Acute effects of different load intensities and rest intervals on muscle strength endurance in male college athletes

The purpose of this study was to compare the effects of different load intensities with rest intervals between sets on heart rate, rating of perceived exertion (RPE), power output, and blood lactate concentration during a squat strength endurance training protocol. A total of 4 sets of strength endurance tests were performed on 15 national Level 2 or above athletes with different load intensities (30% of 1 repetition maximum (1RM), 50% 1RM) and different rest intervals between sets (1 min, 2 min), 20 reps per set. Mean power (P-mean), mean heart-rate (HRmean) and RPE variations during the exercise were collected by using a linear position transducer, heart rate monitor, and Borg 6–20 scale. Besides, finger blood was collected before and after the exercise, and analyzed by using a blood lactate analyzer. HRmean, P-mean and RPE values were significantly higher at 50% 1RM load intensity than at 30% 1RM (p < 0.01), HRmean was significantly higher at 1 min rest interval than at 2 min between sets, while P-mean was significantly higher at 2 min rest interval than at 1 min between sets (p < 0.05); at 30% 1RM loading intensity, blood lactate concentrations were significantly higher at the completion of exercise for the 1 min rest interval between sets than for the 2 min (p < 0.01). However, at 50% 1RM loading intensity, blood lactate increased similarly at the completion of training in multiple sets, independent of the rest interval between sets. From a practical point of view, the results suggest that a 1 min rest interval between sets may be sufficient in a strength endurance training protocol when the load intensity is 30% 1RM. However, when the load intensity is 50% 1RM, we suggest that a 2 min rest interval between sets is required for optimal recovery and maintenance of power output

Analysis between ABO blood group and clinical outcomes in COVID-19 patients and the potential mediating role of ACE2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become the most common coronavirus that causes large-scale infections worldwide. Currently, several studies have shown that the ABO blood group is associated with coronavirus disease 2019 (COVID-19) infection and some studies have also suggested that the infection of COVID-19 may be closely related to the interaction between angiotensin-converting enzyme 2 (ACE2) and blood group antigens. However, the relationship between blood type to clinical outcome in critically ill patients and the mechanism of action is still unclear. The current study aimed to examine the correlation between blood type distribution and SARS-CoV-2 infection, progression, and prognosis in patients with COVID-19 and the potential mediating role of ACE2. With 234 patients from 5 medical centers and two established cohorts, 137 for the mild cohort and 97 for the critically ill cohort, we found that the blood type A population was more sensitive to SARS-CoV-2, while the blood type distribution was not relevant to acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality in COVID-19 patients. Further study showed that the serum ACE2 protein level of healthy people with type A was significantly higher than that of other blood groups, and type O was the lowest. The experimental results of spike protein binding to red blood cells also showed that the binding rate of people with type A was the highest, and that of people with type O was the lowest. Our finding indicated that blood type A may be the biological marker for susceptibility to SARS-CoV-2 infection and may be associated with potential mediating of ACE2, but irrelevant to the clinical outcomes including ARDS, AKI, and death. These findings can provide new ideas for clinical diagnosis, treatment, and prevention of COVID-19

Determination of the optimal drop height for male with different exercise level in drop jump by unilateral lower limb

Background: Drop jump (DJ) is a kind of plyometric training. There is little research on the effect of drop height (DH) on unilateral DJ. This study explored the optimal DH of DJ by unilateral lower limb, aiming to provide a reference for males with different exercise levels to avoid the imbalance between bilateral lower limbs and for coaches to develop accurate and effective unilateral DJ training programs. Methods: 18 college athletes and 13 physically active students were recruited to participate in this study and then asked to take three tests, namely “single-leg DJ at low height (L- SLDJ)”, “single-leg DJ at medium height (M-SLDJ)”, and “single-leg DJ at high height (H-SLDJ)”. Motion Capture System and Force Plate were used to synchronously collect motion parameters. Results: At M-SLDJ, both dominant and non-dominant legs performed significantly better than those at the other two types of DH in terms of leg stiffness and power for males with different exercise levels. At H-SLDJ, for males with different exercise levels, dominant leg had significantly better performance in leg stiffness, power etc. than non-dominant leg. Conclusions: The M-SLDJ designed in this study can be used by college athletes or students majoring in physical education for unilateral lower limb DJ training to maximize the performance of dominant or non-dominant leg. Due to the significant difference between two legs in the case of H-SLDJ, the eccentric contraction ability and stability of the non-dominant leg should be enhanced during the training to avoid bilateral imbalance

Lignin-based materials for electrochemical energy storage devices

Lignin is the most abundant aromatic polymer in nature, which is rich in a large number of benzene ring structures and active functional groups. The molecular structure of lignin has unique designability and controllability, and is a class of functional materials with great application prospects in energy storage and conversion. Here, this review firstly focuses on the concept, classification, and physicochemical property of lignin. Then, the application research of lignin in the field of electrochemical storage materials and devices are summarized, such as lignin-carbon materials and lignin-carbon composites in supercapacitors and secondary batteries. Finally, this review points out the bottlenecks that need to be solved urgently and the prospects for future research priorities

Design and experimental verification of the working mode of an electrostatic suspension accelerometer

An electrostatic suspension accelerometer is an important instrument for measuring quasi-steady micro-acceleration. A reasonable working mode is the premise to ensure acquisition and stable control of the accelerometer in-orbit and then to carry out high-precision linear measurement. Based on the dynamic model analysis of the electrostatic suspension accelerometer, and taking the force balance of inertial proof mass as the fundamental requirement, the design of the acquisition working mode and measurement working mode based on displacement sensing output and feedback control output is proposed. The rationality and feasibility of the proposed working mode design are verified by the ground drop tower test of the Taiji-1 accelerometer prototype and in-flight test of the actual product

Structural basis for hormone recognition and distinctive Gq protein coupling by the kisspeptin receptor

Summary: Kisspeptin signaling through its G protein-coupled receptor, KISS1R, plays an indispensable role in regulating reproduction via the hypothalamic-pituitary-gonadal axis. Dysregulation of this pathway underlies severe disorders like infertility and precocious puberty. Here, we present cryo-EM structures of KISS1R bound to the endogenous agonist kisspeptin-10 and a synthetic analog TAK-448. These structures reveal pivotal interactions between peptide ligands and KISS1R extracellular loops for receptor activation. Both peptides exhibit a conserved binding mode, unveiling their common activation mechanism. Intriguingly, KISS1R displays a distinct 40° angular deviation in its intracellular TM6 region compared to other Gq-coupled receptors, enabling distinct interactions with Gq. This study reveals the molecular intricacies governing ligand binding and activation of KISS1R, while highlighting its exceptional ability to couple with Gq. Our findings pave the way for structure-guided design of therapeutics targeting this physiologically indispensable receptor

Progress on the use of satellite technology for gravity exploration

In this paper, the technological progress on Chinese gravity exploration satellites is presented. Novel features such as ultra-stable structure, high accurate thermal control, drag-free and attitude control, micro-thrusters, aerodynamic configuration, the ability to perform micro-vibration analyses, microwave ranging system and mass center trimmer are described. Keywords: Ultra-stable structure, Precision thermal control, Drag-free, Micro-thruster, K-band ranging, Aerodynamics, Micro-vibration, Gravity satellit