Trends in the mobility of primary healthcare human resources in underdeveloped regions of western China from 2000 to 2021: Evidence from Nanning.

OBJECTIVE: This research aimed to identify the fundamental and geographic characteristics of the primary healthcare personnel mobility in Nanning from 2000 to 2021 and clarify the determinants that affect their transition to non-primary healthcare institutions. METHODS: Through utilizing the Primary Healthcare Personnel Database (PHPD) for 2000-2021, the study conducts descriptive statistical analysis on demographic, economic, and professional aspects of healthcare personnel mobility across healthcare reform phases. Geographic Information Systems (QGIS) were used to map mobility patterns, and R software was employed to calculate spatial autocorrelation (Moran's I). Logistic regression identified factors that influenced the transition to non-primary institutions. RESULTS: Primary healthcare personnel mobility is divided into four phases: initial (2000-2008), turning point (2009-2011), rapid development (2012-2020), and decline (2021). The rapid development stage saw increased mobility with no spatial clustering in inflow and outflow. From 2016 to 2020, primary healthcare worker mobility reached its peak, in which the most significant movement occurred between township health centers and other institutions. Aside from their transition to primary medical institutions, the primary movement of grassroots health personnel predominantly directs towards secondary general hospitals, tertiary general hospitals, and secondary specialized hospitals. Since 2012, the number and mobility distance of primary healthcare workers have become noticeably larger and remained at a higher level from 2016 to 2020. The main migration of primary healthcare personnel occurred in their districts (counties). Key transition factors include gender, education, ethnicity, professional category, general practice registration, and administrative division. CONCLUSIONS: This study provides evidence of the features of primary healthcare personnel mobility in the less developed western regions of China, in which Nanning was taken as a case study. It uncovers the factors that impact the flow of primary healthcare personnel to non-primary healthcare institutions. These findings are helpful to policy refinement and support the retention of primary healthcare workers.

Chloride Corrosion Process of Concrete with Different Water-Binder Ratios under Variable Temperature Drying-Wetting Cycles.

In this paper, four water-binder ratios (w/b) of 0.29, 0.33, 0.39, and 0.46 were designed. A variable test temperature was implemented in the drying-wetting cycle test according to the temperature fluctuations in the actual service environment, and the constant temperature test was established as the control group. The mechanical properties and chloride corrosion resistance of concrete with different w/b ratios under variable temperature drying-wetting cycles, as well as the microstructure changes, phase composition, and damage mechanism inside the concrete, were investigated. The results showed that the mechanical properties of concrete increased first and then decreased with drying-wetting cycles increasing, whereas the chloride corrosion resistance continued to decline. A higher w/b exacerbated the deterioration of the concrete performance. A higher w/b increased the porosity, chloride diffusion depth, and chloride content, thus reducing the resistance of chloride corrosion. Compared with w/b = 0.29, the compressive strength, splitting tensile strength, mass, and relative dynamic elasticity modulus of w/b = 0.46 exposed to 60 drying-wetting cycles decreased by 54.50%, 52.44%, 0.96%, and 6.50%, respectively, while the porosity, peak chloride content, and erosion depth increased by 45.12%, 70.45%, and 45.00%. Compared with the drying-wetting cycle with a constant temperature, the cumulative damage caused by the drying-wetting cycle with a variable temperature was greater, resulting in more severe deterioration of concrete performance. The increase in the test temperature significantly accelerated the diffusion rate, penetration depth, and chemical binding capacity of chloride ions. After 60 drying-wetting cycles, the peak chlorine content and erosion depth of w/b = 0.46 under variable temperature cycles were 15.38% and 10.32% higher than those under a constant temperature, while the compressive strength, splitting tensile strength, mass, and relative dynamic elastic modulus were reduced by 7.76%, 14.81%, 0.33%, and 2.40%, respectively. Microscopic analysis confirmed that higher w/b and variable temperature cycles accelerated the decay of mechanical properties and the decline of chloride corrosion resistance. According to the numerical fitting analysis, the w/b should be 0.29~0.39 under the condition that the mechanical properties and chloride corrosion resistance of concrete are met.

Effects of Manufactured Sand and Steam-Curing Temperature on the Compressive Strength of Recycled Concrete with Different Water/Binder Ratios.

New building materials (manufactured sand and recycled coarse aggregates) can conserve raw materials and protect the environment. Prefabricated members can shorten the construction time of a structure. To use manufactured sand and recycled coarse aggregate in the preparation of precast member concrete, an economical and practical steam-curing scheme must be developed such that the compressive strength of precast manufactured sand recycled concrete (MRC) meets the requirements for hoisting. The effects of different steam-curing temperatures (standard curing, 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C) on the compressive strength of MRC with three water/binder ratios (W/B) (0.46, 0.42, and 0.38) were studied. In addition, the microstructure of MRC was examined using a scanning electron microscope. The equivalent age-compressive strength model was used to estimate the recycled concrete with manufactured sand. The results showed that the strength of MRC with a water-cement ratio of 0.46, 0.42, and 0.38 reached 33.9, 38.7, and 45.1 MPa, respectively, after 28 days of standard curing. The results also indicated that an increase in the steam-curing temperature had a positive effect on the early compressive strength of MRC and a negative effect on the 28 d compressive strength. This behavior was more obvious for MRC with a low W/B ratio. For MRC with a W/B of 0.46, 0.42, and 0.38, after steam-curing for 6 h, the compressive strength reached 32-65%, 36-70%, and 40-77% of the design strength, respectively. The optimum steam-curing temperatures for MRC with W/B of 0.46, 0.42, and 0.38 were 60 °C, 60 °C, and 50 °C. A decrease in W/B has a negative impact on the accuracy of MRC estimation using the equivalent age-compressive strength model. The maximum deviation of the prediction was within 10%, and the accuracy of the model was acceptable. This study provides a useful reference for the production of prefabricated MRC components in factories and subsequent construction.