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Contact angle hysteresis is caused by contact line pinning by geometrical and/or chemical non-uniformities on a solid surface. For small contact angles, theories have been developed for the pinning of contact angles, and an analogy between geometrical and chemical defects has been established. This paper presents LBM results for the interaction of a contact line with a spatially periodic array of chemical defects. The results are for finite contact angles. Qualitative comparisons with existing theories for chemical defects and experimental results for geometrical defects are made for pinned contact lines.

We investigate the roles of flux pinning on vortex motion at low temperatures (T) in two-dimensional (2D) superconductors using two thin (4 nm) amorphous Mo_xSi_1-x films with different pinning strength. We measure the T dependence of resistance R at fields B below the critical field B_c of the 2D superconductor-insulator (SI) transition. For both films we observe the very small T-independent R at T→0 in certain field regions below B_c, suggesting quantum motion of a small number of vortices (dislocations) in the 2D vortex-glass phase in the presence of current. For the film with weaker pinning, the activation energy decreases at T<0.1 K.

Wigner solids in two-dimensional electron systems in high magnetic field B exhibit a striking, microwave or rf resonance, that is understood as a pinning mode. The temperature, T_m, above which the resonance is absent, is interpreted as the melting temperature of the solid. Studies of T_m for many B and many sample densities n show that T_m is a function of the Landau level filling ν alone for a given sample. This indicates that quantum mechanics figures importantly in the melting. T_m also appears to be increased by larger sample disorder.

We report on the equilibrium vortex phase diagram and vortex dynamics driven by dc current in the low-temperature liquid phase of thick amorphous (a-)Mo_xGe_1-x and a-Mo_xSi_1-x films containing weak and moderately strong pinning, respectively. The solid state for the a-Mo_xGe_1-x film is an ordered vortex lattice or Bragg glass, which is different from the disordered vortex glass for the a-Mo_xSi_1-x films. We find that the liquid state is similar to each other, involving the quantum-vortex-liquid (QVL) phase at low temperature. The width of the QVL phase is not enhanced by reduced pinning strength. In both systems we detect the unusual vortex flow in (near) the QVL phase.

We have investigated the behavior of vortices in a polycrystalline YBa₂Cu₃O_7-δ disk sample using rotational magnetization-vector (RMV) measurements. The measurements were conducted in the field-cooled (FC) and the zero-field cooled (ZFC) states for several values of applied magnetic field parallel to the sample surface at 4.2 K and for various angles of rotation (θ_rot) up to 360°. The total magnetic flux density, B, in the sample at any rotational angle was considered to be composed of two types of vortices: weakly pinned vortices that rotate frictionally in the opposite direction of sample rotation and strongly pinned vortices that rotate rigidly in the same direction of sample rotation. From the rate of change of these two types of vortices and the rate of change of B, we were able to develop a tool to qualitatively describe the average strength of pinning centers in high-temperature superconductors.

Using an extensive series of molecular dynamic simulations on driven vortex lattices interacting with nanostructures of periodic square arrays of pinning sites of fixed density, we have obtained the B–T phase diagram representing a Bose glass to vortex liquid-phase transition. In solving the over damped equation of vortex motion, we took into account the vortex–vortex repulsion interaction, the attractive vortex–pinning interaction, and the driving Lorentz force at several values of temperature. We have found that the location of the Bose glass line (T_BG-line) depends on the pinning strength of the pinning sites. We have also found that for each pinning strength value, there is an interesting peak of the T_BG-line that occurs at the first matching field when the number of vortices equals the number of pinning sites in the sample.

In this paper, the softening behavior of higher Nb content X80 pipeline steel was investigated by means of the stress relaxation curve. Deformed above 1050°C, the softening of the steel is fast and controlled by static recrystallization. Although the softening at 1000°C is slower obviously, it was also controlled by static recrystallization, no more than the grain growth rate was declined because of the drag effect of solute Nb. Moreover, the pinning effect of precipitation is more effective to retarding the softening at relatively lower temperature and that can be revealed by the softening curve too.

Based on analytical estimation and lattice simulation, a proposal is made that magnetic skyrmions can be generated through the pinning effect in 2D chiral magnetic materials, in the absence of an external magnetic field or magnetic anisotropy. In our simulation, stable magnetic skyrmions can be generated in the pinning areas. The properties of the skyrmions are studied for various values of ferromagnetic exchange strength and the Dzyaloshinskii–Moriya interaction strength.

Existence of weak solutions is proved for a system of nonlinear parabolic equations/inequalities describing evolution of magnetization, temperature, magnetic field, and electric field in electrically-conductive unsaturated ferromagnets. The system is derived from a recently-proposed thermodynamically-consistent continuum theory for the ferro/paramagnetic transition. Besides the standard viscous-like damping, dissipation due to eddy currents and domain-wall pinning is considered.

Nanoscale frictional phenomena at solid–solid surfaces with lubricants are studied numerically using a lattice model which consists of two rigid substrates and a monolayer of lubricant molecules. The maximum static frictional force, which works on the driven upper solid, is always finite and obeys a certain scaling relation. The lubricant layer, however, shows a kind of phase transition from a pinned state to free sliding state when the strength of the interaction potential with the substrates decreases. We discuss the peculiar pinning mechanism of the upper substrate in the presence of a lubricant monolayer.

Background: Whether percutaneous pinning or plate fixation is more appropriate for metacarpal fractures is still open to debate. Our study purpose was to review the current literature in an attempt to determine the optimal treatment modality for metacarpal fractures on the basis of functional outcomes, radiographic outcome and rates of complications.

Methods: We selected Pubmed, Cochrane library, EMBASE and the relevant English orthopedic journals and pooled data from eligible trials including four comparative studies and one retrospective review. Overall, the studies contained 222 patients with 231 fractures, 143 treated with pinning and 88 treated with plates and screws. Mean follow up was 7.5 months (4-12 months). Data were analyzed and the fixed effects are assumed for meta-analysis.

Results: Patients undergoing pinning for metacarpal fractures have higher motion scores when compared to open reduction and internal fixation with plate and screws. Functional scores, grip strength, radiographic parameters, time to union and complications were found not to be significantly different between the two groups.

Conclusions: There is evidence to support the use of pins over ORIF with plates and screws in the treatment of metacarpal fractures. This may have practical advantages, including minimal dissection, easier insertion and availability of the pins. The limitations of this study include the small number of eligible studies, lack of reporting of standard deviation value, and the lack of DASH score assessments at follow up. Further randomized controlled trials that include a larger patient numbers with longer follow up are needed to substantiate the superiority of one fixation method over another.

We consider minimizers of the Ginzburg–Landau energy with pinning term and zero degree Dirichlet boundary condition. Without any assumptions on the pinning term, we prove that these minimizers do not develop vortices in the limit ε → 0. We next consider the specific case of a periodic discontinuous pinning term taking two values. In this setting, we determine the asymptotic behavior of the minimizers as ε → 0.

The stability and dynamics of hot-spot solutions to two different classes of scalar, nonlocal, singularly perturbed reaction-diffusion equations is analyzed. These problems arise in the modeling of the microwave heating of a ceramic material placed in a single-mode resonant cavity. For the first model, where the coefficients in the differential operator are spatially homogeneous, an explicit characterization of metastable hot-spot behavior is given in the limit of small thermal diffusivity ε. For the second model, where the differential operator has a spatially inhomogeneous term resulting from the variation in the electric field along the ceramic sample, a hot-spot solution is shown to propagate on an algebraically long time-scale of order O(ε^-2) towards the point of maximum field strength. The electrical conductivity of the sample is taken to have either an exponential or a polynomial dependence on the temperature. For the polynomial form, the stability of a hot-spot profile is determined from the eigenvalues of a non-self-adjoint eigenvalue problem. It is proved that a general class of eigenvalue problems of this type may have complex conjugate eigenvalues in the limit ε→0. A careful proof of the stability of the hot-spot profile is given for this delicate case.

Background: The vast majority of acute closed tendinous mallet injuries are treated with a splint. Very few studies have directly compared splinting versus pinning the distal interphalangeal joint for this injury. The aim of this cohort study is to determine the outcomes of both methods.

Methods: A total of 59 patients with acute tendinous mallet injury were retrospectively enrolled (29 patients in conservative treatment and 30 patients in surgical treatment). Conservative treatment was performed using custom-made thermoplastic splint and surgical treatment was conducted with oblique K-wire fixation of the distal interphalangeal (DIP) joint. The DIP joint was immobilized for eight weeks in both treatments. Active ranges of motion of the affected finger and Miller’s classification were evaluated postoperatively.

Results: The mean extension lag of the DIP joint in the surgical treatment group was significantly better than it was with conservative treatment (2.1° vs 13.8°). Three patients who were noncompliant with the splint showed poor results, while no patients in the surgical treatment group had a poor result.

Conclusions: Surgical treatment with K-wire fixation leads to satisfactory results for acute tendinous mallet injury.

Background: The purpose of this study was to identify the optimal pin insertion point to minimize finger motion restriction for proximal phalangeal fixation in cadaver models.

Methods: We used 16 fingers from three fresh-frozen cadavers (age, 82–86 years). Each finger was dissected at the level of the carpometacarpal joint and fixated to a custom-built range of motion (ROM)-measuring apparatus after skin removal. The pin was inserted into the bone through four gliding soft tissues: the interosseous hood, dorsal capsule, lateral band, and sagittal band. Then, each tendon was pulled by a prescribed weight in three finger positions (flexion, extension, and intrinsic plus position). Changes in the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) angles were measured before and after pinning. We compared the differences between the insertion points using the Tukey-Kramer post hoc test.

Results: Placement of pins into the sagittal band significantly restricted MCP joint flexion, while placement into the dorsal capsule and lateral band significantly restricted PIP joint flexion. Only placement into the interosseous hood showed no significant difference in joint angles between the three finger positions compared to pre-pin insertion. There were no significant effects on MCP, PIP, and DIP joint extension.

Conclusions: The ROM of the MCP joint was obstructed due to pinning in most areas of insertion. However, pin insertion to the interosseous hood did not obstruct the finger flexion ROM compared to that of other gliding soft tissues; therefore, we believe that the interosseous hood may be a suitable pin insertion point for proximal phalangeal fixation.

Data from the dynamic scaling analysis of the growth front of silver patterns electroformed in a quasi-2D cell under localized and non-localized random quenched noise are reported. The plating solution either embedded in filter paper (FP), or containing disordered glass beads (GB), or as agarose gels (AG) were utilized. The scaling exponents from the displacement of the driven interface are α = 0.63 ± 0.05 and β = 0.60 ± 0.05 for FP, irrespective of its pore size distribution; α = 0.64 ± 0.05 and β = 0.58 ± 0.05 for GB; and α = 1.25 ± 0.10 and β = 0.88 ± 0.15 for AG. Exponents for FP and GB fit the predictions of the directed percolation depinning (DPD) model for D = 1, whereas for AG they coincide with those calculated by Leschhorn from a lattice model of probabilistic cellular automata. The difference between exponents resulting from FP, GB, and AG can be attributed to a non-localized random pinning in AG, which introduces a size-dependence mobility of obstacles in the gelled medium.