino sheep were compared in this study. Following evisceration and cleaning, fresh meat samples were collected from slaughtered lambs and ewes of different age groups and thermally processed to varying degrees of doneness using sous vide apparatus. A scanning electron microscope (SEM) was used for the characterization of the surface orientation and elemental composition. The results for tenderness showed that edible offal with anisotropic orientation had higher Warner-Bratzler shear force (WBSF) values, but those with some degrees of uniformity (isotropicity) in their surface orientation were comparatively tender. The rumen and trachea from the lambs, six-tooth and eight-tooth sheep at 10 - 12, 23 - 36 and 28 - 48 months old at slaughter had the highest WBSF values among all the meat samples. Our findings showed that edible offal from the lambs with isotropic orientation was more tender and richer in protein than those from ewes. Also, processing the psoas minor muscle and edible offal with sous vide at 100 oC in the shortest cooking time of 30 minutes had the greatest effect on tenderness of the meat samples. In descending order, the psoas minor muscle, liver and tongue from the lambs were found to be inherently more proteinaceous than other meat samples. The differences observed in the tenderness and protein contents of the edible offal and the psoas muscle could be attributed to variations in the microstructural organization of the muscle fibres in Dohne Merino and to their response to thermal processing. Keywords: anisotropy, doneness, isotropy, meat processing, Merino, scanning electron microscopy

FeCl3 Intercalated Microcrystalline Graphite Enables High Volumetric Capacity and Good Cycle Stability for Lithium‐Ion Batteries

To achieve a high volumetric capacity, both high tap density and high gravimetric capacity should be considered in one electrode. Herein, microcrystalline graphite (MG), a type of excellent graphite host, is proposed for the large‐scale preparation of FeCl3‐intercalated graphite intercalation compounds (GICs) to simultaneously meet the requirements of high tap density (0.95 g cm−3) and high gravimetric capacity (905 mAh g−1). FeCl3‐intercalated MG achieves the integration of isotropic orientation structure, amorphous carbon ingredients between graphite grains, and crumpled graphite layers, thus effectively buffering structure expansion and suppressing the dissolution of soluble FeCl3 guest and LiCl discharge products. In a lithium‐ion cell, the anode shows a high volumetric capacity of 859 mAh cm−3 and a stable cycle performance for lithium‐ion storage. More importantly, the influence of microstructure features of GICs on their electrochemical properties is demonstrated, which may be of great value to better design and prepare other GIC anodes for high volumetric capacity and good cycle stability.

Multi-scale mapping for collagen-regulated mineralization in bone remodeling of additive manufacturing porous implants

Abstract Long term success of metallic fusion cages depends on mechanobiological processes through the bone incorporation and rich osseointegration. An optimal configuration of porous titanium-aluminum-vanadium (Ti 6Al 4V) implant fabricated via the additive manufacturing was evaluated in complimentary structure examinations to investigate the growth of autologous osseous at multi-length scales. X-ray microcomputed tomography (micro-CT) and transmission X-ray microscopy (TXM) using newly-built analysis method indicate the porous Ti 6Al 4V is much better for bone ingrowth compared to commercially non-porous titanium (Ti) and porous tantalum (Ta) implants at the ultramicrostructural level. The evolution of bone formation and remodeling acquired by nano X-ray Laue diffraction mapping exhibits the isotropic orientation and low crystallinity of all newly formed bone whereas mature bone in Ti 6Al 4V discloses the preferential alignment and higher crystallinity volumes of constituent hydroxyapatite (HA) crystallites. The high degree in mineral crystallinity of the fully mature bone suggests additive manufactured Ti 6Al 4V pores enhance the collagen-regulated mineralization.

Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale

Polydisperse fibre networks are the basis of many natural and man-made architectures, ranging from high-performance bio-based materials to components of living cells and tissues. The formation and persistence of such networks are given by fibre properties such as length and stiffness as well as the number density and fibre-fibre interactions. Studies of fibre network behavior, such as connectivity or rigidity thresholds, typically assume fixed fibre length and isotropic fibre orientation distributions, specifically for nanoscale fibres where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow-stop procedure, we here propose a methodology allowing investigations of length dependent rotational dynamics of nanoscale polydisperse fibre suspensions, including effects of non-isotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofibre systems. The results show that the proposed method allows characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.

Ca segregation at Au–YSZ interfaces

Au thin films deposited on (111) YSZ single-crystal substrates were dewetted and equilibrated in a low oxygen partial pressure (10−20 atm) at 950 °C. Electron backscattered diffraction of 150 equilibrated Au particles shows that there is no preferred low-index orientation relationship (in-plane orientation relationship) but rather a strong preferred orientation of {111} Au || {111} YSZ. This result is associated with identical interface energies (1.75 ± 0.02 J/m2) measured using Winterbottom analysis from three equilibrated Au particles with different orientation relationships with the YSZ substrate. Energy dispersive spectroscopy in a scanning transmission electron microscope of the interfaces showed a Ca excess of Γ = 1.65 ± 0.20 atoms/nm2 (detection limit of 0.12 atoms/nm2). It is believed that Ca segregation reduces the interface energy of the system, resulting in a more isotropic orientation distribution instead of a low-index orientation relationship normally seen between fcc metals and YSZ.

Evaluation the effect of fiber alignment on particle collection performance of mechanical/electret filters based on Voronoi tessellations

The effect of fiber alignment on particle collection performance of mechanical/electret filters are investigated numerically. Four sets of fiber networks, namely, nearly isotropic, aligned, highly aligned and layered orientations are constructed using Voronoi tessellations. The particle transport and deposition process in these fiber networks under the coupling of flow field and electrostatic field are modeled using hybrid lattice Boltzmann Lagrangian method. The particle collection efficiencies and pressure drops of the mechanical/electret filters are calculated and compared. Results indicate that the mechanical filter with layered networks has the best filtration performance for large particles, and then the aligned networks has the next best performance. However, the sequence reverses when filtering the nanoparticles. In contrast to a mechanical filter, the electret filter with isotropic networks exhibits the best performance for full range of particles size, indicating that the dielectric attraction is less impacted by the 3D fiber orientations. Increasing fibers orientations in the airflow direction and constructing 3D pores of high sphericity are recommended to improve the performance of an electret filter.

Non‐Destructive Surface Energy Measurements on (1 0 0) Galfenol

AbstractDeveloping protocols for making thin sheet FeGa (Galfenol) with abnormally grown Goss or Cube grains, which provide maximum magnetostriction, is challenging because the mechanisms that regulate grain boundary mobility and texture development in these alloys are not yet understood. Grain boundary energy models do not account for forces caused by the control of surface energy from atmospheric annealing conditions. By characterizing the surface energy of specific Galfenol grains, we can develop a more accurate thermodynamic framework for modeling abnormal grain growth and texture development. To non‐destructively measure surface energy of specific crystal orientations and overcome passivation layer difficulties in previous studies, a two‐liquid‐phase contact angle method is utilized. A single‐crystal (1 0 0) Fe82Ga18 is used as a proof of concept for its isotropic surface crystal orientation. The resultant contact angle data shows a high dependence on the use of Ar‐plasma surface preparation to remove native oxides exposing a true interaction between a sessile drop and the Galfenol surface. Experimentally measured surface energy values are in agreement with density functional theory simulations. Surface texture and composition are confirmed using EBSD and XPS measurements. This non‐destructive technique paves the way towards studying surface energies of bare metal surfaces.

Guest–Host Interactions in Mixed CH4–CO2 Hydrates: Insights from Molecular Dynamics Simulations

Classical molecular dynamics simulations of mixed CH4–CO2 gas hydrates provide a thorough analysis of the energetics of both pure CH4 and CO2 hydrates and three intermediate compositions along the (CH4)1–x(CO2)x·5.75(H2O) solid solution. The energy is broken into guest–guest, guest–host, and host–host contributions. Radial distribution functions and three-dimensional density distributions provide insight into the changes in guest orientation and interactions with the host framework as a function of guest composition. Both energetic and structural analyses provide complementary information to previous experimental studies of the system. The experimentally observed isotropic orientation of CH4 molecules in both small and large cages is confirmed and the description of the anisotropic orientation of CO2 molecules in the large cage is confirmed and further enhanced. In mixed hydrates, the presence of CH4 alters the orientation of CO2, an indication that the interactions between guests, either direct (guest–gu...

(Invited) Conjugated Polymer Brushes: A New Platform to Investigate Intramolecular Charge Transport?

The intra-molecular transport along conjugated polymers has long been obscured by the dominant inter-molecular transport. To understand this important aspect of conjugated polymers, we have grown poly(3-methylthiophene) polymer brush films on indium tin oxide up to 120 nm thick. The morphological, structural, and electrical properties of such P3MT films were investigated. Optical and X-ray spectroscopy experiments indicate that the polymer chains have a nearly isotropic average orientation at low (< 10 nm) and high (> 30 nm) thicknesses, with mild vertical anisotropy in between. Atomic force microscopy shows that the film surfaces consist of column-shaped domains with an average cross-sectional area (2.3 × 10-3 µm2) and density (200 µm-2) that are independent of film thickness. Analysis of the contact between printed Au electrodes and the polymer brush film shows that a small fraction of the film surface (i.e., the tallest columns) makes contact with the electrodes. The measured bulk resistivity along the columns is 1.4 × 105 Ω·cm, two orders of magnitude lower than typical values for spuncast poly(3-alkylthiophene) films, while the resistance along individual polymer chains in the columns is estimated to be 360 GΩ/nm per molecule, comparable to molecular wires that exhibit charge transport by intramolecular processes. The enhanced conduction is likely due to additional intramolecular transport pathways enabled by the electrode-polymer brush-electrode device architecture, establishing conjugated polymer brushes as a platform for studying the interplay between synthesis, morphology, and charge transport phenomena. Figure 1

Thin-Film Texture and Optical Properties of Donor/Acceptor Complexes. Diindenoperylene/F6TCNNQ vs Alpha-Sexithiophene/F6TCNNQ

In this work, two novel donor/acceptor (D/A) complexes, namely, diindenoperylene (DIP)/1,3,4,5,7,8-hexafluoro-tetracyanonaphthoquinodimethane (F6TCNNQ) and alpha-sexithiophene (6T)/F6TCNNQ, are studied. The D/A complexes segregate in form of π–π stacked D/A cocrystals and can be observed by X-ray scattering. The different conformational degrees of freedom of the donor molecules, respectively, seem to affect the thin-film crystalline texture and composition of the D/A mixtures significantly. In equimolar mixtures, for DIP/F6TCNNQ, the crystallites are mostly uniaxially oriented and homogeneous, whereas for 6T/F6TCNNQ, a mostly 3D (isotropic) orientation of the crystallites and coexistence of domains of pristine compounds and D/A complex, respectively, are observed. Using optical absorption spectroscopy, we observe for each of the two mixed systems a set of new, strong transitions located in the near-IR range below the gap of the pristine compounds: such transitions are related to charge-transfer (CT) inter...

Quantitative time domain analysis of lifetime‐based Förster resonant energy transfer measurements with fluorescent proteins: Static random isotropic fluorophore orientation distributions

Förster resonant energy transfer (FRET) measurements are widely used to obtain information about molecular interactions and conformations through the dependence of FRET efficiency on the proximity of donor and acceptor fluorophores. Fluorescence lifetime measurements can provide quantitative analysis of FRET efficiency and interacting population fraction. Many FRET experiments exploit the highly specific labelling of genetically expressed fluorescent proteins, applicable in live cells and organisms. Unfortunately, the typical assumption of fast randomization of fluorophore orientations in the analysis of fluorescence lifetime-based FRET readouts is not valid for fluorescent proteins due to their slow rotational mobility compared to their upper state lifetime. Here, previous analysis of effectively static isotropic distributions of fluorophore dipoles on FRET measurements is incorporated into new software for fitting donor emission decay profiles. Calculated FRET parameters, including molar population fractions, are compared for the analysis of simulated and experimental FRET data under the assumption of static and dynamic fluorophores and the intermediate regimes between fully dynamic and static fluorophores, and mixtures within FRET pairs, is explored. Finally, a method to correct the artefact resulting from fitting the emission from static FRET pairs with isotropic angular distributions to the (incorrect) typically assumed dynamic FRET decay model is presented.

Mean shear versus orientation isotropy: effects on inertialess spheroids’ rotation mode in wall turbulence

The orientation of spheroidal particles dispersed in a fluid flow is known to influence the particles’ rotation mode. Rod-like and disk-like particles orient themselves differently and accordingly also rotate differently. In order to explore the role of the deterministic factors, i.e. mean shear and vorticity anisotropy, on the orientational behaviour of inertialess tracer spheroids, we adopted a purpose-made Couette–Poiseuille flow simulated numerically by Yanget al. (Intl J. Heat Fluid Flow, vol. 63, 2017, pp. 14–27). Typical wall turbulence with streamwise-oriented streaky structures caused by the locally high mean shear rate was observed only at one of the walls. The absence of mean shear at the other wall gave rise to an atypical turbulence field. Over a relatively wide and quasi-homogeneous core region, a modest mean shear rate made the vorticity field anisotropic. In spite of the mean shear, rod-like tracers were spinning and disk-like spheroids were tumbling, just as in homogeneous isotropic turbulence. We explained this phenomenon by the isotropic particle orientation and concluded that zero mean shear is not necessary for rod spinning and disk tumbling. The orientation and rotation of the Lagrangian tracer spheroids near the high shear wall were almost indistinguishable from the well-known behaviour in turbulent channel flows. Near the opposite wall, where the mean shear was negligibly small, disk-like particles aligned preferentially in the wall-normal direction and rotated similarly as in the presence of high shear. Rod-like particles, on the contrary, aligned more randomly and accordingly rotated similarly as in the core region. These observations revealed that the degree of particle orientation anisotropy has a major impact on the particle rotation mode, whereas mean shear, irrespective of the actual shear rate, only plays a secondary role in particle rotation. Deduction of the eigenvectors of the left Cauchy–Green tensor showed that the preferential orientation of the tracer spheroids was caused by the alignment of rods and disks with the strongest Lagrangian stretching and compression directions, respectively. Lagrangian stretching/compression determines the particle orientations and the particle orientation affects the particle rotation mode.

Vertical drying of a suspension of sticks: Monte Carlo simulation for continuous two-dimensional problem.

The vertical drying of a two-dimensional colloidal film containing zero-thickness sticks (lines) was studied by means of kinetic Monte Carlo (MC) simulations. The continuous two-dimensional problem for both the positions and orientations was considered. The initial state before drying was produced using a model of random sequential adsorption with isotropic orientations of the sticks. During the evaporation, an upper interface falls with a linear velocity in the vertical direction, and the sticks undergo translational and rotational Brownian motions. The MC simulations were run at different initial number concentrations (the numbers of sticks per unit area), p_{i}, and solvent evaporation rates, u. For completely dried films, the spatial distributions of the sticks, the order parameters, and the electrical conductivities of the films in both the horizontal, x, and vertical, y, directions were examined. Significant evaporation-driven self-assembly and stratification of the sticks in the vertical direction was observed. The extent of stratification increased with increasing values of u. The anisotropy of the electrical conductivity of the film can be finely regulated by changes in the values of p_{i} and u.

Constitutive Theory of fiber suspensions

We will demonstrate, that in fiber suspensions the stress tensor has a skew-symmetric part, i.e. fiber suspensions are micropolar fluids with non-zero couple stresses. Consequently, a continuum mechanical description of fiber suspensions requires the consideration of the balance of angular momentum in addition to the balance equations of mass, momentum and energy. An antisymmetric stress tensor is found for an isotropic orientation distribution of deformable fibers as well as for an anisotropic distribution of fiber orientations.Mainly, the method of classical Thermodynamics of Irreversible Processes with internal variables is applied. The internal variables are fiber deformation variables and an orientation tensor in the case of a non-isotropic distribution of fiber orientations. In addition to the result on couple stresses, relaxation equations for the bend and twist deformation variables are derived.Finally a mesoscopic background theory is discussed. In this approach a distribution of different fiber orientations and fiber deformations is assumed. The fiber orientation and deformation are additional variables in the domain of field quantities. The usual macroscopic fields of continuum mechanics are averages of mesoscopic fields over the different orientations and deformations. Macroscopic quantities characterizing the orientational order, the alignment tensors, and quantities characterizing fiber deformation, are defined by the help of the distribution function. They are internal variables in the macroscopic theory. The mesoscopic theory also demonstrates, that there is a skew symmetric part of the stress tensor in fiber suspensions.

Orientational disorder and phase transitions in ammonium oxofluorovanadates, (NH4)3VOF5 and (NH4)3VO2F4

Single crystals of (NH4)3VOF5 and (NH4)3VO2F4 were obtained from aqueous fluoride solutions and phase transitions in these compounds were investigated using X-ray diffraction, differential scanning microcalorimetry (DSM) and vibrational spectroscopy. The room-temperature (RT) phases of these compounds belong to orthorhombic symmetry [Immm and I222, Z = 6, for (NH4)3VOF5 and (NH4)3VO2F4, respectively] with similar unit-cell parameters and two independent vanadium atoms. Above RT [at 350 and 440 K for (NH4)3VOF5 and (NH4)3VO2F4, respectively], the compounds undergo reversible phase transitions into high-symmetry dynamically disordered elpasolite-like (Fm{\bar 3}m, Z = 4) structures with six and 12 spatial orientations of the vanadium octahedron for (NH4)3VOF5 and (NH4)3VO2F4, respectively. The ligand atoms are distributed in a mixed (split) position of 24e + 96j, one of the ammonium groups is disordered on the tetrahedron 32f site, but another one forms eight spatial orientations due to disorder of its hydrogen atoms in the 96j position. DSM and spectroscopic data enable the phase transition from high temperature to room temperature to be connected with the transition from isotropic orientations of the octahedron to its two different dynamic states.

Enhanced antibacterial activity through the controlled alignment of graphene oxide nanosheets

The cytotoxicity of 2D graphene-based nanomaterials (GBNs) is highly important for engineered applications and environmental health. However, the isotropic orientation of GBNs, most notably graphene oxide (GO), in previous experimental studies obscured the interpretation of cytotoxic contributions of nanosheet edges. Here, we investigate the orientation-dependent interaction of GBNs with bacteria using GO composite films. To produce the films, GO nanosheets are aligned in a magnetic field, immobilized by cross-linking of the surrounding matrix, and exposed on the surface through oxidative etching. Characterization by small-angle X-ray scattering and atomic force microscopy confirms that GO nanosheets align progressively well with increasing magnetic field strength and that the alignment is effectively preserved by cross-linking. When contacted with the model bacterium Escherichia coli, GO nanosheets with vertical orientation exhibit enhanced antibacterial activity compared with random and horizontal orientations. Further characterization is performed to explain the enhanced antibacterial activity of the film with vertically aligned GO. Using phospholipid vesicles as a model system, we observe that GO nanosheets induce physical disruption of the lipid bilayer. Additionally, we find substantial GO-induced oxidation of glutathione, a model intracellular antioxidant, paired with limited generation of reactive oxygen species, suggesting that oxidation occurs through a direct electron-transfer mechanism. These physical and chemical mechanisms both require nanosheet penetration of the cell membrane, suggesting that the enhanced antibacterial activity of the film with vertically aligned GO stems from an increased density of edges with a preferential orientation for membrane disruption. The importance of nanosheet penetration for cytotoxicity has direct implications for the design of engineering surfaces using GBNs.

Crystal growth patterns in DC and pulsed plated galvanic copper films on (1 1 1), (1 0 0) and (1 1 0) copper surfaces

Copper films for printed circuit board applications have to be fine-grained to achieve even filling of vias. Electroplated Cu films on roll annealed Cu substrates may have unacceptably large epitaxial crystals. Here galvanic films were plated on oriented single-crystal Cu substrates from an additive-free electrolyte, as well as DC plating and pulse reverse (PR) plating with additives. The distribution of crystallite orientations was mapped with XRD and compared with the microstructure determined by SEM. For the additive-free bath on [111] and [100] oriented surfaces a gradual transition from epitaxial to polycrystalline is seen, while films on [110] substrates are persistently epitaxial. Without bath additives, twinning is the main mechanism for the transition to polycrystalline texture. For DC plating, additives (carriers, accelerators and levelers) promote fine-grained films with isotropic grain orientations, with films on [110] substrates being partially isotropic. Plating with carriers and accelerators (no leveler) yields films with many distinct crystallite orientations. These orientations result from up to five steps of recursive twinning. PR plating produces isotropic films with no or very few twins (〈111〉 and 〈100〉 substrates, respectively), while on 〈110〉 oriented surfaces the deposits are about 20% epitaxial.

Birefringent Stable Glass with Predominantly Isotropic Molecular Orientation.

Birefringence in stable glasses produced by physical vapor deposition often implies molecular alignment similar to liquid crystals. As such, it remains unclear whether these glasses share the same energy landscape as liquid-quenched glasses that have been aged for millions of years. Here, we produce stable glasses of 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene molecules that retain three-dimensional shapes and do not preferentially align in a specific direction. Using a combination of angle- and polarization-dependent photoluminescence and ellipsometry experiments, we show that these stable glasses possess a predominantly isotropic molecular orientation while being optically birefringent. The intrinsic birefringence strongly correlates with increased density, showing that molecular ordering is not required to produce stable glasses or optical birefringence, and provides important insights into the process of stable glass formation via surface-mediated equilibration. To our knowledge, such novel amorphous packing has never been reported in the past.

Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10-7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

Collective Optomechanical Effects in Cavity Quantum Electrodynamics.

We investigate a cavity quantum electrodynamic effect, where the alignment of two-dimensional freely rotating optical dipoles is driven by their collective coupling to the cavity field. By exploiting the formal equivalence of a set of rotating dipoles with a polymer we calculate the partition function of the coupled light-matter system and demonstrate that it exhibits a second order phase transition between a bunched state of isotropic orientations and a stretched one with all the dipoles aligned. Such a transition manifests itself as an intensity-dependent shift of the polariton mode resonance. Our work, lying at the crossroad between cavity quantum electrodynamics and quantum optomechanics, is a step forward in the ongoing quest to understand how strong coupling can be exploited to influence matter internal degrees of freedom.