Configuration Transformation Research Articles

Dynamic Modeling and Configuration Transformation of Origami with Soft Creases

Origami has attracted much attention from scientists and engineers in recent years. Classic origami only permits rotations around creases, while origami-like structures in nature can also undergo a certain degree of extension at creases. In this paper, an earwig-inspired origami with rotational symmetry is proposed and analyzed by introducing soft creases. Such a soft crease is equivalent to a combination of a rotational spring and an extensional spring. The motion of the earwig-inspired origami is described using spherical triangles. Based on Lagrange's Equation, the nonlinear dynamic equation of the system is formulated. It is then solved by using the fourth-order Runge-Kutta method. The results of theoretical calculations are consistent with those of simulations in ADAMS. With the established framework, the bifurcation behaviors of the equilibria of the proposed system, including supercritical pitchfork and saddle-node bifurcations, are investigated. Such origami can realize both mono-stable and bi-stable mechanisms, while the corresponding design parameters are demonstrated in the design map. In particular, the properties of the bi-stable origami can vary with different equilibria. The configuration transformation could be achieved using a continuous excitation. However, it is sometimes sensitive to the initial conditions. Inspired by the working mechanism of earwig wings, a simple control approach for origami configuration transformation is proposed. The key is to stop exciting the origami when its deformation crosses an energy barrier. This work lays a foundation for the design and study of novel multi-stable and morphing structures and provides an efficient approach for their configuration transformation.

Dynamic Analysis of Metamorphic Mechanisms with Impact Effects During Configuration Transformation

Metamorphic mechanisms have attracted considerable attention owing to their capability to switch their topology to adapt to different operational tasks. One feature of topological change is the re-contact of different bodies, which inevitably causes collisions affecting operation accuracy and service life. Consequently, in this study, a collision incidence matrix was introduced to describe the topology of a system involved in collisions, and a method for reducing the closed-loop system to an open-loop system was proposed. The complex movement of the metamorphic mechanism in a changing topology was classified into two different running stages of the source metamorphic mechanism. Based on the relative coordinate method, dynamic modeling of the source metamorphic mechanism considering the impact effects was conducted. Combining the classical collision theory and Newton–Euler equation, the generated impact impulse and the motion after collision were determined. Subsequently, a dynamic analytical method for the full configuration of metamorphic mechanisms was proposed to reflect the changes in the topological structure in the dynamic model. Finally, two typical metamorphic mechanisms used in packaging and spinning were considered as examples to verify the correctness and effectiveness of the proposed method, and their impact characteristics during configuration transformation were analyzed. The proposed analytical method of internal impact for a variable topology process provides effective theoretical guidance for the stability analysis of configuration transformation and structural design aimed at minimizing impacts.

Application of finite screw method for multi-mode mechanism classification and determination

To enrich the theoretical system of multi-mode mechanisms, a classification method and a determination method are proposed in this paper. From the perspective of configuration transformation, the multi-mode mechanisms are divided into two types: one based on lockable joints and the other based on the principle of bifurcated motion. Furthermore, the mechanisms based on the principle of bifurcated motion are categorized into two types: one based on the variable mobility branch and the other based on constraint singularity generated by branches. The principles of classification are expounded and the determination method is developed. The proposed classification and the determination methods of the multi-mode mechanism provide new insights for their analysis.

Investigating Dislocation Arrays Induced by Seed Scratches during PVT 4H-SiC Crystal Growth Using Synchrotron X-Ray Topography

The influence of seed preparation on crystal defect generation is studied by investigating the effect of damage from surface scratches not completely removed during polishing on the seed crystal on the nucleation and evolution of dislocation arrays. Synchrotron X-ray topography is conducted on several wafers sliced from a PVT-grown 4H-SiC boule. Topographic results in conjunction with ray tracing simulation reveal the generation of TSD/TMD and TED arrays associated with the scratches in the newly grown wafer adjacent to the seed. Configuration transformation of those arrays is observed as these opposite-signed dislocation pairs composing the arrays were affected by the overgrowth of macro-steps when propagating into the newly grown crystal.

Magnetic Structure-Dependent Spin Texture Lattice in Hexagonal MnFeCoGe Magnets.

Topological spin textures are of great significance in magnetic information storage and spintronics due to their high storage density and low drive current. In this work, the transformation of magnetic configuration from chaotic labyrinth domains to uniform stripe domains was observed in MnFe1-xCoxGe magnets. This change occurs due to the noncollinear magnetic structure switching to a uniaxial ferromagnetic structure with increasing Co content, as identified by neutron diffraction results and Lorentz transmission electron microscopy (L-TEM). Of utmost importance, a hexagonal lattice of high-density robust type-II magnetic bubble lattice was established for x = 0.8 through out-of-plane magnetic field stimulation and field-cooling. The dimensions of the type-II magnetic bubbles were found to be tuned by the sample thickness. Therefore, the stabilization of complex magnetic spin textures, associated with enhanced uniaxial ferromagnetic interaction and magnetic dipole-dipole interaction in MnFe1-xCoxGe through magnetic structure manipulation, as further confirmed by the micromagnetic simulations, will provide a convenient and efficient strategy for designing topological spin textures with potential applications in spintronic devices.

Temperature‐Induced Transformation of the Atomic Configuration of the BO2* Defect in Boron‐Doped Czochralski Si

In this study, the new data concerning the electronic and vibrational properties of the BsO2i* defect in Czochralski‐grown boron‐doped silicon are reported. In silicon subjected to treatment at elevated temperatures, a new boron‐related defect is detected. An additional intracenter electronic transition for boron associated with the revealed defect is observed. The defect is identified as BsO2i due to the linear dependence of its formation efficiency on the boron content and the quadratic dependence on the oxygen concentration. The revealed complex is formed synchronously with the annealing of the previously identified BsO2i* defect. The detected complex is formed as a result of temperature transformation of the atomic configuration of the BsO2i* defect. The transformation occurs with activation energy of 2.59 eV. The local vibrational modes associated with both configurations of the BsO2i* complex are identified. The results of the study suggest that the BsO2i* defect in both configurations exists in a wide temperature interval, impacts the optical and electronic properties of the material, and must be taken into consideration when developing Si:B‐based devices.

Solvent-Activated Transformation of Polymer Configurations for Advancing the Interfacial Reliability of Perovskite Photovoltaics.

Organic materials have been widely used as the charge transport layers in perovskite solar cells due to their structural versatility and solution processability. However, their low surface energy usually causes unsatisfactory thin-film wettability in contact with the perovskite solution, which limits the interfacial performance of the photovoltaic devices. Although solvent post-treatment could occasionally regulate the wetting behavior of organic films, the mechanism of the solid-liquid interaction is still unclear. Here, we present evidence of a possible correlation between the solvent and the wettability of a conventional polymer, poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), and reveal the critical roles of Hansen solubility parameters (HSPs) of solvents in wetting mechanisms. Our results suggest that the conventional solvent N,N-dimethylformamide (DMF) improves the wettability of PTAA by the morphological disruption mechanism but negatively impacts interfacial charge collection and stability. In contrast, 2-methoxyethanol (2-Me) with an appropriate HSP value induces the transformation of the PTAA configuration in an orderly manner, which simultaneously improves the wetting property and maintains the film topography. After careful optimization of the surface conformation of the PTAA film, both perovskite crystallization and interfacial compatibility have been enhanced. Benefiting from superior interfacial properties, the perovskite solar cells based on 2-Me deliver a champion efficiency of 24.15% compared to 21.4% for DMF-based ones. More encouragingly, the use of 2-Me minimizes the perovskite buried interfacial defects, enabling the unencapsulated devices to maintain about 95% of their initial efficiencies after light illumination for 1100 h. The present study demonstrates the high effectiveness of solvent-polymer interaction for adjusting interfacial properties and strengthening the robustness of perovskite solar cells.

Improving Stability, Crystallinity, and Photo‐Responsiveness of Supramolecular Frameworks by Surface Polymerization

AbstractMetal–organic cage‐based photo‐responsive supramolecular frameworks (PSMFs) with permanent porosity have gained attention for their modular properties, controllable functionality, and light‐induced reversible responsiveness. However, their high porosity and photo‐responsive efficiency are often compromised due to poor structural stability upon solvent removal, limiting their potential applications. Here, a solution to overcome this challenge by employing a surface polymerization strategy using isophorone diisocyanate (IDI) to stabilize PSMF (PCC‐20t) is presented. This approach results in the composite of PCC‐20t@PolyIDI, which preserves crystallinity and permanent high‐porosity while avoiding structural collapse commonly observed in highly porous supramolecular frameworks. Moreover, compared to activated PCC‐20t, PCC‐20t@PolyIDI exhibits an 18.6‐fold increase in specific surface area. Remarkably, the structural variability of PCC‐20t@PolyIDI can be observed in the photo‐regulation behavior of CO2 capacity under the irradiation of vis‐ and UV‐light, showing a 27.9% change in adsorption amount for CO2 which is significantly higher than that of the activated PCC‐20t with 7.0% for CO2. Grand Canonical Monte Carlo simulations demonstrate the light‐regulated adsorption performance is attributed to the configuration transformation of azobenzene from trans‐ to buckling state. The findings may pave the way for stabilizing high‐porosity materials to simultaneously meet demands for high‐porosity and photo‐responsive efficiency.

Organoplatinum Complex Exhibiting Aggregation-Enhanced Emission (AEE) and Dual-Channel Ion-Sensing Properties by Terminating the Molecular Configuration Transformation (MCT) and Excited-State Intramolecular Proton Transfer (ESIPT).

Emitters produce weak emissions when they undergo structural changes such as molecular configuration transformation (MCT) or excited-state intramolecular proton transfer (ESIPT) but give out strong emissions after terminating these distortions. Herein, an organoplatinum complex, Pt-ppy-ABP, carrying a salicylaldehyde-based Schiff base unit is synthesized. It exhibits weak emission in dilute solutions but shows bright emission at the aggregated state or after interacting with F- and Zn2+. This suggests that it has an aggregation-enhanced emission (AEE) property and holds potential in ion detection. Supported by theoretical calculations and femtosecond transient absorption results, this complex suffers excited-state structural changes including MCT from a square-planar configuration to a tetrahedral one, as well as intramolecular rotation of a monodentate ligand and ESIPT, showing weak emission in its solutions. At the aggregated state, it releases strong yellow emissions because of the restraints of MCT and ligand rotation. Upon interacting with F- or Zn2+, it emits bright-red or -green emissions, achieving detection limits of 10-7 M. The sensing mechanism is concluded as deprotonation- and coordination-induced ESIPT terminations, respectively. Given its AEE property and ion-responsive emissions, its application in information encryption is also explored. Finally, these findings should provide valuable clues for the developments of chemosensors with dual-channel recognition abilities.

Unraveling the Dynamic Molecular Motions of a Twin‐Cavity Cage with Slow Configurational but Rapid Conformational Interconversions

AbstractFeaturing diverse structural motions/changes, dynamic molecular systems hold promise for executing complex tasks. However, their structural complexity presents formidable challenge in elucidating their kinetics, especially when multiple structural motions are intercorrelated. We herein introduce a twin‐cavity cage that features interconvertible C3‐ and C1‐configurations, with each configuration exhibiting interchangeable P‐ and M‐conformations. This molecule is therefore composed of four interconnected chiral species (P)‐C3, (M)‐C3, (P)‐C1, (M)‐C1. We showcase an effective approach to decouple these sophisticated structural changes into two kinetically distinct pathways. Utilizing time‐dependent 1H NMR spectroscopy at various temperatures, which disregards the transition between mirror‐image conformations, we first determine the rate constant (kc) for the C3‐ to C1‐configuration interconversion, while time‐dependent circular dichroism spectroscopy at different temperatures quantifies the observed rate constant (kobs) of the ensemble of all the structural changes. As kobs kc, it allows us to decouple the overall molecular motions into a slow configurational transformation and rapid conformational interconversions, with the latter further dissected into two independent conformational interchanges, namely (P)‐C3 (M)‐C3 and (P)‐C1 (M)‐C1. This work, therefore, sheds light on the comprehensive kinetic study of complex molecular dynamics, offering valuable insights for the rational design of smart dynamic materials for applications of sensing, separation, catalysis, molecular machinery, etc.

Unraveling the Dynamic Molecular Motions of a Twin-Cavity Cage with Slow Configurational but Rapid Conformational Interconversions.

Featuring diverse structural motions/changes, dynamic molecular systems hold promise for executing complex tasks. However, their structural complexity presents formidable challenge in elucidating their kinetics, especially when multiple structural motions are intercorrelated. We herein introduce a twin-cavity cage that features interconvertible C3- and C1-configurations, with each configuration exhibiting interchangeable P- and M-conformations. This molecule is therefore composed of four interconnected chiral species (P)-C3, (M)-C3, (P)-C1, (M)-C1. We showcase an effective approach to decouple these sophisticated structural changes into two kinetically distinct pathways. Utilizing time-dependent 1H NMR spectroscopy at various temperatures, which disregards the transition between mirror-image conformations, we first determine the rate constant (kc) for the C3- to C1-configuration interconversion, while time-dependent circular dichroism spectroscopy at different temperatures quantifies the observed rate constant (kobs) of the ensemble of all the structural changes. As kobs kc, it allows us to decouple the overall molecular motions into a slow configurational transformation and rapid conformational interconversions, with the latter further dissected into two independent conformational interchanges, namely (P)-C3 (M)-C3 and (P)-C1 (M)-C1. This work, therefore, sheds light on the comprehensive kinetic study of complex molecular dynamics, offering valuable insights for the rational design of smart dynamic materials for applications of sensing, separation, catalysis, molecular machinery, etc.

Upgraded and Light-Up Biosensing Platform: Entropy-Driven Catalysis Circuit Manipulates the Configuration Transformation of Novel DNA Silver Nanoclusters on the Graphene Oxide Surface.

To tackle the predicament of the traditional turn-off mechanism, exploring an activated turn-on system remains an intriguing and crucial objective in biosensing fields. Herein, a dark DNA Ag nanocluster (NC) with hairpin-structured DNA containing a six-base cytosine loop (6C loop) as a template is atypically synthesized. Intriguingly, the dark DNA Ag NCs can be lit to display strong red-emission nanoclusters. Building upon these exciting findings, an unprecedented and upgraded turn-on biosensing system [entropy-driven catalysis circuit (EDCC)-Ag NCs/graphene oxide (GO)] has been created, which employs an EDCC to precisely manipulate the conformational transition of DNA Ag NCs on the GO surface from adsorption to desorption. Benefiting from the effective quenching of GO and signal amplification capability of the EDCC, the newly developed EDCC-Ag NCs/GO biosensing system displays a high signal-to-background (S/B) ratio (26-fold) and sensitivity (limit of detection as low as 0.4 pM). Meanwhile, it has good specificity, excellent stability, and reliability in both buffer and biological samples. To the best of our knowledge, it is the first example that adopts an EDCC to precisely modulate the configuration transformation of DNA Ag NCs on the GO surface to obtain a biosensor with low background, strong fluorescence, high contrast, and sensitivity. This exciting finding may provide a new route to fabricate a novel turn-on biosensor based on hairpin-templated DNA Ag NCs in the optical imaging and bioanalytical fields.

An ultrasensitive, selective pseudoesterase-activated fluorescent probe for monitoring acetylation modification, configuration transformation and biological levels of human serum albumin

Quantitative assays and the structural monitoring of human serum albumin (HSA) are essential for disease diagnosis, drug development, and physiological studies. Commonly used methods for quantifying HSA are based on the dye-HSA binding mechanism, which involves determining the absorption or fluorescence signal when the dye binds non-covalently to HSA. However, these methods generally suffer from poor selectivity and susceptibility to interference from co-existing species. Herein, an ultrasensitive and selective fluorescent probe, 2-(2-morpholinoethyl)-1,3-dioxo-2,3-dihydro-1 H-benzo[de]isoquinolin-6-yl cyclopropanecarboxylate (MDDH), was designed based on the pseudoesterase activity of HSA and used to monitor the acetylation modification, configuration transformation, and biological levels of HSA. Upon catalysis by HSA, the cyclopropanecarbonyl ester bound to MDDH undergoes hydrolysis, yielding a strong fluorescent signal. In contrast to conventional HSA-binding dyes, MDDH demonstrates superior sensitivity (with a 302-fold fluorescence enhancement), high selectivity for distinguishing between HSA and bovine serum albumin, and strong anti-interference against various coexisting species. By sensing HSA pseudoesterase activity, MDDH allows for the sensitive monitoring of structural changes in HSA, including aspirin-induced acetylation, guanidine hydrochloride-induced defolding and trypsin-induced cleavage. Moreover, MDDH exhibits strong stability, low cytotoxicity and good cell membrane permeability. It is suitable for the quantitative determination of HSA in the serum and urine, as well as for the fluorescence imaging of HSA in cells. Our work provides an efficient tool for monitoring the acetylation modifications, configuration changes, and biological content of HSA.

Temperature effects on the structure of lead metasilicate glass, supercooled liquid, crystal, and liquid: Vibrational anharmonicity and configurational transformations analyzed by molecular dynamics and Raman scattering

Raman spectroscopy and Molecular Dynamics (MD) simulations were employed to explore in detail the effects of temperature on the four stages of the PbO∙SiO2 system: glass, supercooled liquid, crystalline phases, and liquid. The Qn distribution up to 1153 K and the wavenumber temperature coefficients derived from vibrational anharmonicity were determined from the Raman data, whereas the structural transformation reflected in changes in the Qn population distribution up to 2400 K was inferred from MD simulations. The results indicate that reversible configurational transformations occur only in the higher temperature ranges of the supercooled liquid and more notably in the liquid state. During these transformations, the increase in the Q0 and Q1 populations occurs at the expense of the Q3 and Q4 populations. On the other hand, only vibrational anharmonicity was observed in the glass and crystalline states.

Self-assembled sensing interface based on specific aptamer functionalized Ti3C2 MXene for ultrasensitive antibiotic detection in milk

A self-assembled sensing interface based on Ti3C2 MXene functionalized by aptamer had been successfully constructed in this work, which fully utilizes the electrical properties of Ti3C2 MXene and the specific recognition ability of the aptamer. Subsequently, we studied the performance of the sensing interface using two antibiotic residues as examples. Under the optimal conditions, the sensing interface showed a linear range of 100 fM–1 μM and a limit of detection of 1 fM to detect kanamycin and tetracycline, furthermore the recovery rates were 97.15%–103.00% and 99.559%–106.36%, respectively. In addition, the sensing behaviors of aptamers specific recognition of target can be perceived by the interface, thereby exhibiting different electrical responses. Therefore, the self-assembled sensing interface not only provided a new avenue for the development of ultrasensitive technology in the food analysis field but also for investigating aptamer configurational transformations.

A bioinspired heterostructured nanochannel based on dendrimer-gold network and aluminum oxide arrays for sensitive detection of miRNA

BackgroundMicroRNAs, as oncogenes or tumor suppressors, enable to up or down-regulate gene expression during tumorigenesis. The detection of miRNAs with high sensitivity is crucial for the early diagnosis of cancer. Inspired by biological ion channels, artificial nanochannels are considered as an excellent biosensing platform with relatively high sensitivity and stability. The current nanochannel biosensors are mainly based on homogeneous membranes, and their monotonous structure and functionality limit its further development. Therefore, it is necessary to develop a heterostructured nanochannel with high ionic current rectification to achieve highly sensitive miRNA detection. ResultsIn this work, an asymmetric heterostructured nanochannel constructed from dendrimer-gold nanoparticles network and anodic aluminum oxide are designed through an interfacial super-assembly method, which can regulate ion transport and achieve sensitive detection of target miRNA. The symmetry breaking is demonstrated to endow the heterostructured nanochannels with an outstanding ionic current rectification performance. Arising from the change of surface charges in the nanochannels triggered by DNA cascade signal amplification in solution, the proposed heterogeneous nanochannels exhibits excellent DNA-regulated ionic current response. Relying on the nucleic acid's hybridization and configuration transformation, the target miRNA-122 associated with liver cancer can be indirectly quantified with a detection limit of 1 fM and a wide dynamic range from 1 fM to 10 pM. The correlation fitting coefficient R2 of the calibration curve can reach to 0.996. The experimental results show that the method has a good recovery rate (98%–105 %) in synthetic samples. SignificanceThis study reveals how the surface charge density of nanochannels regulate the ionic current response in the heterostructured nanochannels. The designed heterogeneous nanochannels not only possess high ionic current rectification property, but also enable to induce superior transport performance by the variation of surface chemistry. The proposed biosensor is promising for applications in early diagnosis of cancers, life science research, and single-entity electrochemical detection.

Affine formation maneuver control of underactuated surface vessels: Guaranteed safety under moving obstacles in narrow channels

This research tackles the challenge of dynamic formation control and collision avoidance in underactuated surface vessels (USVs). Firstly, an affine transformation is employed to implement arbitrary configuration transformations within the multi-USV system. Secondly, by considering both distances and velocities between USVs and obstacles, a novel collision avoidance scheme is proposed based on conventional distance-based artificial potential field methods. This method, building on traditional distance-based artificial potential fields, offers a more precise assessment of collision risks, thereby notably shrinking the potential collision zones. Such refinement leads to reduced energy consumption and minimizes disruption to formation integrity. Thirdly, an anti-perturbation formation maneuver safety control scheme is introduced to achieve a time-varying target formation without collisions, ensuring that local position tracking errors remain bounded. The effectiveness of the proposed approaches is substantiated through comprehensive theoretical analysis and extensive numerical simulations, underscoring their practical applicability.

Amorphous ZnSnOx Hollow Spheres Enable Highly Efficient CO2 Reduction.

Carbon dioxide (CO2) adsorption and electron transport play an important role in CO2 reduction reaction (CO2RR). Herein, we have demonstrated a new class of diverse hollow ZnSnOx (ZSO) through the amorphization of hydroxides to enhance CO2 adsorption and accelerate electron transport. The amorphization is occurred by calcination process, as indicated by Fourier transform infrared spectroscopy and Raman spectra. In particular, the ZnSnOx hollow spheres (ZSO HSs) achieve a high Faradaic efficiency (FE) of HCOOH up to 92.7 % at best, outperforming the commercial ZSO (Comm. ZSO, 85.7 %). ZSO HSs also exhibit durable stability with negligible activity decay after 10 h of successive electrolysis. In-situ attenuated total reflectance infrared absorption spectroscopy further reveals strong adsorption of CO2 and rapid intermediate configuration transformation in amorphous ZSO HSs. This work demonstrates the practical application of ZSO for CO2RR and provides a new insight to create efficient CO2RR electrocatalysts.

Unlocking Multicolor Emissions in the Crystalline State through Dimerization and Configurational Transformation of a Single Fluorophore

Unlocking Multicolor Emissions in the Crystalline State through Dimerization and Configurational Transformation of a Single Fluorophore

Multi-stimuli fluorescence responsiveness of α-cyanostilbene derivative: AIEE, stimuli response to polarity, acid, force and light, applications in anti-counterfeiting and single phosphor w-OLED

Recently, the small molecule functional materials with a simple synthesis have attracted more and more attention. A multi-stimuli-responsive aggregation-induced emission (AIE) molecule is expected to have great applications in the near future. Identically, the single-component white organic light diode (w-OLED) has a good application field. Herein, a cyanostilbene derivative (TSC) was efficiently synthesized by Vilsmeier and Knoevenagel reactions with only 2 steps under mild conditions. TSC was characterized by NMR (1H, 13C), FT-IR, HRMS and elemental analysis. TSC has aggregation-induced enhanced emission (AIEE) effect, and significant polar-, acid-, force- and light-stimuli fluorescence responsiveness properties. The AIE effect and four different stimulus responses are all simultaneously presented in TSC. This phenomenon is relatively rare in small molecule fluorescent compounds. The results of SEM and DLS reveal the AIEE of TSC is mainly due to the fact that molecular self-assembly into nanofiber networks in the aggregated state limiting the distortion of molecules. DFT calculations show that the polarity stimuli-response (fluorescence from green to orange) is closely related to intramolecular charge transfer (ICT). Acid/base 1H NMR titration proves that the acidochromism results from reversible protonation/deprotonation. The results of DSC, SEM, PXRD and POM prove that the essence of mechanical force stimuli-response is the change of crystallinity. The results of 1H NMR, UV–vis and fluorescence spectra, DFT calculations and SEM reveal that the light stimuli-response is attributed to the Z/E configuration transformation. Based on multi-stimuli responsive properties, TSC can be used for recognition of solvents polarity by naked eyes or fluorophotometer, used as an acid indicator and also used to quantitatively test the concentration of trace acids, used in anti-counterfeiting including safty ink, data rewriting, even can be used to construct supramolecular liquid crystals materials. In addition, TSC can be used to fabricate single phosphor w-OLED, avoiding using multicomponent composite materials.