Zhihua Zhang

Soil surface roughness (RR) and its spatiotemporal variations are important for understanding soil erosion process, but how the erosion‐induced evolution of RR affects flow pathways and sediment connectivity patterns remains unclear. This study used high‐resolution topographic data sets from a long‐term rainfall simulation experiment in semi‐arid environments. A total of approximately 1,500–2,400 mm of rainfall was applied on 2.0 m by 6.1 m plots with stony soil at three slope treatments (5%, 12%, and 20%). The temporal variations in RR, flow pathway length (FL), sinuosity (SS), and longitudinal profile roughness (PR) were investigated. The ratio of RR to slope relief, λ , was incorporated into a newly proposed sediment connectivity index (RIC). The results showed: (a) RR and PR continuously increased by 73.9% and 34.6% as compared to the initial surfaces, respectively, and steeper slopes developed greater RR and PR; (b) FL and SS increased due to the combined effects of increased RR and surficial rock fragment coverage; (c) RIC decreased because of the increases in FL, RR, and PR; (d) λ , SS and RIC were found to be appropriate predictors for sediment yield rates with determination coefficients of 0.50, 0.72 and 0.38, respectively, signifying that SS would be a promising parameter for modeling sediment yield. This study also highlighted the important roles of RR and λ in regulating flow and sediment connectivity, and suggested that stony hillslopes might evolve in a way wherein sediment connectivity and the effects of slope gradient on connectivity will decrease as erosion progresses.

Construction projects often involve intensive excavation and backfilling activities, resulting in the creation of spoil heaps. Rill erosion on spoil heaps poses a severe threat to the ecological security of construction sites and their surrounding areas. Previous studies largely concentrated on the spoil heaps rill erosion characteristics and the conservation benefits of vegetation measures, while the controlling mechanisms and efficiency of physical conservation structures to rill erosion are not clear. The objective of this study is to investigate the controlling mechanisms by characterizing rill erosion processes on physical structures‐treated spoil heaps. A series of artificial rainfalls was simulated on a 2 by 3 m artificial spoil heap plot under the intensities of 150 and 200 mm h⁻¹, at the slope gradients of 20° and 30° with replications. Blocking wattles were simply made using soil bags as physical conservation structures and were deployed at the lower end of the plot. Results showed that: (1) blocking wattles reduced sediment yield up to 85%, and were more efficient in sediment reduction than in runoff reduction; (2) significant rills were found under 150 and 200 mm h⁻¹ rainfalls, and rill density tended to increase with increasing slope gradient and rainfall intensity; (3) stream power was the best hydraulic parameter for predicting sediment yield rate at the bare plots; (4) blocking wattles decreased rill density and averaged rill depth by 45.9% and 31.5%, respectively, which was attributed to the decreasing stream power and runoff velocity. We therefore concluded that physical blocking structures reduced sediment yield on spoil heaps by directly trapping sediment and by mitigating rill development to indirectly abate further soil erosion and sediment transport. This latter effect is the novelty of this study. The present results would benefit the understanding of erosion processes on spoil heaps and promote conservation practices at construction sites.

Soil treatment with natural materials is an effective method to improve the mechanical properties of the original soil for recycling engineering construction. This research aims to evaluate the synergistic effects of lignin fiber and cement on sandy clayey silt stabilization. A factorial experimental design was employed, testing five lignin fiber contents (0%, 2%, 4%, 6%, and 8%) and three cement contents (0%, 2%, and 4%) across four curing periods (1, 7, 14, and 30 days). Unconfined compressive strength (UCS) tests were conducted in triplicate for each combination (total *n* = 180 samples), and failure surfaces were analyzed using Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM-EDX). Results indicate a critical lignin fiber threshold of 4%, beyond which UCS decreased by 15–20% due to increased void ratios. Statistical analysis (ANOVA, *p* < 0.05) confirmed significant interactions between lignin fiber, cement content, and curing time. For instance, 4% lignin fiber and 4% cement yielded a 139% UCS increase after 30-day curing compared to untreated soil. SEM-EDX revealed that lignin fiber networks enhance ductility by bridging soil particles, while cement hydration reduced particle detachment. These findings provide a quantitative framework for optimizing lignin fiber-cement stabilization in sustainable geotechnical applications.

In Japan, the demand for nursing homes is increasing due to the rapid aging of the population, while the shortage of caregivers has become a serious problem. This problem has been recognized as a social issue because it leads to an increase in the workload per caregiver. In response, we have been developing a platform that can easily collect nursing care activities in an effort to reduce the workload. In the process, we thought that the mental state (i.e., stress) of caregivers, which changes due to their care activities, might dramatically affect their work efficiency. The objective of this study is to obtain new knowledge for reducing the workload of caregivers by visualizing and analyzing his/her stress. In this paper, we ask caregivers to wear a heart-rate sensor, and measure objective stress indicators such as R-R interval (RRI) and low frequency (LF) /high frequency (HF) ratio obtained from each sensor, as well as subjective stress indicators obtained from questionnaires administered “before work,” “during lunch breaks,” and “after work.” To be specific, we analyzed and visualized the changes in stress associated with care activities based on psychological indicators of caregivers collected in an actual nursing home. As a result, we found that tended to increase during certain care activities and there were some relationships between those activities and stress indicators.

Due to the specific natural conditions and high intensity of human activities in Shenzhen, the characteristics of water and soil erosion of Shenzhen are prone and frequent. There are no large rivers, lakes and reservoirs in Shenzhen, and the rainwater storage capacity is unsubstantial that result in some problems such as ecological environment deterioration, river siltation, drainage pipe network blockage, and aggravation of flood disasters. The work of soil and water conservation in Shenzhen is still grim. In this paper, the sediment under different soil and water conservation measures were measured based on long-term observation of typical road engineering, river engineering and pipeline engineering in Shenzhen. Then, the effect of soil and water conservation measures implemented in these typical engineering were analyzed. At last, the optimal proposals of soil and water conservation measures for these typical engineering were proposed. This research aims to provide data support for the formulation and modification of soil and water conservation technical specifications for production and construction projects in Shenzhen.

Dengue affects tropical and subtropical regions, including Guangdong province of China. Dengue cases have been reported almost every year in Shantou city in Guangdong province. To understand the molecular characteristics of dengue viruses (DENVs) isolated in Shantou, we performed a molecular epidemiological study based on envelope protein (E) gene of the DENVs isolated from the cases. Totally, 174 serum samples were collected from 174 dengue-suspected patients during 2015-2017. 33.9% (59/174) were diagnosed with dengue. Serotypes of DENVs were identified in 27 samples, 37% (10/27), 55.6% (15/27), 3.7% (1/27), 3.7% (1/27) were DENV-1, DENV-2 DENV-3 and DENV-4, respectively. Genotype Ⅰ and Ⅳ were detected in DENV-1 while only Cosmopolitan genotype was detected in DENV-2. The replacement of predominant serotype (genotype)，which took place every year，implied that the dengue endemic in Shantou might be caused by imported infection rather than local circulation. Our results suggested that DENVs in Shantou were closely related to the strains circulating in Southeast Asian countries, which were possibly transmitted to Shantou through some relay point cities.