Intruder trajectory tracking in a three-dimensional vibration-driven granular system:Unveiling the mechanism of the Brazil nut effect

We employ a Hall-effect magnetic sensor array to accurately track the trajectory of a single magnetic sphere,referred to as the“intruder,”within a three-dimensional vibro-fluidized granular bed to unravel the underlying physical mechanism governing the motion of the intruder.Within the acceleration range of 3.5 g≥Γ≥1.5 g,we find that,regardless of the intruder's initial position,it consistently reaches the same equilibrium depth when the vibration acceleration(Γ)and frequency(ω)are fixed.ForΓ≤2.5 g,the equilibrium position lies on the surface of the granular bed,while forΓ>2.5 g,it shifts below the surface.Additionally,intruders with different densities exhibit varying equilibrium depths,with higher density resulting in a deeper equilibrium position.To understand the mechanism behind the intruder's upward or downward motion,we measure its rising or sinking velocities under different vibration parameters.Our findings demonstrate that the rising velocity of the intruder,under varying vibration accelerations(Γ)and frequencies(ω),can be collapsed using the ratioΓ/ω,while the sinking velocity remains unaffected by the vibration strength.This confirms that the upward motion of the larger sphere,associated with the Brazil nut effect,primarily arises from the void-filling mechanism of the bed particles.Furthermore,our experiments reveal that the presence of convection within the bed particles has minimal impact on the motion of the intruder.

Observing the Jumping Laser Dogs

Jumping sun dogs are rapid light flashes changing over clouds, with some of them located close to the places of halo formation in thunder storms clouds. This paper presents an outline of some aspects that are required for understanding the jumping sun dogs, using some experiments with light scattering in complex fluids. In our analogy, we have observed the jumping laser dogs, in which the ice crystals are replaced by needlelike structures of ferrofluid, the electric field in the atmosphere is represented by an external magnetic field, and the laser beam scattered by the ferrofluid structure has the same role of the sun as the source of light scattered by the ice crystals subjected to changing electric fields in thunderstorm clouds.

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Living organisms,from plants to animals,have inspired and guided the design and fabrication of polymeric hydrogels with biomimetic morphology,shape deformation,and actuation behavior.However,the existing polymeric hydrogels are fragile and vulnerable,which seriously hinders further application.Therefore,endowing hydrogels with a biomimetic self-growth property and regenerating the macroscopic shape of hydrogels after they suffer significant damage are highly desirable for the next generation of adaptive biomimetic hydrogels.Inspired by the tail regeneration of geckos,we herein report an efficient and universal strategy of interfacial diffusion polymerization(IDP),which can regenerate the polymeric layer at a solid–liquid interface,thereby growing new hydrogels on the existing hydrogel layers.Through changing the solvent viscosity and/or monomer type of the hydrogel precursor,diverse new hydrogels have been regenerated to endow the initial hydrogels with additional fluorescent functions and/or actuating properties.Due to the high efficiency and universality of IDP,an injured hydrogel actuator can be repaired,regenerated,and recovered to its initial condition,even after suffering severe damage such as cutting or piercing.We believe that the regeneration strategy of polymeric hydrogels will inspire the design of biomimetic materials and motivate the fabrication of the next generation of soft robots with adaptive and multifunctional properties.

Oriented attachment(OA) mediated characteristic growth of Gd_2O_3 nanorods from nanoparticle seeds

Herein, we demonstrated the oriented attachment (OA) driven formation and characterization of Gd2O3 nanorods. The nanorods were synthesized via a surfactant free, inexpensive hydrothermal route and considering ~30 nm nanoparticles as the seed. While maintaining a cubic phase throughout the process, complete transformation of Gd2O3nanoparticles to nanorods was found to occur at an elevated temperature (~180 oC) of the hydrothermal reaction. The elongated Gd2O3 nanostructures, as revealed from transmission electron microscopic imaging, possessed an average diameter of ~33 nm and an approximate length of 172 nm. From the kinetics of OA process, the activation energy of formation was estimated to be ~25 kJ/mole. The existence of defect mediated radia-tive emission was ascertained from the asymmetric broadening of luminescence spectra. The defect emission arising from the Gd2O3 nanorods was nearly 1.4 times stronger than that of nanoparticles. The morphological evolution and growth kinetics were discussed along with the luminescence and electron paramagnetic resonance features.

Dimensions of receptor-ligand complex and the optimal radius of endocytosed virus-like particle

Recent experiments have pointed out that cellular uptake is strongly dependent on the physical dimensions of endocytosed nanoparticles and tile optimal radius of endocytosed virus-like particle coated by transferrin is around 50 nm. As the same time, the dimensions of receptor-ligand complex have strong effects on the size-dependent exclusion of proteins ill cell environments. Inspired by these experimental results, a continuum elastic model is constructed to resolve the relationship between the dinlensions of receptor-ligand complex and the optimal radius of endocytosed virus-like particle. These results demonstrate that the optimal radius of endocytosed virus-like particle depends on the dimensions of reeeptor-ligand complex and the dimension of receptor-ligand complex reduces the depletion zone.

Surface-wettability and Structural Colouration Property of Certain Rosaceae Cultivars with Off-to-dark Pink Appearances

The present work reports microstructure-based wettability and reflectance responses of three varieties of Indian Rosaceae （Rosa） cultivars, viz. white rose （Rosa chinensis var spontanea）, light pink rose （Rosa ehinensis var minima） and dark pink rose （Rosa chinensis var minima）. As for wettability, static and advancing and receding Contact Angles （CA） have been measured, for each type of matured rose petals. The surface roughness factors （rφ）, which are largely dependent on the micro-papillae assembly within the rose petal, are estimated to be, 2.74, 2.27 and 2.94 in case of White （W）, Light Pink （LP） and Dark Pink （DP） petals; respectively. Moreover, the respective Contact Angle Hysteresis （CAH） values are measured as 51 °, 27° and 59°. In order to exploit structural colouration through the reflectance char- acteristics, the specimens were dipped in three different media of different Refractive Indices （R1）, viz. ethanol （RI = 1.36）, propanol （RI= 1.39） and glycerine （R/= 1.47） for about 24 h. Upon ethanol and propanol adsorption, the LP and DP rose petals showed unusually similar reflectance patterns over a wide range of wavelengths, thus indicating a common microstructural share and structural colour contribution. The wetting-dewetting and structural colouration in natural systems, to a great extent, are dictated by the surface structure and solid-liquid and liquid-air interfaces, not only offer fundamental interest but also give scope for mimicking in artificial designs of technological interest.

Optimal aspect ratio of endocytosed spherocylindrical nanoparticle

Recent simulations have demonstrated that bioparticle size and shape modulate the process of endocytosis, and studies have provided more quantitative information that the endocytosis efficiency of spherocylindrical bioparticles is decided by its aspect ratio. At the same time, the dimensions of the receptor-ligand complex have strong effects on the size-dependent exclusion of proteins within the cellular environment. However, these earlier theoretical works including simulations did not consider the effects of ligand-receptor complex dimension on the endocytosis process. Thus, it is necessary to resolve the effects of ligand-receptor complex dimension and determine the optimal aspect ratio of spherocylindrical bioparticles in the process of endocytosis. Accordingly, we proposed a continuum elastic model, of which the results indicate that the aspect ratio depends on the ligand-receptor complex dimension and the radius of the spherocylindrical bioparticle. This model provides a phase diagram of the aspect ratio of endocytosed spherocylindrical bioparticles, the larger aspect ratio of which appears in the phase diagram with increasing ligand density, and highlights the bioparticle design.

Effect of Annealing Temperature on the Morphology and Sensitivity of the Zinc Oxide Nanorods-Based Methane Senor

ZnO nanorods in the form of thin films were synthesized by a facile chemical route and the effect of annealing temperature on the structure and sensitivity of such ZnO-based sensors was studied in detail towards methane sensing.Morphological analyses of such films were carried out by scanning electron microscopy,whereas,the crystalline structure and phase purity of the films were analysed by X-ray diffraction technique.The films were observed to display a gradual change in their morphology from granular to dense nanorods and each of them was used to fabricate methane sensor prototype.They were also tested for temperature-dependent methane-sensing capability with varying methane concentrations.The optimized sensor exhibited highest gas response of ＊80% at 250 °C with significantly low response and recovery time.