Lattice Form Research Articles

Efficient and stable PtFe alloy catalyst for electrocatalytic methanol oxidation with high resistance to CO

Direct methanol fuel cells (DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation. Herein, the PtFe alloy nanoparticles (NPs) with small particle size (∼4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios (Pt1Fe2/C, Pt3Fe4/C, Pt1Fe1/C, and Pt2Fe1/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction (MOR). The optimal atomic ratio of Pt/Fe for the MOR is 1:2, and the mass activity of Pt1Fe2/C (5.40 A mg−1Pt) is 13.5 times higher than that of conventional commercial Pt/C (Pt/C-JM) (0.40 A mg−1Pt). The introduction of Fe into the Pt lattice forms the PtFe alloy phase, and the electron density of Pt is reduced after forming the PtFe alloy. In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR. The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites, promoting the cleavage of C–O bonds with good selectivity of CO2 (58.1%). Moreover, the Pt1Fe2/C catalyst exhibits higher CO tolerance, methanol electrooxidation activity, and long-term stability than other PtxFey/C catalysts.

Phase diagram of QCD matter with magnetic field: domain-wall Skyrmion chain in chiral soliton lattice

QCD matter in strong magnetic field exhibits a rich phase structure. In the presence of an external magnetic field, the chiral Lagrangian for two flavors is accompanied by the Wess-Zumino-Witten (WZW) term containing an anomalous coupling of the neutral pion π0 to the magnetic field via the chiral anomaly. Due to this term, the ground state is inhomogeneous in the form of either chiral soliton lattice (CSL), an array of solitons in the direction of magnetic field, or domain-wall Skyrmion (DWSk) phase in which Skyrmions supported by π3[SU(2)] ≃ ℤ appear inside the solitons as topological lumps supported by π2(S2) ≃ ℤ in the effective worldvolume theory of the soliton. In this paper, we determine the phase boundary between the CSL and DWSk phases beyond the single-soliton approximation, within the leading order of chiral perturbation theory. To this end, we explore a domain-wall Skyrmion chain in multiple soliton configurations. First, we construct the effective theory of the CSL by the moduli approximation, and obtain the ℂP1 model or O(3) model, gauged by a background electromagnetic gauge field, with two kinds of topological terms coming from the WZW term: one is the topological lump charge in 2+1 dimensional worldvolume and the other is a topological term counting the soliton number. Topological lumps in the 2+1 dimensional worldvolume theory are superconducting rings and their sizes are constrained by the flux quantization condition. The negative energy condition of the lumps yields the phase boundary between the CSL and DWSk phases. We find that a large region inside the CSL is occupied by the DWSk phase, and that the CSL remains metastable in the DWSk phase in the vicinity of the phase boundary.

Influence of the method of inputing a cobalt-containing emitter on the depth of the diffusion layer of chrome

The results of thermal diffusion chromium plating of samples of steel 35CrNi2-3 in technological back filling containing oxide-emitters of oxygen anions in the separating part, which create a thermionic field during heating, are presented. In one variant of saturation, powder of metallic cobalt was added to the metal part, in the second case, to accelerate diffusion processes, a cumulative lattice made of cobalt sheet was installed near the saturating surface. The saturation was carried out at a temperature of 1000 °C for 24 hours. The elemental composition of the diffusion layer was monitored using a JEOL JSM-6460LV universal scanning (scanning) electron microscope. The microhardness of the coatings was measured using an FM-800 microhardness tester. Microstructural analysis was carried out on an opti-cal microscope Axio Observer D1.m. It has been established that the presence of cobalt both in the form of a powder and in the form of a cumulative lattice contributes to the acceleration of the diffusion of chromium by 1.2–1.5 times compared with saturation without the addition of cobalt. The results obtained are experimental confirmation of the hypothesis about the mechanism of acceleration of chromium diffusion during thermal diffusion chromium plating by a thermionic flux of charged particles. The phase composition of the saturated surfaces consists of a solid solution of Cr–Fe, carbide ((Cr,Fe)7C3) and nitride ((Cr,Fe)2N and CrN) phases. Cobalt, being a non-carbide-forming element, is present in insignificant amounts in the Cr–Fe solution and does not form separate phases. It has been established that the oxide and metal components of the mixture upon heating have a complex nature of interaction, which determines the gas formation of the saturated surface and requires investigation by thermodynamic modeling methods.

Pre‐intercalation of Ammonium Ions in Layered δ‐MnO2 Nanosheets for High‐Performance Aqueous Zinc‐Ion Batteries

AbstractLayered manganese dioxide is a promising cathode candidate for aqueous Zn‐ion batteries. However, the narrow interlayer spacing, inferior intrinsic electronic conductivity and poor structural stability still limit its practical application. Herein, we report a two‐step strategy to incorporate ammonium ions into manganese dioxide (named as AMO) nanosheets as a cathode for boosted Zn ion storage. K+‐intercalated δ‐MnO2 nanosheets (KMO) grown on carbon cloth are chosen as the self‐involved precursor. Of note, ammonium ions could replace K+ ions via a facile hydrothermal reaction to enlarge the lattice space and form hydrogen‐bond networks. Compared with KMO, the structural stability and the ion transfer kinetics of the layered AMO are enhanced. As expected, the obtained AMO cathode exhibits remarkable electrochemical properties in terms of high reversible capacity, decent rate performance and superior cycling stability over 10000 cycles.

Pre-intercalation of Ammonium Ions in Layered δ-MnO2 Nanosheets for High-Performance Aqueous Zinc-Ion Batteries.

Layered manganese dioxide is a promising cathode candidate for aqueous Zn-ion batteries. However, the narrow interlayer spacing, inferior intrinsic electronic conductivity and poor structural stability still limit its practical application. Herein, we report a two-step strategy to incorporate ammonium ions into manganese dioxide (named as AMO) nanosheets as a cathode for boosted Zn ion storage. K+ -intercalated δ-MnO2 nanosheets (KMO) grown on carbon cloth are chosen as the self-involved precursor. Of note, ammonium ions could replace K+ ions via a facile hydrothermal reaction to enlarge the lattice space and form hydrogen-bond networks. Compared with KMO, the structural stability and the ion transfer kinetics of the layered AMO are enhanced. As expected, the obtained AMO cathode exhibits remarkable electrochemical properties in terms of high reversible capacity, decent rate performance and superior cycling stability over 10000 cycles.

Computational study of effects of doping Ni and Pd on CoAl for hydrogen storage capacity, elastic and electronic properties

Intermetallic compounds in B2 structure which have low density, fracture, and high strength have important applications in different engineering applications. For energy storage apparatus, the researchers have investigated new materials to improve effective efficiency in energy storage devices such as batteries and green energy technologies. The investigation of transition metal–aluminide alloys has increased due to their attractive elastic features. Like many hydrogen storage alloys, B2-type hydrogen storage alloys such as ZrCo utilize the systems of hydrogen storage in atomic gaps. If hydrogen atoms settle in the interstitial spaces, lattice expansion forms due to lattice distortion. Since plastic and elastic deformations change pressure and temperature, they are important for the material during hydrogen desorption and absorption. According to the literature, element doping effects boost hydrogen storage sufficiency. The effects of Ni- and Pd-substituted dopants on hydrogen storage, electronic and elastic features of a Cobalt-Aluminum alloy were performed using the first-principles calculations with and without spin-polarized configurations. Obtained lattice parameters for Co8Al8 are good agreement with literature values. Interstitial H doping has changed the crystal structure from cubic (BCC) to tetragonal. It is concluded that all investigated CoAl alloys included H doping has negative formation energies showing thermodynamically stabilities. All investigated alloys are stable mechanically and dynamically. Doping of H2 atoms to CoAl changes from a brittle to ductile nature. Also, Ni contributions improve ductility behavior to improve the cycle performance of the Co7NiAl8 and Co8Al7Ni alloy. It can be concluded from electronic band structure that they exhibite metallic behavior. Our obtained gravimetric and volumetric capacities which are comparable with B2 hydrogen storage material such as ZrCo, FeAl, indicate that CoAl alloys may be suitable for hydrogen storage applications.

BCOV cusp forms of lattice polarized K3 surfaces

We introduce the BCOV formula for the lattice polarized K3 surfaces. We find that it yields cusp forms expressed by certain eta products for many families of rank 19 lattice polarized K3 surfaces over P1. Moreover, for Clingher-Doran's family of U⊕E8(−1)⊕E7(−1)-polarized K3 surfaces, we obtain the Igusa cusp forms χ10 and χ12 from the formula. Inspired by the arithmetic properties of mirror maps studied by Lian-Yau, we also derive the K3 differential operators for all the genus zero groups of type Γ0(n)+.

A New Statistical Theory for Constructing Sorption Isotherms in Mesoporous Structures Represented by Bethe Lattices.

In the present work, a new statistical theory is developed to describe adsorption and desorption in mesoporous materials (pore sizes ranging from 2 to 50 nm) represented by pore networks in the form of Bethe lattices. The new theory is an extension of a previous theory applied for Statistically Disordered Chain Model (SDCM) structures and incorporates the cooperative effects emerging during phase transitions in pore networks. The theory is validated against simulations and algorithmic models that describe sorption of lattice and real fluids in Bethe lattices. It is seen that the pore network coordination number, or pore connectivity, z, has a significant impact on two important processes observed in pore networks: pore assisting condensation during adsorption and evaporation by percolation during desorption. The inclusion of pore connectivity in the earlier developed framework accounting for cooperativity effects is an important step, rendering the existing models to mimic fluid behavior in real materials more accurately. Hence, the new theory inherently contains all essential elements that may offer the extraction of more reliable pore size distributions utilizing both the adsorption and desorption branches of the isotherm.

Safety and Efficacy of Spatially Fractionated Radiation Therapy Using Lattice Radiation for Metastatic and/or Bulky Disease

Spatially fractionated radiation therapy (Lattice) delivers ablative doses to metastatic and/or unresectable tumors with a curative or palliative goal. Through different forms of three-dimensional focusing, lattice forms several spherical high-dose areas(vertices) within the tumor, to produce a more obvious peak-valley effect and limit exposure to surrounding normal tissue. This study aimed to evaluate the efficacy and toxicity of patients with metastatic and/or bulky tumors treated with Lattice radiation. Between April 2017 and February 2021, 76 patients with metastatic or bulky tumors treated with spatially-fractionated high-dose external beam radiation using the Lattice technique were included. A median dose of 15 Gy/1 fraction (range 10-45 Gy in 1/3 fractions) was delivered to the vertices in the gross tumor volumes (GTV). 46 patients were treated with Lattice radiation combined with conventional fractionated external irradiation, and 30 patients were treated with Lattice alone. Patients were evaluated for clinical response, survival, and toxicity. A total of 76 patients with 85 sites were included in the analysis, 63 (82.9%) patients had metastatic diseases. Median GTV was 138.6cc (range 4.9-3784.1cc) in volume and 6.2 cm (range:2.3-21.4cm) in greatest axial diameter. 38 tumors were in the thorax, 13 abdomen/pelvis, 19 metastatic lymph nodes, 8 bone, 5 head and neck, and 2 extremities. The median follow-up was 11.6 months (range 1.27-57.37 months). At the time of analysis, 23 patients (29.9%) were alive, without the progression of disease. 90.7% of the deceased patients died of disease progression. Median overall survival (OS) was 11.4 months (95% CI: 8.4-17.6), the 1-year OS and cancer specific survival were 46.8% and 48.7% respectively. The disease control rate (DCR) was 91.8%, including 2.4% complete remission, 48.2% partial remission, and 41.2% stable disease. Symptomatic improvement was observed in 98.7% of patients. No mortality was associated with Lattice therapy. There was no treatment-associated acute or late grade 3+ toxicity. Lattice radiation is feasible and well-tolerated in the treatment of metastatic and/or bulky diseases, and may provide a high DCR. In light of these preliminary results, it seems that this therapy may be a new paradigm for treating patients with advanced cancers.

Spin-density separation of spin-orbit coupled Bose-Einstein condensates under rotation

We investigate spatial separation of spin-density in rotating two-component Bose-Einstein condensates that feature spin-orbit coupling of the pxσˆy+pyσˆz type. The origin of this separation lies in the fact that, due to the spin-orbit coupling, each component of atoms condenses at opposite points in the py-direction. This separation is further amplified as the rotation frequency increases. The underlying physics can be explained through the use of an ansatz wavepacket in momentum space. In the case of weak density-density interaction and faster rotation, vortex-antivortex pair emerges in the condensates, which exhibits a antimeron pair textures. However, for strong density-density interaction and fast rotation, skyrmions-vortex-antivortex pair lattice forms in the condensates, which feature Néel-type skyrmions textures and antimeron pair textures. We also explore the effects of anisotropic spin-orbit couplings on the spin-density separation.

Probing Hidden Mott Gap and Incommensurate Charge Modulation on the Polar Surfaces of PdCrO_{2}.

Here we report a combined study of low-temperature scanning tunneling microscopy and dynamical mean-field theory on PdCrO_{2}, a delafossite metal with an antiferromagnetic order below ∼37.5 K. First, on the CrO_{2}-terminated polar surface we detect a gaplike feature both below and above the Néel temperature. The dynamical mean-field theory calculations indicate that this gap is opened due to the strong correlations of Cr-3d electrons, suggesting the hidden Mott nature of the gap. Then, we observe two kinds of Pd-terminated polar surfaces. One is a well-ordered Pd surface with the Fermi-surface-nesting-induced incommensurate charge modulation, while the other one is a reconstructed Pd surface with the individual nanoscale nonperiodic domain structures. On the well-ordered Pd surface, the interference between the incommensurate charge modulation and the atomic lattice forms the periodic moiré pattern. Our results provide important microscopic information for fully understanding the correlated electronic properties of this class of materials.

Analysis of the band structure of transient in-plane elastic waves based on the localized radial basis function collocation method

In this paper, the localized radial basis function collocation method is applied to investigate the in-plane elastic wave propagation of 2D phononic crystals. The direct method with local support domain in one line is used to enhance the stability of the localized radial basis function collocation method when dealing with the derivative calculations in the boundary and interface conditions. The Houbolt method is employed to discretize the time, and then the Fast Fourier Transform is adopted to obtain the band structure according to the wave vectors in the first Brillouin Zone. Different acoustic impedance ratios, filling rates, and lattice forms are studied. The numerical results can be used to validate the band structures obtained directly from the frequency domain.

Fuzzy concept lattices induced by doubly distance spaces

We introduce three algebraic structures induced by a doubly distance space on a complete co-residuated lattice. We show that (1) the two families of f-stable fuzzy sets and g-stable fuzzy sets induced by a doubly distance space are complete lattices and (2) these two families are isomorphic as lattices. We define the fuzzy concept lattice induced by a doubly distance space and show that this fuzzy concept lattice forms a complete lattice. Moreover, we give two examples related to them for an information system.

Phase transitions in chrome

In astronautics, stainless steel is widely used for the manufacture of spacecraft. Rocket fuel tanks are now made of stainless steel. In order for steel to be stainless, for example, grades 08X13 and 12X13, it must contain up to 13% chromium. In pure chromium and its alloys, phase transitions occur under temperature fluctuations and mechanical loads, during which the plastic, strength, and magnetic characteristics of steel alloys change. The article describes distinguishes between phase transformations of the 1st and 2nd kind in chromium and the inconsistency in the definition of the type of transition by different authors. The change in the form of the crystal lattice during the transition from an antiferromagnet to a paramagnet at the Neel point TN = 38 85 °C, is described. An analysis of the relationship between the type of phase transition and the type of symmetry is given. An explanation is given for the difficulties in studying phase transitions in chromium due to the imperfection of the model of the electronic configuration in the 3d layer of the chromium atom.

Experimental investigation of mechanical stiffness in lattice structures fabricated with PLA using fused deposition modelling

The objective of the paper is to design and characterise with polylactic acid (PLA) material three cellular structures in the form of lattices which are diagonal-octet-centred shapes for two sizes 6x6x6 and 12x12x12 with a compression test to examine their stiffness using FDM technology compared to polyjet technology.The study used two analytical approaches to investigate lattice structures: experimental analysis and theoretical analysis. Experimental methods such as compression tests were conducted to determine the characteristics of lattice structures. In addition, theoretical analysis was conducted using Hook's law and Ashby's Gibson model to predict appropriate behaviour. The combination of experimental and theoretical methods provided a comprehensive understanding of lattice structures and their properties.The experimental study examined the impact of the shape and size of a lattice structure on the stiffness and lightness of objects 3D printed with FDM technology by PLA material. The research revealed that the 6x6x6 diagonal lattice structure size provided a good balance between stiffness and lightness. While the 6x6x6 byte structure was even lighter, with a mass ratio of 2.09 compared to the diagonal structure, it was less rigid, with a ratio of 0.43, making the diagonal structure more suitable for certain applications. The study highlights the importance of considering both the shape and size of the lattice structure when designing 3D-printed objects with specific mechanical properties; the chosen structure could be a good choice for applications where stiffness and lightness are important.The limitations of the research lie in its limited scope, focusing primarily on the effect of shape (octet-diagonal centred) and unit cell size on Young's modulus of PLA material. Other aspects of 3D printing, such as material selection and thermal properties, were not considered. Furthermore, the results obtained are specific to the printing parameters and experimental conditions chosen, which limits their generalizability to other 3D printing configurations or methods. However, these results have important implications for optimising the PLA printing process. They enable the identification of optimal parameters, such as unit cell shape and size, to produce stiffer, higher-quality structures. In addition, the research is helping to improve the mechanical properties of 3D-printed lattice parts, paving the way for more efficient manufacturing methods and stronger components.Our analysis can be used as a decision aid for the design of FDM lattice parts. Indeed, we can choose the diagonal structure of 6x6x6, which would provide favourable stiffness for functional parts.The paper explores the compression test of lattice structures using FDM technology, which presents a new direction for additive manufacturing. The study takes an experimental approach to evaluate the reliability of various additive manufacturing technologies for creating lattice structures. The study results provide insight into the most reliable technology for producing lattice structures.

Multi-qubit quantum computing using discrete-time quantum walks on closed graphs

Universal quantum computation can be realised using both continuous-time and discrete-time quantum walks. We present a version based on single particle discrete-time quantum walk to realize multi-qubit computation tasks. The scalability of the scheme is demonstrated by using a set of walk operations on a closed lattice form to implement the universal set of quantum gates on multi-qubit system. We also present a set of experimentally realizable walk operations that can implement Grover’s algorithm, quantum Fourier transformation and quantum phase estimation algorithms. An elementary implementation of error detection and correction is also presented. Analysis of space and time complexity of the scheme highlights the advantages of quantum walk based model for quantum computation on systems where implementation of quantum walk evolution operations is an inherent feature of the system.

Predicting a Stable Dimeric Form of the PD1-PDL1 Complex: Implications for Understanding the PD1 Activation Mechanism.

The activation of T cells is typically accompanied by inhibitory mechanisms within which the programmed cell death (PD1) receptor stands out. Upon binding the ligands PDL1 and PDL2, PD1 drives T cells to an unresponsive state called exhaustion, characterized by a markedly decreased capacity to exert effector functions. For this reason, PD1 has become one of the most important targets in cancer immunotherapy. Despite the numerous studies about PD1 signaling modulation, how the PD1 signaling is activated upon the ligands' binding remains an open question. Several experimental facts suggest that the activation of the PD1-PLD1 pathway depends on the interaction with an unknown partner at the cellular membrane. In this work, we investigate the possibility that the target of PD1-PDL1 is the same PD1-PDL1 complex. We combined molecular docking with molecular dynamics and umbrella sampling simulations to explore different binding modes and assess the complexes' stability. We predicted a stable dimeric form of the extracellular domains of the PD1-PDL1 complex. This dimeric complex has an affinity comparable to the PD1-PDL1 interaction and resembles the form of a linear lattice. We proposed a new model for PD1 activation where the PD1-PDL1 dimeric form could facilitate the interaction of the intracellular domains of PD1 and the further binding and activation of the SHP2 phosphatase. This model might explain the inhibitory effect of anti-PD1/PDL1 antibodies through the prevention of the formation of the PD1-PDL1 dimers and, subsequently, the abrogation of the SHP2 phosphatase activation.

Privacy-preserving federated learning on lattice quantization

Federated learning (FL) is an important approach to cooperate with multiple devices for learning without exchanging data between devices and central server. However, due to bandwidth and other reasons, the communication efficiency should be considered when the volume of information transmitted is limited. In this paper, we utilize the tool of lattice quantization form quantization theory and the variable intercommunication interval to improve communication efficiency. Meanwhile, to make strong privacy guarantee, we incorporate the notion of differential privacy (DP) to the FL framework with local SGD algorithm. By adding calibrated noises, we propose a universal lattice quantization for differentially private federated averaging algorithm (ULQ-DP-FedAvg). We provide tight privacy bound by using some privacy techniques. We also analyze the convergence bound of ULQ-DP-FedAvg based on bits rate constraints and the growing inter-communication interval as well as the data are non-independent identically distribution (Non-IID). It turns out that the algorithm converges and preserves that the privacy has scarcely influenced on the convergence rate. The effectiveness of our algorithm is demonstrated by synthetic and real datasets.

Defect-induced atomic-level intimate interface of a hollow Ov-CeO2/CdS photocatalyst with a Z-scheme to boost hydrogen evolution

Construction of Z-scheme heterojunction catalysts with high-speed charge transfer channels for efficient photocatalytic hydrogen production from water splitting is still a challenge. In this work, a lattice-defect-induced atom migration strategy is proposed to construct an intimate interface. The oxygen vacancies of cubic CeO2 obtained from a Cu2O template are used to induce lattice oxygen migration and form SO bonds with CdS to form a close contact heterojunction with a hollow cube. The hydrogen production efficiency reaches ∼12.6 mmol·g−1·h−1 and maintains a high value over 25 h. A series of photocatalytic tests combined with density functional theory (DFT) calculations show that the close contact heterostructure not only promotes the separation/transfer of photogenerated electron-hole pairs but also regulates the intrinsic catalytic activity of the surface. A large number of oxygen vacancies and SO bonds at the interface participate in charge transfer, which accelerates the migration of photogenerated carriers. The hollow structure improves the ability to capture visible light. Therefore, the synthesis strategy proposed in this work, as well as the in-depth discussion of the interface chemical structure and charge transfer mechanism, provides new theoretical support for the further development of photolytic hydrogen evolution catalysts.

Unconventional Flat Chern Bands and 2e Charges in Skyrmionic Moiré Superlattices

The interplay of topological characteristics in real space and reciprocal space can lead to the emergence of unconventional topological phases. In this Letter, we implement a novel mechanism for generating higher-Chern flat bands on the basis of twisted bilayer graphene (TBG) coupled to topological magnetic structures in the form of the skyrmion lattice. In particular, we discover a scenario for generating |C| = 2 dispersionless electronic bands when the skyrmion periodicity and the moiré periodicity match. Following the Wilczek argument, the statistics of the charge-carrying excitations in this case is bosonic, characterized by electronic charge Q = 2e, which is even in units of electron charge e. The skyrmion coupling strength triggering the topological phase transition is realistic, with its lower bound estimated as 4 meV. The Hofstadter butterfly spectrum results in an unexpected quantum Hall conductance sequence for TBG with the skyrmion order.