Longitudinal trends in river functioning: Patterns of nutrient and carbon processing in three Australian rivers

Understanding longitudinal trends in the processing of carbon in rivers represents a much conceptualised, but infrequently tested, issue in aquatic ecology. In this study, we conducted concurrent longitudinal examinations of three very different rivers in eastern Australia to determine whether general principles in river functioning exist across broad geographic and hydrologic scales. Specifically, we examined trends in ambient basic water chemistry, nutrient concentrations, dissolved organic carbon (DOC), extracellular enzymes and food web structure and functioning and conducted bioassays to examine the degree to which DOC and nutrients limit heterotrophic bacterial respiration. These parameters revealed striking similarities across all sites. For metazoan communities, stable isotope analysis showed that algal carbon was the dominant basal resource utilised by consumers in all three rivers, suggesting that in‐stream primary producers strongly underpin trophic pathways regardless of the position within a catchment or catchment condition. Analyses of extracellular enzymes revealed that microbial communities are actively utilising DOC at all sites. In fact, heterotrophic microbial respiration was strongly limited by DOC at all sites, with nutrient additions resulting in only relatively minor increases in respiration. Ultimately, this study demonstrates that DOC and algal carbon are critically important drivers of ecosystem processes in Australian riverine ecosystems. Furthermore, across all of our sites and rivers, ambient nutrient concentrations did not influence carbon processing. The consistent longitudinal trends in river function identified in this study provide useful insights for catchment managers and modellers with respect to identifiying key principles that underpin ecosystem functioning in Australian rivers. Copyright © 2009 John Wiley & Sons, Ltd.     

Facile Synthesis and Characterization of Palm CNF-ZnO Nanocomposites with Antibacterial and Reinforcing Properties

Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites.     

大都市区的棋盘博弈：区域设计中形态学主题的运用

中国空前的城市化速度与规模亟需更先进的规划设计策略。探索基于形态学的区域设计研究教学方法,从而制定体现中国大都市区特征的空间策略。在设计课程背景下,介绍了以形态学主题为基础的探索性棋盘博弈这一方法论,并应用到粤港澳大湾区空间转型的场景设计中。评估了香港理工大学设计学院和代尔夫特理工大学城市学系连续4年的一系列合作成果。1）沿着设计课程的流程,阐明了教学轨迹。2）调查了不同形态学主题如何影响学生的设计成果,对比了成果的空间特异性以及设计提案的激进程度。3）探讨了是否部分形态学主题更适用于大湾区社会文化与环境的特殊性。在6次课程中,学生们研究了8个形态学主题：点状、线状、条状、巨型街区、放射状、环状、交叉状和边缘状。实践表明存在冗余的主题,因此对主题的进一步确立值得深入研究。需要指出,2所大学的设计课程存在差异,这似乎也影响了棋盘博弈法在各自课程中扮演的作用。整体而言,此教学方法论可以产生远超传统空间规划的设计策略。因此,以形态学主题为基础的棋盘博弈是一套充满前景的方法论,并且今后有望结合更多利益相关方的参与,进行进一步深化和测试。     

Enhanced thermal stability of biomedical thermoplastic polyurethane with the addition of cellulose nanocrystals

Freeze‐dried cellulose nanocrystals (CNCs) were dispersed in the thermoplastic polyurethane [Pellethane 2363‐55D (P55D)] by a solvent casting method to fabricate CNC‐reinforced nanocomposites. This study demonstrated that the addition of small amounts (1–5 wt %) of CNCs to P55D increased the thermal degradation temperature while maintaining a similar stiffness, strength, and elongation of the neat P55D. CNC additions to P55D did not alter the glass‐transition temperature, but the onset decomposition temperature was shifted from 286 to 327°C when 1 wt % CNCs was dispersed in the matrix. The higher onset decomposition temperature was attributed to the formation of hydrogen bonds between the hydroxyl groups on the CNC surface and urethane groups in the hard block of P55D. The ultimate tensile strength and strain to failure (ε_f) of the nanocomposites were minimally affected by additions up to 5 wt % CNCs, whereas the elastic modulus was increased by about 70%. The observation that ε_f was unchanged with the addition of up to 5 wt % CNCs suggested that the flow/sliding of the hard blocks and chains were not hindered by the presence of the CNCs during plastic deformation. The ramifications of this study was that CNC additions resulted in wider processing temperatures of P55D for various biomedical devices while maintaining a similar stiffness, strength, and elongation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41970.     

Role of soil health in maintaining environmental sustainability of surface coal mining

Mountaintop coal mining (MCM) in the Southern Appalachian forest region greatly impacts both soil and aquatic ecosystems. Policy and practice currently in place emphasize water quality and soil stability but do not consider upland soil health. Here we report soil organic carbon (SOC) measurements and other soil quality indicators for reclaimed soils in the Southern Appalachian forest region to quantify the health of the soil ecosystem. The SOC sequestration rate of the MCM soils was 1.3 MgC ha(-1) yr(-1) and stocks ranged from 1.3 ± 0.9 to 20.9 ± 5.9 Mg ha(-1) and contained only 11% of the SOC of surrounding forest soils. Comparable reclaimed mining soils reported in the literature that are supportive of soil ecosystem health had SOC stocks 2.5-5 times greater than the MCM soils and sequestration rates were also 1.6-3 times greater. The high compaction associated with reclamation in this region greatly reduces both the vegetative rooting depth and infiltration of the soil and increases surface runoff, thus bypassing the ability of soil to naturally filter groundwater. In the context of environmental sustainability of MCM, it is proposed that the entire watershed ecosystem be assessed and that a revision of current policy be conducted to reflect the health of both water and soil.     

查找无线嵌入式系统中的噪声来源

在把无线电芯片或模块集成到典型的嵌入式系统中时,设计人员必须面临的一项常见任务是追踪和消除噪声和杂散信号。潜在的噪声来源包括：开关电源、来自系统其它部分的数字噪声、以及外部噪声来源。     

Construction of self‐organized free‐standing TiO2 nanotube arrays for effective disinfection of drinking water

BACKGROUND: In this study, the efficacy of disinfection surface water using anodic TiO₂ films was investigated. The as‐prepared photocatalyst demonstrated excellent photocatalytic disinfection of E. coli cells. Free‐standing and self‐organized TiO₂ nanotube arrays were synthesized via a facile electrochemical anodization method, prior to calcination. RESULTS: Over 95% of the initial 10⁶ cpu mL^?1 E. coli cells were inactivated within 50 min of UV‐A photocatalytic disinfection, despite the influence of various ionic species and organic compounds commonly present in groundwater. This was justified by the unique double‐walled nanotubular structure of the TiO₂ photocatalyst, which provided efficient delocalization of electron carriers and promoted anti‐recombination of photogenerated pairs of electrons and holes. Based on the experimental results obtained, cations enhanced the overall disinfection process while anions had an inhibitory effect on disinfection rates. CONCLUSION: The photocatalyst exhibited high efficiency in terms of photocatalytic disinfection of E. coli cells present in groundwater. It is deemed promising for applications in drinking water treatment owing to its superior disinfection performance, as well as high settleability, which promotes recovery and reuse of the catalyst. Copyright © 2010 Society of Chemical Industry     

Improving condom use intentions and behavior by changing perceived partner norms: An evaluation of condom promotion videos for college students.

Objective: To examine the effectiveness of 2 condom promotion videotapes on self-efficacy, intentions, and behavior. Design: Two hundred twenty college students completed social-cognitive and behavioral measures and were then randomly assigned to receive one of two 30-min condom promotion videotapes (male or female student presenters) or to a wait-list control condition. Participants who watched 1 of the videotapes completed immediate posttest measures, and 85% of participants completed a 4-month follow-up. Main Outcome Measures: Self-efficacy for condom use, intentions to use condoms, use of condom during last sex, and consistent condom use over the last month. Results: Participants who received either video reported greater self-efficacy to refuse to have unprotected sex and intentions than controls at follow-up. Individuals who received either video were more likely than controls to report using a condom during last sex with a regular partner, and those who watched the female presenter were more likely to report consistent condom use. Conclusion: Participants benefited in terms of self-efficacy and intentions from receiving either video, but both men and women benefited more in terms of condom use behavior from receiving the female video. Future research is needed to determine whether opposite-sex speaker videos could be beneficial with a larger (and more sexually active) sample and whether these effects are maintained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)