Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures.

Field emission data from aligned high-density carbon nanotubes (CNTs) with orientations parallel, 45°, and perpendicular to the substrate have been obtained. The large-area uniformly distributed CNTs were synthesized on smooth nickel substrates via dc plasma-assisted hot filament chemical vapor deposition. CNTs with diameters in the range of 100–200 nm were employed in this study. The different orientations were obtained by changing the angle between the substrate and the electrical field direction. The growth mechanism for the alignment and orientation control of CNTs has been discussed. The CNTs oriented parallel to the substrate have a lower onset applied field than those oriented perpendicular to the substrate. This result indicates that electrons can emit from the body of the CNT, which means that the CNT can be used as a linear emitter. The small radius of the tube wall and the existence of defects are suggested as the reasons for the emission of electrons from the body of the tubes.

The introduction of Prussian blue (PB), an inexpensive pigment material, elegantly breaks the solubility limit of the [Fe(CN) 6 ] 4À/3À electrolyte, and substantially boosts the capacity via an off-electrode chemical reaction. In the reversible redoxtargeting reaction cycles, PB acts as the energy reservoir, while [Fe(CN) 6 ] 4À/3À plays a role in mediating the reactions between the electrode and storage tank. The volumetric capacity surpasses other reported [Fe(CN) 6 ] 4À/3À -based and most other organic aqueous redox flow batteries.

Flexible lithium batteries with high energy density have recently received tremendous interest due to their potential applications in flexible electronic devices. Herein, we report a novel method to fabricate highly flexible and robust carbon nanotube–graphene/sulfur (CNTs–RGO/S) composite film as free-standing cathode for flexible Li/S batteries with increased capacity and significantly improved rate capability. The free-standing CNTs–RGO/S cathode was able to deliver a peak capacity of 911.5 mAh g–1 sulfur (∼483 mAh g–1 electrode) and maintain 771.8 mAh g–1 sulfur after 100 charge–discharge cycles at 0.2C, indicating a capacity retention of 84.7%, which were both higher than the cathodes assembled without CNTs. Even after 100 cycles, the cathode showed a high tensile strength of 62.3 MPa. More importantly, the rate capability was improved by introducing CNTs. The CNTs–RGO/S cathode exhibited impressive capacities of 613.1 mAh g–1 sulfur at 1C with a capacity recuperability of ∼94% as the current returned to 0.2C. These results demonstrate that the well-designed nanocomposites are of great potential as the cathode for flexible lithium sulfur (Li/S) batteries. Such improved electrochemical properties could be attributed to the unique coaxial architecture of the nanocomposite, in which the evenly dispersed CNTs enable electrodes with improved electrical conductivity and mechanical properties and better ability to avoid the aggregation and ensure the dispersive distribution of the sulfur species during the charge/discharge process.

The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.

A closed-loop overconstrained spatial mechanism composed of six hinge-jointed bars, which has three planes of symmetry in any position, is called a threefold-symmetric Bricard linkage. In this paper a kinematic analysis of these linkages is presented. It is pointed out that for particular parameter values, kinematic bifurcation of the linkages can occur. Features of the kinematic bifurcation are discussed in detail. The applicability of threefold-symmetric Bricard linkages and of their alternative forms to deployable structures is investigated. In addition, by using the theory of kinematic bifurcation, a snap-through phenomenon appearing in a deployable hexagonal ring is explained.

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Articles you may be interested inHydrogen storage for carbon nanotubes synthesized by the pyrolysis method using lanthanum nickel alloy as catalyst J. Appl. Phys. 94, 6417 (2003); 10.1063/1.1621082Theoretical evaluation of hydrogen storage capacity in pure carbon nanostructures Aligned carbon nanotubes ͑CNTs͒ with diameters of 50-100 nm, synthesized by plasma-assisted hot filament chemical vapor deposition, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. Quadruple mass spectroscopy and thermogravimetric analysis show a hydrogen storage capacity of 5-7 wt% was achieved reproducibly at room temperature under modest pressure ͑10 atm͒ for the as-prepared samples. Pretreatments, which include heating the samples to 300°C and removing of the catalyst tips, can increase the hydrogen storage capacity up to 13 wt% and decrease the pressure required for storage. The weight gains were measured after the samples moved out of the hydrogen environment. The release of the adsorbed hydrogen can be achieved by heating the samples up to 300°C.