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Energy storage of passive muscles plays an important part in frequent activities of honey bee abdomens due to the muscle distribution and open circulatory system. However, the elastic energy and mechanical properties of structure in passive muscles remain unclear. In this article, stress relaxation tests on passive muscles from the terga of the honey bee abdomens were performed under different concentrations of blebbistatin and motion parameters. In stress relaxation, the load drop with the rapid and slow stages depending on stretching velocity and stretching length reflects the features of myosin–titin series structure and cross-bridge–actin cyclic connections in muscles. Then a model with 2 parallel modules based on the 2 feature structures in muscles was thus developed. The model described the stress relaxation and stretching of passive muscles from honey bee abdomen well for a good fitting in stress relaxation and verification in loading process. In addition, the stiffness change of cross-bridge under different concentrations of blebbistatin is obtained from the model. We derived the elastic deformation of cross-bridge and the partial derivatives of energy expressions on motion parameters from this model, which accorded the experimental results. This model reveals the mechanism of passive muscles from honey bee abdomens suggesting that the temporary energy storage of cross-bridge in terga muscles under abdomen bending provides potential energy for springback during the periodic abdomen bending of honey bee or other arthropod insects. The finding also provides an experimental and theoretical basis for the novel microstructure and material design of bionic muscle.

The mechanical properties of the honeybee's abdominal muscles endow its abdomen with movement flexibility to perform various activities. However, the biomechanical properties of abdominal muscles during stretch activation remain unclear. To clarify this issue, we observed the microstructures of the abdominal muscles to obtain structural information. The similarity and symmetry of abdominal muscle distribution contribute to the ability to drive abdominal movement. Combined with the segmented structure characteristics, an experimental device to measure muscle stretch measurement of honeybees was developed to investigate the mechanical properties of the abdominal muscles. During measurement, the muscles were kept in a solution to maintain a physiological environment. The mechanical properties of abdominal muscles included phases: the ascending phase with proportional increase, stable phase with slight fluctuation, and decay phase with parabolic decline. These findings indicate that the nonlinear and rate-sensitive mechanical properties of the abdominal muscles enable them to rapidly adapt to environmental changes. The stretch force and stiffness coefficient reached 0.660 ± 0.139 mN and 14.364 ± 2.961 N/m, respectively. A simplified biomechanical model of the muscle fiber considering the hierarchical microstructure was introduced, in which the mechanical properties were consistent with the experimental data. Further analysis of the effects of the activation probability and the effective range of binding sites on the mechanical properties demonstrated the critical role in force generation, revealing the mechanism of underlying muscle stretch activation in the honeybee abdomen. The findings can provide a new reference for studying the biomechanical properties of the muscles of other arthropod insects.

Background The transconjunctival technique is an effective approach to mild to moderate blepharoptosis repair that does not involve skin incision. However, accurate surgical manipulation of this method is greatly restricted by poor intraoperative evaluation. Objectives The aim of this study was to introduce a modified transconjunctival approach with flexible intraoperative adjustments in order to achieve more accurate ptosis correction. Methods Taking a transconjunctival approach, the levator aponeurosis and Müller’s muscle were folded with a square-like mattress suture for flexible adjustment and accurate correction. Results In 18 mild ptosis eyelids, 94.5% (17 eyelids) achieved adequate or normal correction. In 9 eyelids with moderate ptosis, 88.9% (8 eyelids) achieved adequate or normal correction. Of 24 ptosis patients, 23 (95.8%) achieved a good or fair symmetry result. Conclusions This study presents a modified transconjunctival technique for repair of mild to moderate ptosis, which is characterized by flexible intraoperative adjustments that produce satisfying functional and aesthetic outcomes. Level of Evidence: 4

Hypertrophic scar (HS) is a fibroproliferative disorder that causes cosmetic as well as functional problems; however, to our knowledge, there is no satisfactory treatment for HS to date. Previous studies have indicated that angiogenesis plays a crucial role in HS formation; therefore, anti-angiogenetic therapies are considered effective in improving HS. Although tacrolimus (TAC) has been proven effective in preventing HS formation in vivo and in vitro, its underlying mechanism remains controversial and ambiguous. Because of its anti-angiogenic effects in other diseases, we aimed to determine whether TAC reduces HS by suppressing angiogenesis. Using a rabbit ear HS model that we developed, HS was treated once a week with normal saline, dimethyl sulfoxide, or TAC for 3 weeks. Histological evaluation indicated that TAC significantly reduced collagen deposition and microvessel density in scar tissues. Moreover, immunofluorescence staining for CD31 and vascular endothelial growth factor (VEGF)-A revealed that TAC significantly inhibited HS angiogenesis. In vitro analysis showed that TAC inhibited endothelial cell migration and tubulogenesis as well as the viability and proliferation of human umbilical vascular endothelial cells (HUVECs) and HS fibroblasts (HSFBs). Furthermore, TAC significantly downregulated the expression of the human angiogenetic factors VEGF-A, FGF-2, PDGF-β, and TGF-β1 in HUVECs and HSFBs. Additionally, TAC-mediated inhibition of angiogenesis decreased the gene expression of crucial fibrotic markers, including α- smooth muscle actin and collagens 1 and 3, in HSFBs. This is the first study to demonstrate the inhibitory effects of TAC on HS formation mediated by a mechanism involving the suppression of scar angiogenesis.

A 16-month-old boy was admitted with cough for 2 days and fever for 1 day. Chest computed tomography (CT) scan of the child revealed large areas of ground-glass opacities in both lungs. Nucleic acid amplification tests (NAATs) were performed repeatedly to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the results were all negative. On day 13 of hospitalization, no clinical symptoms except diarrhea were present in the patient, and re-examination by chest CT revealed lesion shrinkage, but the NAAT on throat swabs was positive. On day 22 of hospitalization, the NAAT on throat swabs was negative and the fecal samples were positive. Positive fecal samples nucleic acid lasted for 62 days. Suggesting that pediatric patients may be important sources of infection during the recovery phase of clinical symptoms and whether SARS-CoV-2 has fecal–oral transmission needs further study.

To reduce the amount of time required for the formulation, adjustment, and application of a hardened plugging agent in the field, this study performed an in-depth analysis of the hydration mechanism of a slag-based plugging agent by heat of hydration characterization, transmission electron microscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The study shows that the NaOH activation of the slag-based plugging agent can produce an intermediate product Ca(OH)2 that is dissolved continuously to produce OH−, allowing the reaction to proceed continuously. Slag hardening occurs as follows: after the structure is destroyed, the recombination of groups changes their mutual spatial positions, thereby increasing the force between the groups and hardening the slurry. During the hydration process, a certain degree of substitution of Si by nonskeletal-element Al atoms in the slag occurs to form aluminosilicate, promoting the strength development of the slurry structure. The study results reveal a theoretical basis for shortening the time for the formulation and adjustment of the hardened slag-based plugging agent and provide new ideas for the development of new activators.

The improper treatment of smelter slag is a prominent issue regarding environmental protection. To resolve this issue, we explored the possible application of a slag plugging fluid in the field of oil and gas field development. Specifically, the thermal effect during the hydration process, the microstructure, the water function mechanism, and the mechanical characteristics of a hardened body of the slag plugging fluid were investigated using a combination of characterization equipment including a hydration heat calorimeter, nuclear magnetic resonance (NMR) spectrometer, scanning electron microscope, NMR crosslink density meter, and medium-sized NMR analysis and imaging system. The results of this study show that the degree of polymerization of Si increases during the hydration process, accompanied by the generation of a large amount of 6-coordinated Al. At the same time, the spacing between particles is reduced by the physical and chemical reactions in the hydration product formed through the hydration reaction of the slag. This behavior causes the slurry to cement and harden. During the hardening process of the slurry, the water binding force, the water form, and the pore structure are all affected and changed by the components in the slurry. These combined effects further cause the T2 spectrum curve of water to change during the hydration process. Finally, a hardened slurry can form a slug that effectively seals the leaking channel. The theoretical results obtained from this study can help guide the recycling utilization of slag in the area of oil and gas field development. Such a direction will provide an effective means of resolving the slag treatment issue.