Topological Transformation Research Articles

Optimizing Photoelectrochemical UV Imaging Photodetection: Construction of Anatase/Rutile Heterophase Homojunctions and Oxygen Vacancies Engineering in MOF-Derived TiO2.

Self-powered photoelectrochemical (PEC) ultraviolet photodetectors (UVPDs) are promising for next-generation energy-saving and highly integrated optoelectronic systems. Constructing a heterojunction is an effective strategy to increase the photodetection performance of PEC UVPDs because it can promote the separation and transfer of photogenerated carriers. However, both crystal defects and lattice mismatch lead to deteriorated device performance. Here, we introduce a structural regulation strategy to prepare TiO2 anatase-rutile heterophase homojunctions (A-R HHs) with oxygen vacancies (OVs) photoanodes through an in situ topological transformation of titanium metal-organic framework (Ti-MOF) by pyrolysis treatment. The cooperative interaction between A-R HHs and OVs suppresses carrier recombination and accelerates carrier transport, thereby significantly enhancing the photodetection performance of PEC UVPDs. The obtained device realizes a high on/off ratio of 10,752, a remarkable responsivity of 24.15 mA W-1, an impressive detectivity of 3.28 × 1011 Jones, and excellent cycling stability. More importantly, under 365 nm light illumination, a high-resolution image of "HUST" (the abbreviation of Harbin University of Science and Technology) was obtained perfectly, confirming the excellent optical imaging capability of the device. This research not only presents an advanced methodology for constructing TiO2-based PEC UVPDs, but also provides strategic guidance for enhancing their performance and practical applications.

Adiabatic Time Evolution of Highly Excited States

Adiabatic time evolution of quantum systems is a widely used tool with applications ranging from state preparation through simplifications of computations and topological transformations to optimization and quantum computing. Adiabatic time evolution generally works well for gapped ground states, but not for thermal states in the middle of the spectrum that lack a protecting energy gap. Here we show that quantum many-body scars—a particular type of highly excited states—are suitable for adiabatic time evolution despite the absence of a protecting energy gap. Considering two rather different models, namely a one-dimensional model constructed from tensor networks and a two-dimensional fractional quantum Hall model with anyons, we find that the quantum scars perform similarly to gapped ground states with respect to adiabatic dynamics when the required final adiabatic fidelity is around 0.99. The maximum speed at which the scar state of the one-dimensional model can be adiabatically transformed decreases as a power law with system size, as opposed to exponentially for both generic thermal and disorder-driven localized states. At constant and very low ramp speed, we find that the deviation of the fidelity from unity scales linearly with ramp speed for scar states, but quadratically for gapped ground states. The gapped ground states hence perform better when the required adiabatic fidelities are very high, such as 0.9999 and above. We identify two mechanisms for leakage out of the scar state and use them to explain our results. While manipulating a single, isolated ground state is common in quantum applications, adiabatic evolution of scar states provides the flexibility to manipulate an entire tower of ground-state-like states simultaneously in a single system. Published by the American Physical Society 2024

Sulfato‐β‐cyclodextrin induced multivalent supramolecular directional aggregation of cyanovinylene derivatives for achieving reversible near‐infrared fluorescence

AbstractMolecular aggregation or supramolecular aggregation‐induced emission is one of the research hotspots in chemistry, biology, and materials. Herein, we report negatively charged sulfato‐β‐cyclodextrin (SCD) induced cyanovinylene derivatives (DPy‐6C) directional aggregation to form regular nanorods (DPy‐6C@SCD) through supramolecular multivalent interactions, not only achieves ultraviolet‐visible absorption redshifted from 453 to 521 nm but also displays near‐infrared (NIR) aggregation‐induced emission with a large spectral redshift of 135 nm. The DPy‐6C monomer presents random nanosheets with weak fluorescence but obtains regular aggregates after assembly with SCD through electrostatic interactions. In the presence of H+, the DPy‐6C@SCD can further aggregate into elliptical nanosheets without fluorescence changes due to the protonation of secondary amines. In contrast, the morphology of DPy‐6C@SCD becomes flexible and sticks together upon the addition of OH− with an emission blue shift of 72 nm and a 90‐fold intensity increase because of disrupting the stacking mode of aggregates, thereby achieving acid‐base regulated reversible fluorescence behaviors that cannot be realized by DPy‐6C monomer. The DPy‐6C@SCD can efficiently select the detection of volatile organic amines both in liquid and gas phases within 5 s at the nanomolar level. Taking advantage of RGB analysis and calculation formula application, the DPy‐6C@SCD has been successfully used to monitor various organic amines on a smartphone, accompanied by naked‐eye visible photoluminescence. Therefore, the present research provides an efficient directional aggregation method through supramolecular multivalent interactions, which not only realizes topological morphology transformation but also achieves reversible NIR luminescent molecular switch and high sensitivity organic amines fluorescent sensing devices.

A Topological and Technological Transformation Model of Mimar Sinan’s Mosques to the Present

A Topological and Technological Transformation Model of Mimar Sinan’s Mosques to the Present

Topological Transformation of Hydrogen-Terminated Germanium to Germanium Nanosheets for Fast Lithium Storage.

Germanium has been recognized as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and excellent lithium-ion diffusivity. Nonetheless, it is challenging to enhance both the high-rate performance and long-term cycling stability simultaneously. This study introduces a novel heterostructure composed of germanium nanosheets integrated with graphene (Ge NSs@Gr). These nanosheets undergo an in situ phase transformation from a hydrogen-terminated multilayer germanium compound termed germanane (GeH) derived via topochemical deintercalation from CaGe2. This approach mitigates oxidation and prevents restacking by functionalizing the exfoliated germanane with octadecenoic organic molecules. The resultant germanium nanosheets retain their structural integrity from CaGe2 and present an exposed, active (111) surface that features an open crystal lattice, facilitating swift lithium-ion migration conducive to lithium storage. The composite material delivers a substantial reversible capacity of 1220 mA h g-1 at a current density of 0.2 C and maintains a capacity of 456 mA h g-1 even at an ultrahigh current density of 10 C over extended cycling. Impressively, a capacity of 316 mA h g-1 remains after 5000 cycles. The exceptional high-rate performance and durable cycling stability underscore the Ge NSs@Gr anode's potential as a highly viable option for LIBs.

Encoding signal propagation on topology-programmed DNA origami.

Biological systems often rely on topological transformation to reconfigure connectivity between nodes to guide the flux of molecular information. Here we develop a topology-programmed DNA origami system that encodes signal propagation at the nanoscale, analogous to topologically efficient information processing in cellular systems. We present a systematic molecular implementation of topological operations involving 'glue-cut' processes that can prompt global conformational change of DNA origami structures, with demonstrated major topological properties including genus, number of boundary components and orientability. By spatially arranging reactive DNA hairpins, we demonstrate signal propagation across transmission paths of varying lengths and orientations, and curvatures on the curved surfaces of three-dimensional origamis. These DNA origamis can also form dynamic scaffolds for regulating the spatial and temporal signal propagations whereby topological transformations spontaneously alter the location of nodes and boundary of signal propagation network. We anticipate that our strategy for topological operations will provide a general route to manufacture dynamic DNA origami nanostructures capable of performing global structural transformations under programmable control.

Highly dispersed MgInCe-mixed metal oxides catalyzed direct carbonylation of glycerol and CO2 into glycerol carbonate

Glycerol carbonate, an important glycerol value-added product, has been widely used as the active intermediates and inert solvents in the synthesis of cosmetics, detergents, chemical intermediates, polymers, and so on. The direct carbonylation from glycerol with CO2 is considered as a promising route, but still a tough work due to the thermodynamic stability and the kinetic inertness of CO2. In this work, highly-selective direct carbonylation of glycerol and CO2 into glycerol carbonate has been achieved over highly dispersed MgInCe-mixed metal oxides (MgInCe-MMO), which were prepared through the topological transformation derived from the MgInCe-layered double hydroxides (MgInCe-LDHs). By precisely modulating the surface basic-acidic properties and the oxygen vacancies, an efficient carbonylation of glycerol with CO2 has been achieved with a selectivity of up to > 99% to glycerol carbonate. Deep investigation on the synergistic catalysis of base-acid sites and oxygen vacancies has been clarified.

Topological transformations of meridional motion in a three-liquid vortex

Topological transformations of meridional motion in a three-liquid vortex

The Topological Transformation of Trefoil Knots to Solomon Links via Diels-Alder Click Reaction.

The quest for more efficient, user-friendly, and less wasteful topological transformations remains a significant challenge in the realm of postassembly modifications. In this article, high yields of two molecular trefoil knots (Rh-1, Ir-1) were obtained using ligand 3,6-bis(3-(pyridin-4-yl)phenyl)-1,2,4,5-tetrazine (L1) with reactive tetrazine units and binuclear half-sandwich organometallic units [Cp*2M2(μ-TPPHZ)(OTf)2](OTf)2 (Rh-B, M = RhIII; Ir-B, M = IrIII). 2,5-Norbornadiene was used as an inducer of the Diels-Alder click reaction to modulate rapidly and efficiently the transformation of Trefoil knots to Solomon links. However, the key to achieving this topological structural change is the subtle increase in site steric of the pyridazine fragments (L2), which allows the molecular structures to spread and bend in three-dimensional space, as confirmed by single-crystal X-ray diffraction, ESI-TOF/MS, elementary analysis and detailed solution-state NMR techniques.

Mathematical Model of the Process of Data Transmission over the Radio Channel of Cyber-Physical Systems

This article introduces a refined mathematical model to evaluate the quality of mobile radio channels within cyber-physical systems, employing the topological transformation of stochastic networks. The operation of the radio channel is conceptualized as a stochastic network, enabling the derivation of critical metrics such as an equivalent function, mathematical expectation, variance, and the time distribution function of the implemented processes. The model uses the Gamma distribution for the initial distribution functions of random variables, enhancing its analytical precision. A significant advancement of this study is the development of a comprehensive model that describes the data transmission process through phases of connection establishment, information transmission, and connection maintenance. The innovative aspect of this research lies in applying an equivalent function to a stochastic network that includes a logical “AND” node with gamma-distributed incoming branches. The stochastic network presented in the article, which includes a logical “AND” node, helps to elucidate the mechanism for obtaining an equivalent function for such networks, allowing the application area of the GERT method to be expanded. This methodological enhancement extends the previously limited scope of topological transformation methods, which only applied to exponential distribution models for the timing of branch inputs. By integrating a Gamma distribution, the model simplifies the equivalent function and reduces the computational complexity required to assess the radio channel’s quality, ensuring the accuracy needed for engineering calculations. Moreover, the proposed method requires 25–40% fewer series members than the traditional Taylor series decomposition, while maintaining comparable computational complexity for the typical series members. Furthermore, the maximum absolute error in the calculations is capped at 9 × 10−3, which is well within acceptable limits for engineering purposes. Primarily designed for radio channels in cyber-physical systems, the model’s applicability extends to wireless communications, providing a valuable tool for evaluating channel efficiency and security in the face of increasing cyber threats.

Bilinear stiffness and bimodular Poisson's ratio in cylindrical sinusoidal lattices through topology morphing

Bilinear elastic behaviour allows structural designs to respond in either a stiff or compliant manner depending on the load. Here a cylindrical sinusoidal lattice structure is described that stiffens beyond a certain load. When subjected to axial compression, the lattice can undergo a topological transformation by forming contact connections. This topology change involves a transition from rectangular-like unit cells to kagome-like unit cells, associated with an approximately fourfold increase in stiffness. The lattice exhibits negative Poisson's ratio with a step-change from ≈−0.66 to ≈−0.23 prior to and during contact formation, respectively. After contact formation, it displays a nonlinear Poisson's ratio behaviour. The mechanics underpinning these behaviours are analysed using a combination of experiments and numerical modelling. A comparison with similar planar lattices reveals the effect of the global topology of the lattice (e.g. planar, cylindrical) on the unit cell-level topology morphing. The proposed topology-morphing cylindrical sinusoidal lattice introduces new design possibilities in the application-rich context of tubular structures with nonlinear mechanical properties.

Proton-triggered topological transformation in superbase-mediated selective polymerization enables access to ultrahigh-molar-mass cyclic polymers.

The selective synthesis of ultrahigh-molar-mass (UHMM, >2 million Da) cyclic polymers is challenging as an exceptional degree of spatiotemporal control is required to overcome the possible undesired reactions that can compete with the desired intramolecular cyclization. Here we present a counterintuitive synthetic methodology for cyclic polymers, represented here by polythioesters, which proceeds via superbase-mediated ring-opening polymerization of gem-dimethylated thiopropiolactone, followed by macromolecular cyclization triggered by protic quenching. This proton-triggered linear-to-cyclic topological transformation enables selective, linear polymer-like access to desired cyclic polythioesters, including those with UHMM surpassing 2 MDa. In addition, this method eliminates the need for stringent conditions such as high dilution to prevent or suppress linear polymer contaminants and presents the opposite scenario in which protic-free conditions are required to prevent cyclic polymer formation, which is capitalized to produce cyclic polymers on demand. Furthermore, such UHMM cyclic polythioester exhibits not only much enhanced thermostability and mechanical toughness, but it can also be quantitatively recycled back to monomer under mild conditions due to its gem-disubstitution.

Wavelength-tuned transformation between photonic skyrmion and meron spin textures

Topological spin textures, among which skyrmions and merons are typical examples, have with their swirling vectorial structures triggered enormous interest in physical systems including elementary particles and magnetic materials. Manipulating their symmetry and topology is important for understanding the mechanisms that underlie their topological phase transformation as well as offering tunable degrees of freedom to encode information, which has already been demonstrated in magnetic materials. Recently, the photonic counterparts of skyrmions and merons were constructed in a 2D wave system with deep-subwavelength features promising for optical sensing, imaging, and information decoding. However, their experimental realization relied on stringent excitation conditions that only support a single spin texture type on a specific structure. Here, we demonstrate for the first time the transformation between photonic skyrmion and meron spin lattices on the same metallic meta-surface having a well-designed structural period. We show experimentally the wavelength-tuned symmetry transformation of the photonic spin lattices, which are also found to be robust against disorder in the structure to a certain degree. This work provides new insights into controlling the electromagnetic field symmetry and topology, as well as in developing applications in spin optics and topological photonics.

Representations of groups on Banach spaces

We establish a general framework for representability of a metric group on a (well-behaved) class of Banach spaces. More precisely, let G \mathcal {G} be a topological group, and A \mathcal {A} a unital symmetric C ∗ C^* -subalgebra of U C ( G ) \mathrm {UC}(\mathcal {G}) , the algebra of bounded uniformly continuous functions on G \mathcal {G} . Generalizing the notion of a stable metric, we study A \mathcal {A} -metrics δ \delta , i.e., the function δ ( e , ⋅ ) \delta (e, \cdot ) belongs to A \mathcal {A} ; the case A = W A P ( G ) \mathcal {A}=W\hskip -0.7mm A\hskip -0.2mm P(\mathcal {G}) , the algebra of weakly almost periodic functions on G \mathcal {G} , recovers stability. If the topology of G G is induced by a left invariant metric d d , we prove that A \mathcal {A} determines the topology of G \mathcal {G} if and only if d d is uniformly equivalent to a left invariant A \mathcal {A} -metric. As an application, we show that the additive group of C [ 0 , 1 ] C[0,1] is not reflexively representable; this is a new proof of Megrelishvili [Topological transformation groups: selected topics, Elsevier, 2007, Question 6.7] (the problem was already solved by Ferri and Galindo [Studia Math. 193 (2009), pp. 99–108] with different methods and later the results were generalized by Yaacov, Berenstein, and Ferri [Math. Z. 267 (2011), pp.129–138]). Let now G \mathcal {G} be a metric group, and assume A ⊆ L U C ( G ) \mathcal {A}\subseteq \mathrm {LUC}(\mathcal {G}) , the algebra of bounded left uniformly continuous functions on G \mathcal {G} , is a unital C ∗ C^* -algebra which is the uniform closure of coefficients of representations of G \mathcal {G} on members of F \mathscr {F} , where F \mathscr {F} is a class of Banach spaces closed under ℓ 2 \ell _2 -direct sums. We prove that A \mathcal {A} determines the topology of G \mathcal {G} if and only if G \mathcal {G} embeds into the isometry group of a member of F \mathscr {F} , equipped with the weak operator topology. As applications, we obtain characterizations of unitary and reflexive representability.

Hydrothermal Hydrolyzation-Driven Topological Transformation of Ni-Co Bimetallic Compounds with Hollow Nanoflower Structure for Optimizing Hydrogen Evolution Catalysis.

Composition screening and structure optimization are two critical factors in improving the electrocatalytic performance of hybrid materials. Herein, we present a straightforward hydrothermal hydrolyzation-topological transformation strategy for the synthesis of a range of Ni-Co bimetallic compounds with a hollow nanoflower structure. Among these Ni-Co compounds, Ni2P/Co2P hollow nanoflowers (HNFs) exhibit the most impressive electrocatalytic activity for the hydrogen evolution reaction (HER), necessitating only an 153 mV overpotential to achieve a current density of 10 mA cm-2 under alkaline conditions. Importantly, this performance remains stable for over 48 h, indicating exceptional durability. The exceptional catalytic performance of Ni2P/Co2P HNFs arises from the synergy between the hybrid Ni2P/Co2P components and the hollow nanoflower structure. The former provides abundant catalytic sites, while electron rearrangement at the heterointerfaces enhances the adsorption/desorption of active species and facilitates electron transfer. The latter contributes to the exposure of catalytic sites, shortening mass and charge transfer routes, and bolstering structural stability during prolonged electrocatalysis. This research offers valuable insights into the screening and optimization of advanced hybrid electrocatalysts, holding significant promise for applications in the emerging field of new energy technologies.

Topology-Accelerated and Selective Cascade Depolymerization of Architecturally Complex Polyesters.

Despite considerable recent advances already made in developing chemically circular polymers (CPs), the current framework predominantly focuses on CPs with linear-chain structures of different monomer types. As polymer properties are determined by not only composition but also topology, manipulating the topology of the single-monomer-based CP systems from linear-chain structures to architecturally complex polymers could potentially modulate the resulting polymer properties without changing the chemical composition, thereby advancing the concept of monomaterial product design. To that end, here, we introduce a chemically circular hyperbranched polyester (HBPE), synthesized by a mixed chain-growth and step-growth polymerization of a rationally designed bicyclic lactone with a pendent hydroxyl group (BiLOH). This HBPE exhibits full chemical recyclability despite its architectural complexity, showing quantitative selectivity for regeneration of BiLOH, via a unique cascade depolymerization mechanism. Moreover, distinct differences in materials properties and performance arising from topological variations between HBPE, hb-PBiLOH, and its linear analogue, l-PBiLOH, have been revealed where generally the branched structure led to more favorable interchain interactions, and topology-amplified optical activity has also been observed for chiral (1S, 4S, 5S)-hb-PBiLOH. More intriguingly, depolymerization of l-PBiLOH proceeds through an unexpected, initial topological transformation to the HBPE polymer, followed by the faster cascade depolymerization pathway adopted by hb-PBiLOH. Overall, these results demonstrate that CP design can go beyond typical linear polymers, and rationally redesigned, architecturally complex polymers for their unique properties may synergistically impart advantages in topology-augmented depolymerization acceleration and selectivity for exclusive monomer regeneration.

Selective Phosphate Adsorption Using Topologically Regulated Binary-Defect Metal-Organic Frameworks: Essential Role of Interfacial Electron Mobility.

Metal-organic framework (MOF)-modified biochars (BC) have gained recognition as potent adsorbents for phosphate. However, essential insights into the electronic interfacial state of the MOFs remain lacking. In this study, we propose a novel topological transformation strategy to directionally regulate the interfacial electronic states of BC/MOFs composites. The optimized BC/MOFs exhibited an excellent selective phosphate adsorption capacity of 188.68 mg·g-1, coupled with rapid sorption kinetics of 6.81 mg·(g·min0.5)-1 in simulated P-laden wastewater. When challenged with real bioeffluent, such efficacy was still maintained (5 mg·L-1, 25.92 mg·g-1). This superior performance was due to the Fe(III) → Fe(II) transition, promoting electron mobility and leading to the anchoring of Mg(II) to form specific coordination unsaturated sites (Mg-CUS) for phosphate adsorption. Importantly, the simultaneous regulation of binary defects further enhances electron mobility, resulting in the formation of sp3 unequal hybrid orbitals with a stronger internal coupling capability between Mg 3s in Mg-CUS and O 2p in phosphate. Furthermore, the high electron affinity of Mg effectively promotes electron cycling, endowing BC/MOFs with a distinct self-healing capability to facilitate phosphate desorption. The outcomes of this study provide novel perspectives for electronic regulated phosphate adsorption.

Topological Spin Textures in an Insulating van der Waals Ferromagnet.

Generation and control of topological spin textures constitutes one of the most exciting challenges of modern spintronics given their potential applications in information storage technologies. Of particular interest are magnetic insulators, which due to low damping, absence of Joule heating and reduced dissipation can provide energy-efficient spin-textures platform. Here, it is demonstrated that the interplay between sample thickness, external magnetic fields, and optical excitations can generate a prolific paramount of spin textures, and their coexistence in insulating CrBr3 van der Waals (vdW) ferromagnets. Using high-resolution magnetic force microscopy and large-scale micromagnetic simulation methods, the existence of a large region in T-B phase diagram is demonstrated where different stripe domains, skyrmion crystals, and magnetic domains exist and can be intrinsically selected or transformed to each-other via a phase-switch mechanism. Lorentz transmission electron microscopy unveils the mixed chirality of the magnetic textures that are of Bloch-type at given conditions but can be further manipulated into Néel-type or hybrid-type via thickness-engineering. The topological phase transformation between the different magnetic objects can be further inspected by standard photoluminescence optical probes resolved by circular polarization indicative of an existence of exciton-skyrmion coupling mechanism. The findings identify vdW magnetic insulators as a promising framework of materials for the manipulation and generation of highly ordered skyrmion lattices relevant for device integration at the atomic level.

Sortase-Catalyzed Protein Domain Inversion.

Topological transformations and permutations of proteins have attracted significant interest as strategies to generate new protein functionalities or stability. These efforts have mainly been inspired by naturally occurring post-translational modifications, such as head-to-tail cyclization, circular permutation, or lasso-like entanglement. Such approaches can be realized experimentally via genetic encoding, in the case of circular permutation, or via enzymatic processing, in the case of cyclization. Notably, these previously described strategies leave the polypeptide backbone orientation unaltered. Here we describe an unnatural protein permutation, the protein domain inversion, whereby a C-terminal portion of a protein is enzymatically inverted from the canonical N-to-C to a C-to-C configuration with respect to the N-terminal part of the protein. The closest conceptually analogous biological process is perhaps the inversion of DNA segments as catalyzed by recombinases. We achieve these inversions using an engineered sortase A, a widely used transpeptidase. Our reactions proceed efficiently under mild conditions at 4-25 °C and are compatible with entirely heterologously-produced protein substrates.

Sortase‐Catalyzed Protein Domain Inversion

AbstractTopological transformations and permutations of proteins have attracted significant interest as strategies to generate new protein functionalities or stability. These efforts have mainly been inspired by naturally occurring post‐translational modifications, such as head‐to‐tail cyclization, circular permutation, or lasso‐like entanglement. Such approaches can be realized experimentally via genetic encoding, in the case of circular permutation, or via enzymatic processing, in the case of cyclization. Notably, these previously described strategies leave the polypeptide backbone orientation unaltered. Here we describe an unnatural protein permutation, the protein domain inversion, whereby a C‐terminal portion of a protein is enzymatically inverted from the canonical N‐to‐C to a C‐to‐C configuration with respect to the N‐terminal part of the protein. The closest conceptually analogous biological process is perhaps the inversion of DNA segments as catalyzed by recombinases. We achieve these inversions using an engineered sortase A, a widely used transpeptidase. Our reactions proceed efficiently under mild conditions at 4–25 °C and are compatible with entirely heterologously‐produced protein substrates.