Monitoring soil moisture in winter wheat with crop water stress index based on canopy-air temperature time lag effect.

Crop water stress index (CWSI) has been widely used in soil moisture monitoring. However, the influence of the time lag effect between canopy temperature and air temperature on the accuracy of soil moisture monitoring with different CWSI models has not been further investigated. Therefore, based on the continuous record of canopy temperature and air temperature, this study explored the influence of canopy-air temperature hysteresis on the diagnosis of soil moisture with three CWSI models (CWSIT-theoretical, CWSIE-empirical, CWSIH-hybrid). The results show (1) the peak time of canopy temperature was ahead of that of air temperature, and the lag time varied under different soil moisture conditions. When the soil moisture was seriously deficient, the lag time decreased. However, from jointing-heading period to filling-ripening period, the lag time became longer. (2) The values of CWSIT, CWSIE, and CWSIH decreased when the time lag effect was considered. In jointing-heading period, heading-filling period, and filling-ripening period, CWSIT had the highest accuracy in soil moisture monitoring without the consideration of the time lag effect. When the time lag effect was considered, the monitoring accuracy of CWSIE and CWSIH was greatly improved and higher than that of CWSIT, while that of CWSIT was reduced. The findings provided a basis for further improving the accuracy of soil moisture monitoring with CWSI models.

Naphthoquinone-dopamine hybrids disrupt α-synuclein fibrils by their intramolecular synergistic interactions with fibrils and display a better effect on fibril disruption.

α-Synuclein (αSyn) is an intrinsically disordered protein and its abnormal aggregation into amyloid fibrils is the main hallmark of Parkinson's disease (PD). The disruption of preformed αSyn fibrils using small molecules is considered as a potential strategy for PD treatment. Recent experiments have reported that naphthoquinone-dopamine hybrids (NQDA), synthesized by naphthoquinone (NQ) and dopamine (DA) molecules, can significantly disrupt αSyn fibrils and cross the blood-brain barrier. To unravel the fibril-disruptive mechanisms at the atomic level, we performed microsecond molecular dynamics simulations of αSyn fibrils in the absence and presence of NQDA, NQ, DA, or NQ+DA molecules. Our simulations showed that NQDA reduces the ß-sheet content, disrupts K45-E57 and E46-K80 salt-bridges, weakens the inter-protofibril interaction, and thus destabilizes the αSyn fibril structure. NQDA has the ability to form cation-π and H-bonding interactions with K45/K80, and form π-π stacking interactions with Y39/F94. Those interactions between NQDA and αSyn fibrils play a crucial role in disaggregating αSyn fibrils. Moreover, we found that NQDA has a better fibril destabilization effect than that of NQ, DA, and NQ+DA molecules. This is attributed to the synergistic fibril-binding effect between NQ and DA groups in NQDA molecules. The DA group can form strong π-π stacking interactions with aromatic residues Y39/F94 of the αSyn fibril, while the DA molecule cannot. In addition, NQDA can form stronger cation-π interactions with residues K45/K80 than those of both NQ and DA molecules. Our results provide the molecular mechanism underlying the disaggregation of the αSyn fibril by NQDA and its better performance in fibril disruption than NQ, DA, and NQ+DA molecules, which offers new clues for the screening and development of promising drug candidates to treat PD.

Expanding the Structural Diversity and Functional Scope of Diphenylalanine-Based Peptide Architectures by Hierarchical Coassembly.

Modulation of the structural diversity of diphenylalanine-based assemblies by molecular modification and solvent alteration has been extensively explored for bio- and nanotechnology. However, regulation of the structural transition of assemblies based on this minimal building block into tunable supramolecular nanostructures and further construction of smart supramolecular materials with multiple responsiveness are still an unmet need. Coassembly, the tactic employed by natural systems to expand the architectural space, has been rarely explored. Herein, we present a coassembly approach to investigate the morphology manipulation of assemblies formed by N-terminally capped diphenylalanine by mixing with various bipyridine derivatives through intermolecular hydrogen bonding. The coassembly-induced structural diversity is fully studied by a set of biophysical techniques and computational simulations. Moreover, multiple-responsive two-component supramolecular gels are constructed through the incorporation of functional bipyridine molecules into the coassemblies. This study not only depicts the coassembly strategy to manipulate the hierarchical nanoarchitecture and morphology transition of diphenylalanine-based assemblies by supramolecular interactions but also promotes the rational design and development of smart hydrogel-based biomaterials responsive to various external stimuli.

Walking stability in patients with benign paroxysmal positional vertigo: an objective assessment using wearable accelerometers and machine learning.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is one of the most common peripheral vestibular disorders leading to balance difficulties and increased fall risks. This study aims to investigate the walking stability of BPPV patients in clinical settings and propose a machine-learning-based classification method for determining the severity of gait disturbances of BPPV. METHODS: Twenty-seven BPPV outpatients and twenty-seven healthy subjects completed level walking trials at self-preferred speed in clinical settings while wearing two accelerometers on the head and lower trunk, respectively. Temporo-spatial variables and six walking stability related variables [root mean square (RMS), harmonic ratio (HR), gait variability, step/stride regularity, and gait symmetry] derived from the acceleration signals were analyzed. A support vector machine model (SVM) based on the gait variables of BPPV patients were developed to differentiate patients from healthy controls and classify the handicapping effects of dizziness imposed by BPPV. RESULTS: The results showed that BPPV patients employed a conservative gait and significantly reduced walking stability compared to the healthy controls. Significant different mediolateral HR at the lower trunk and anteroposterior step regularity at the head were found in BPPV patients among mild, moderate, and severe DHI (dizziness handicap inventory) subgroups. SVM classification achieved promising accuracies with area under the curve (AUC) of 0.78, 0.83, 0.85 and 0.96 respectively for differentiating patients from healthy controls and classifying the three stages of DHI subgroups. Study results suggest that the proposed gait analysis that is based on the coupling of wearable accelerometers and machine learning provides an objective approach for assessing gait disturbances and handicapping effects of dizziness imposed by BPPV.

Location-dependent change of median nerve mobility in the carpal tunnel of patients with carpal tunnel syndrome.

INTRODUCTION: The purpose of this study was to investigate in vivo median nerve longitudinal mobility in different segments of the carpal tunnel associated with active finger motion in carpal tunnel syndrome (CTS) patients in a comparison with healthy controls. METHODS: Eleven healthy volunteers and 11 CTS patients participated in this study. Dynamic ultrasound images captured location-dependent longitudinal median nerve mobility within the carpal tunnel during finger flexion at the metacarpophalangeal joints using a speckle cross-correlation algorithm. RESULTS: Median nerve longitudinal mobility in the carpal tunnel was significantly smaller in CTS patients (0.0037 ± 0.0011 mm/degree) compared with controls (0.0082 ± 0.0026 mm/degree) (P < .05), especially in the proximal (0.0064 vs 0.0132 mm/degree on average) and middle (0.0033 vs 0.0074 mm/degree on average) carpal tunnel sections. DISCUSSION: Median nerve mobility can potentially serve as a biomechanical marker when diagnosing CTS, or when assessing the effectiveness of surgical and conservative treatments.

Co-Assembly between Fmoc Diphenylalanine and Diphenylalanine within a 3D Fibrous Viscous Network Confers Atypical Curvature and Branching.

Supramolecular polymer co-assembly is a useful approach to modulate peptide nanostructures. However, the co-assembly scenario where one of the peptide building blocks simultaneously forms a hydrogel is yet to be studied. Herein, we investigate the co-assembly formation of diphenylalanine (FF), and Fmoc-diphenylalanine (FmocFF) within the 3D network of FmocFF hydrogel. The overlapping peptide sequence between the two building blocks leads to their co-assembly within the gel state modulating the nature of the FF crystals. We observe the formation of branched microcrystalline aggregates with an atypical curvature, in contrast to the FF assemblies obtained from aqueous solution. Optical microscopy reveal the sigmoidal kinetic growth profile of these aggregates. Microfluidics and ToF-SIMS experiments exhibit the presence of co-assembled structures of FF and FmocFF in the crystalline aggregates. Molecular dynamics simulation was used to decipher the mechanism of co-assembly formation.

Bioinspired Supramolecular Packing Enables High Thermo-Sustainability.

Bottom-up self-assembled bioinspired materials have attracted increasing interest in a variety fields. The use of peptide supramolecular semiconductors for optoelectronic applications is especially intriguing. However, the characteristic thermal unsustainability limits their practical application. Here, we report the thermal sustainability of cyclo-ditryptophan assemblies up to 680 K. Non-covalent interactions underlie the stability mechanism, generating a low exciton-binding energy of only 0.29 eV and a high thermal-quenching-activation energy of up to 0.11 eV. The contributing forces comprise predominantly of aromatic interactions, followed by hydrogen bonding between peptide molecules, and, to a lesser extent, water-mediated associations. This thermal sustainability results in a temperature-dependent conductivity of the supramolecular semiconductors, showing 93 % reduction of the resistance from 320 K to 440 K. Our results establish thermo-sustainable peptide self-assembly for heat-sensitive applications.

Relations between the Crowe classification and the 3D femoral head displacement in patients with developmental dysplasia of the hip.

BACKGROUND: The purpose of this study was to investigate the relationship between the three dimensional (3D) femoral head displacement in patients with developmental dysplasia of the hip (DDH) and Crowe classification. METHODS: Retrospectively, CT scans of 60 DDH patients and 55 healthy demography-matched healthy control subjects were analyzed. Using the anterior pelvic plane a pelvic anatomic coordinate system was established. The center coordinates of the femoral heads of both the DDH patients and control subjects were quantified relative to the pelvic coordinate system and were mapped proportionally to a representative normal pelvis for comparison. RESULTS: In the anteroposterior (AP) direction, the center of the femoral head was significantly more anterior in the DDH patients (type I, II, and III, respectively45.0 ± 5.5, 42.9 ± 7.1, and 43.9 ± 4.6 mm) when compared to the controls (50.0 ± 5.2 mm) (p < 0.001 for all). In the medial-lateral (ML) direction, the center of the femoral head was significantly more lateral in the DDH patients (type I, II, and III =103.5 ± 8.6, 101.5 ± 6.6, 102.1 ± 11.2 mm) when compared to the controls (87.5 ± 5.1 mm) (p < 0.001 for all). In the superior-inferior (SI) direction, the center of the femoral head was significantly more proximal in the DDH patients (type I, II, and III =62.4 ± 7.3, 50.0 ± 6.3, and 43.2 ± 6.6 mm) when compared to the controls (66.0 ± 6.2 mm) (p < 0.001 for all). CONCLUSIONS: The severity of DDH using the Crowe classification was related to the degree of the femoral head displacement in the SI direction, but not in the ML or AP directions. By assessing the 3D femoral head displacement in DDH patients, individualized component positioning might benefit surgical outcome.

The contest between artificial management and natural environment determines the adaptive strategies of leaf morphogenesis in Sabina chinensis.

Sabina chinensis is a typically heteromorphic leaf evergreen tree worldwide with both ornamental and ecological value. However, the shaping mechanism of heteromorphic leaves of S. chinensis and its adaptability to environment are important factors determining its morphology. The morphological change of S. chinensis under different habitats (tree around) and treatments (light, pruning and nutrients) was investigated. Our findings suggested that the prickle leaves proportion was associated with low light intensity and soil nutrient scarcity. Stems and leaves are pruned together to form clusters of large prickle leaves, while only pruning leaves often form alternately growing small prickle leaves and scale leaves, and the length of the prickle leaves is between 0.5 cm and 1 cm. The gene expression of prickle leaves is higher than that of scale leaves under adverse environmental conditions, and the gene expression correlations between small prickle leaf and scale leaf were the highest. Homologous and heterologous mutants of gene structure in prickle leaves were larger than those in scale leaves. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway showed that phenylpropanone and flavonoid biosynthesis were common enrichment pathways, and that the enrichment genes were mainly related to metabolism, genetic information processing and organismal systems. Therefore, we concluded that the occurrence of the heteromorphic leaf phenomenon was related to the changes in photosynthesis, mechanical damage and nutrient supplementation. The organic matter in the S. chinensis prickle leaves was reduced under environmental stresses, and it will be allocated to the expression of prickle leaf or protective cuticles formation.

Five similar anthocyanidin molecules display distinct disruptive effects and mechanisms of action on Aß1-42 protofibril: A molecular dynamic simulation study.

Alzheimer's disease (AD) is associated with the deposition of amyloid-ß (Aß) fibrillary aggregates. Disaggregation of Aß fibrils is considered as one of the promising AD treatments. Recent experimental studies showed that anthocyanidins, one type of flavonoids abundant in fruits/vegetables, can disaggregate Aß fibrillary aggregates. However, their relative disruptive capacities and underlying mechanisms are largely unknown. Herein, we investigated the detailed interactions between five most common anthocyanidins (cyanidin, aurantinidin, peonidin, delphinidin, and pelargonidin) and Aß protofibril (an intermediate of Aß fibrillization) by performing microsecond molecular dynamic simulations. We found that all five anthocyanidins can destroy F4-L34-V36 hydrophobic core and K28-A42 salt bridge, leading to Aß protofibril destabilization. Aurantinidin exhibits the strongest damage to Aß protofibril (with the most severe disruption on K28-A42 salt bridges), followed by cyanidin (with the most destructive effect on F4-L34-V36 core). Detailed analyses reveal that the protofibril-destruction capacities of anthocyanidins are subtly modulated by the interplay of anthocyanidin-protofibril hydrogen bonding, hydrophobic, aromatic stacking interactions, which are dictated by the number or location of hydroxyl/methyl groups of anthocyanidins. These findings provide important mechanistic insights into Aß protofibril disaggregation by anthocyanidins, and suggest that aurantinidin/cyanidin may serve as promising starting-points for the development of new drug candidates against AD.

Hippocampal proteome comparison of infant and adult Fmr1 deficiency mice reveals adult-related changes associated with postsynaptic density.

Deficiency in fragile X mental retardation 1 (Fmr1) leads to loss of its encoded protein FMRP and causes fragile X syndrome (FXS) by dysregulating its target gene expression in an age-related fashion. Using comparative proteomic analysis, this study identified 105 differentially expressed proteins (DEPs) in the hippocampus of postnatal day 7 (P7) Fmr1-/y mice and 306 DEPs of P90 Fmr1-/y mice. We found that most DEPs in P90 hippocampus were not changed in P7 hippocampus upon FMRP absence, and some P90 DEPs exhibited diverse proteophenotypes with abnormal expression of protein isoform or allele variants. Bioinformatic analyses showed that the P7 DEPs were mainly enriched in fatty acid metabolism and oxidoreductase activity and nutrient responses; whereas the P90 PEPs (especially down-regulated DEPs) were primarily enriched in postsynaptic density (PSD), neuronal projection development and synaptic plasticity. Interestingly, 25 of 30 down-regulated PSD proteins present in the most enriched protein to protein interaction network, and 6 of them (ANK3, ATP2B2, DST, GRIN1, SHANK2 and SYNGAP1) are both FMRP targets and autism candidates. Therefore, this study suggests age-dependent alterations in hippocampal proteomes upon loss of FMRP that may be associated with the pathogenesis of FXS and its related disorders. SIGNIFICANCE: It is well known that loss of FMRP resulted from Fmr1 deficiency leads to fragile X syndrome (FXS), a common neurodevelopmental disorder accompanied by intellectual disability and autism spectrum disorder (ASD). FMRP exhibits distinctly spatiotemporal patterns in the hippocampus between early development and adulthood, which lead to distinct dysregulations of gene expression upon loss of FMRP at the two age stages potentially linked to age-related phenotypes. Therefore, comparison of hippocampal proteomes between infancy and adulthood is valuable to provide insights into the early causations and adult-dependent consequences for FXS and ASD. Using a comparative proteomic analysis, this study identified 105 and 306 differentially expressed proteins (DEPs) in the hippocampi of postnatal day 7 (P7) and P90 Fmr1-/y mice, respectively. Few overlapping DEPs were identified between P7 and P90 stages, and the P7 DEPs were mainly enriched in the regulation of fatty acid metabolism and oxidoreduction, whereas the P90 DEPs were preferentially enriched in the regulation of synaptic formation and plasticity. Particularly, the up-regulated P90 proteins are primarily involved in immune responses and neurodegeneration, and the down-regulated P90 proteins are associated with postsynaptic density, neuron projection and synaptic plasticity. Our findings suggest that distinctly changed proteins in FMRP-absence hippocampus between infancy and adulthood may contribute to age-dependent pathogenesis of FXS and ASD.

Motor Imagery Performance through Embodied Digital Twins in a Virtual Reality-Enabled Brain-Computer Interface Environment.

This study introduces an innovative framework for neurological rehabilitation by integrating brain-computer interfaces (BCI) and virtual reality (VR) technologies with the customization of three-dimensional (3D) avatars. Traditional approaches to rehabilitation often fail to fully engage patients, primarily due to their inability to provide a deeply immersive and interactive experience. This research endeavors to fill this gap by utilizing motor imagery (MI) techniques, where participants visualize physical movements without actual execution. This method capitalizes on the brain's neural mechanisms, activating areas involved in movement execution when imagining movements, thereby facilitating the recovery process. The integration of VR's immersive capabilities with the precision of electroencephalography (EEG) to capture and interpret brain activity associated with imagined movements forms the core of this system. Digital Twins in the form of personalized 3D avatars are employed to significantly enhance the sense of immersion within the virtual environment. This heightened sense of embodiment is crucial for effective rehabilitation, aiming to bolster the connection between the patient and their virtual counterpart. By doing so, the system not only aims to improve motor imagery performance but also seeks to provide a more engaging and efficacious rehabilitation experience. Through the real-time application of BCI, the system allows for the direct translation of imagined movements into virtual actions performed by the 3D avatar, offering immediate feedback to the user. This feedback loop is essential for reinforcing the neural pathways involved in motor control and recovery. The ultimate goal of the developed system is to significantly enhance the effectiveness of motor imagery exercises by making them more interactive and responsive to the user's cognitive processes, thereby paving a new path in the field of neurological rehabilitation.

Electro-oxidative quinylation of sulfides to sulfur ylides in batch and continuous flow.

An unprecedented strategy for preparing a series of sulfur ylides through electro-oxidative quinylation of sulfides in batch and continuous flow has been developed. Good to excellent yields were obtained with excellent functional group compatibility and good concentration tolerance under exogenous oxidant- and transition metal-free conditions. Advantageously, this electrosynthesis methodology was scalable with higher daily production and steady production was achieved attributing to the use of micro-flow cells.

Hydrogen peroxide preconditioning is of dual role in cardiac ischemia/reperfusion.

Moderate reactive oxygen species (ROS) at reperfusion would trigger cardioprotection and various antioxidants for pharmacological preconditioning failed to achieve cardioprotection. The causes for different roles of preischemic ROS during cardiac ischemia/reperfusion (I/R) require reevaluation. We investigated the precise role of ROS and its working model in this study. Different doses of hydrogen peroxide (H2O2, the most stable form of ROS) were added 5 min before ischemia using isolated perfused rat hearts, only moderate-dose H2O2 preconditioning (H2O2PC) achieved contractile recovery, whereas the low dose and high dose led to injury. Similar results were observed in isolated rat cardiomyocytes on cytosolic free Ca2+ concentration ([Ca2+]c) overload, ROS production, the recovery of Ca2+ transient, and cell shortening. Based on the data mentioned above, we set up a mathematics model to describe the effects of H2O2PC with the fitting curve by the percentage of recovery of heart function and Ca2+ transient in I/R. Besides, we used the two models to define the initial thresholds of H2O2PC achieving cardioprotection. We also detected the expression of redox enzymes and Ca2+ signaling toolkits to explain the mathematics models of H2O2PC in a biological way. The expression of tyrosine 705 phosphorylation of STAT3, Nuclear factor E2-related factor 2, manganese superoxide dismutase, phospholamban, catalase, ryanodine receptors, and sarcoendoplasmic reticulum calcium ATPase 2 were similar with the control I/R and low-dose H2O2PC but were increased in the moderate H2O2PC and decreased in the high-dose H2O2PC. Thus, we concluded that preischemic ROS are of dual role in cardiac I/R.

The Effects of Subthreshold Vibratory Noise on Cortical Activity During Motor Imagery.

Previous studies have demonstrated that both visual and proprioceptive feedback play vital roles in mental practice of movements. Tactile sensation has been shown to improve with peripheral sensory stimulation via imperceptible vibratory noise by stimulating the sensorimotor cortex. With both proprioception and tactile sensation sharing the same population of posterior parietal neurons encoding within high-level spatial representations, the effect of imperceptible vibratory noise on motor imagery-based brain-computer interface is unknown. The objective of this study was to investigate the effects of this sensory stimulation via imperceptible vibratory noise applied to the index fingertip in improving motor imagery-based brain-computer interface performance. Fifteen healthy adults (nine males and six females) were studied. Each subject performed three motor imagery tasks, namely drinking, grabbing, and flexion-extension of the wrist, with and without sensory stimulation while being presented a rich immersive visual scenario through a virtual reality headset. Results showed that vibratory noise increased event-related desynchronization during motor imagery compared with no vibration. Furthermore, the task classification percentage was higher with vibration when the tasks were discriminated using a machine learning algorithm. In conclusion, subthreshold random frequency vibration affected motor imagery-related event-related desynchronization and improved task classification performance.

EGCG attenuates α-synuclein protofibril-membrane interactions and disrupts the protofibril.

The fibrillary aggregates of α-synuclein (α-syn) are closely associated with the etiology of Parkinson's disease (PD). Mounting evidence shows that the interaction of α-syn with biological membranes is a culprit for its aggregation and cytotoxicity. While some small molecules can effectively inhibit α-syn fibrillization in solution, their potential roles in the presence of membrane are rarely studied. Among them, green tea extract epigallocatechin gallate (EGCG) is currently under active investigation. Herein, we investigated the effects of EGCG on α-syn protofibril (an intermediate of α-syn fibril formation) in the presence of a model membrane and on the interactions between α-syn protofibril and the membrane, as well as the underlying mechanisms, by performing microsecond all-atom molecular dynamics simulations. The results show that EGCG has destabilization effects on α-syn protofibril, albeit to a lesser extent than that in solution. Intriguingly, we find that EGCG forms overwhelming H-bonding and cation-π interactions with membrane and thus attenuates protofibril-membrane interactions. Moreover, the decreased protofibril-membrane interactions impede the membrane damage by α-syn protofibril and enable the membrane integrity. These findings provide atomistic understanding towards the attenuation of α-syn protofibril-induced cytotoxicity by EGCG in cellular environment, which is helpful for the development of EGCG-based therapeutic strategies against PD.

Precision agriculture management based on a surrogate model assisted multiobjective algorithmic framework.

Sustainable intensification needs to optimize irrigation and fertilization strategies while increasing crop yield. To enable more precision and effective agricultural management, a bi-level screening and bi-level optimization framework is proposed. Irrigation and fertilization dates are obtained by upper-level screening and upper-level optimization. Subsequently, due to the complexity of the problem, the lower-level optimization uses a data-driven evolutionary algorithm, which combines the fast non-dominated sorting genetic algorithm (NSGA-II), surrogate-assisted model of radial basis function and Decision Support System for Agrotechnology Transfer to handle the expensive objective problem and produce a set of optimal solutions representing a trade-off between conflicting objectives. Then, the lower-level screening quickly finds better irrigation and fertilization strategies among thousands of solutions. Finally, the experiment produces a better irrigation and fertilization strategy, with water consumption reduced by 44%, nitrogen application reduced by 37%, and economic benefits increased by 7 to 8%.

A finite element analysis of the carpal arch with various locations of carpal tunnel release.

Objective: The purpose of this study was to investigate the effects of the location of transverse carpal ligament (TCL) transection on the biomechanical property of the carpal arch structure. It was hypothesized that carpal tunnel release would lead to an increase of the carpal arch compliance (CAC) in a location-dependent manner. Methods: A pseudo-3D finite element model of the volar carpal arch at the distal carpal tunnel was used to simulate arch area change under different intratunnel pressures (0-72 mmHg) after TCL transection at different locations along the transverse direction of the TCL. Results: The CAC of the intact carpal arch was 0.092 mm2/mmHg, and the simulated transections ranging from 8 mm ulnarly to 8 mm radially from the center point of the TCL led to increased CACs that were 2.6-3.7 times of that of the intact carpal arch. The CACs after radial transections were greater than those ulnarly transected carpal arches. Conclusion: The TCL transection in the radial region was biomechanically favorable in reducing carpal tunnel constraint for median nerve decompression.

Stiffening of the gluteal muscle increased the intramuscular stress: An in-silico implication of deep tissue injury.

Objectives: Deep tissue injury is a common form of pressure ulcers in muscle tissues under bony prominences caused by sustained pressure or shear, which has a great impact on patients with restricted mobility such as spinal cord injury. Frequent spasms in spinal cord injury patients featured by muscle stiffening may be one of the factors leading to deep tissue injury. The purpose of this study was to investigate the relationship between the gluteal muscle shear modulus and intramuscular compressive/shear stress/strain. Methods: A semi-3D finite element model of the human buttock was established using COMSOL software and the acquired biomechanical data were analyzed through Pearson correlation and Spearman correlation. Results: Results showed that the compressive stress, strain energy density, and average von Mises stress increased with the increase of the gluteal muscle shear modulus. Conclusion: These results may indicate muscle stiffening caused by muscle spasms could lead to higher deep tissue injury development risk as well as shed light on effective treatments for relieving muscular sclerosis mechanically.

Inoculation with Azorhizobium caulinodans ORS571 enhances plant growth and salt tolerance of switchgrass (Panicum virgatum L.) seedlings.

BACKGROUND: Switchgrass (Panicum virgatum L.) is an important biofuel crop that may contribute to replacing petroleum fuels. However, slow seedling growth and soil salinization affect the growth and development of switchgrass. An increasing number of studies have shown that beneficial microorganisms promote plant growth and increase tolerance to salinity stress. However, the feasibility of inoculating switchgrass with Azorhizobium caulinodans ORS571 to enhance the growth and salt tolerance of its seedlings is unclear. Our previous study showed that A. caulinodans ORS571 could colonize wheat (Triticum aestivum L.) and thereby promote its growth and development and regulate the gene expression levels of microRNAs (miRNAs). RESULTS: In this study, we systematically studied the impact of A. caulinodans ORS571 on switchgrass growth and development and the response to salinity stress; we also studied the underlying mechanisms during these biological processes. Inoculation with A. caulinodans ORS571 significantly alleviated the effect of salt stress on seedling growth. Under normal conditions, A. caulinodans ORS571 significantly increased fresh plant weight, chlorophyll a content, protein content, and peroxidase (POD) activity in switchgrass seedlings. Under salt stress, the fresh weight, dry weight, shoot and root lengths, and chlorophyll contents were all significantly increased, and some of these parameters even recovered to normal levels after inoculation with A. caulinodans ORS571. Soluble sugar and protein contents and POD and superoxide dismutase (SOD) activities were also significantly increased, contrary to the results for proline. Additionally, A. caulinodans ORS571 may alleviate salt stress by regulating miRNAs. Twelve selected miRNAs were all upregulated to different degrees under salt stress in switchgrass seedlings. However, the levels of miR169, miR171, miR319, miR393, miR535, and miR854 were decreased significantly after inoculation with A. caulinodans ORS571 under salt stress, in contrast to the expression level of miR399. CONCLUSION: This study revealed that A. caulinodans ORS571 increased the salt tolerance of switchgrass seedlings by increasing their water content, photosynthetic efficiency, osmotic pressure maintenance, and reactive oxygen species (ROS) scavenging abilities and regulating miRNA expression. This work provides a new, creative idea for improving the salt tolerance of switchgrass seedlings.