We report the preparation of discrete nanometer-scale zinc-based clusters and use them to form sub-15 nm structures by means of extreme ultraviolet lithography. By taking advantage of a metal-containing building unit derived by a metal–organic frameworkMOF-2, we found the 3-methyl-phenyl-modified Zn-mTA cluster that formed is well-defined with controlled size and structure and demonstrates extremely high solubility. Progress in recent years in metal–organic frameworks has created a rich variety of metal-containing structures that are useful for numerous applications. Substitution of the bridging ligands with monovalent ligands produces a discrete metal–organic cluster that strongly interacts with soft X-rays at a wavelength of 13 nm. Here we describe the design, preparation, computational modeling, and physical characterization of these new materials. Such metal-containing structures may form the basis of photoresists that enable the next generation of microelectronic devices.

Membranes are ubiquitous in nature with primary functions that include adaptive filtering and selective transport of chemical/molecular species. Being critical to cellular functions, they are also fundamental in many areas of science and technology. Of particular importance are the adaptive and programmable membranes that can change their permeability or selectivity depending on the environment. Here, we explore implementation of such biological functions in artificial membranes and demonstrate two-dimensional self-assembled heterostructures of grapheneoxide and polyamine macromolecules, forming a network of ionic channels that exhibit regulated permeability of water and monovalent ions. This permeability can be tuned by a change of pH or the presence of certain ions. Unlike traditional membranes, the regulation mechanism reported here relies on interactions between the membranes internal structure and ions. This allows fabrication of membranes with programmable, predetermined permeability and selectivity, governed by the choice of components, their conformation and charging state. in = GO-PA ⁄ , where is the elementary charge, ≈ 2 nm is the interlayer distance, and GO-PA is shown in Fig. 2b for the two used PAs.

High-quality graphene sheets with lateral size over 20 μm have been obtained by bath sonicating after subjecting the wormlike graphite marginally to mixed oxidizer. To date, to our knowledge, they are the largest graphene sheets prepared by exfoliation in the liquid phase. A saturable absorber mirror was fabricated based on these sheets. We exploited it to realize mode-locking operation in a diode-pumped Nd:GdVO(4) laser. A pulse duration of 16 ps was produced with an average power of 360 mW and a highest pulse energy of 8.4 nJ for a graphene mode-locked laser.

This paper considers about the control problem for an underactuated quadrotor UAV system with model parameter uncertainty. Backstepping based techniques are utilized to design a nonlinear adaptive controller which can compensate for the mass uncertainty of the vehicle. Lyapunov based stability analysis shows that the proposed control design yields asymptotic tracking for the UAV's motion in x, y, z direction and the yaw rotation, while keep the stability of the closed loop dynamics of the quadrotor UAV. Numerical simulation results are provided to show the good tracking performance of proposed control laws. I. INTRODUCTIONThe automatic control of a quadrotor UAV is not a straight on mainly due to its underactuated properties [1]. The dynamic model of quadrotor UAV has six degree-of-freedom (DOF) with only four independent thrust forces generated by four rotors. It is difficult to control all these six outputs with only four control inputs. Moreover, uncertainties associate with dynamic model also bring more challenge for control design. Different strategies have been proposed to deal with uncertain quadrotor model, such as adaptive control, neural network based control, sliding mode control, H ∞ control and so on. In [2], a direct adaptive control algorithm was designed for the tracking control of a quadrotor UAV's roll, pitch, yaw angles, together with altitude while compensating for the model parameter uncertainties. A reference system corresponding to a virtual UAV which contains a third order oscillator was utilized to track the desired trajectory. In [3], a backstepping based approach was used for quadrotor UAV control, while two neural networks were used to approximate the uncertain aerodynamic components. By dividing the quadrotor's dynamic model into an underactuated subsystem and a full actuated system, [4] designed a sliding mode controller for the underactuated system and a bounded PID controller for the full actuated system, these two controller drove the UAV to reach a desired position with a desired yaw angle while keep roll and pitch angles zero. More literature review for quadrotor UAV control can be found in [5].One of the main parameter uncertainties associated with the quadoror UAV's dynamic model is the unknown mass

All solid‐state pulsed lasers (ASSPLs) play a significant role in the fields of medical, military, industry, and scientific research. Passive Q‐switching and mode‐locking are two of the most effective techniques for generating ASSPLs, in which a saturable absorber (SA) is the key element that has great impact on laser output parameters. Recently, 2D layered materials have been widely studied due to their intriguing properties. Their advantages of ultrafast dynamic processing, excellent nonlinear optical response, broadband operation, and easy fabrication and integration with lasers, enable them to be excellent SAs. Herein, the recent progress of ASSPLs with 2D layered material‐based SAs is reviewed, including a brief introduction of the fundamental characteristics, fabrication methods, characterization techniques of ultrafast dynamics, and nonlinear optical properties of 2D materials, design criteria of passively Q‐switched and mode‐locked bulk lasers, and their applications in ASSPLs. Finally, the potential developments and perspectives on 2D material‐based ASSPLs are also highlighted.