Background In the context of China's rapid economic growth and social acceleration, long working hours are emerging as a key factor affecting well-being and contributing to depression. Objective To examine the longitudinal interaction between working hours and depressive symptoms, and evaluate potential mediating role of internet use in the relationship between working hours and depressive symptoms. Method This study utilized two waves of panel data from the China Family Panel Studies (CFPS) collected between 2016 and 2018. It constructed a longitudinal sample of 4900 individuals aged 18-70 years who were employed with known working hours across various occupations. Based on survey data and the Center for Epidemiologic Studies Depression Scale (CES-D), we measured and compared working hours, internet use, and depressive symptoms. Pearson correlation analysis was employed to examine the associations among key variables. Through cross-lagged panel models and a semi-longitudinal mediation model, we examined the bidirectional interactive mechanisms between working hours and depressive symptoms, with a particular focus on revealing the mediating pathways of internet use and any group heterogeneity. Result The study sample comprised 4900 participants, aged 18 to 70 years. Of these, 43.8% were male, and 77.35% were married. In 2016, the average working hours were (48.55 ± 22.17) h, and over half of the participants used the internet (59.84%). The average score on the depressive symptoms scale was (5.11 ± 3.78). The cross-lagged panel models revealed a dynamic interplay between working hours, internet use, and depressive symptoms. Specifically, working hours, internet use, and depressive symptoms in 2016 all positively predicted their respective counterparts in 2018. Furthermore, working hours in 2016 positively predicted internet use in 2018 (β=0.045, P < 0.001) and depressive symptoms in 2018 (β=0.027, P < 0.05), indicating that longer working hours were associated with an increased likelihood of internet use and worsened depressive symptoms. The half-longitudinal mediation models demonstrated a significant mediating effect of internet use in the relationship between working hours and depressive symptoms (effect size=−0.0013, P < 0.05), suggesting that internet use may buffer the adverse effects of long working hours on depressive symptoms. The subgroup analyses of the half-longitudinal mediation model revealed significant mediation effects of internet use within the female and married female subgroups, as well as significant mediating pathways within the older adult and employment stability subgroups. The Panel Logit regression results indicated that internet use (high or low) was associated with a lower risk of depressive symptoms compared to non-internet use, positioning internet use as a protective factor against depressive symptoms symptoms among younger adults, those with stable employment, and married women. Conclusion This study confirms that prolonged working hours are detrimental to psychological health. Internet use mediates the relationship between working hours and depressive symptoms, effectively mitigating the psychological harm of long working hours. This mediating effect is particularly pronounced for women, especially married women.

Background In the context of China's rapid economic growth and social acceleration, long working hours are emerging as a key factor affecting well-being and contributing to depression. Objective To examine the longitudinal interaction between working hours and depressive symptoms, and evaluate potential mediating role of internet use in the relationship between working hours and depressive symptoms. Method This study utilized two waves of panel data from the China Family Panel Studies (CFPS) collected between 2016 and 2018. It constructed a longitudinal sample of 4900 individuals aged 18-70 years who were employed with known working hours across various occupations. Based on survey data and the Center for Epidemiologic Studies Depression Scale (CES-D), we measured and compared working hours, internet use, and depressive symptoms. Pearson correlation analysis was employed to examine the associations among key variables. Through cross-lagged panel models and a semi-longitudinal mediation model, we examined the bidirectional interactive mechanisms between working hours and depressive symptoms, with a particular focus on revealing the mediating pathways of internet use and any group heterogeneity. Result The study sample comprised 4900 participants, aged 18 to 70 years. Of these, 43.8% were male, and 77.35% were married. In 2016, the average working hours were (48.55 ± 22.17) h, and over half of the participants used the internet (59.84%). The average score on the depressive symptoms scale was (5.11 ± 3.78). The cross-lagged panel models revealed a dynamic interplay between working hours, internet use, and depressive symptoms. Specifically, working hours, internet use, and depressive symptoms in 2016 all positively predicted their respective counterparts in 2018. Furthermore, working hours in 2016 positively predicted internet use in 2018 (β=0.045, P < 0.001) and depressive symptoms in 2018 (β=0.027, P < 0.05), indicating that longer working hours were associated with an increased likelihood of internet use and worsened depressive symptoms. The half-longitudinal mediation models demonstrated a significant mediating effect of internet use in the relationship between working hours and depressive symptoms (effect size=−0.0013, P < 0.05), suggesting that internet use may buffer the adverse effects of long working hours on depressive symptoms. The subgroup analyses of the half-longitudinal mediation model revealed significant mediation effects of internet use within the female and married female subgroups, as well as significant mediating pathways within the older adult and employment stability subgroups. The Panel Logit regression results indicated that internet use (high or low) was associated with a lower risk of depressive symptoms compared to non-internet use, positioning internet use as a protective factor against depressive symptoms symptoms among younger adults, those with stable employment, and married women. Conclusion This study confirms that prolonged working hours are detrimental to psychological health. Internet use mediates the relationship between working hours and depressive symptoms, effectively mitigating the psychological harm of long working hours. This mediating effect is particularly pronounced for women, especially married women.

Objective To compare the biomechanical characteristics between S2 alar-iliac (S2AI) screw and sacroiliac joint screw in treating unilateral type C sacroiliac joint dislocation. Methods A 25 year-old healthy male adult agreed to take computed tomography scan of the pelvis. The pelvic floor thickness was 1 mm and the image data were saved in DCOM format. A three dimensional finite element model of intact pelvis was reconstructed by Mimics, Geomagic, SolidWorks, and Abaqus softwares. A finite element model of type C unilateral sacroiliac dislocation was established. One S1 vertebral sacroiliac screw of 6.5 mm in diameter (S1 group), one S2AI screw (S2AI group) and one Si vertebra sacroiliac screw + one S2 vertebra sacroiliac screw (S1+S2 group) were placed in the model, respectively. The500 N vertical load on the upper surface of the sacrum was simulated. The displacement value of sacroiliac joint, the displacement of sacrum, the stress value of the internal fixation and surrounding bone, and the stress distribution cloud map were recorded and analyzed. Results The displacement data showed that displacement distribution in the three groups had a consistent trend. In terms of the absolute value of displacement the result was S, group＞S 2AI group＞S1+ S2 group, of which the maximum displacement of sacroiliac joint in S1 groups was 0.87 mm and that of sacrum was 1.6 mm; the maximum displacement of sacroiliac joint in S2 AI group was 0.22 mm, and that of sacrum was 0.24 mm; the maximum displacement of the sacroiliac joint in S1 + S2 group was 0.06 mm, and that of sacrum was0.16 mm. Stress data showed that the stress in the internal fixation was mainly distributed at the sacroiliac joint, and the stress result was S2AI group＞S, group＞S, + S2 group, of which the maximum stress value was 52.8 MPa in S1 group, 62.1 MPa in S2AI group, and 38.2 MPa in S1 + S2 group. The stress around the screws was also concentrated at the sacroiliac joint, and the stress result was S1 group＞S2AI group＞S1 + S2 group, of which the maximum stress value was 56.8 MPa in S1 group, 11.2 MPa in S2AI group, and 5.8 MPa in S1 + S2 group. Conclusions Single S1 screw, single S2 AI screw and S, screws combined S2 screws can be used for the treatment of unilateral C type sacroiliac joint dislocation. Early weight bearing of single S1 screw might lead to the risks of increased sacroiliac joint displacement and internal fixation failure. S2 AI screw fixation and S1 + S2 screw fixation have similar biomechanical strength, allowing early weight-bearing and contributing to better postoperative rehabilitation.

Minimally invasive surgical techniques reduce the damages to skin and soft tissue due to a high rate of complications following open reduction and internal fixation for dorsal pelvic ring injuries. However, they can still cause iatrogenic injuries to nerves, vessels and even organs because of reduced surgical exposure. Transiliac Internal Fixator ( TIFI ) , which was first designed by Füchtmeier, has been widely used in clinics because it successfully reduces iatrogenic injuries and ensures stability of internal fixation. This paper focuses on the principles, clinical outcomes, biomechanical studies and probable improvements of TIFI.

Objective: To investigate the effect of rat hyperplasia suppressor gene-1(rHSG-1) on the proliferation of aortic vascular smooth muscle cells(VSMCs) from spontaneously hypertensive rats(SHR). Methods:VSMCs were transfected with an adenoviral vector expressing rHSG-1(Ad5rHSG-1). The effect of rHSG-1 on the proliferation of VSMCs was investigated by cell counting, MTT assay and 3H-thymidine incorporation. We also analyzed the cell-cycle using flow cytometry and detected the expression of p27 Kip1 and p21 Cip1 by Western Blot. Results:The proliferation of VSMCs infected with Ad5rHSG-1 was inhibited,a 40% reduction compared with the control group(P