Structural Restraint Research Articles

Photochromic webbing structures for monitoring UV-induced mechanical strength degradation

Abstract Webbing structures are critical load-bearing components in a wide array of applications from structural restraint layers in inflatable space habitats to safety harness belts used by construction workers. In the field, webbings are subjected to ultraviolet (UV) irradiation from sunlight, leading to material degradation and a loss of mechanical strength. To date, health monitoring of webbings has relied on empirically correlating UV-induced strength loss with variations in their inherent color, which often yields inconsistent and imprecise results. To fill this gap, we propose a novel class of photochromic webbing structures that afford noninvasive monitoring of UV-induced degradation of their mechanical strength. The webbings’ sensing capabilities are achieved by integrating a class of photochromic yarns, fabricated through a pressurized coating process. Under continuous UV irradiation, the proposed photochromic webbings exhibit a substantial color change, demonstrating a sensing lifetime equivalent to several months in field conditions. We establish a strong correlation between the webbings’ photochromic response and their strength loss, supporting the feasibility of the proposed webbings in monitoring their mechanical integrity. To elucidate the sensing mechanism, we propose a physics-based mathematical model that describes the underlying photochemical reactions. Through an asymptotic analysis, we demonstrate that the model accurately predicts the webbing’s long-term photochromic responses under extended UV irradiation. The proposed photochromic webbing structures and the predictive mathematical model could enhance the safety and integrity of webbing-based engineering systems.

Acoustic Characteristics of a Plate Silencer with a Flexible Back Cavity Under Arbitrary Boundary Conditions

The flexible back cavity (FBC) plate silencer is composed of an FBC and a flexible inner plate. Through the coupling of the sound field with the flexible inner and outer plates, the transmitted sound energy of the downstream is reduced, and it has a good broadband muffling effect at low frequencies. In order to obtain the transmission loss (TL) of the FBC plate silencer under arbitrary boundary conditions, this paper establishes the acoustic-vibration coupling model of the FBC plate silencer based on the energy principle. Translational restraints and rotational restraints are used to simulate the arbitrary boundary conditions of the flexible plate, and then the influence of the boundary conditions of the flexible plate on the TL is analyzed. The results show that the results of the proposed method are in good agreement with the finite element method (FEM) results. The structural boundary restraint has a significant influence on the acoustic characteristics of the system, and the rotational restraints suppress the muffling effect. By appropriately releasing the translational restraints, a better low-frequency broadband muffling effect can be achieved, with the minimum muffling frequency reduced by 44.8% and the muffling bandwidth broadened by 57.4%.

Ultrafast photophysics of an orange-red thermally activated delayed fluorescence emitter: the role of external structural restraint.

The application of thermally activated delay fluorescence (TADF) emitters in the orange-red regime usually suffers from the fast non-radiative decay of emissive singlet states (kSNR), leading to low emitting efficiency in corresponding organic light-emitting diode (OLED) devices. Although kSNR has been quantitatively described by energy gap law, how ultrafast molecular motions are associated with the kSNR of TADF emitters remains largely unknown, which limits the development of new strategies for improving the emitting efficiency of corresponding OLED devices. In this work, we employed two commercial TADF emitters (TDBA-Ac and PzTDBA) as a model system and attempted to clarify the relationship between ultrafast excited-state structural relaxation (ES-SR) and kSNR. Spectroscopic and theoretical investigations indicated that S1/S0 ES-SR is directly associated with promoting vibrational modes, which are considerably involved in electronic-vibrational coupling through the Huang-Rhys factor, while kSNR is largely affected by the reorganization energy of the promoting modes. By restraining S1/S0 ES-SR in doping films, the kSNR of TADF emitters can be greatly reduced, resulting in high emitting efficiency. Therefore, by establishing the connection among S1/S0 ES-SR, promoting modes and kSNR of TADF emitters, our work clarified the key role of external structural restraint for achieving high emitting efficiency in TADF-based OLED devices.

Effect of structural restraint caused by the stiffener on welding residual stress and deformation in thick-plate T-joints

Two T-joints with and without a stiffener were manufactured using 30 mm thick Q390 steel, and their welding residual stress (WRS) distribution and deformation were measured. Based on ABAQUS software, a thermo-elastic-plastic finite element method was developed to model the stress-strain field of multi-pass welding joints. The WRS distribution and deformation of two T-joints were carefully assessed according to the simulation and experimental results. Further, the effect of the location and dimensions of the stiffener on the WRS and angular distortion of the web for T-joints before and after the removal of the stiffener was numerically analyzed. The findings reveal that the structural restraint has a remarkable effect on the distribution and magnitude of the WRS for T-joints, and after removing the stiffener, the WRS of the T-joint is slightly lower than that of the T-joint under free condition. The structural restraint has a little effect on the angular distortion of the flange, but can effectively alleviate the angular distortion of the web. Before and after the removal of the stiffener, the WRS and angular distortion of the web lessen with the growth of the distance between the stiffener and backing plate or the stiffener width.

Numerical simulation of residual stress of butt-welded joint involved in complex column-beam welded structure

The objective of this work is to clarify the effect of the structural restraint and the adjacent welded joints in column-beam welded structure on the final residual stress distribution and its evolution process of the butt-welded joint between the diaphragm and the flange through numerical simulation method. Based on ABAQUS software, a three dimensional thermal-mechanical coupled method was developed to predict the residual stress distribution for multi-pass welded joints. To improve calculation efficiency, an effective computational approach that combines a relatively coarse mesh design and an instantaneous heat source model was proposed to analyze the residual stress distribution for complex welded structures. Firstly, both a fine mesh model with moving heat source and a relatively coarse mesh model with instantaneous heat source were employed to predict the residual stress distribution in the same thick-plate butt-welded joint made of high strength low alloy steel. The computational accuracy of the proposed computational method was verified through comparing the results of the fine mesh model with moving heat source and the corresponding experimental data. Then, the residual stress distributions of the column-beam welded structure, the butt-welded joint under structural restraint condition and free state were calculated using the proposed computational approach. Results suggest that the structural restraint and the adjacent welded joints in the structure have a significant effect on the residual stress distribution.

Removing the Destructive Quantum Interference in Cross Conjugation System by Structural Restraint

Removing the Destructive Quantum Interference in Cross Conjugation System by Structural Restraint

Structural and Functional Characterization of Electron Transfer Complex between Cytochrome C and Cytochrome C Oxidase

The electron transfer (ET) system in the respiratory chain is terminated by the four-electron reduction of molecular oxygen in cytochrome c oxidase, concomitant with the proton pumping from the matrix to the intermembrane space in mitochondria. The last ET reaction in the respiratory chain is mediated by a small ET protein, cytochrome c (Cyt c), and the interprotein ET reaction from Cyt c to CcO plays crucial roles in the four-electron reduction of molecular oxygen and proton pumping essential for the ATP generation in mitochondria. Although the well-defined structures of Cyt c and CcO have been already reported and the structure of the ET complex between Cyt c and CcO is indispensable to examine the regulation mechanism for the ET reaction from Cyt c to CcO, the huge molecular weight of CcO as a membrane-bound protein and large dissociation constant of CcO to Cyt c have been prevented us from the detailed analysis of the ET reaction based on molecular spectroscopies and X-ray crystallography. However, we successfully determined the structure of the ET complex between Cyt c and CcO under steady-state turnover conditions by utilizing protein-protein docking simulation combined with the experimentally determined interaction site for CcO in Cyt c and the Michaelis constants for the ET reaction from various kinds of the Cyt c mutants to CcO. The complex structure determined by the simulation revealed that the ET distance between the redox centers of two proteins, heme iron of Cyt c (Fe c ) and cupper of the CuA site of CcO (CuA), is nearly 23 Å, which is much longer than that previously suggested. To experimentally confirm the ET distance between two redox centers, the ET rate from Cyt c to CcO in the Cyt c – CcO complex was determined by temperature-dependent flow-flash measurements. In the flow-flash measurements, the solution containing carbon monoxide bound CcO was rapidly mixed with the oxygen-saturated solution, and, after the mixing, the four-electron reduction reaction of molecular oxygen in CcO was initiated by irradiating flash light to the reaction mixture to dissociate carbon monoxide from heme a 3 of CcO and to bind molecular oxygen to the heme a 3 site. Associated with the reduction of molecular oxygen, the successive ET reactions from Cyt c to CcO are induced. The ET rate from Fe c of Cyt c to CuA of CcO can be determined by the oxidation rate of Fe c of Cyt c. Based on the Marcus equation for the ET reaction, the ET distance estimated from the oxidation rate of Cyt c was less than 19 Å, which is substantially shorter than the Fe c –CuA distance in the simulated Cyt c–CcO complex. This finding allows us to speculate that the “ET-active complex” showing the ET rate as detected in the flow-flush experiments would have a different binding orientation of Cyt c on CcO from that in the complex, “energetically stable complex”, determined by the previous docking simulation. To structurally characterize the “ET-active complex”, a protein-protein docking simulation under the structural restraint of the short Fe c –CuA distance was applied, and we found a stable complex structure showing that the Fe c –CuA distance is ~ 18 Å, corresponding to the experimentally determined ET distance (< 18.6 Å). The orientation of Cyt c on CcO in the newly determined Cyt c – CcO complex was significantly different from that in the “energetically stable complex”, suggesting the “conformational gating” where the thermal motions of the protein induce the conformational changes of the protein from the most energetically stable structure to the less stable but more active structure of the proteins. In the ET reaction from Cyt c to CcO, the “ET-active complex showing fast ET rate and the short ET distance between two redox centers would not be the most energetically stable structure in the Cyt c – CcO complexes and the structural fluctuation induced by the thermal motion would be a trigger to the conformational changes from the “energetically stable complex” to the “ET-active complex”. The much slower oxidation rate of Cyt c by CcO observed for the steady-state kinetics measurements also supports the “conformational gating” mechanism in the ET reaction from Cyt c to CcO, where the rate for the conformational changes from the “energetically stable complex” to the “ET-active complex” would be the rate-determinant step for the ET reaction from Cyt c to CcO.

Improving complex knowledge base question answering via structural information learning

Responding to complex questions is one of the most difficult and valuable goals of KBQA. Current efforts mainly follow two approaches to extract the in-depth semantics of questions. Information retrieval-based methods tend to encode questions directly and ignore the explicit analysis of the question structure. Besides, although retaining the analysis ability of question structure, semantic parsing-based methods rely on the expensive query graph labels and suffer from sparse reward due to wrong explorations. To benefit from both sides, this paper proposes a novel semantic parsing model, structural information restraint (SIR) for KBQA. SIR applies structural information of questions for reinforcement-based path reasoning for the first time. Specifically, SIR synthesizes the dependency tree, constituency tree, and the first token to build a composited structural attention (StrucAtt) and realizes reasoning without expensive query graphs labels. Such an attention mechanism improves the efficiency of path reasoning by distinguishing different knowledge paths, based on the relevance between path features and question structure. In addition, we also design a type-assisted reward based on answer concepts (person, location, etc.) instead of simple variable types (string, number, etc.), which alleviates the sparse reward problem effectively. Besides, the experiment results clearly show that our model achieves SOTA on CWQ, CQ, and WQSP datasets.

Experimental study of fire damage to reinforced concrete tunnel slabs

Fire hazards are a major threat to tunnel structures; however, the existing understanding of the behavior of tunnel linings under fire is limited, which restricts cost-effective and safe design of tunnels for fire. The research work in this paper aims to experimentally evaluate and quantify fire damage to tunnel linings considering a combination of influencing factors. The effects of three parameters on fire damage to the ceiling (typically the most damaged area) of a tunnel lining are studied through five furnace tests on large-scale reinforced concrete slabs. The parameters include: (1) concrete composition - presence/absence of polypropylene fibers, (2) the level of structural restraint (induced using post-tensioned strands), and (3) the fire intensity and duration. These parameters are selected to reflect realistic scenarios and provide a rational basis for evaluating tunnel damage, in terms of crack pattern, spalling, discoloration, non-destructive testing, and deflections during fire and after cooling. This research provides vital experimental data for fire damage assessment of reinforced concrete tunnel linings, and assists in verifying numerical models for analyzing structural performance during both the heating and cooling phases of fire.

CURLING BEHAVIOR MECHANISM OF CEMENT CONCRETE PAVEMENT AT EARLY AGE

In order to understand the behavior and formation mechanism of cement concrete pavement curling at its early age, vibrating wire sensors with a large range were designed to monitor the vertical displacement of slabs, and the whole vertical deformation in the first 14 days of slabs under summer conditions was continuously monitored. The behavior and formation mechanism of early-age curling were numerically analyzed by the special early-age character simulation program. The results show that: the evolution behavior of the early-age curling has three stages, namely, flat slab to corner curling, corner curling to intermediate curling with slab uplift at 1/4 positions, and corner curling to intermediate curling to curling at the middle of a slab. There are several curling modes and asymmetric phenomena in the early age of slab deformation. Early-age curling is significantly correlated with an environmental field, with concrete modulus, with creep and with structural restraint. Creep has a significant dissipation effect on the early-age behavior of a slab. In the combination case of insufficient constraint and insufficient driving of temperature deformation, the solidification shape of 1/4 diagonal slab uplift and will be produced, resulting in local unevenness and the void in corresponding position of a slab. It is suggested that the action characteristics of early-age built-in deformation and basis parameters should be distinguished, and the effect of built-in deformation can be equivalently reflected by support states.

Urea-induced denaturation of immobilized yeast iso-1 cytochrome c: Role of Met80 and Tyr67 in the thermodynamics of unfolding and promotion of pseudoperoxidase and nitrite reductase activities

The Met80Ala and Met80Ala/Tyr67Ala variants of S. cerevisiae iso-1 cytochrome c (ycc) immobilized on a decane-1-thiol coated gold electrode subjected to the denaturing action of urea were studied through variable temperature cyclic voltammetry and Surface-Enhanced Resonance Raman spectroscopy (SERRS). We found that the His/OH− axial heme iron coordination in both variants is unaffected by urea up to 7 M, although some conformational changes occur that increase exposure of the heme center to solvent. The thermodynamics of the unfolding process were determined with an unprecedented approach, which can be of general use for electroactive proteins. The free energy of unfolding for both variants includes relevant entropic contributions and is lower than that for the species carrying an intact Met/His coordination, consistent with the role of the axial Fe-(S)Met bond and the H-bond network involving Tyr67 in stabilizing the polypeptide matrix in the heme crevice. Their lower conformational stability results in a different interaction with the MUA/MU SAM compared to the His/Met ycc forms. Denaturation invariably slows down the heterogeneous electron transfer process, but its effect on the activation enthalpy and pre-exponential factor differs for the species with and without His/Met axial heme ligation. In particular, urea unfolding of the M80A and M80A/Y67A mutants lowers the structural restraint to the heterogeneous ET. Here we show that removal of the Met ligand and an increased accessibility of the heme center to solvent through partial protein unfolding– which mimic the molecular stress experienced by mammalian cytochromes c upon binding to cardiolipin in the early events of apoptosis - add up to transform cytochrome c into an efficient electrocatalyst toward the reduction of hydrogen peroxide and nitrite.

Estimation of thermal stresses in the field test under the restraint method

The restraint degree of the early-age concrete structure is an important factor for the generation of the thermal stress. When the concrete cannot deform freely as a result of the restrained deformation, the thermal stress, will generate until it increases to the degree that is great enough to affect the service life and safety of the concrete structure. Therefore, a new prediction method based on the time-restraint is proposed in this study. In the field test, a combination of the strain history of the newly cast concrete wall and the linear logarithmic creep model was adopted to calculate the thermal stresses. Compared with the traditional method, the complex structural restraint development can be described by a restraint model. The restraint coefficient of a specified location in the concrete wall changes from complete restraint to non-complete restraint, which can be transformed into a function of restraint coefficient related to the curing age. Compared with previous restraint evaluations, the restraint model reflects the restraint development of early-age concrete structures more authentically. Combined with the new restraint model, the thermal stress can be estimated with the completely restrained stress.

EMG-Informed Musculoskeletal Modeling to Estimate Realistic Knee Anterior Shear Force During Drop Vertical Jump in Female Athletes.

The anterior cruciate ligament is the primary structural restraint to tibial anterior shear force. The anterior force occurring at the knee during landing contributes to anterior cruciate ligament injury risk, but it cannot be directly measured experimentally. The objective of this study was to develop electromyography-informed musculoskeletal simulations of the drop vertical jump motor task and assess the contribution of knee muscle forces to tibial anterior shear force. In this cross-sectional study, musculoskeletal simulations were used to estimate the muscle forces of thirteen female athletes performing a drop vertical jump using an electromyography-informed method. Muscle activation and knee loads that resulted from these simulations were compared to the results obtained with the more common approach of minimization of muscle effort (optimization-based method). Quadriceps-hamstrings and quadriceps-gastrocnemius co-contractions were progressively increased and their contribution to anterior shear force was quantified. The electromyography-informed method produced co-contraction indexes more consistent with electromyography data than the optimization-based method. The muscles that presented the largest contribution to peak anterior shear force were the gastrocnemii, likely from their wrapping around the posterior aspect of the tibia. The quadriceps-hamstring co-contraction provided a protective effect on the ACL and reduced peak anterior shear force by 292N with a co-contraction index increase of 25% from baseline (31%), whereas a quadriceps-gastrocnemius co-contraction index of 61% increased peak anterior shear force by 797N compared to baseline (42%). An increase in gastrocnemius contraction, which might be required to protect the ankle from the impact with the ground, produced a large quadriceps-gastrocnemius co-activation, increasing peak anterior shear force. A better understanding of each muscle's contribution to anterior shear force and, consequently, anterior cruciate ligament tension may inform subject-specific injury prevention programs and rehabilitation protocols.

Effects of α-tubulin acetylation on microtubule structure and stability

Acetylation of K40 in α-tubulin is the sole posttranslational modification to mark the luminal surface of microtubules. It is still controversial whether its relationship with microtubule stabilization is correlative or causative. We have obtained high-resolution cryo-electron microscopy (cryo-EM) reconstructions of pure samples of αTAT1-acetylated and SIRT2-deacetylated microtubules to visualize the structural consequences of this modification and reveal its potential for influencing the larger assembly properties of microtubules. We modeled the conformational ensembles of the unmodified and acetylated states by using the experimental cryo-EM density as a structural restraint in molecular dynamics simulations. We found that acetylation alters the conformational landscape of the flexible loop that contains αK40. Modification of αK40 reduces the disorder of the loop and restricts the states that it samples. We propose that the change in conformational sampling that we describe, at a location very close to the lateral contacts site, is likely to affect microtubule stability and function.

지역주민의 관광호텔 이용제약요인과 관계지향성 간 관계 연구 : 부산지역을 중심으로 한 세대별 비교 연구

As a research for analyzing the relationship between the factors that restrain the use of the tourist hotels and the relationship-orientation in order to overcome the restraint matters regarding the use of the hotels by the local residents and in order to form a long-term relationships, this research had been proceeded with the comparative research by age according to each household by being centered on the Busan region, especially. The questionnaire survey had been carried out with the local residents residing in the Busan region who have the experience of using a tourist hotel in the Busan region in the recent one year as the subjects. And the implications after collecting and analyzing a total of the 296 samples are the following: irstly, with regard to the use of the tourist hotels on the part of the local residents, it was tested that the biggest restraint condition had been the structural restraint. And, in detail, it had been able to confirm that the economic cost, the time, the crowding of the hotel, etc. had been becoming the problems. Eventually, regarding the viewpoint through which the local residents look at the tourist hotels within the region, it had been recognized as their life zone and the special domain that had been distinguished by centering on the physical object of the tourist hotel, the psychological sense of distance, etc. And, accordingly, it had been confirmed once again that they are directly connected to the economic and time conditions in the domain for using the tourist hotels. Secondly, regarding the difference according to the age and the household in relation to the use of the tourist hotels on the part of the local residents, the usage restraint of the minors in terms of the structural restrain, the relationship-orientation, etc. had stood out. However, it was confirmed the influence relationships according to the special characteristics by household did not have any difference. If we take a look at the results of the analysis by putting them together, it can be inferred that the structural restraint matters that are perceived by the local residents are the elements that can be largely perceived mainly by the youths bracket, including the economic costs, the time, etc. But, the thing that is important is the point that the level of the perception does not show any differences on the regardful levels between the youth bracket, the middle-aged bracket, and the elderly bracket by generation.

Controlling angular distortion in high strength low alloy steel thick-plate T-joints

Both numerical approach and experimental method were employed to investigate angular distortion and welding residual stress of thick-plate multi-pass T-joints made of high strength low alloy steel. The efficiency of controlling angular distortion by the structural restraint method and the presetting method was quantitatively examined based on the simulation results and the experimental measurements. The structural restraint method can reduce angular distortion of the T-joint by 73%, while the presetting method can almost completely eliminate the angular distortion through setting an appropriate initial presetting. The structural restraint method can slightly mitigate the final welding residual stress, and the presetting method has a negligible influence on the welding residual stress distribution.

Crystal Structure of the Labile Complex of IL-24 with the Extracellular Domains of IL-22R1 and IL-20R2.

Crystal structure of the ternary complex of human IL-24 with two receptors, IL-22R1 and IL-20R2, has been determined at 2.15 Å resolution. A crystallizable complex was created by a novel approach involving fusing the ligand with a flexible linker to the presumed low-affinity receptor, and coexpression of this construct in Drosophila S2 cells together with the presumed high-affinity receptor. This approach, which may be generally applicable to other multiprotein complexes with low-affinity components, was necessitated by the instability of IL-24 expressed by itself in either bacteria or insect cells. Although IL-24 expressed in Escherichia coli was unstable and precipitated almost immediately upon its refolding and purification, a small fraction of IL-24 remaining in the folded state was shown to be active in a cell-based assay. In the crystal structure presented here, we found that two cysteine residues in IL-24 do not form a predicted disulfide bond. Lack of structural restraint by disulfides, present in other related cytokines, is most likely reason for the low stability of IL-24. Although the contact area between IL-24 and IL-22R1 is larger than between the cytokine and IL-20R2, calculations show the latter interaction to be slightly more stable, suggesting that the shared receptor (IL-20R2) might be the higher-affinity receptor.

Investigation of Occupant Lower Extremity Injures under Various Overlap Frontal Crashes

With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments. A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance. Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle. Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.

Cryo-Electron Microscopy Structure of Porcine Deltacoronavirus Spike Protein in the Prefusion State

Coronavirus spike proteins from different genera are divergent, although they all mediate coronavirus entry into cells by binding to host receptors and fusing viral and cell membranes. Here, we determined the cryo-electron microscopy structure of porcine deltacoronavirus (PdCoV) spike protein at 3.3-Å resolution. The trimeric protein contains three receptor-binding S1 subunits that tightly pack into a crown-like structure and three membrane fusion S2 subunits that form a stalk. Each S1 subunit contains two domains, an N-terminal domain (S1-NTD) and C-terminal domain (S1-CTD). PdCoV S1-NTD has the same structural fold as alpha- and betacoronavirus S1-NTDs as well as host galectins, and it recognizes sugar as its potential receptor. PdCoV S1-CTD has the same structural fold as alphacoronavirus S1-CTDs, but its structure differs from that of betacoronavirus S1-CTDs. PdCoV S1-CTD binds to an unidentified receptor on host cell surfaces. PdCoV S2 is locked in the prefusion conformation by structural restraint of S1 from a different monomeric subunit. PdCoV spike possesses several structural features that may facilitate immune evasion by the virus, such as its compact structure, concealed receptor-binding sites, and shielded critical epitopes. Overall, this study reveals that deltacoronavirus spikes are structurally and evolutionally more closely related to alphacoronavirus spikes than to betacoronavirus spikes; it also has implications for the receptor recognition, membrane fusion, and immune evasion by deltacoronaviruses as well as coronaviruses in general. IMPORTANCE In this study, we determined the cryo-electron microscopy structure of porcine deltacoronavirus (PdCoV) spike protein at a 3.3-Å resolution. This is the first atomic structure of a spike protein from the deltacoronavirus genus, which is divergent in amino acid sequences from the well-studied alpha- and betacoronavirus spike proteins. Here, we described the overall structure of the PdCoV spike and the detailed structure of each of its structural elements. Moreover, we analyzed the functions of each of the structural elements. Based on the structures and functions of these structural elements, we discussed the evolution of PdCoV spike protein in relation to the spike proteins from other coronavirus genera. This study combines the structure, function, and evolution of PdCoV spike protein and provides many insights into its receptor recognition, membrane fusion, and immune evasion.

&lt;i&gt;In Situ&lt;/i&gt; EDXRD Study of MAG-Welding Using LTT Weld Filler Materials under Structural Restraint

Welding using low transformation temperature (LTT) filler materials is an innovative approach to mitigate detrimental welding residual stresses without cost-intensive post weld-treatments [1, 2]. Due to the local generation of compressive residual stresses in the weld line by means of a delayed martensite transformation a significant enhancement of the cold cracking resistance of highly stressed welded components can be expected. For the effective usage of these materials a deeper understanding of the microstructural evolution inside the weld material is necessary to determine the complex processes that cause the residual stress formation during welding. Solid-state phase transformation kinetics and the evolution of strain in LTT weld filler materials are monitored in-situ at the instrument ID15A@ESRF in Grenoble. The transferability to real components is implemented by using a realistic MAG welding process under consideration of structural restraint. During welding of multilayer joints, the phase transformation and phase specific strain evolution of each individual layer is investigated in transmission geometry by means of energy-dispersive X-ray diffraction EDXRD using high energy synchrotron radiation with a counting rate of 2.5 Hz. The measurement results of a 10% Cr / 10% Ni LTT weld filler are compared to data monitored for the conventional weld filler material G89. The in-situ data clearly indicate a strong effect on the local strain evolution and the formation of compressive strain. This results from the restraint volume expansion during the postponed austenite to martensite transformation of the LTT weld filler, which counteracts the thermal shrinkage. In contrast, for the conventional weld filler material the thermal contraction strains lead to tensile residual strain during welding. Furthermore, the results of in-situ observation during welding show that the transformation kinetic is dependent on the welding sequence.