Spatial and temporal regeneration patterns within gaps in the primary forests vs. secondary forests of Northeast China

Forest gaps play an important role during forest succession in temperate forest ecosystems. However, the differences in spatial distribution and replacement patterns of woody plants (trees and shrubs) between primary and secondary forests remain unclear during the gap-filling processes, especially for temperate forests in Northeast China. We recorded 45,619 regenerated trees and shrubs in young gaps (<10 years), old gaps (10~20 years), and closed forest stands (i.e., filled gaps) in the primary broadleaved Korean pine (Pinus koraiensis Sieb. Rt Zucc.) forests vs. secondary forests (degraded from primary forests). The gap-filling processes along horizontal (Cartesian coordinate system) and vertical (lower layer: 0~5 m, medium layer: 5~10 m, and upper layer: >10 m) dimensions were quantified by shade tolerance groups of trees and shrubs. We found that gap age, competition between species, and pre-existing regeneration status resulted in different species replacement patterns within gaps in primary vs. secondary forests. Gap formation in both primary and secondary forests increased species richness, with 33, 38, 39, and 41 in the primary closed stands, primary forest gaps, secondary closed stands, and secondary forest gaps, respectively. However, only 35.9% of species in primary forest gaps and 34.1% in secondary forest gaps successfully reached the upper layer. Based on the importance values (IVs) of tree species across different canopy heights, light-demanding trees in the upper layer of the secondary forests were gradually replaced by intermediate and shade-tolerant trees. In the primary forests, Korean pine exhibited intermittent growth patterns at different canopy heights, while it had continuous regeneration along vertical height gradients in the secondary forests. The differences in Korean pine regeneration between the primary and secondary forests existed before gap formation and continued during the gap-filling processes. The interspecific competition among different tree species gradually decreased with increasing vertical height, and compared to the primary forests, the secondary forests showed an earlier occurrence of competition exclusion within gaps. Our findings revealed the species replacement patterns within gaps and provided a further understanding of the competition dynamics among tree species during the gap-filling processes

synthesisandseparationperformanceofsilicalite1membranesonsilicatubes

High-performance silicalite-1 membranes were synthesized on silica tubes by in-situ hydrothermal synthesis. By using the "solution-filling (SF)" method, the average flux of membranes with the SF method was improved by about 25% compared to that of the membranes without using the SF method; the flux and the separation factor of the membranes prepared with the SF method for an ethanol/water mixture at 60A degrees C were 0.99 kg/(m(2)center dot h) and 73, respectively. It was found that the membranes synthesized on silica tubes exhibited high thermal stability and high reproducibility, and the relatively standard deviations (R.S.D.) of the average flux and separation factor were only 9.6% and 5.6%, respectively, which suggests that the silica support is more suitable than other kinds of supports for preparing high-performance silicalite-1 membranes

synthesisandseparationperformanceofsilicalite1membranesonsilicatubes

High-performance silicalite-1 membranes were synthesized on silica tubes by in-situ hydrothermal synthesis. By using the "solution-filling (SF)" method, the average flux of membranes with the SF method was improved by about 25% compared to that of the membranes without using the SF method; the flux and the separation factor of the membranes prepared with the SF method for an ethanol/water mixture at 60A degrees C were 0.99 kg/(m(2)center dot h) and 73, respectively. It was found that the membranes synthesized on silica tubes exhibited high thermal stability and high reproducibility, and the relatively standard deviations (R.S.D.) of the average flux and separation factor were only 9.6% and 5.6%, respectively, which suggests that the silica support is more suitable than other kinds of supports for preparing high-performance silicalite-1 membranes

A Titania-Supported Polyoxometalate and Au Cocatalyst for Efficient Photocatalytic Environmental Remediation

Photocatalysis has been considered an effective method for environmental purification and pollutant removal, with many experiments having being performed. The sustainable development of environmentally friendly materials that can photocatalytically oxidize and degrade contaminants is widely studied. Here, we report the results of the photocatalytic oxidation of contaminants (over 99% conversion of the contaminants was achieved) on a tri-component photocatalyst by the simultaneous decoration of Au nanoparticles and a new type of Sn-substituted Keggin structure polyoxometalate (POM) on a TiO2 semiconductor (denoted as AuPT). The light absorption and the electron–hole pair separation capacity of TiO2 was significantly ameliorated on AuPT. The synergistic effect of the Au resonance energy transfer (RET) course and the POM redox transformation can be advantageous to the efficient transmission of photogenerated electrons and holes in a way that achieves efficient photocatalytic oxidation of contaminants

Study on the modified montmorillonite for adsorbing formaldehyde

It is very important to develop a cost-effective and environmentally friendly adsorbent for the efficient removal of indoor formaldehyde (HCHO). Herein we present the modified montmorillonite as adsorbents for HCHO. A series of alumina cross-linked montmorillonite with surfactant modification (Al-SCLM) were synthesized in the presence of polyvinyl alcohol (PVA). These adsorbents are safe and cheap, in rich sources, acceptable appearance for daily use. By the characterization such as XRD, FTIR, HCHO adsorption/desorption capacity measurement, it is found that the interlayer environment is a key factor for the superior adsorption capacity of the modified montmorillonite. The introduction of surfactant molecules is very favorable for the improvement of the montmorillonite's adsorption capacity. With optimization, the adsorbing capacity of HCHO over Al-SCLM is obviously superior to conventional inorgano-montmorillonite and organo-montmorillonite, and can be over 80% of that over activated carbon with the same volume. We can conveniently recover the adsorbents by heating them to 353 K. The strategy that improving the adsorbing capacity by increasing the interlayer distance of materials with surfactant modification will be crucial for developing highly effective adsorbents for hazardous wastes, and has a good prospect for getting rid of HCHO in industrialization. (C) 2015 Elsevier B.V. All rights reserved

Developing Key Safety Management Factors for Construction Projects in China: A Resilience Perspective

It is acknowledged that construction safety is pivotal to the project management objectives. Meanwhile, the concept of resilience provides an effective and pragmatic countermeasure to improve the safety management level of construction projects. However, the “resilience” has not gained considerable attention in the construction safety management system. In this context, the paper aims to develop the key safety management factors for construction projects from the resilience perspective. Firstly, the theoretical framework and key safety management factors of construction safety management system based on the resilience theory are proposed. The importance of each factor is then obtained by using the method of structural equation modeling (SEM). The results indicate that information management, material and technology management, organization management and personnel management would improve the safety and resilience of the project. Specifically, improving the resilience of information flow to strengthen the interaction among elements of the system can enhance the safety management level. These findings can be used as references for construction safety managers to improve the abilities of preventing safety accidents and recovering after safety accidents

Morphology and Structure Controls of Single-atom Fe-N-C Catalysts Synthesized Using FePc Powders as the Precursor

Understanding the origin of the high electrocatalytic activity of Fe–N–C electrocatalysts for oxygen reduction reaction is critical but still challenging for developing efficient sustainable nonprecious metal catalysts used in fuel cells. Although there are plenty of papers concerning the morphology on the surface Fe–N–C catalysts, there is very little work discussing how temperature and pressure control the growth of nanoparticles. In our lab, a unique organic vapor deposition technology was developed to investigate the effect of the temperature and pressure on catalysts. The results indicated that synthesized catalysts exhibited three kinds of morphology—nanorods, nanofibers, and nanogranules—corresponding to different synthesis processes. The growth of the crystal is the root cause of the difference in the surface morphology of the catalyst, which can reasonably explain the effect of the temperature and pressure. The oxygen reduction reaction current densities of the different catalysts at potential 0.88 V increased in the following order: FePc (1.04 mA/cm2) < Pt/C catalyst (1.54 mA/cm2) ≈ Fe–N–C-f catalyst (1.64 mA/cm2) < Fe–N–C-g catalyst (2.12 mA/cm2) < Fe–N–C-r catalyst (2.35 mA/cm2). By changing the morphology of the catalyst surface, this study proved that the higher performance of the catalysts can be obtaine