Granular materials are ubiquitous in the world around us. They have properties that different from those commonly associated with either solids, liquids, or gases. In this review authors select some of special granular and describe recent research developments.[S0034-6861(96)00204-8]

Gripping and holding of objects are key tasks for robotic manipulators. The development universal grippers able to pick up unfamiliar widely varying shape surface properties remains, however, challenging. Most current designs based on the multifingered hand, but this approach introduces hardware software complexities. These include large numbers controllable joints, need force sensing if be handled securely without crushing them, computational overhead decide how much stress each finger...

Granular materials display a variety of behaviors that are in many ways different from those other substances. They cannot be easily classified as either solids or liquids. This has prompted the generation analogies between physics found simple sandpile and complicated microscopic systems, such flux motion superconductors spin glasses. Recently, unusual behavior granular systems led to number new theories era experimentation on systems.

Local control of the domain orientation in diblock copolymer thin films can be obtained by application electric fields on micrometer-length scales. Thin an asymmetric polystyrene-polymethylmethacrylate copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation electrodes and structure transmission electron microscopy. cylinders...

Recent research in the field of nanometer-scale electronics has focused on operating principles small-scale devices and schemes to realize useful circuits. In contrast established “top-down” fabrication techniques, molecular self-assembly is emerging as a “bottom-up” approach for fabricating nanostructured materials. Biological macromolecules, especially proteins, provide many valuable properties, but poor physical stability electrical characteristics have prevented their direct use Here we...

We describe a simple passive universal gripper, consisting of mass granular material encased in an elastic membrane. Using combination positive and negative pressure, the gripper can rapidly grip release wide range objects that are typically challenging for grippers, such as flat objects, soft or with complex geometries. The passively conforms to shape target object, then vacuum-hardens it rigidly, later utilizing pressure reverse this transition-releasing object returning deformable state....

We have investigated the rise of a single large glass bead through vibrated cylindrical column smaller particles and found that vibration-induced size separation in this geometry arises from convective processes rather than local rearrangements as had been proposed previously. A convection cycle, rising middle dropping thin stream along walls cell, is responsible for all particle movement. Particles larger width downward zone are carried to top then trapped, resulting segregation. For...

We have investigated the distribution of avalanches which occur when slope a sandpile exceeds metastable given by angle repose. In contradiction to recent models Bak, Tang, and Wiesenfeld for dynamics granular systems, we do not observe power-law distributions. also find that decays as $log(t)$ vibrations are introduced. propose simple model this effect.

We report on systematic measurements of the distribution normal forces exerted by granular material under uniaxial compression onto interior surfaces a confining vessel. Our experiments three-dimensional, random packings monodisperse glass beads show that this is nearly uniform for below mean force and decays exponentially greater than mean. The shape value exponential decay constant are unaffected changes in system preparation history or boundary conditions. An empirical functional form...

We report measurements of the density a vibrated granular material as function time. The studied consists monodisperse spherical glass particles confined to long, thin cylindrical tube. Vibrations cause pile evolve from low initial configuration toward steady state with final that depends on intensity vibrations. find complex time evolution is incompatible single exponential relaxation. There appears be characteristic value acceleration separates two regimes packing behavior. results are...

Shear thickening is a type of non-Newtonian behavior in which the stress required to shear fluid increases faster than linearly with rate. Many concentrated suspensions particles exhibit an especially dramatic version, known as Discontinuous Thickening (DST), suddenly jumps increasing rate and produces solid-like behavior. The best example such counter-intuitive response applied stresses occurs mixtures cornstarch water. Over last several years, this shear-induced together variety other...

Victor Hugo suggested the possibility that patterns created by movement of grains sand are in no small part responsible for shape and feel natural world we live in. Certainly, granular materials, which is but one example, ubiquitous our daily lives. They play an important role industries, such as mining, agriculture construction. also geological processes, landslides erosion and, on a larger scale, plate tectonics, determine much Earth's morphology. Practically everything eat started out...

We report systematic measurements of the density a vibrated granular material as function time. Monodisperse spherical beads were confined to cylindrical container and shaken vertically. Under vibrations, pile slowly reaches final steady-state value about which fluctuates. have investigated frequency dependence amplitude these fluctuations vibration intensity \ensuremath{\Gamma}. The spectrum around steady state provides probe internal relaxation dynamics system link recent thermodynamic...

The evolution of superconductivity in ultrathin films Sn, Pb, Ga, Al, and In has been examined as a function thickness temperature. were grown increments by condensation from the vapor onto substrates held at temperatures below 18 K. For each metal, global or zero electrical resistance was found when normal-state sheet ${R}_{N}$ fell value close to h/4${e}^{2}$, 6.45 k\ensuremath{\Omega}/\ensuremath{\square}, an observation uncorrelated with either structural material parameters such...

Many densely packed suspensions and colloids exhibit a behavior known as Discontinuous Shear Thickening in which the shear stress jumps dramatically reversibly rate is increased. We performed rheometry video microscopy measurements on variety of to determine mechanism for this behavior. distinguish from inertial effects by showing that latter are characterized Reynolds number but only found lower packing fractions higher rates than former. profiles normal indicate that, thickening regime,...

Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, tension, contact angle of gallium a eutectic gallium-indium alloy while controlling such surrounding with an acid bath variable concentration. Rheometry measurements reveal yield stress directly attributable oxide skin that obscures intrinsic behavior liquid metals. demonstrate...

In materials science, high performance is typically associated with regularity and order, while disorder the presence of defects are assumed to lead sub-optimal outcomes. This holds for traditional solids such as crystals well many types nanoscale devices. However, there circumstances where can be harnessed achieve not possible approaches based on regularity. Recent research has shown opportunities specifically soft matter. There, phenomenon jamming leads unique emergent behavior that...

Particle−particle and particle−substrate interactions cause nanocrystals to self-assemble into superlattice structures upon drying from a colloidal suspension on solid surface. Rapid dewetting of volatile solvent, however, can significantly undermine the degree ordering. We demonstrate here that by increasing concentration nonvolatile dodecanethiol ligand, be controlled gold nanocrystal superlattices formed silicon nitride substrates with long range ordering over several microns. Monolayer...