Adaptive and Ultrahigh-Affinity Recognition in Water by Sulfated Conjugated Corral[5]arene.

The pursuit of synthetic receptors with high binding affinities has long been a central focus in supramolecular chemistry, driven by their significant practical relevance in various fields. Despite the numerous synthetic receptors that have been developed, most exhibit binding affinities in the micromolar range or lower. Only a few exceptional receptors achieve binding affinities exceeding 109  M-1 , and their substrate scopes remain rather limited. In this context, we introduce SC[5]A, a conjugated corral-shaped macrocycle functionalized with ten sulfate groups. Owing to its deep one-dimensional confined hydrophobic cavity and multiple sulfate groups, SC[5]A displays an extraordinarily high binding strength of up to 1011  M-1 towards several size-matched, rod-shaped organic dications in water. Besides, its conformation exhibits good adaptability, allowing it to encapsulate a wide range of other guests with diverse molecular sizes, shapes, and functionalities, exhibiting relatively strong affinities (Ka =106 -108  M-1 ). Additionally, we've explored the preliminary application of SC[5]A in alleviating blood coagulation induced by hexadimethrine bromide in vitro and in vivo. Therefore, the combination of ultrahigh binding affinities (towards complementary guests) and adaptive recognition capability (towards a wide range of functional guests) of SC[5]A positions it as exceptionally valuable for numerous practical applications.

Polarization insensitive flexible ultra-broadband terahertz metamaterial absorber.

We propose a polarization insensitive, flexible ultra-broadband terahertz (THz) metamaterial absorber. It consists of a chromium composite resonator on the top, a polyimide (PI) dielectric layer in the middle, and a chromium substrate. The simulation results show that the absorption achieves more than 90% ultra-wideband absorption in the range of 1.92-4.34 THz. The broadband absorption is produced by the combination of electric dipole resonance and magnetic resonance, as well as impedance matching with free space. Due to the rotational symmetry of the unit structure, the absorber is insensitive to polarization of the THz wave and has a larger range of incident angles. The total thickness of the absorber is only 13.4 µm, showing highly flexible and excellent high-temperature resistance characteristics. Therefore, it has potential applications in THz wave stealth and electromagnetic shielding.

Time-frequency analysis of the tip motion in liquids using the wavelet transform in dynamic atomic force microscopy.

The tip motion of the dynamic atomic force microscope in liquids shows complex transient behaviors when using a low stiffness cantilever. The second flexural mode of the cantilever is momentarily excited. Multiple impacts between the tip and the sample might occur in one oscillation cycle. However, the commonly used Fourier transform method cannot provide time-related information about these transient features. To overcome this limitation, we apply the wavelet transform to perform the time-frequency analysis of the tip motion in liquids. The momentary excitation of the second mode and the phenomenon of multiple impacts are clearly shown in the time-frequency plane of the wavelet scalogram. The instantaneous frequencies and magnitudes of the second mode are extracted by the wavelet ridge analysis, which can provide quantitative estimations of the tip motion in the second mode. Moreover, the relations of the maximum instantaneous magnitude (MIM) to the amplitude setpoint and the Young's modulus of the sample surface are investigated. The results suggest that the MIM can be used to characterize the nanomechanical property of the sample surface at high amplitude setpoints.

Three-dimensional architecture hybrid perovskite solar cells using CdS nanorod arrays as an electron transport layer.

Three-dimensional (3D) architecture perovskite solar cells (PSCs) using CdS nanorod (NR) arrays as an electron transport layer were designed and prepared layer-by-layer via a physical-chemical vapor deposition (P-CVD) process. The CdS NRs not only provided a scaffold to the perovskite film, but also increased the interfacial contact between the perovskite film and electron transport layer. As an optimized result, a high power conversion efficiency of 12.46% with a short-circuit current density of 19.88 mA cm-2, an open-circuit voltage of 1.01 V and a fill factor of 62.06% was obtained after 12 h growth of CdS NRs. It was four times the efficiency of contrast planar structure with a similar thickness. The P-CVD method assisted in achieving flat and voidless CH3NH3PbI3-x Cl x perovskite film and binding the CdS NRs and perovskite film together. The different density of CdS NRs had obvious effects on light transmittance of 350-550 nm, the interfacial area and the difficulty of combining layers. Moreover, the efficient 1D transport paths for electrons and multiple absorption of light, which are generated in 3D architecture, were beneficial to realize a decent power conversion efficiency.

A Phosphine-Free Route to Size-Adjustable CdSe and CdSe/CdS Core-Shell Quantum Dots for White-Light-Emitting Diodes.

The selenium dioxide was used as the precursor to synthesize wide-size-ranged CdSe quantum dots (2.4-5.7 nm) via hot-injection route. The CdSe quantum dots are featured with high crystalline, monodisperse, zinc blende structure and wide emission region (530-635 nm). In order to improve the stability and quantum yield, a phosphine-free single-molecular precursor approach is used to obtain CdSe/CdS core/shell quantum dots. The CdSe/CdS quantum dots are highly fluorescent with quantum yield up to 65%, and persist the good monodispersity and high crystallinity. Moreover, the quantum dots white light-emitting-diodes are fabricated by using the resultant red emission core/shell quantum dots and Y3Al5O12:Ce3+ yellow phosphors as color-conversion layers on a blue InGaN chip. The prepared light-emitting-diodes show good performance with CIE-1931 coordinated of (0.3583, 0.3349), an Ra of 92.9, and a Tc of 4410 K at 20 mA, which indicate that the combination of red-emission QDs and yellow phophors as a promising approach to obtain warm WLEDs with good color rendering.

A High-Q AFM Sensor Using a Balanced Trolling Quartz Tuning Fork in the Liquid.

A quartz tuning fork (QTF) has been widely used as a force sensor of the frequency modulation atomic force microscope due to its ultrahigh stiffness, high quality factor and self-sensing nature. However, due to the bulky structure and exposed surface electrode arrangement, its application is limited, especially in liquid imaging of in situ biological samples, ionic liquids, electrochemical reaction, etc. Although the complication can be resolved by coating insulating materials on the QTF surface and then immersing the whole QTF into the liquid, it would result in a sharp drop of the quality factor, which will reduce the sensitivity of the QTF. To solve the problem, a novel method, called the balanced trolling quartz tuning fork (BT-QTF), is introduced here. In this method, two same probes are glued on both prongs of the QTF separately while only one probe immersed in the liquid. With the method, the hydrodynamic interaction can be reduced, thus the BT-QTF can retain a high quality factor and constant resonance frequency. The stable small vibration of the BT-QTF can be achieved in the liquid. Initially, a theoretical model is presented to analyze the sensing performance of the BT-QTF in the liquid. Then, the sensing performance analysis experiments of the BT-QTF have been performed. At last, the proposed method is applied to atomic force microscope imaging different samples in the liquid, which proves its feasibility.

A novel method to remove impulse noise from atomic force microscopy images based on Bayesian compressed sensing.

A novel method based on Bayesian compressed sensing is proposed to remove impulse noise from atomic force microscopy (AFM) images. The image denoising problem is transformed into a compressed sensing imaging problem of the AFM. First, two different ways, including interval approach and self-comparison approach, are applied to identify the noisy pixels. An undersampled AFM image is generated by removing the noisy pixels from the image. Second, a series of measurement matrices, all of which are identity matrices with some rows removed, are constructed by recording the position of the noise-free pixels. Third, the Bayesian compressed sensing reconstruction algorithm is applied to recover the image. Different from traditional compressed sensing reconstruction methods in AFM, each row of the AFM image is reconstructed separately in the proposed method, which will not reduce the quality of the reconstructed image. The denoising experiments are conducted to demonstrate that the proposed method can remove the impulse noise from AFM images while preserving the details of the image. Compared with other methods, the proposed method is robust and its performance is not influenced by the noise density in a certain range.

Wavelet analysis of higher harmonics in tapping mode atomic force microscopy.

Higher harmonics have been widely used to characterize nanomechanical properties of the sample surface in tapping mode atomic force microscopy. They are usually analyzed by the Fourier transform method which provides time-averaged amplitude and phase information. In this paper, we apply the analytic wavelet transform to analyze higher harmonics. The intuitive descriptions of higher harmonics are obtained by the time-frequency analysis of the tip motion signal. The temporal evolutions of the higher harmonics are analyzed. The higher harmonics extracted by the analytic wavelet transform are closely related to the wavelet parameters. Different time and frequency features of higher harmonics can be analyzed through adjusting the wavelet parameters. Moreover, the root-mean-square amplitude and the peak amplitude obtained by the analytic wavelet transform can provide better characterization of sample properties than the amplitude obtained by the Fourier transform method.

Intelligent tuning method of PID parameters based on iterative learning control for atomic force microscopy.

Proportional-integral-derivative (PID) parameters play a vital role in the imaging process of an atomic force microscope (AFM). Traditional parameter tuning methods require a lot of manpower and it is difficult to set PID parameters in unattended working environments. In this manuscript, an intelligent tuning method of PID parameters based on iterative learning control is proposed to self-adjust PID parameters of the AFM according to the sample topography. This method gets enough information about the output signals of PID controller and tracking error, which will be used to calculate the proper PID parameters, by repeated line scanning until convergence before normal scanning to learn the topography. Subsequently, the appropriate PID parameters are obtained by fitting method and then applied to the normal scanning process. The feasibility of the method is demonstrated by the convergence analysis. Simulations and experimental results indicate that the proposed method can intelligently tune PID parameters of the AFM for imaging different topographies and thus achieve good tracking performance.

Shape and phase evolution from CsPbBr3 perovskite nanocubes to tetragonal CsPb2Br5 nanosheets with an indirect bandgap.

Tetragonal CsPb2Br5 nanosheets were obtained by an oriented attachment of orthorhombic CsPbBr3 nanocubes, involving a lateral shape evolution from octagonal to square. Meanwhile, the experimental results, together with DFT simulation results, indicated that the tetragonal CsPb2Br5 is an indirect bandgap semiconductor that is PL-inactive with a bandgap of 2.979 eV.