Objective The objective of this study was to explore the morphological characteristics of paraspinal muscles in young patients with unilateral neurological symptoms of lumbar disc herniation. Methods This study retrospectively analyzed young patients aged 18–40 years who were hospitalized for lumbar disc herniation in our hospital from June 2017 to June 2020. Data on sex, age, body mass index (BMI), subcutaneous fat tissue thickness (SFTT) at the L1-L2 level, duration of symptoms, degree of lumbar disc herniation, visual analog scale (VAS) for the lower back, Mo-fi-disc score, relative cross-sectional area (RCAS) of the paravertebral muscles (psoas major [PM], multifidus [MF], and erector spinae [ES]), and degree of fat infiltration (DFF) of the paravertebral muscles were collected. The VAS was used to evaluate the intensity of low back pain. Patients with VAS-back >4 points were defined as the low back pain group, and patients with ≤4 points were defined as the control group. The demographic characteristics, as well as the bilateral and ipsilateral paravertebral muscles, of the two groups were compared and analyzed. Result A total of 129 patients were included in this study (52 patients in the LBP group and 77 patients in the control group). There were no significant differences in sex, BMI, or Pfirrmann grade of lumbar disc herniation between the two groups (P > 0.05). The age of the LBP group (33.58 ± 2.98 years) was greater than that of the control group (24.13 ± 2.15 years) (P = 0.002), and the SFTT at the L1-L2 level (13.5 ± 7.14 mm) was higher than that of the control group (7.75 ± 6.31 mm) (P < 0.05). Moreover, the duration of symptoms (9.15 ± 0.31 months) was longer than that of the control group (3.72 ± 0.48 months) (P < 0.05), and the Mo-fi-disc score (8.41 ± 3.16) was higher than that of the control group (5.53 ± 2.85) (P < 0.05). At L3/4 and L5/S1, there was no significant difference in the RCSA and DFF of the bilateral and ipsilateral paraspinal muscles between the LBP group and the control group. At L4/5, there was no significant difference in the RCSA and DFF of the paraspinal muscles on either side in the LBP group (P > 0.05). In the control group, the RCSA of the MF muscle on the diseased side was smaller than that on the normal side (P < 0.05), and the DFF of the MF muscle on the diseased side was larger than that on the normal side (P < 0.05). In addition, there was no significant difference in the ES and PM muscles on both sides (P > 0.05). At L4/5, the RCSA of the MF muscle on the normal side was significantly smaller in the LBP group than in the control group (P < 0.05), and the DFF of the MF muscle on the normal side was significantly larger in the LBP group than in the control group (P < 0.05). There was no significant difference in the ES and PM muscles on the same side between the two groups (P > 0.05). Conclusion In young patients with unilateral neurological symptoms of lumbar disc herniation, symmetrical atrophy of the bilateral MF muscle is more prone to causing low back pain. Older age, higher SFTT at the L1-L2 levels, longer symptom duration, higher Mo-fi-di score, and greater muscle atrophy on the normal side of the MF increased the incidence of low back pain in young patients with unilateral lumbar disc herniation.

(Photo-)electrocatalytic artificial photosynthesis driven by electrical and/or solar energy that converts water (H2O) and carbon dioxide (CO2) into hydrogen (H2), carbohydrates and oxygen (O2), has proven to be a promising and effective route for producing clean alternatives to fossil fuels, as well as for storing intermittent renewable energy, and thus to solve the energy crisis and climate change issues that we are facing today. Basic (photo-)electrocatalysis consists of three main processes: (1) light absorption, (2) the separation and transport of photogenerated charge carriers, and (3) the transfer of photogenerated charge carriers at the interfaces. With further research, scientists have found that these three steps are significantly affected by surface and interface properties (e.g., defect, dangling bonds, adsorption/desorption, surface recombination, electric double layer (EDL), surface dipole). Therefore, the catalytic performance, which to a great extent is determined by the physicochemical properties of surfaces and interfaces between catalyst and reactant, can be changed dramatically under working conditions. Common approaches for investigating these phenomena include X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning probe microscopy (SPM), wide angle X-ray diffraction (WAXRD), auger electron spectroscopy (AES), transmission electron microscope (TEM), etc. Generally, these techniques can only be applied under ex situ conditions and cannot fully recover the changes of catalysts in real chemical reactions. How to identify and track alterations of the catalysts, and thus provide further insight into the complex mechanisms behind them, has become a major research topic in this field. The application of in situ/operando characterization techniques enables real-time monitoring and analysis of dynamic changes. Therefore, researchers can obtain physical and/or chemical information during the reaction (e.g., morphology, chemical bonding, valence state, photocurrent distribution, surface potential variation, surface reconstruction), or even by the combination of these techniques as a suite (e.g., atomic force microscopy-based infrared spectroscopy (AFM-IR), or near-ambient-pressure STM/XPS combined system (NAP STM-XPS)) to correlate the various properties simultaneously, so as to further reveal the reaction mechanisms. In this review, we briefly describe the working principles of in situ/operando surface/interface characterization technologies (i.e., SPM and X-ray spectroscopy) and discuss the recent progress in monitoring relevant surface/interface changes during water splitting and CO2 reduction reactions (CO2RR). We hope that this review will provide our readers with some ideas and guidance about how these in situ/operando characterization techniques can help us investigate the changes in catalyst surfaces/interfaces, and further promote the development of (photo-)electrocatalytic surface and interface engineering.

Background: Hidden blood loss (HBL) is of increasing interest to spine surgeons. This retrospective study aimed to evaluate perioperative HBL and its risk factors in patients undergoing one-segment posterior circumferential decompression surgery on thoracic ossification of the posterior longitudinal ligament (T-OPLL). Method: We retrospectively studied 112 patients diagnosed with T-OPLL following posterior circumferential decompression surgery from August 2015 to June 2020. Patient demographics, blood loss-related parameters, surgery-related data and imaging parameters were extracted. Postoperative complications were also recorded. Pearson or Spearman correlation analysis was used to investigate the correlation between patient demographics and HBL. Multivariate linear regression analysis was performed to determine the independent risk factors associated with HBL. Results: Forty-five men and 67 women were involved in this research, with an average age of 56.4 ± 10.2 years. The mean HBL was 459.6±275.4 ml, accounting for 56.5% of the total blood loss. Multiple linear regression analysis showed that double-layer sign (P＝0.000), ossification occupancy ratio (OOR) >60%(P=0.030), age (P=0.010), hematocrit (Hct) loss (P=0.034), and postoperative Hct (P = 0.016) were independent risk factors for HBL. However, OPLL morphology (P=0.319), operation time (P=0.587), hemoglobin (Hb) loss (P=0.644), and postoperative Hb (P=0.952) were not significantly different from HBL. Conclusion: A high proportion of HBL was found after posterior circumferential decompression surgery on T-OPLL during the perioperative period,which should not be overlooked. Double-layer sign, OOR> 60%, age, Hct loss and postoperative Hct are independent risk factors for HBL.

Background Hidden blood loss (HBL) is of increasing interest to spine surgeons. This retrospective study aimed to evaluate perioperative HBL and its risk factors in patients undergoing one-segment posterior circumferential decompression surgery on thoracic ossification of the posterior longitudinal ligament (T-OPLL). Method We retrospectively studied 112 patients diagnosed with T-OPLL following posterior circumferential decompression surgery from August 2015 to June 2020. Patient demographics, blood loss-related parameters, surgery-related data and imaging parameters were extracted. Postoperative complications were also recorded. Pearson or Spearman correlation analysis was used to investigate the correlation between patient demographics and HBL. Multivariate linear regression analysis was performed to determine the independent risk factors associated with HBL. Results Forty-five men and 67 women were involved in this research, with an average age of 56.4 ± 10.2 years. The mean HBL was 459.6 ± 275.4 ml, accounting for 56.5% of the total blood loss. Multiple linear regression analysis showed that double-layer sign (P = 0.000), ossification occupancy ratio (OOR) > 60% (P = 0.030), age (P = 0.010), hematocrit (Hct) loss (P = 0.034), and postoperative Hct (P = 0.016) were independent risk factors for HBL. However, OPLL morphology (P = 0.319), operation time (P = 0.587), hemoglobin (Hb) loss (P = 0.644), and postoperative Hb (P = 0.952) were not significantly different from HBL. Conclusion A high proportion of HBL was found after posterior circumferential decompression surgery on T-OPLL during the perioperative period, which should not be overlooked. Double-layer sign, OOR > 60%, age, Hct loss and postoperative Hct are independent risk factors for HBL.

Objective: The objective of this study was to explore the morphological characteristics of paraspinal muscles in young patients with unilateral neurological symptoms of lumbar disc herniation. Methods: This study retrospectively analyzed young patients aged 18–40 years who were hospitalized for lumbar disc herniation in our hospital from June 2017 to June 2020. The data of gender, age, body mass index (BMI), duration of symptoms, degree of lumbar disc herniation, (Visual Analogue Scale) VAS score for LBP, relative cross-sectional area (RCAS) of paravertebral muscles (psoas major, PM, multifidus, MF and erector spinae, ES), and degree of fat infiltration (DFF) of paravertebral muscles were collected. According to whether the VAS score > 4, patients were divided into low back pain (LBP) group and no-low back pain (NLBP) group. The demographic characteristics, bilateral and ipsilateral paravertebral muscles of the two groups were compared and analyzed. Result: A total of 129 patients were included in this study, 52 with LBP and 77 with NLBP. There were no significant differences in gender, BMI, and Pfirrmann grade of lumbar disc herniation between the two groups (P > 0.05). The duration of symptoms in the LBP group(9.15 ± 0.31 months) was longer than that in the NLBP group (3.72 ± 0.48 months)(P < 0.05), and the age (33.58 ± 2.98 years) was longer than that in the NLBP group (24.13 ± 2.15 years) (P = 0.002).At L3/4 and L5/S1,there was no significant difference in RCSA and DFF of bilateral and ipsilateral paraspinal muscles between the LBP group and the NLBP group. At L4/5, there was no significant difference in RCSA and DFF of the paraspinal muscles on both sides of the LBP group (P > 0.05); In the NLBP group, the RCSA of the MF muscle on the diseased side was smaller than that on the normal side (P < 0.05), and the DFF of the MF muscle on the diseased side was larger than that on the normal side(P < 0.05), there was no significant difference in the ES and PM muscle on both sides (P > 0.05).At L4/5, the RCSA of the normal side MF muscle was signifcantly smaller in the LBP group than in the NLBP group (P < 0.05), the DFF of the normal side MF muscle was signifcantly larger in the LBP group than in the NLBP group (P < 0.05). There was no significant difference in the ES and PM muscle on the same side between the two groups (P > 0.05). Conclusion: In young patients with unilateral neurological symptoms of lumbar disc herniation, symmetrical atrophy of the bilateral MF muscle is more prone to cause low back pain. Longer duration of symptoms, older age, and greater atrophy of the normal side MF muscle could increase the incidence of low back pain in young patients with unilateral neurological symptoms of lumbar disc herniation.