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BackgroundTemporal interference (TI) stimulation, an innovative non-invasive brain stimulation approach, has the potential to activate neurons in deep brain regions. However, the dynamic mechanisms underlying its neuromodulatory effects are not fully understood. This study aims to investigate the effects of TI stimulation on dynamic functional connectivity (dFC) in the motor cortex.Methods40 healthy adults underwent both TI and tDCS in a double-blind, randomized crossover design, with sessions separated by at least 48 h. The total stimulation intensity of TI is 4 mA, with each channel’s intensity set at 2 mA and a 20 Hz frequency difference (2 kHz and 2.02 kHz). The tDCS stimulation intensity is 2 mA. Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected before, during, and after stimulation. dFC was calculated using the left primary motor cortex (M1) as the region of interest (ROI) and analyzed using a sliding time-window method. A two-way repeated measures ANOVA (group × time) was conducted to evaluate the effects of TI and tDCS on changes in dFC.ResultsFor CV of dFC, significant main effects of stimulation type (P = 0.004) and time (P < 0.001) were observed. TI showed lower CV of dFC than tDCS in the left postcentral gyrus (P < 0.001). TI-T2 displayed lower CV of dFC than TI-T1 in the left precentral gyrus (P < 0.001). For mean dFC, a significant main effect of time was found (P < 0.001). TI–T2 showed higher mean dFC than tDCS-T2 in the left postcentral gyrus (P = 0.018). Within-group comparisons revealed significant differences between time points in both TI and tDCS groups, primarily in the left precentral and postcentral gyri (all P < 0.001). Results were consistent across different window sizes.Conclusion20 Hz TI stimulation altered dFC in the primary motor cortex, leading to a significant decreasing variability and increasing mean connectivity strength in dFC. This outcome indicates that the 20 Hz TI frequency interacted with the motor cortex’s natural resonance.

Abstract Background Temporal interference (TI) stimulation, an innovative non-invasive brain stimulation technique, has the potential to activate neurons in deep brain regions. The objective of this study was to evaluate the effects of repetitive TI stimulation targeting the lower limb motor control area (i.e., the M1 leg area) on lower limb motor function in healthy individuals, which could provide evidence for further translational application of non-invasive deep brain stimulation. Methods In this randomized, double-blinded, parallel-controlled trial, 46 healthy male adults were randomly divided into the TI or sham group. The TI group received 2 mA (peak-to-peak) TI stimulation targeting the M1 leg area with a 20 Hz frequency difference (2 kHz and 2.02 kHz). Stimulation parameters of the sham group were consistent with those of the TI group but the current input lasted only 1 min (30 s ramp-up and ramp-down). Both groups received stimulation twice daily for five consecutive days. The vertical jump test (countermovement jump [CMJ], squat jump [SJ], and continuous jump [CJ]) and Y-balance test were performed before and after the total intervention session. Two-way repeated measures ANOVA (group × time) was performed to evaluate the effects of TI stimulation on lower limb motor function. Results Forty participants completed all scheduled study visits. Two-way repeated measures ANOVA showed significant group × time interaction effects for CMJ height (F = 8.858, p = 0.005) and SJ height (F = 6.523, p = 0.015). The interaction effect of the average CJ height of the first 15 s was marginally significant (F = 3.550, p = 0.067). However, there was no significant interaction effect on the Y balance (p > 0.05). Further within-group comparisons showed a significant post-intervention increase in the height of the CMJ (p = 0.004), SJ (p = 0.010) and the average CJ height of the first 15 s (p = 0.004) in the TI group. Conclusion Repetitive TI stimulation targeting the lower limb motor control area effectively increased vertical jump height in healthy adult males but had no significant effect on dynamic postural stability.

This paper proposes a new geometric control method for homography-based visual servo control of Underactuated UAVs. In order to solve the application difficulties of geometric control in HBVS and explore a visual servo control technology that can be applied to aerial detection operations, this paper integrates the geometric control into the visual servoing framework and design a new homography-based geometric visual servoing controller. The outer loop is used as feedback information using the virtual homography matrix between the two images. The inner loop controls the orientation of the UAVs through geometric control. The stability of the proposed controller is proved based on Lyapunov’s theory. The proposed method has better transient performance and dynamic performance than the conventional visual servo method. The excellent performance of the controller has been proven by a large number of experiments. In addition, the application of the controller on an unmanned aerial manipulator is demonstrated.

In this work, the effect of temperature on interfaces with viscoelastic behavior was investigated using experimental and theoretical means. In particular, rubber/woven fabrics with thickness of 0.5 mm were subjected to self-designed shear tests at temperatures ranging from 263.15 to 383.15 K. Derived interface cyclic regeneration was observed through shear tests. Subsequently, a bi-linear cohesive zone model (CZM) was used to describe the shear test data. A novel image processing algorithm was developed to analyze the damaged morphology of the rubber/weave interface. It was found that hairniness amount decreased by 68.4 % when the temperature increased from 263.15 to 383.15 K. In addition, by combining the bi-linear CZM with the Kohlrausch–William–Watts law, Wiliams-Landel-Ferry equation and BK criterion, a 3D temperature-dependent constitutive model (KBW) was developed. The model successfully simulated the viscoelasticity of interfaces at different temperatures with margin of error less than 9 %. Thus, this study provides a strategy for elucidating the temperature dependence of interfaces with viscoelastic behavior.

Abstract In order to employ periodic corrugated microstrip lines for reducing or suppressing electromagnetic interference in high‐speed or high‐frequency circuits, a precise method is necessary to calculate and measure the characteristic impedance of periodic microstrip lines. The equation for characteristic impedance (depending on frequency) of lossless periodic microstrip lines was obtained based on the transfer matrix method. A time domain pulse was used to measure the instantaneous impedance of conventional microstrip lines, and when the instantaneous impedance does not change with distance, it can be identified as the characteristic impedance of microstrip lines. However, when the time‐domain pulses are employed to measure the instantaneous impedance of periodic microstrip lines, rapid oscillations occur with distance. Therefore, a standard for spacing between adjacent grooves in the microstrip line can be suggested by analysing the interaction between the time‐domain pulses and the microstrip line grooves. Once such a standard is satisfied, many grooves etched along the microstrip line would no longer be distinguished by the time‐domain pulses. Such a principle and method can be used to determine the instantaneous impedance for the microstrip lines that have periodic grooves. On the other hand, when several periodic structures with different lattice constants coexist on a microstrip line, they can also be distinguished via the instantaneous impedance. A time domain reflectometer was used for measuring the instantaneous impedance of periodic microstrip lines, and the measured results are in agreement with the theoretical analysis.

Abstract Since a planar periodic transmission line can suppress drastically the electromagnetic coupling, it would be advantageous to use such a kind of transmission lines in solving the problem of miniaturization of circuit area. By adjusting the lattice constants and geometric parameters of periodic microstrip lines, a time domain characteristic impedance that is the same as that of conventional microstrip lines (CMLs) can be achieved. Such periodic microstrip lines can therefore be used to trick high-speed digital signals, causing a digital signal to misjudge the time domain characteristic impedance of the transmission lines. The theoretical analysis has been verified by our experimental measurement results. Besides, a specific expression for the characteristic impedance of lossless periodic artificial materials is deduced by a circuit model and a standard of misidentification for the characteristic impedance of periodic microstrip lines is given for the digital signals.

In order to directly observe the conversion between guided-wave modes and leaky-wave modes in a periodic structure, quadrilateral periodic metal diaphragms arranged in two ways on metal surfaces were analyzed. In the first scheme, each unit cell in the periodic structure contains a metal diaphragm, of which the dispersion characteristics of periodic structures were analyzed by the finite element method. The results of the numerical simulation show that by adjusting lattice constants of periodic structures and geometrical parameters of metal diaphragms, the transmission bandwidth of the present 1-D periodic metal diaphragm structures could be limited to X-band, where the transmission characteristics are easy to be measured. In the second scheme, a pair of mirror-symmetric and staggered quadrilateral metal diaphragms is introduced into a unit cell. It can be found in the theoretical calculation that a new dispersion curve, which passes through the light line in a high frequency range, can be exhibited. The propagation constants of dispersion curves become complex numbers and provide highly directional electromagnetic radiation that scans as the frequency changes. After the relative positions of the two metal diaphragms were properly adjusted, the frequency range of the forbidden band gap between two dispersion curves can be minimized, so as to increase the transmission bandwidth of the 1-D periodic metal structures. The experimentally measured results show that the dispersion curves of the two periodic structures were highly consistent with the theoretical results. The narrowing of the band gap could be verified by measuring the $S$ -parameters. The near-field measurement of the periodic metal structures can demonstrate the conversion between the guided-wave modes and the leaky-wave modes, and the far-field measurement can show the frequency dependence of beam elevation. We expect that these artificial material structures could be widely used for designing new microwave and terahertz band devices.

This paper proposed a kind of guard traces based on a subwavelength periodic structure to reduce the far-end crosstalk (FEXT) of parallel microstrip lines in the PCB. This technology can be used to improve the false triggering and signal transmitting capacity of a multiconductor transmission line circuit system. In order to explore the present novel guard trace effect on isolating electromagnetic interference (EMI), the frequency response of the mutual capacitance and mutual inductance of the overall circuit system was provided and an equivalent circuit model was built. In comparison to the conventional microstrip line for isolating the EMI between parallel microstrip lines, the novel guard trace can efficiently reduce the mutual capacitance and mutual inductance of the overall circuit system. Thus, it is favorable for suppressing the crosstalk between microstrip lines. The $S$ -parameters calculation result showed that this kind of subwavelength periodic microstrip guard trace can isolate the EMI between two microstrip lines more effectively. Particularly, the conventional grounded guard trace needs a lot of dense grounded holes, which severely influences the wiring design of various layers of a multilayer circuit board. However, the proposed guard trace requires only one grounded hole, which has little influence on the circuit wiring of each layer of a multilayer printed circuit board. In our experiment, the step function signal of 30 ps rise time was imported into one microstrip line to measure the FEXT of the other microstrip line. It was demonstrated by the measurement result that the subwavelength periodic microstrip guard trace can reduce the FEXT to be below 5% of the transmission signal amplitude and is more flexible in practice. In compliance with the actual demand for a high-speed circuit, three isolation structures were proposed, and their isolation effects on the electromagnetic coupling between microstrip lines were verified individually.

BackgroundTemporal interference (TI) stimulation is a novel technique that enables the non-invasive modulation of deep brain regions. However, the implementation of this technology in humans has not been well-characterized or examined, including its safety and feasibility.ObjectiveWe aimed to examine the feasibility, safety, and blinding of using TI on human participants in this pilot study.Materials and methodsIn a randomized, single-blinded, and sham-controlled pilot study, healthy young participants were randomly divided into four groups [TI and transcranial alternating current stimulation (tACS) targeting the right frontoparietal region, TI-sham, and tACS-sham]. Each participant was asked to complete N-back (N = 1 to 3) tasks before, during, and after one session of stimulation to assess their working memory (WM). The side effects and blinding efficacy were carefully assessed. The accuracy, reaction time (RT), and inverse efficiency score (IES, reaction time/accuracy) of the N-back tasks were measured.ResultsNo severe side effects were reported. Only mild-to-moderate side effects were observed in those who received TI, which was similar to those observed in participants receiving tACS. The blinding efficacy was excellent, and there was no correlation between the severity of the reported side effects and the predicted type of stimulation that the participants received. WM appeared to be only marginally improved by TI compared to tACS-sham, and this improvement was only observed under high-load cognitive tasks. WM seemed to have improved a little in the TI-sham group. However, it was not observed significant differences between TI and TI-sham or TI and tACS in all N-back tests.ConclusionOur pilot study suggests that TI is a promising technique that can be safely implemented in human participants. Studies are warranted to confirm the findings of this study and to further examine the effects of TI-sham stimulation as well as the effects of TI on deeper brain regions.

Hydrogen sulfide (H2S) has been implicated to have antidepressive effects. We sought to investigate the prevention effects of H2S donor NaHS on depression-like behavior induced by lipopolysaccharide (LPS) in mice and its potential mechanisms. Sucrose preference, force swimming, open field, and elevate zero maze were used to evaluate depression-like behavior. NF-κB and NLRP3 inflammasome activation and mitochondrial function in the hippocampus were determined. It was found that depression-like behavior induced by LPS was prevented by NaHS pretreatment. LPS caused NF-κB and NLRP3 inflammasome activation in the hippocampus as evidenced by increased phosphorylated-p65 levels and increased NLRP3, ASC, caspase-1, and mature IL-1β levels in the hippocampus, which were also blocked by NaHS. LPS increased GSDMD-N levels and TUNEL-positive cells in the hippocampus, which was prevented by NaHS. Abnormal mitochondrial morphology in the hippocampus was found in LPS-treated mice. Mitochondrial membrane potential and ATP production were reduced, and ROS production was increased in the hippocampus of LPS-treated mice. NaHS pretreatment improved impaired mitochondrial morphology and increased membrane potential and ATP production and reduced ROS production in the hippocampus of LPS-treated mice. Our data indicate that H2S prevents LPS-induced depression-like behaviors by inhibiting NLRP3 inflammasome activation and pyroptosis and improving mitochondrial function in the hippocampus.

Temporal interference (TI) could stimulate deep motor cortex and induce movement without affecting the overlying cortex in previous mouse studies. However, there is still lack of evidence on potential TI effects in human studies. To fill this gap, we collected resting-state functional magnetic resonance imaging data on 40 healthy young participants both before and during TI stimulation on the left primary motor cortex (M1). We also chose a widely used simulation approach (tDCS) as a baseline condition. In the stimulation session, participants were randomly allocated to 2 mA TI or tDCS for 20 minutes. We used a seed-based whole brain correlation analysis method to quantify the strength of functional connectivity among different brain regions. Our results showed that both TI and tDCS significantly boosted functional connection strength between M1 and secondary motor cortex (premotor cortex and supplementary motor cortex). This is the first time to demonstrate substantial stimulation effect of TI in the human brain.

This paper focuses on the disposal of iron tailings sand (ITS) and recycled aggregate of inorganic (RAI) and proposed the “ITS plus RAI” solid waste treatment methods, which uses ITS and RAI as a new base course material to replace new aggregates by 100% to apply in the pavement renovation project of national and provincial roads in Linfen city, Shanxi Province. In this paper, the compressive strength characteristic of recycled mixture with different ratios is studied for the dual waste treatment methods, and the influence factors are analyzed by multiple regression analysis. Results show that the strength of the recycled mixture composed of a high content of ITS (the mass ratio to RAI exceeds 60 : 40) ups to 7 MPa, which can meet the pavement requirements of 7d unconfined compressive strength of inorganic stabilized base material under various traffic load conditions. The factors affecting the strength of recycled materials include the content of various components, while the particle size of iron tailings sand is the most significant influence factor. Therefore, the proportion of iron tailings sand in the recycled mixture can be further improved by screening coarse iron tailings sand so as to maximize the content of iron tailings sand, which will lead to an excellent engineering value.

The pathogenesis of type 2 diabetes (T2D) is highly related to the abnormal self-assembly of the human islet amyloid polypeptide (hIAPP) into amyloid aggregates. To inhibit hIAPP aggregation is considered a promising therapeutic strategy for T2D treatment. Melatonin (Mel) was reported to effectively impede the accumulation of hIAPP aggregates and dissolve preformed fibrils. However, the underlying mechanism at the atomic level remains elusive. Here, we performed replica-exchange molecular dynamics (REMD) simulations to investigate the inhibitory effect of Mel on hIAPP oligomerization by using hIAPP20–29 octamer as templates. The conformational ensemble shows that Mel molecules can significantly prevent the β-sheet and backbone hydrogen bond formation of hIAPP20–29 octamer and remodel hIAPP oligomers and transform them into less compact conformations with more disordered contents. The interaction analysis shows that the binding behavior of Mel is dominated by hydrogen bonding with a peptide backbone and strengthened by aromatic stacking and CH–π interactions with peptide sidechains. The strong hIAPP–Mel interaction disrupts the hIAPP20–29 association, which is supposed to inhibit amyloid aggregation and cytotoxicity. We also performed conventional MD simulations to investigate the influence and binding affinity of Mel on the preformed hIAPP1–37 fibrillar octamer. Mel was found to preferentially bind to the amyloidogenic region hIAPP20–29, whereas it has a slight influence on the structural stability of the preformed fibrils. Our findings illustrate a possible pathway by which Mel alleviates diabetes symptoms from the perspective of Mel inhibiting amyloid deposits. This work reveals the inhibitory mechanism of Mel against hIAPP20–29 oligomerization, which provides useful clues for the development of efficient anti-amyloid agents.

This paper focuses on the disposal of iron tailings sand (ITS) and reclaimed inorganic binder stabilized aggregate (RAI), and a new “ITS plus RAI” solid waste treatment method is innovatively proposed, which uses ITS and RAI as a new base course material to replace of new aggregates by 100%. It is found that the new ITS and RAI mixture has excellent compressive performance by designing the material composition of the mixture, which can meet the design strength of different levels of pavement under various load conditions. A series of laboratory tests are used to study the effect of the content of special cementitious material and iron tailings on the uniaxial compressive strength, flexural-tensile strength, compressive resilience modulus, and flexural-tensile resilience modulus of recycled mixture. And, the scanning electron microscope test (SEM) and X-ray diffraction test (XRD) are used to compare the surface morphology characteristics and hydration products of the recycled mixture under different ratios and to discuss the formation mechanism of the strength of the mixture. The test results show that the macroscopic change pattern in laboratory tests is basically consistent with the results in microanalysis. The relationship between compressive strength and compressive resilience modulus and flexural resilience modulus is also established by linear regression. This solid waste treatment method is applied to the pavement renovation project of national and provincial roads in Shanxi Province (within Linfen), to replace the existing base material by using recycled mixture, and the results show that it can save not only the carbon emission from stone mining and processing but also the construction cost, while producing good social and economic benefits and promoting the process of carbon neutralization in the world.

Traditional bridge monitoring has found it difficult to meet the current diversified needs, and frequent replacement of sensor batteries is neither economical nor environmentally friendly. This paper presents a wireless acceleration sensor with low power consumption and high sensitivity through integrated circuit design, data acquisition and wireless communication design, package design, etc. The accuracy of the sensor in data collection was verified through calibration and performance comparison tests. The ability of triangular piezoelectric cantilever beam (PCB) was tested through design and physical manufacture. Finally, the self-powered performance of the sensor was tested by connecting the sensor and the triangular PCB through a circuit, which verifies the feasibility of using the PCB to collect bridge vibration energy and convert it into electrical energy to supply power for sensor, and also explore the green energy collection and application.

In order to study dynamic characteristics of warm mix foamed asphalt mixture in seasonal frozen area, cylinder dynamic modulus test of four kinds of mixture with two gradations and three kinds of asphalt was carried out by UTM-100. Then, the effects of test temperature, loading frequency, and foaming water consumption on dynamic modulus were analyzed. Finally, the compressive resilient modulus trial was made to compare mechanical properties. Results show that dynamic modulus for warm mix foamed asphalt mixture increases with rising temperature and decreased frequency. The inflection points of the dynamic modulus vs frequency curves at low temperature, normal temperature, and high temperature are 2 Hz, 10 Hz, and 15 Hz, respectively. Static modulus of SBS# modified and nonmodified warm mix foamed asphalt mixture is corresponding to the dynamic modulus 0.001 Hz–0.1 Hz and 0.00001 Hz–0.05 Hz. The effect on gradation type on the dynamic modulus of asphalt mixture is AC-20 > AC-13, and the degree of sensitivity of the water consumption to the master curve equation of dynamic modulus under different gradations is AC-13 > AC-20.

Assessing protein localization within lipid membranes is problematic. Here, the authors describe a single molecule visualization method based on surface-induced fluorescence attenuation (SIFA) to determine the insertion depth and lateral diffusion of a peptide in a lipid bilayer.

The aggregation of amyloid-β peptides is associated with the pathogenesis of Alzheimer's disease, in which the 30-36 fragments play an important part as a fiber-forming hydrophobic region. The fibrillar structure of Aβ30-36 has been detected by means of X-ray diffraction, but its oligomeric structural determination, biophysical characterization, and pathological mechanism remain elusive. In this study, we have investigated the structures of Aβ30-36 hexamer as well as its G33V and L34T mutants in explicit water environment using replica-exchange molecular dynamics (REMD) simulations. Our results show that the wild-type (WT) Aβ30-36 hexamer has a preference to form β-barrel and bilayer β-sheet conformations, while the G33V or L34T mutation disrupts the β-barrel structures: the G33V mutant is homogenized to adopt β-sheet-rich bilayers, and the structures of L34T mutant on the contrary get more diverse. The hydrophobic interaction plays a critical role in the formation and stability of oligomeric assemblies among all the three systems. In addition, the substitution of G33 by V reduces the β-sheet content in the most populated conformations of Aβ30-36 oligomers through a steric effect. The L34T mutation disturbs the interpeptide hydrogen bonding network, and results in the increased coil content and morphological diversity. Our REMD runs provide structural details of WT and G33V/L34T mutant Aβ30-36 oligomers, and molecular insight into the aggregation mechanism, which will be helpful for designing novel inhibitors or amyloid-based materials.

The pathology Alzheimer’s disease (AD) is associated with the self-assembly of amyloid-β (Aβ) peptides into β-sheet enriched fibrillar aggregates. A promising treatment strategy is focused on the inhibition of amyloid fibrillization of Aβ peptide. Fullerene C60 is proved to effectively inhibit Aβ fibrillation while the poor water-solubility restricts its use as a biomedicine agent. In this work, we examined the interaction of fullerene C60 and water-soluble fullerenol C60(OH)6/C60(OH)12 (C60 carrying 6/12 hydroxyl groups) with preformed Aβ40/42 protofibrils by multiple molecular dynamics simulations. We found that when binding to the Aβ42 protofibril, C60, C60(OH)6 and C60(OH)12 exhibit distinct binding dynamics, binding sites and peptide interaction. The increased number of hydroxyl groups C60 carries leads to slower binding dynamics and weaker binding strength. Binding free energy analysis demonstrates that the C60/C60(OH)6 molecule primarily binds to the C-terminal residues 31−41, whereas C60(OH)12 favors to bind to N-terminal residues 4−14. The hydrophobic interaction plays a critical role in the interplay between Aβ and all the three nanoparticles, and the π-stacking interaction gets weakened as C60 carries more hydroxyls. In addition, the C60(OH)6 molecule has high affinity to form hydrogen bonds with protein backbones. The binding behaviors of C60/C60(OH)6/C60(OH)12 to the Aβ40 protofibril resemble with those to Aβ42. Our work provides a detailed picture of fullerene/fullerenols binding to Aβ protofibril, and is helpful to understand the underlying inhibitory mechanism.

Recent experiments in function mechanism study reported that a pH low-insertion peptide (pHLIP) can insert into a zwitterionic palmitoyloleoylphosphatidylcholine (POPC) lipid bilayer at acidic pH while binding to the bilayer surface at basic pH. However, the atomic details of the pH-dependent interaction of pHLIP with a POPC bilayer are not well understood. In this study, we investigate the detailed interactions of pHLIP with a POPC bilayer at acidic and basic pH conditions as those used in function mechanism study, using all-atom molecular dynamics (MD) simulations. Simulations have been performed by employing the initial configurations, where pHLIP is placed in aqueous solution, parallel to bilayer surface (system S), partially-inserted (system P), or fully-inserted (system F) in POPC bilayers. On the basis of multiple 200-ns MD simulations, we found (1) pHLIP in system S can spontaneously insert into a POPC bilayer at acidic pH, while binding to the membrane surface at basic pH; (2) pHLIP in system P can insert deep into a POPC bilayer at acidic pH, while it has a tendency to exit, and stays at bilayer surface at basic pH; (3) pHLIP in system F keeps in an α-helical structure at acidic pH while partially unfolding at basic pH. This study provides at atomic-level the pH-induced insertion of pHLIP into POPC bilayer.

Protein misfolding and aggregation cause serious degenerative diseases, such as Alzheimer’s and type II diabetes. Human islet amyloid polypeptide (hIAPP) is the major component of amyloid deposits found in the pancreas of type II diabetic patients. Increasing evidence suggests that β-cell death is related to the interaction of hIAPP with the cellular membrane, which accelerates peptide aggregation. In this study, as a first step towards understanding the membrane-mediated hIAPP aggregation, we investigate the atomic details of the initial step of hIAPP-membrane interaction, including the adsorption orientation and conformation of hIAPP monomer at an anionic POPG lipid bilayer by performing all-atom molecular dynamics simulations. We found that hIAPP monomer is quickly adsorbed to bilayer surface, and the adsorption is initiated from the N-terminal residues driven by strong electrostatic interactions of the positively-charged residues K1 and R11 with negatively-charged lipid headgroups. hIAPP binds parallel to the lipid bilayer surface as a stable helix through residues 7–22, consistent with previous experimental study. Remarkably, different simulations lead to the same binding orientation stabilized by electrostatic and H-bonding interactions, with residues R11, F15 and S19 oriented towards membrane and hydrophobic residues L12, A13, L16 and V17 exposed to solvent. Implications for membrane-mediated hIAPP aggregation are discussed.

Increasing evidence suggests that the interaction of human islet amyloid polypeptide (hIAPP) with lipids may facilitate hIAPP aggregation and cause the death of pancreatic islet β-cells. However, the detailed hIAPP-membrane interactions and the influences of lipid compositions are unclear. In this study, as a first step to understand the mechanism of membrane-mediated hIAPP aggregation, we investigate the binding behaviors of hIAPP monomer at zwitterionic palmitoyloleoyl-phosphatidylcholine (POPC) bilayer by performing atomistic molecular dynamics simulations. The results are compared with those of hIAPP at anionic palmitoyloleoyl-phosphatidylglycerol (POPG) bilayers. We find that the adsorption of hIAPP to POPC bilayer is mainly initiated from the C-terminal region and the peptide adopts a helical structure with multiple binding orientations, while the adsorption to POPG bilayer is mostly initiated from the N-terminal region and hIAPP displays one preferential binding orientation, with its hydrophobic residues exposed to water. hIAPP monomer inserts into POPC lipid bilayers more readily than into POPG bilayers. Peptide-lipid interaction analyses show that the different binding features of hIAPP at POPC and POPG bilayers are attributed to different magnitudes of electrostatic and hydrogen-bonding interactions with lipids. This study provides mechanistic insights into the different interaction behaviors of hIAPP with zwitterionic and anionic lipid bilayers.

Neisseria meningitidis is a major public health concern worldwide, including China. A few cases of serogroup W meningococcal disease have been reported in southeast China in recent years. Thus far, invasive disease due to W isolates has involved sequence type 11. We report two cases of N. meningitidis infection caused by CC4821 serogroup W strains.

In this paper, we introduce a novel Multi-scale and Auto-tuned Semi-supervised Deep Subspace Clustering (MAS-DSC) algorithm, aimed at addressing the challenges of deep subspace clustering in high-dimensional real-world data, particularly in the field of medical imaging. Traditional deep subspace clustering algorithms, which are mostly unsupervised, are limited in their ability to effectively utilize the inherent prior knowledge in medical images. Our MAS-DSC algorithm incorporates a semi-supervised learning framework that uses a small amount of labeled data to guide the clustering process, thereby enhancing the discriminative power of the feature representations. Additionally, the multi-scale feature extraction mechanism is designed to adapt to the complexity of medical imaging data, resulting in more accurate clustering performance. To address the difficulty of hyperparameter selection in deep subspace clustering, this paper employs a Bayesian optimization algorithm for adaptive tuning of hyperparameters related to subspace clustering, prior knowledge constraints, and model loss weights. Extensive experiments on standard clustering datasets, including ORL, Coil20, and Coil100, validate the effectiveness of the MAS-DSC algorithm. The results show that with its multi-scale network structure and Bayesian hyperparameter optimization, MAS-DSC achieves excellent clustering results on these datasets. Furthermore, tests on a brain tumor dataset demonstrate the robustness of the algorithm and its ability to leverage prior knowledge for efficient feature extraction and enhanced clustering performance within a semi-supervised learning framework. [ABSTRACT FROM AUTHOR]

Background: Alzheimer's disease (AD) is one of the most popular tauopathies. Neurofibrillary tangles and senile plaques are widely recognized as the pathological hallmarks of AD, which are mainly composed of tau and ß-amyloid (Aß) respectively. Recent failures of drugs targeting Aß have led scientists to scrutinize the crucial impact of tau in neurodegenerative diseases. Mutated or abnormal phosphorylated tau protein loses affinity with microtubules and assembles into pathological accumulations. The aggregation process closely correlates to two amyloidogenic core of PHF6 (306VQIVYK311) and PHF6* (275VQIINK280) fragments. Moreover, tau accumulations display diverse morphological characteristics in different diseases, which increases the difficulty of providing a unifying neuropathological criterion for early diagnosis. Results: This review mainly summarizes atomic-resolution structures of tau protein in the monomeric, oligomeric and fibrillar states, as well as the promising inhibitors designed to prevent tau aggregation or disaggregate tau accumulations, recently revealed by experimental and computational studies. We also systematically sort tau functions, their relationship with tau structures and the potential pathological processes of tau protein. Conclusion: The current progress on tau structures at atomic level of detail expands our understanding of tau aggregation and related pathology. We discuss the difficulties in determining the source of neurotoxicity and screening effective inhibitors. We hope this review will inspire new clues for designing medicines against tau aggregation and shed light on AD diagnosis and therapies. [ABSTRACT FROM AUTHOR]

Our previous work demonstrated that liquid water can freeze continuously into either pentagonal or helical solid-like ice nanotubes in a single-walled carbon nanotube (SWCNT) with a tube diameter of 1.2 nm, depending on the strengths of an external electric (E) field applied along the tube axis. In this study, the structure and the structure transition behavior of water confined in a wider SWCNT (diameter = 1.31 nm) under the influence of E-fields are investigated by molecular dynamics simulations using the TIP4P model for water at atmospheric pressure. We find that confined water can freeze into three different polygonal (including hexagonal, heptagonal, and mixed hexagonal-heptagonal) ice nanotubes through a first-order phase transition at lower E (<0.75 V/nm), while form a helical ice nanotube encapsulating a helical water nanoline through a continuous phase transition at higher E (1.0 < E < 2.0 V/nm), different from the phase transition behavior of water in a SWCNT with a diameter = 1.2 nm. The populations of the three different polygonal ice nanotubes are modulated by both temperature and electric field. In addition, an E-induced discontinuous solidsolid phase transition between polygonal and helical ice nanotubes is observed at low temperature (T < 230 K) with a significant electric hysteresis loop of 1.0 V/nm. Finally, we present a rich phase diagram of confined water as a function of temperature and electric field, in which the boundaries of the first-order phase transition at lower E and the continuous phase transition at higher E are connected by a connecting line which corresponds to the hysteresis region. [ABSTRACT FROM AUTHOR]

The effect of polydispersity on surface segregation of a lower molecular weight polymer component in a higher molecular weight linear polymer melt host is investigated theoretically. We show that the integrated surface excess zM of a polymer component of molecular weight M satisfies a simple relation zM=2Ue(M/Mw-1)φM, where Mw is the weight averaged molecular weight, φM is the polymer volume fraction, and Ue is the attraction of polymer chain ends to the surface. Ue is principally of entropic origin, but also reflects any energetic preference of chain ends to the surface. We further show that the surface tension γM of a polydisperse melt of high molar mass components depends on the number average degree of polymerization Mn as, γM=γ∞+2UeρbRT/Mn. The parameter γ∞ is the asymptotic surface tension of an infinitely long polymer of the same chemistry, ρb is the bulk density of the polymer, R is the universal gas constant, and T is the temperature. The predicted γM compare favorably with surface tension values obtained from self-consistent field theory simulations that include equation of state effects, which account for changes in polymer density with molecular weight. We also compare the predicted surface tension with available experimental data. [ABSTRACT FROM AUTHOR]

The macro-texture of asphalt pavement greatly affects the traffic safety of driving. In this study, the 3D laser scanning data, which is captured from the pavements, is used for reverse modeling. FE software ANSYS is used to analyze the contact stress distribution of pavement macro-texture and tire. The results show that the macro texture will be affected by fatigue failure considering the size effect of coarse aggregate. The fatigue life distribution of pavements is analyzed using the fatigue analysis software FE-SAFE which is based on linear cumulative damage theory. The developing tendency of texture depth with respect to the number of loading times is obtained by analyzing the results of fatigue life. Compared with the results of accelerated loading test shows that the factor of fatigue failure has remarkably affected the macro texture under low loading times. This effect is gradually decreased with the increasing of cyclic loading times. [ABSTRACT FROM AUTHOR]

The accumulation of the human islet amyloid polypeptide (hIAPP) deposits in the pancreas is regarded as an important factor that leads to the depletion of islet β-cells and islet transplantation failure. In recent experiments, it was reported that a small organic molecule O4 inhibits the formation of hIAPP1-37 oligomers and fibrils. However, the interaction between O4 molecules and hIAPP oligomers is largely unknown on the atomic level. In this work, we studied the influence of O4 molecules on fibril-like hIAPP pentamer and decamer by performing atomistic molecular dynamics simulations. Our results show that O4 molecules mostly bind to the amyloid core region spanning residues 22NFGAI26 for both hIAPP pentamer and decamer, which leads to the local disruption of interpeptide β-sheets. The calculation of contact probability and binding energy indicates that the binding of O4 molecules is mostly driven by aromatic stacking and hydrophobic interactions. Our work reveals the detailed disruption mechanism of full-length hIAPP protofibrils by O4 molecules and may be helpful to the design of more efficient inhibitors against hIAPP aggregation. [ABSTRACT FROM AUTHOR]

Amphiphilic peptides can self-assembleinto ordered nanostructureswith different morphologies. However, the assembly mechanism and thestructures of the early assemblies prior to nanostructure formationremain elusive. In this study, we investigated the oligomeric structuresof two amphiphilic heptapeptides A6K and V6Kby all-atom explicit-solvent replica-exchange molecular dynamics (REMD)simulations, and then examined the assembly dynamics of large aggregatesby coarse-grained (CG) MD simulations. Our 200 ns REMD simulationsshow that A6K peptides predominantly adopt loosely packeddisordered coil aggregates, whereas V6K peptides mostlyassemble into compact β-sheet-rich conformations, consistentwith the signal measured experimentally in aqueous solution. Well-organizedβ-sheet-rich conformations, albeit with low population, arealso populated for V6K octamers, including bilayer β-sheetsand β-barrels. These ordered β-sheet-rich conformationsare observed for the first time for amphiphilic peptides. Our 10-μsCG-MD simulations on 200 peptide chains demonstrate that A6K and V6K peptides follow two different self-assemblyprocesses, and the former form monolayer lamellas while the latterassemble into plate-like assemblies. CG-MD simulations also show thatV6K peptides display higher assembly capability than A6K, in support of our all-atom REMD simulation results. Interpeptideinteraction analyses reveal that the marked differences in oligomericstructures and assembly dynamics between A6K and V6K result from the subtle interplay of competition among hydrophobic,hydrogen-bonding, and electrostatic interactions of the two peptides.Our study provides structural and mechanistic insights into the initialself-assembly process of A6K and V6K at themolecular level. [ABSTRACT FROM AUTHOR]

The structural engineering codes dictate the design criteria of the facility. Given that different countries use different parameters to design a facility, different codes are followed. Current code comparison focus on the clauses analysis in the code gives theoretical guideline. When the US facility design team needs to make a decision to follow which code to in China, the current study cannot provide a business decision input. This study evaluates the design process to illustrate when and where the codes will be applied and calculated through a design process where the loading and coefficient factors of different codes are analyzed. Software programs built-in codes are then used to design the structure to obtain the structure result in terms of volume of the concrete and weight of the rebar being calculated. The study also presents a case study and calculates that the United States code uses 8–10% more rebar compared to the Chinese code. The study result can be a reference for the project management team who has to make a business decision over which code to be followed at what cost. The paper also identifies the choice of the seismic coefficient factor has a significant impact on the usage of the rebar and might be justified for the future study.

Recent experiments in function mechanism study reported that a pH low-insertion peptide (pHLIP) can insert into a zwitterionic palmitoyloleoylphosphatidylcholine (POPC) lipid bilayer at acidic pH while binding to the bilayer surface at basic pH. However, the atomic details of the pH-dependent interaction of pHLIP with a POPC bilayer are not well understood. In this study, we investigate the detailed interactions of pHLIP with a POPC bilayer at acidic and basic pH conditions as those used in function mechanism study, using all-atom molecular dynamics (MD) simulations. Simulations have been performed by employing the initial configurations, where pHLIP is placed in aqueous solution, parallel to bilayer surface (system S), partially-inserted (system P), or fully-inserted (system F) in POPC bilayers. On the basis of multiple 200-ns MD simulations, we found (1) pHLIP in system S can spontaneously insert into a POPC bilayer at acidic pH, while binding to the membrane surface at basic pH; (2) pHLIP in system P can insert deep into a POPC bilayer at acidic pH, while it has a tendency to exit, and stays at bilayer surface at basic pH; (3) pHLIP in system F keeps in an a-helical structure at acidic pH while partially unfolding at basic pH. This study provides at atomic-level the pH-induced insertion of pHLIP into POPC bilayer. [ABSTRACT FROM AUTHOR]

Protein misfolding and aggregation cause serious degenerative diseases, such as Alzheimer's and type II diabetes. Human islet amyloid polypeptide (hIAPP) is the major component of amyloid deposits found in the pancreas of type II diabetic patients. Increasing evidence suggests that β-cell death is related to the interaction of hIAPP with the cellular membrane, which accelerates peptide aggregation. In this study, as a first step towards understanding the membrane-mediated hIAPP aggregation, we investigate the atomic details of the initial step of hIAPP-membrane interaction, including the adsorption orientation and conformation of hIAPP monomer at an anionic POPG lipid bilayer by performing all-atom molecular dynamics simulations. We found that hIAPP monomer is quickly adsorbed to bilayer surface, and the adsorption is initiated from the N-terminal residues driven by strong electrostatic interactions of the positively-charged residues K1 and R11 with negatively-charged lipid headgroups. hIAPP binds parallel to the lipid bilayer surface as a stable helix through residues 7--22, consistent with previous experimental study. Remarkably, different simulations lead to the same binding orientation stabilized by electrostatic and H-bonding interactions, with residues R11, F15 and S19 oriented towards membrane and hydrophobic residues L12, A13, L16 and V17 exposed to solvent. Implications for membrane-mediated hIAPP aggregation are discussed. [ABSTRACT FROM AUTHOR]

An ionic-complementary peptide, EFK16-II, was used to modify a highly ordered pyrolytic graphite (HOPG) electrode surface. The nanofiber structure of the self-assembling peptide on the electrode surface was characterized by atomic force microscopy (AFM). Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectra showed that, upon addition of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), EFK16-II molecules tend to be cross-linked among themselves. Cross-linking of the peptide diminishes the number of carboxyl groups available for immobilizing a sensing enzyme, which is glucose oxidase (GOx) in the present case. A simple method based on premixing of the carbodiimide and GOx was developed; it inhibited peptide cross-linking and significantly improved enzyme immobilization. Biosensors constructed in this way showed increased overall signal intensity and a much higher sensitivity at 4.94 mA M−1cm−2, a 6-fold increase compared to the previously reported peptide-modified electrodes. The results presented here demonstrate significant potential for ionic-complementary peptides for constructing electrochemical biosensors. [ABSTRACT FROM AUTHOR]

To evaluate the effect of polymer architecture on surface tension, glass transition, and other thermodynamic properties, we synthesized a series of 4-arm and 11-arm symmetric star polystyrenes. Surface tension was measured as a function of molecular weight of the stars and temperature in the melt using a modified Wilhelmy plate technique. We find that architectural effects play a significant role in determining the molecular weight dependence of polymer melt surface tension. A variable density lattice model that considers effects of entropic attraction of polymer chain ends to surfaces, compressibility and density gradients in the region near the surface is used to determine the origin of this observation. This analysis is complemented with surface tension calculations using more classical thermodynamic models that consider only bulk property changes with polymer architecture and molecular weight. Bulk thermodynamic properties for selected stars were derived from pressure−volume−temperature ( PVT) measurements. These data are used to calculate the cohesive energy density (CED). This was then used to determine surface tension of the stars using a recently developed theory. Possible effects of the chemical differences of the sec-butyl terminal groups versus the backbone segments are also discussed in terms of bulk property modification and surface segregation of end groups. [ABSTRACT FROM AUTHOR]

Since the emergence of digital media in the 1990s, a new realm of interaction between the visual arts and religion has been forged and evolved. The spread of visual media technologies has significantly influenced the study of religious visual art worldwide after the 1990s. Despite this, the field of religious visual art during the digital era is still relatively uncharted, with a notable absence of comprehensive theoretical frameworks. To address this gap, the present paper employs bibliometric methods, conducting a thorough review and analysis of 2544 pieces of international academic literature in the domain of religion and visual arts post-1990s. The analytical framework is structured into three primary sections, each dedicated to answering key questions: (1) what constitutes the inherent relationship in the study of religion and visual art?, (2) what disciplinary context do these interplays occur within?, and (3) in which domains and regions does this interplay predominantly unfold? The outcomes of this rigorous analysis offer valuable insights into interdisciplinary influences and evolving research trends within the realm of religious visual art. These findings stand to benefit art researchers and practitioners, providing a comprehensive overview of potential avenues for the exploration of visual arts with religious themes. Through a systematic investigation, this research endeavors to heighten scholars’ awareness of the significance of visual arts in the field of religion and illuminate the interdisciplinary trends at the intersection of religion and visual arts.

The friction between tire and road surface is fundamentally depending on the molecular forces. In this paper, the nanoscale 3D contact model is employed to investigate the tire-aggregate friction mechanism. The tire and aggregate micro-structure are both constructed to evaluate the microscopic performance of tire-aggregate friction influence. Simulation results show for a high velocity, the energy dissipation of sliding on crystal structure is small, which results in a small friction coefficient; temperature will have influences on the friction coefficient, and with the increasing of velocity, the effect will gradually reduce. [ABSTRACT FROM AUTHOR]