Rheological, mechanical, and abrasion characteristics of polymer-modified cement mortar and concrete

The settlement of fresh concrete or improper operation during construction usually makes the water to cement (w/c) ratio of the cement mortar on the concrete pavement surface higher than designed, which may influence the abrasion resistance of concrete pavement. This study firstly tried to establish relationships between abrasion of hardened cement mortar and rheological characteristics of fresh cement mortar in the laboratory. Secondly, a polymer-modified cement mortar was developed with carboxyl styrene butadiene rubber latex added to the cement mortar. Its rheological properties in mixing, mechanical properties, and abrasion were investigated. It is found that the polymer-modified cement mortar has a much better abrasion resistance and flexural strength while lower compressive strength than cement mortar. A stronger correlation was observed between flexural strength rather than compressive strength and abrasion resistance of cement mortar. The proposed polymer-modified concrete also exhibited good abrasion resistance.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Constructing Landscape Ecological Security Patterns of an Ancient Capital Based on Cellular Automata Theory

Urban sprawl in developing countries changes urban land use structure and function, and threatens the sustainable development of regional ecology and security patterns of city landscapes. A new way to control urban sprawl is to develop a comprehensive landscape security plan, analyze factors influencing urban growth, optimize land use and demarcate a growth boundary. Here, we use Xi’an, China, as a case study to analyze scenarios of landscape security pattern and urban spatial control to explore urban spatial zoning. We construct a theoretical framework of a landscape security pattern to manage urban spatial expansion from the perspective of landscape security and urban smart growth. As a first step, the integrated landscape security pattern is constructed based on four factors: hydrology, geological disasters, cultural heritage, and recreation. Second, the urban spatial expansion model is simulated based on a cellular automata model. Finally, nine land-use patterns are developed by overlaying integrated landscape security patterns and urban spatial expansion. Thus, urban space is divided into three types of zoning scenarios: suitable construction, restricted construction, and prohibited construction. The calculations indicate that the zoning area of the three types accounted for 10.4%, 14.7%, and 74.9%, respectively, of the total area in Xi’an. It is of great significance to determine the spatial contradiction between development and protection in the process of urban expansion and to establish a schema of suitable urban land use. We discuss the rapid urbanization process in developing countries at the macro scale, and formulate a land use plan that balances development and protection

Constructing Landscape Ecological Security Patterns of an Ancient Capital Based on Cellular Automata Theory

Urban sprawl in developing countries changes urban land use structure and function, and threatens the sustainable development of regional ecology and security patterns of city landscapes. A new way to control urban sprawl is to develop a comprehensive landscape security plan, analyze factors influencing urban growth, optimize land use and demarcate a growth boundary. Here, we use Xi’an, China, as a case study to analyze scenarios of landscape security pattern and urban spatial control to explore urban spatial zoning. We construct a theoretical framework of a landscape security pattern to manage urban spatial expansion from the perspective of landscape security and urban smart growth. As a first step, the integrated landscape security pattern is constructed based on four factors: hydrology, geological disasters, cultural heritage, and recreation. Second, the urban spatial expansion model is simulated based on a cellular automata model. Finally, nine land-use patterns are developed by overlaying integrated landscape security patterns and urban spatial expansion. Thus, urban space is divided into three types of zoning scenarios: suitable construction, restricted construction, and prohibited construction. The calculations indicate that the zoning area of the three types accounted for 10.4%, 14.7%, and 74.9%, respectively, of the total area in Xi’an. It is of great significance to determine the spatial contradiction between development and protection in the process of urban expansion and to establish a schema of suitable urban land use. We discuss the rapid urbanization process in developing countries at the macro scale, and formulate a land use plan that balances development and protection

Social Value of Urban Green Space Based on Visitors’ Perceptions: The Case of the Summer Palace, Beijing, China

Urban green spaces play a key role in constructing an ecological civilization in China. In this context, the realization and assessment of the social value of urban green spaces have received increasing attention. Taking the visitors of the Summer Palace in Beijing as the research object, this study used the public participation geographic information system (PPGIS) to collect research data, assess the social value of ecosystem services in the Summer Palace, and determine its spatial distribution. By examining the social value of urban green spaces, this study explored the relationship between the spatial distribution of ecosystem social value and environmental landscape features. The influence of different environmental values on the spatial distribution of the visitors’ perceived social value was also investigated to provide a decision-making basis for the planning and management of urban ecological spaces and the supply and protection of urban ecological products. This study found that cultural, historical, and aesthetic values were preferred by an increasing number of visitors. The hotspots of social value in the Summer Palace of Beijing have three cores and multiple centers. By analyzing the relationship between the three value types with higher preference and the environmental landscape features of the Summer Palace, this study found that the distribution of social values is closely related to the architectural complexes and waters. Anthropocentrists have smaller sample sizes and generally lower social value indices within the sample group, and ecocentrists have higher perceptions of overall social values

The efficacy of GnRH-a followed by SanJieZhenTong capsules in long-term management of endometriosis: Study protocol for a multicenter, double-blinded, double-dummy randomized clinical trial

Background: Endometriosis is a common benign gynecological disorder with high risk of recurrence and adverse impact on fertility-sparing. This study aims to evaluate the effectiveness and safety of SanJieZhenTong Capsules, a traditional Chinese medicine, in the long-term management of endometriosis postoperatively. Methods: and analysis: A prospective, double-blinded, double-dummy parallel-group randomized controlled trial will be conducted at three university-based medical centers in China. A total of 600 patients with rAFS III-IV endometriosis diagnosed by laparoscopy will be enrolled. After fundamental treatment (gonadotropin-releasing hormone agonists injection starts on the first day of menstruation postoperatively, and repeats 3 times every 28 days), participants will be randomly allocated to the oral contraceptive group (oral contraceptive + dummy A) or SanJieZhenTong Capsules group (SanJieZhenTong Capsules + dummy B) in a 1:1 ratio. All participants will be treated and followed up for 52 weeks. The primary outcome is a recurrence rate based on endometriosis-related symptoms, physical examination, and/or ultrasound/MRI findings. The secondary outcome includes changes in quality of life and organic function outcome via the 36-item Short-Form scores and gastrointestinal function score. Conclusion: The current trial could provide rigorous evidence on SanJieZhenTong Capsules application in the long-term management of advanced-stage endometriosis

The existence of weak solutions for a generalized Camassa-Holm equation

A Camassa-Holm type equation containing nonlinear dissipative effect is investigated. A sufficient condition which guarantees the existence of weak solutions of the equation in lower order Sobolev space H(s) with 1 <= s <= 3/2 is established by using the techniques of the pseudoparabolic regularization and some prior estimates derived from the equation itself