The Quagga Mussel Invades the Lake Superior Basin

Prior studies recognized the presence of a single dreissenid species in Lake Superior—the zebra mussel Dreissena polymorpha. However, taxonomic keys based on traditional shell morphology are not always able to differentiate dreissenid species with confidence. We thus employed genetic and morphological analyses to identify dreissenids in a major river-embayment of Lake Superior—the lower St. Louis River/Duluth-Superior Harbor—during 2005–2006. Our results revealed the presence of a second dreissenid species—the quagga mussel D. bugensis (alternatively known as D. rostriformis bugensis). Both species occurred in mixed clusters, in which zebra mussels outnumbered quagga mussels (20–160:1). The largest quagga mussel collected in 2005 was 26.5 mm long and estimated to be two years old, suggesting that the initial introduction occurred no later than 2003. Further monitoring is necessary to determine whether the quagga mussel will colonize Lake Superior. Our results indicate that the coupling of conventional morphological and molecular approaches is essential for monitoring dreissenid species.     

A Biomimetic Mussel‐Inspired ε‐Poly‐l‐lysine Hydrogel with Robust Tissue‐Anchor and Anti‐Infection Capacity

In situ hydrogels have attracted considerable attention in tissue engineering because of their minimal invasiveness and ability to match the irregular tissue defects. However, hydrous physiological environments and the high level of moisture in hydrogels severely hamper binding to the target tissue and easily cause wound infection, thereby limiting the effectiveness in wound care management. Thus, forming an intimate assembly of the hydrogel to the tissue and preventing wound infecting still remains a significant challenge. In this study, inspired by mussel adhesive protein, a biomimetic dopamine‐modified ε‐poly‐l ‐lysine‐polyethylene glycol‐based hydrogel (PPD hydrogel) wound dressing is developed in situ using horseradish peroxidase cross‐linking. The biomimetic catechol–Lys residue distribution in PPD polymer provides a catechol–Lys cooperation effect, which endows the PPD hydrogels with superior wet tissue adhesion properties. It is demonstrated that the PPD hydrogel can facilely and intimately integrate with biological tissue and exhibits superior capacity of in vivo hemostatic and accelerated wound repair. In addition, the hydrogels exhibit outstanding anti‐infection property because of the inherent antibacterial ability of ε‐poly‐l ‐lysine. These findings shed new light on the development of mussel‐inspired tissue‐anchored and antibacterial hydrogel materials serving as wound dressings.     

Evaluation of single and two‐stage adaptive sampling designs for estimation of density and abundance of freshwater mussels in a large river

Reliable estimates of abundance are needed to assess consequences of proposed habitat restoration and enhancement projects on freshwater mussels in the Upper Mississippi River (UMR). Although there is general guidance on sampling techniques for population assessment of freshwater mussels, the actual performance of sampling designs can depend critically on the population density and spatial distribution at the project site. To evaluate various sampling designs, we simulated sampling of populations, which varied in density and degree of spatial clustering. Because of logistics and costs of large river sampling and spatial clustering of freshwater mussels, we focused on adaptive and non‐adaptive versions of single and two‐stage sampling. The candidate designs performed similarly in terms of precision (CV) and probability of species detection for fixed sample size. Both CV and species detection were determined largely by density, spatial distribution and sample size. However, designs did differ in the rate that occupied quadrats were encountered. Occupied units had a higher probability of selection using adaptive designs than conventional designs. We used two measures of cost: sample size (i.e. number of quadrats) and distance travelled between the quadrats. Adaptive and two‐stage designs tended to reduce distance between sampling units, and thus performed better when distance travelled was considered. Based on the comparisons, we provide general recommendations on the sampling designs for the freshwater mussels in the UMR, and presumably other large rivers. Published in 2009 by John Wiley & Sons, Ltd.     

基于OSPF协议的Graceful Restart技术的研究与实现

随着网络规模的不断扩大，网络速度的快速提升，网络与通信的新技术不断融入．用户越来越需要更丰富、更方便，更及时的网络应用和服务，互联网的这些特征导致新一代互联网概念的产生。为了提高网络可用性，IETF提出了对路由协议的扩展来减少由于路由协议失效造成的业务损失。在网络边缘路由器和其邻居路由器都支持OSPF平稳重启情况下，即使控制平面失效．数据平面也能够继续处理和转发报文。由于减少了路由抖动，平稳重启能够增加网络稳定性并减少控制平面资源的消耗。从而不单单增强了单台路由器的可用性，更提高了整个网络的可用性。     

Response of zebra mussel veligers to chemical oxidants

Experimental studies using chlorine, hydrogen peroxide and ozone showed two responses by zebra mussel veligers. First, veligers readily perceived the presence of oxidants (> 0.1 mg/l for chlorine and ozone) and responded by retracting the velum and ceasing swimming and feeding activities. Under these conditions, veligers are prevented from attaching to solid surfaces. Second, continuous exposure to these oxidants caused death. Complete mortality by chlorine or ozone (0.5–1 mg/l) at 18–22°C required continuous exposure of about 18 and 5 h, respectively. Either chlorine or ozone should be effective in controlling zebra mussel veligers. Hydrogen peroxide was observed to be effective in preventing attachment but only at high doses relative to chlorine and ozone.     

An All-in-One “4A Hydrogel”: through First-Aid Hemostatic,Antibacterial, Antioxidant,and Angiogenic to Promoting Infected Wound Healing

Currently used wound dressings are ineffective. Hence, there is a need to develop introduce a high-performance medicament with multiple functions including rapid hemostasis and excellent antibacterial activity to meet the growing worldwide demand for wound healing products. Here, inspired by the strong adhesion of mussels and the enzyme-mimicking activity of nanometallic biomaterials, the authors developed an injectable hydrogel to overcome multiple limitations of current wound dressings. The hydrogel is synthesized via esterification reaction between poly(vinyl alcohol) (PVA) and 3,4-dihydroxyphenylalanine (DOPA), followed by catechol-metal coordination between Cu²⁺ and the catechol groups of DOPA to form a PVA-DOPA-Cu (PDPC) hydrogel. The PDPC hydrogel possesses excellent tissue adhesive, antioxidative, photothermal, antibacterial, and hemostatic properties. The hydrogel rapidly and efficiently stopped bleeding under different traumatic conditions, including otherwise-lethal liver injury, high-pressure carotid artery rupture, and even fatal cardiac penetration injuries in animal models. Furthermore, it is demonstrated that the PDPC hydrogel affected high-performance wound repair and tissue regeneration by accelerating re-epithelialization, promoting collagen deposition, regulating inflammation, and contributing to vascularization. The results show that PDPC hydrogel is a promising candidate for rapid hemorrhage control and efficient wound healing in multiple clinical applications.     

An Evaluation of Streamflow Augmentation as a Short‐Term Freshwater Mussel Conservation Strategy

Recurrent and prolonged droughts, coupled with increased water resource demand, threaten freshwater mussel populations through stream drying and water quality degradation. Augmentation of stream discharge was proposed as a short‐term strategy to maintain adequate streamflows and water quality in reaches with important freshwater mussel populations during exceptionally low flow periods. We investigated the effects of water augmentation on seven freshwater mussel species in a small creek between 2011 and 2014. Using capture‐mark‐recapture methods, we monitored mussel populations in a control reach upstream of an augmentation outlet and two reaches immediately downstream of an augmentation outlet. Water quality measurements during our study indicated that augmentation improved water temperature and dissolved oxygen conditions during low flow periods. For all mussel species, apparent survival was positively related to minimum streamflows and declined precipitously as streamflows decreased. However, mean apparent survival between sampling occasions was high among all species but did not differ among treatment units, suggesting that flow augmentation rates in this study were insufficient for abating the effects of basin‐wide reductions in streamflow. Temporary emigration differed among study reaches but did not support hypothesized relationships because it increased with stream stage and was highest in an augmented reach. This suggests that streamflows did not drop below thresholds, which invoked burrowing as a response to decreased streamflows. Streamflow augmentation may be a viable short‐term mussel conservation strategy in small streams but will likely require higher augmentation volume capacity than evaluated during our study. Copyright © 2015 John Wiley & Sons, Ltd.     

SDN与传统IP网络互联架构的设计与实现

所提出的软件定义网络SDN与传统IP网络互联的架构基于以下核心思想:把整体SDN当成一个传统IP网络的"路由器",由IP网络和该"路由器"通过BGP协议进行域间网络层可达性信息NLRI的交互,从而使得全网的NLRI经过路由同步后达到一致。在此思想下分析设计了互联架构,对该互联架构进行了模块功能测试、多SDN场景下的仿真和性能测试。仿真结果表明所提出的互联架构可以完成SDN与传统IP网络的互联互通。设计的互联架构对原有网络设备的改动很少,所做的改动集中在可软件编程的控制器上,这有利于本架构在具体网络环境中的实施和部署。     

Evidence of neuroendocrine disruption in freshwater mussels exposed to municipal wastewaters

The purpose of this study was to test the hypothesis that exposure to municipal effluents can disrupt the neuroendocrine system in Elliptio complanata freshwater mussels. The capacity of ozonation to mitigate these effects was also examined. Mussels were exposed for 14 days to a continuous flow of increasing concentrations of the effluent before and after ozonation. Neuroendocrinal effects were examined by tracking changes in acetylcholinesterase, glutamate, gamma-aminobutyrate, serotonin, dopamine and their respective adenylcyclase activities in synapse membranes, monoamine oxidase and vitellogenin-like proteins. Oxidative stress and damage were examined by superoxide dismutase and lipid peroxidation, respectively, in the visceral tissues. The results revealed that the exposure of freshwater mussels increased the levels of vitellogenin-like proteins in both the primary-treated and ozonated effluents, dopamine and glutamate, and decreased the turnover of the neurostimulant acetylcholine. Moreover, these endpoints were significantly correlated with oxidative stress and damage. A canonical analysis of the responses revealed that dopamine and the neuroexcitatory neuromediators-acetylcholesterase and glutamate-were the endpoints more strongly related with oxidative stress and damage. Mussel morphology and estrogenic biomarkers (vitellogenin-like proteins, gonad lipid stores) were also significantly related, albeit to a lesser extent, to oxidative stress and damage. In general, ozone treatment was not sufficient to mitigate the observed neuroendocrinal effects in freshwater mussels. We conclude that the continuous exposure of freshwater mussels to municipal wastewater effluents leads to neuroendrocinal alterations and to oxidative stress.     

Commercially sterilized mussel meats (Mytilus chilensis): a study on process yield

The processing steps most responsible for yield loss in the manufacture of canned mussel meats are the thermal treatments of precooking to remove meats from shells, and thermal processing (retorting) to render the final canned product commercially sterile for long-term shelf stability. The objective of this study was to investigate and evaluate the impact of different combinations of process variables on the ultimate drained weight in the final mussel product (Mytilu chilensis), while verifying that any differences found were statistically and economically significant. The process variables selected for this study were precooking time, brine salt concentration, and retort temperature. Results indicated 2 combinations of process variables producing the widest difference in final drained weight, designated best combination and worst combination with 35% and 29% yield, respectively. Significance of this difference was determined by employing a Bootstrap methodology, which assumes an empirical distribution of statistical error. A difference of nearly 6 percentage points in total yield was found. This represents a 20% increase in annual sales from the same quantity of raw material, in addition to increase in yield, the conditions for the best process included a retort process time 65% shorter than that for the worst process, this difference in yield could have significant economic impact, important to the mussel canning industry.