Lattice Formation Research Articles

Surface barrier effect as evidence of chiral soliton lattice formation in chiral dichalcogenide CrTa3S6 crystals

The formation of chiral magnetic soliton lattice (CSL) is investigated in monoaxial chiral dichalcogenide CrTa3S6 crystals in terms of a surface barrier, which prevents the penetration of chiral solitons into the system and is an intrinsic origin of hysteresis for the continuous phase transition of nucleation-type, as discussed in the system of quantized vortices in type-II superconductors. The magnetoresistance (MR) was examined with microfabricated platelet samples in different dimensions with regard to the c-axis direction of the crystal. The CSL formation was confirmed by the discrete MR changes, reflecting the number of chiral solitons, as well as by the presence of a surface barrier, recognized as a fixed ratio of critical magnetic fields during the hysteresis field cycle. We also argue the influence of the surface barrier in bulk CrTa3S6 crystals.

Multicomponent Mixed Ionic and Electronic Conducting (MIEC) Air Electrodes and Their Heterointerface for Effective Application in Reversible Solid Oxide Cell (R-SOC): Efficacy of Stoichiometric and Off-Stoichiometric Compositions

Reversible solid oxide cell (R-SOC) has triggered research interest from the past few years for its reversible applicability for power-to-fuel (P2F) in electrolyser cell (SOEC) to generate hydrogen by splitting of high temperature steam and fuel-to-power (F2P) in fuel cell (SOFC) mode of operation to produce power by oxidation of fuel with >80% conversion efficiency [1]. Primarily, R-SOC consists of a dense electrolyte conventionally yttria stabilized zirconia (YSZ), bridged between two porous electrodes, e.g., strontium doped lanthanum manganite (LSM) as air electrode and Nickel (Ni)-YSZ cermet as fuel electrode. Significant research has been devoted to carry out the long-term stability (≥ 2000 h) degradation in endurance test primarily due to major challenges like highly humid environment in the fuel electrode, microstructural flaws and polarization losses under high operational temperature. In this context, mixed ionic and electronically conducting (MIEC) oxide-based La-Sr-Co-Fe-O (LSCF) and Ba-Sr-Co-Fe-O (BSCF) air electrodes has drawn significant attention for the effective oxygen reduction (ORR) and oxygen evolution (OER) reaction in the context of SOFC and SOEC operational mode [2,3].An attempt has been made in this present research work to establish the effect of off-stoichiometry in A-site lattice over the stoichiometric pristine compositions of La/Ba-Sr-Co-Fe-O (LSCF/BSCF)-based multicomponent MIEC-oxides and their associated heterostructure with optimised off-stoichiometric compositions that governs the electrochemical redox phenomena in conjunction with the functionally engineered Gd-doped ceria-based interlayer and buffer layer. Vacancy driven oxygen reduction (ORR) and oxide ion oxidation (OER) kinetics as a function of aliovalent charge compensation mechanism associated with the defect chemistry has also been investigated for these A-site non-stoichiometric compositions in the range of 1-0.92 for La/Ba(1-x)SrxCo1-yFeyO3-δ [x=0.4 and y=0.2]. A comparative study between the performance of the off-stoichiometric heterostructure synthesised using the optimised pristine compositions with that of the stoichiometric heterointerface has also been evaluated for their efficiency as catalyst for OER/ORR in reversible SOC mode of operation. The increasing trend of oxygen non-stoichiometry (δ) upon the transition from A-site stoichiometry to non-stoichiometric compositions reflected the formation of higher aliovalent cation of ‘Co’ to maintain the charge neutrality and thereby accelerates the associated oxygen redox kinetics. An optimum δ-value of 0.33 and 0.37 are found for LSCF and BSCF-compositions respectively having A-site non-stoichiometry of 0.94. Current density of 0.45 A.cm-2 at an applied voltage of 1.5 V @800℃ is obtained for stoichiometric composition of LSCF wherein 0.5 A.cm-2 is found for the off-stoichiometric batch corresponding to the hydrogen flux of 0.21Nl.h-1.cm-2. Such augmentation in performance may be related to the formation of higher lattice defect which eases the path for oxide ion oxidation. Formation of the interpenetrating heterointerface network at the air electrodes and electrode/electrolyte interfaces in the morphologically engineered cells having gradation in porosity has further been confirmed from Transmission Electron Microscopy (TEM) studies involving the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and the STEM-EDS elemental spectrum mapping images of the cross-section of the sintered cells and clinically corelated with SOC performances. Orientation of the crystal lattice planes in the two types of grains across the heterojunction has also been determined from the High-Resolution Transmission Electron Microscopy (HRTEM) images. Further study to envisage the presumed hypothesis, based on the rate determining steps involving the defect lattice formation and probable mechanism for selective ORR/OER application, will also be described through hole and/or oxygen vacancy formalism using XPS and density functional theory (DFT) for such hetero-interpenetrating air electrodes.

Synthesis of Thiapillar[6]arenes Bearing Redox-Active (Hydro)quinone Groups. Electrochemical and XRD Study.

Pillar[n]arenes are among the newest members of the macrocyclic family. Nevertheless, their conformational behavior and binding properties as well as redox properties of dealkylated pillar[n]arenes are well-studied. At the same time, introducing a heteroatom into a cyclophane macrocycle is already known to alter all the above properties drastically. This study presents a simple synthetic approach based on thia-Michael addition cyclization that readily resulted into hexathiapillar[6]arene with four phenylene units alternated by two redox-active hydroquinone moieties. The straightforward synthesis of the macrocycle enabled a systematic study of its conformation and redox behavior. The modification of hexathiapillar[6]arene afforded five functionalized derivatives, which were studied structurally in detail. The findings revealed interesting redox and structural properties of the macrocycle and its derivatives including the formation of crystal lattices with continuous channels and empty voids.

First‐principles Screening of Transition‐Metal Doped FeS2 As Sulfur Cathode Host for Sulfur Redox Chemistry

AbstractThe sulfur cathode host Fe1‐xMxS2 (M=transition‐metal; x=0, 0.125, and 0.25) for the sulfur redox chemistry is essential to facilitate the fast charge‐discharge kinetics of lithium‐sulfur‐batteries (LSBs). Applying first‐principles calculations, the formation energy, conductivity, work function, charge redistribution, chemical adsorption, and catalytic performance of Fe1‐xMxS2 are systematically investigated. Ti/V‐doped FeS2 has low lattice distortion and formation energy, and facilitates the Li+ diffusion due to charge redistribution. Chemical adsorption for polysulfides (LiPSs) is closely related to d‐band center of Fe1‐xMxS2. Li2S's activation begins with the transfer of electrons from the electron‐rich metal center to the empty orbitals of Li2S. Gibbs free energy change of Li2S4 to Li2S determines the catalytic efficiency. Li2S deposition and decomposition affects the redox kinetics of sulfur. Ti/V‐doped FeS2 has superior conductivity, chemical adsorption, and has low thermodynamic barrier of Li2S deposition. Li2S decomposition tends to occur on Fe0.875Ti0.125S2(001) surface. In general, Ti/V‐doped FeS2, as the host material of the sulfur cathode, is more beneficial to the cycle performance of LSBs. The electrochemical properties of sulfur cathode host materials can be controlled by doping, and can be manipulated and optimized in a certain range through electronic structure and chemical composition design in LSBs.

Harnessing negative refraction and evanescent waves toward super-resolution Lamb wave imaging

We numerically and experimentally demonstrate super-resolution focusing of the lowest anti-symmetric (A0) mode Lamb waves in a thin aluminum plate. The subwavelength focusing/imaging is achieved by exploiting the anisotropy in phononic crystal (PC) lattices and amplification of evanescent waves. To this end, we embedded a PC flat lens in the aluminum plate, consisting of holes arranged in a square lattice formation. We revealed that the bound slab phonon modes amplify evanescent waves, as previously observed for electromagnetic and acoustic waves. Hence, the slab mode helps propagate subwavelength information through the PC lens to reach the near-field image formed due to negative refraction and result in the high resolution image.

Direct Imaging of Lattice Structure and Formation Kinetics of Metal-organic Layer Composites.

Direct Imaging of Lattice Structure and Formation Kinetics of Metal-organic Layer Composites.

Understanding optical and structural properties of the CH3NH3PbI3 nanocrystal thin films under humidity conditions

Low-dimensional organic-inorganic hybrid perovskite materials have drawn a lot of interest in optoelectronic applications because of their unique optoelectronic performance in comparison to their bulk counterparts. There is an influence of humidity conditions on the stability of perovskite in both positive and negative ways. The passivation of surface and bulk defects in the thin film of perovskite by the H2O molecules is a positive way. The negative way is that the material's stability will hinder the commercialization of perovskite-based devices. Herein, CH3NH3PbI3 nanocrystals are synthesized by the hot-injection method. The optical and structural properties of the thin film of the synthesized nanocrystals under different humidity conditions are studied through photoluminescence (PL), TRPL, Raman, X-ray diffraction (XRD), UV–Vis, spectroscopic ellipsometry, and FTIR techniques for 4 weeks. The redshift in the PL spectra of the thin film with an increase in PL intensity and carrier lifetime is caused by the shallow trap-assisted radiative recombination and localization of the charge carriers at the interface of the CH3NH3PbI3/water. The XRD, Raman, and FTIR peaks of the thin film are also shifted due to defect formation and structure distortion of the CH3NH3PbI3 crystal lattice. The thin films of these nanocrystals exhibit very high PLQY of 56% and 60% after 5 h and 1 week respectively. The results pave the way to analyse the stability of CH3NH3PbI3 nanocrystals through their optical and structural behaviour under different humidity conditions. The results also reflect that the photoemission of the synthesized material can be tuned by regulating the defect density and the structural deformation of the nanocrystals under controlled humidity conditions.

High-temperature graphitization characteristics of vitrinite and inertinite

In order to explore the graphitization characteristic differences between vitrinite and inertinite in coal, this study conducted high-temperature thermal simulation experiments (at five temperature points: 1800°C, 2100°C, 2400°C, 2700°C, and 3000°C) using inertinite-rich and vitrinite-rich samples as graphitization precursors. The quantitative comparison for the evolution characteristics of their graphite lattice was carried out using high-resolution transmission electron microscopy (HRTEM), X-ray diffractometer (XRD), and Raman spectroscopy (Raman) techniques. HRTEM revealed that an evident increase in carbon layer numbers and degree of extension was observed with increasing treatment temperature, XRD showed the variation of lattice parameters (d002/La/Lc) with temperature, Raman data revealed the variation of lattice defects (R2/R3) with temperature. It was discussed about the differences of graphite lattice construction processes between inertinite and vitrinite, throughout the entire temperature range of the experiment, the d002 spacing of inertinite was always smaller than that of vitrinite, indicating a higher degree of graphitization. vitrinite exhibited a uniform and smooth evolution state throughout the entire heating process, while inertinite exhibited an “inert” state between 1800°C and 2100°C (d002 values stagnated near at 0.3440 nm). With increasing simulated temperature, the defect level (R2 and R3) of vitrinite rapidly decreased below that of inertinite, throughout the entire temperature range, vitrinite demonstrated superior defect healing ability in terms of both rate and capability compared to inertinite. Under high-temperature thermal simulation, the three-dimensional lattice construction and defect elimination of vitrinite exhibited synchronous evolution characteristics. On the other hand, the formation of the graphite lattice in inertinite showed an evolutionary trend of “first three-dimensional lattice construction, followed by gradual defect elimination”.

First-principles study on the effects of Er/Hf ratio on the properties of L12-Al3(Er,Hf)

L12-structured tri-aluminides in additively manufactured (AM) Al alloys refine α-Al grains while playing a significant role in precipitation strengthening. To precipitate the tri-aluminide dispersoids with an improved nucleation efficiency and coarsening resistance in AM Al alloys, the joint addition of Er and Hf into Al is proposed to form ternary L12-Al3(Er,Hf) precipitates. The work applies the first-principles method of projected augmented wave (PAW) under the framework of density functional theory (DFT), to calculate the lattice constant, formation energy, binding energy, bulk modulus, and density of states of L12-Al3(Erx,Hf1-x) (x = 0, 0.25, 0.5, 0.75, 1). The effects of Er/Hf ratios on certain key properties and features of the L12-Al3(Er,Hf) compounds and an Al alloy that contains the compounds are discussed.

Atomic level decomposition mechanism of Ti2AlC into TiCx

It has proved that outwards diffusion of Al from A layers of Ti2AlC and Ti3AlC2 leads to the formation of Al2O3 layer and TiC during oxidation above 800 °C. While, no atomic level observation was conducted to reveal this transformation process. We demonstrated that the replacement of Al by Ti atoms in A planes leads to the formation of TiCx rather than the connection of two adjacent Ti2C or Ti3C2 layers after the outwards diffusion of Al atoms from A layers. This replacement arouses an adjustment of atomic distance between two adjacent Ti layers and produces one local strain. This further induces one rotation of lattice and TiCx formation instead of the twin formation Ti2C or Ti3C2 along A layer. Due to the lack of one Ti or Al layer, Edge-like structure similar to out-of-plane dislocations formed at the junctions of Ti3C2 and Ti3AlC2 or Ti2AlC and Ti3AlC2. Our observations prove that it is impossible to produce MXene at 800 °C or even high temperature.

Temporal control by cofactors prevents kinetic trapping in retroviral Gag lattice assembly

For retroviruses like HIV to proliferate, they must form virions shaped by the self-assembly of Gag polyproteins into a rigid lattice. This immature Gag lattice has been structurally characterized and reconstituted in vitro, revealing the sensitivity of lattice assembly to multiple cofactors. Due to this sensitivity, the energetic criterion for forming stable lattices is unknown, as are their corresponding rates. Here, we use a reaction-diffusion model designed from the cryo-ET structure of the immature Gag lattice to map a phase diagram of assembly outcomes controlled by experimentally constrained rates and free energies, over experimentally relevant timescales. We find that productive assembly of complete lattices in bulk solution is extraordinarily difficult due to the large size of this ∼3700 monomer complex. Multiple Gag lattices nucleate before growth can complete, resulting in loss of free monomers and frequent kinetic trapping. We therefore derive a time-dependent protocol to titrate or “activate” the Gag monomers slowly within the solution volume, mimicking the biological roles of cofactors. This general strategy works remarkably well, yielding productive growth of self-assembled lattices for multiple interaction strengths and binding rates. By comparing to the in vitro assembly kinetics, we can estimate bounds on rates of Gag binding to Gag and the cellular cofactor IP6. Our results show that Gag binding to IP6 can provide the additional time delay necessary to support smooth growth of the immature lattice with relatively fast assembly kinetics, mostly avoiding kinetic traps. Our work provides a foundation for predicting and disrupting formation of the immature Gag lattice via targeting specific protein-protein binding interactions.

MgAl2O4-based glass ceramics synthesized by thermal plasma melting

The relevance of research and application of glass-ceramic materials based on spinel (MgAl2O4) is due to its unique properties such as strength, heat resistance, and high thermal conductivity. These properties make spinel a popular material for creating hi-tech products and coatings.The paper presents the experimental results of the production spinel-based glass ceramics with the silicon dioxide content 10 to 50 wt.%. Thermal plasma melting is used obtain glassceramic samples, at 10 kW power and 90 s melting time. The obtained samples are studied by XRF, EDX, IRFS, SEM methods.It is shown that the introduction of SiO2 in the amount of not over 20 wt.% into the mixture with stoichiometric spinel, phase transformations with the formation of binary 2MgO·SiO2, MgO·SiO2, 3Al2O3·2SiO2 compounds do not occur. With increasing SiO2 content from 30 to 50 wt.%, the effect from SiO2 is significant, a quasi-amorphous phase appears in the material matrix. At the same time, the SiO2 content of 30 wt.% provides weak intensity of the stoichiometric crystalline phase MgAl2O4 at 2θ = 36.6, 44.7, 59.3, 65.4 degrees. Samples with the SiO2 content 40 to 50 wt.% are X-ray amorphous. In this case, the diffusion halo narrows due to the dominance of Si4+ during the lattice formation. This phenomenon is also confirmed by IRFS results.Based on SEM observations, a complete dissolution of the MgAl2O4 crystalline phase occurs. When the content of SiO2 is 30 to 40 wt.%, dissolution of the spinel crystalline phase is accompanied by the formation of local regions rich in Mg and Al, i.e., differentiation proceeds in the condensed phase.The research results will be of interest for the development of heat-shielding materials, and can be used for the catalyst development, in electronics and other industries producing hi-tech ceramics.

DNA Origami Tessellations.

Molecular tessellation research aims to elucidate the underlying principles that govern intricate patterns in nature and to leverage these principles to create precise and ordered structures across multiple scales, thereby facilitating the emergence of novel functionalities. DNA origami nanostructures are excellent building blocks for constructing tessellation patterns. However, the size and complexity of DNA origami tessellation systems are currently limited by several unexplored factors relevant to the accuracy of essential design parameters, the applicability of design strategies, and the compatibility between different tiles. Here, we present a general method for creating DNA origami tiles that grow into tessellation patterns with micrometer-scale order and nanometer-scale precision. Interhelical distance (D) was identified as a critical design parameter determining tile conformation and tessellation outcome. Finely tuned D facilitated the accurate geometric design of monomer tiles with minimized curvature and improved tessellation capability, enabling the formation of single-crystalline lattices ranging from tens to hundreds of square micrometers. The general applicability of the design method was demonstrated by 9 tile geometries, 15 unique tile designs, and 12 tessellation patterns covering Platonic, Laves, and Archimedean tilings. Particularly, we took two strategies to increase the complexity of DNA origami tessellation, including reducing the symmetry of monomer tiles and coassembling tiles of different geometries. Both yielded various tiling patterns that rivaled Platonic tilings in size and quality, indicating the robustness of the optimized tessellation system. This study will promote DNA-templated, programmable molecular and material patterning and open up new opportunities for applications in metamaterial engineering, nanoelectronics, and nanolithography.

The pairing symmetry in quasi-one-dimensional superconductor Rb[formula omitted]Mo[formula omitted]As[formula omitted

Quasi-one-dimensional electron systems display intrinsic instability towards long-range ordered phases at sufficiently low temperatures. The superconducting orders are of particular interest as they can possess either singlet or triplet pairing symmetry and frequently compete with magnetism. Here we report on muon spin rotation and relaxation (μSR) study of Rb2Mo3As3 characterised by one of the highest critical temperatures Tc=10.4 K among quasi-one-dimensional superconductors. The transverse-field μSR signal shows enhanced damping below Tc due to the formation of vortex lattice. Comparison of vortex lattice broadening against single gap s−, p− and d−wave models shows the best agreement for the s−wave scenario but with the anomalously small superconducting gap, Δ0, to Tc ratio of 2Δ0/kBTc=2.74(1). The alternative nodal p−wave or d−wave scenarios with marginally worse goodness of fit would yield more realistic 2Δ0/kBTc=3.50(2) and 2Δ0/kBTc=4.08(1), respectively, and thus they cannot be ruled out when accounting for the superconducting state in Rb2Mo3As3.

Fluorosulfide La2+xSr1–xF4+xS2 with a Triple-Fluorite Layer Enabling Interstitial Fluoride-Ion Conduction

Fluoride-ion conducting solid materials are applicable as solid electrolytes for sensing devices and next-generation rechargeable batteries. Most of the previously reported materials have been limited to the single-anion compounds such as fluorite-type, tysonite-type, and perovskite-type structures. These suffered from further improvements by crystal structure modification which derives a paradigm shift in the material tailoring. Fluoride and sulfide ions prefer respective coordination environments because of the different ionic radii and electronegativity. This feature implies that fluorosulfide mixed-anion compounds have potential to form anion-ordering crystal structures with new fluoride-ion conducting layers. Herein, we have found that the fluorosulfide La2+xSr1–xF4+xS2 exhibits fluoride-ion conduction. The presence of multiple anions results in the formation of an anion-ordering two-dimensional crystal lattice with triple fluorite layers, which cannot be realized for metal fluorides. Sulfide ions in the crystal structure increase the number of interstitial sites of fluoride ions, forming a fluoride-ion conduction pathway.

The Effect of Inositol Hexakisphosphate on HIV-1 Particle Production and Infectivity can be Modulated by Mutations that Affect the Stability of the Immature Gag Lattice

The assembly of an HIV-1 particle begins with the construction of a spherical lattice composed of hexamer subunits of the Gag polyprotein. The cellular metabolite inositol hexakisphosphate (IP6) binds and stabilizes the immature Gag lattice via an interaction with the six-helix bundle (6HB), a crucial structural feature of Gag hexamers that modulates both virus assembly and infectivity. The 6HB must be stable enough to promote immature Gag lattice formation, but also flexible enough to be accessible to the viral protease, which cleaves the 6HB during particle maturation. 6HB cleavage liberates the capsid (CA) domain of Gag from the adjacent spacer peptide 1 (SP1) and IP6 from its binding site. This pool of IP6 molecules then promotes the assembly of CA into the mature conical capsid that is required for infection. Depletion of IP6 in virus-producer cells results in severe defects in assembly and infectivity of wild-type (WT) virions. Here we show that in an SP1 double mutant (M4L/T8I) with a hyperstable 6HB, IP6 can block virion infectivity by preventing CA-SP1 processing. Thus, depletion of IP6 in virus-producer cells markedly increases M4L/T8I CA-SP1 processing and infectivity. We also show that the introduction of the M4L/T8I mutations partially rescues the assembly and infectivity defects induced by IP6 depletion on WT virions, likely by increasing the affinity of the immature lattice for limiting IP6. These findings reinforce the importance of the 6HB in virus assembly, maturation, and infection and highlight the ability of IP6 to modulate 6HB stability.

Reconfigurable pH-Responsive DNA Origami Lattices.

DNA nanotechnology enables straightforward fabrication of user-defined and nanometer-precise templates for a cornucopia of different uses. To date, most of these DNA assemblies have been static, but dynamic structures are increasingly coming into view. The programmability of DNA not only allows for encoding of the DNA object shape but also it may be equally used in defining the mechanism of action and the type of stimuli-responsiveness of the dynamic structures. However, these "robotic" features of DNA nanostructures are usually demonstrated for only small, discrete, and device-like objects rather than for collectively behaving higher-order systems. Here, we show how a large-scale, two-dimensional (2D) and pH-responsive DNA origami-based lattice can be assembled into two different configurations ("open" and "closed" states) on a mica substrate and further switched from one to the other distinct state upon a pH change of the surrounding solution. The control over these two configurations is achieved by equipping the arms of the lattice-forming DNA origami units with "pH-latches" that form Hoogsteen-type triplexes at low pH. In short, we demonstrate how the electrostatic control over the adhesion and mobility of the DNA origami units on the surface can be used both in the large lattice formation (with the help of directed polymerization) and in the conformational switching of the whole lattice. To further emphasize the feasibility of the method, we also demonstrate the formation of pH-responsive 2D gold nanoparticle lattices. We believe this work can bridge the nanometer-precise DNA origami templates and higher-order large-scale systems with the stimuli-induced dynamicity.

Atomistic simulation of local chemical order in NbTiZrMoV high entropy alloy based on a newly-developed interatomic potential

Numerous studies have demonstrated the importance of local chemical order (LCO) in influencing the mechanical properties of high entropy alloys (HEAs). However, experimental investigation of LCO remains a challenging task. In this paper, the potential parameters for NbTiZrMoV system based on the modified embedded atom method are determined by fitting the lattice constants and formation enthalpies of various binary and ternary alloys. A comparison with the results from first-principles calculations shows that the newly-developed potential has a relatively high accuracy. A hybrid MD/MC simulation is performed using the newly-developed potential to investigate the microstructural evolution of equimolar NbTiZrMoV HEA at room temperature. The simulation results show that clustering and dispersion of different elemental pairs can occur after prolonged annealing. Additionally, the Zr-V pair is observed to form LCOs with B2 structure, which may be an early stage of the experimentally observed Laves phase. Furthermore, the simulation results reveal a relationship between LCO and lattice distortion, indicating that an increase in LCO can lead to a decrease in lattice distortion, which is a significant factor in the investigation of HEA mechanical properties.

Studies on the Light-Induced Phase Transition of CsPbBr3 Metal Halide Perovskite Materials.

We investigate the internal mechanism of the light-induced phase transition of CsPbBr3 perovskite materials via density functional theory simulations. Although CsPbBr3 tends to appear in the orthorhombic structure, it can be changed easily by external stimulus. We find that the transition of photogenerated carriers plays the decisive role in this process. When the photogenerated carriers transit from the valence band maximum to conduction band minimum in the reciprocal space, they actually transit from Br ions to Pb ions in the real space, which are taken away by the Br atoms with higher electronegativity from Pb atoms during the initial formation of the CsPbBr3 lattice. The reverse transition of valence electrons leads to the weakening of bond strength, which is proved by our calculated Bader charge, electron localization function, and integral value of COHP results. This charge transition releases the distortion of the Pb-Br octahedral framework and expands the CsPbBr3 lattice, providing possibilities to the phase transition from the orthorhombic structure to tetragonal structure. This phase transition is a self-accelerating positive feedback process, increasing the light absorption efficiency of the CsPbBr3 material, which is of great significance for the widespread promotion and application of the photostriction effect. Our results are helpful to understand the performance of CsPbBr3 perovskite under a light irradiation environment.

Structural insights into HIV-1 polyanion-dependent capsid lattice formation revealed by single particle cryo-EM

The HIV-1 capsid houses the viral genome and interacts extensively with host cell proteins throughout the viral life cycle. It is composed of capsid protein (CA), which assembles into a conical fullerene lattice composed of roughly 200 CA hexamers and 12CA pentamers. Previous structural analyses of individual CA hexamers and pentamers have provided valuable insight into capsid structure and function, but detailed structural information about these assemblies in the broader context of the capsid lattice is lacking. In this study, we combined cryoelectron tomography and single particle analysis (SPA) cryoelectron microscopy to determine structures of continuous regions of the capsid lattice containing both hexamers and pentamers. We also developed a method of liposome scaffold-based invitro lattice assembly ("lattice templating") that enabled us to directly study the lattice under a wider range of conditions than has previously been possible. Using this approach, we identified a critical role for inositol hexakisphosphatein pentamer formation and determined the structure of the CA lattice bound to the capsid-targeting antiretroviral drug GS-6207 (lenacapavir). Our work reveals key structural details of the mature HIV-1 CA lattice and establishes the combination of lattice templating and SPA as a robust strategy for studying retroviral capsid structure and capsid interactions with host proteins and antiviral compounds.