Nanoribbon waveguides for subwavelength photonics integration

Although the electrical integration of chemically synthesized nanowires has been achieved with lithography, optical integration, which promises high speeds and greater device versatility, remains unexplored. We describe the properties and functions of individual crystalline oxide nanoribbons that act as subwavelength optical waveguides and assess their applicability as nanoscale photonic elements. The length, flexibility, and strength of these structures enable their manipulation on surfaces, including the optical linking of nanoribbon waveguides and other nanowire elements to form networks and device components. We demonstrate the assembly of ribbon waveguides with nanowire light sources and detectors as a first step toward building nanowire photonic circuitry.     

Validation of Fermentation and Processing Procedures for the Commercial-Scale Production of a Live,Attenuated Edwardsiella ictaluri Vaccine for Use in Channel Catfish Aquaculture

Abstract

Mortality associated with Edwardsiella ictaluri infection is a serious impediment to the commercial production of fingerling Channel Catfish Ictalurus punctatus. A patented, live, attenuated, orally delivered vaccine has been developed that offers exceptional protection against E. ictaluri infection in both laboratory and small-scale pond trials. Further vaccine development is contingent on the successful completion of large-scale field trials that accurately reflect industry conditions. This current work focuses on the validation of fermentation protocols and the optimization of downstream processing procedures to produce sufficient quantities of vaccine to conduct commercial-scale field trials. Eight vaccine serials were produced from a master seed stock (S97-773-340X2) in a 50-L floor model fermenter over two consecutive years. Following fermentation, cells were harvested, concentrated 10-fold, and cryogenically stored (?74°C). To assess processing protocols and determine shelf life of cryogenically stored vaccine, serials were tested for cell viability and vaccine potency at various intervals over 24 months. There were no significant differences in cell viability between the fresh vaccine and the stored frozen product. All serials provided a high level of protection (77–100% relative percent survival) against E. ictaluri infection in juvenile Channel Catfish and exhibited excellent poststorage viability. This data demonstrates that the live, attenuated, orally delivered vaccine can be stored at ?74°C for at least 2 years with no reduction in cell viability or vaccine potency.

Received May 17, 2016; accepted January 19, 2017 Published online April 4, 2017     

Comparative Susceptibility of Channel Catfish,Blue Catfish,and their Hybrid Cross to Experimental Challenge with Bolbophorus damnificus (Digenea: Bolbophoridae) Cercariae

Abstract

The digenetic trematode Bolbophorus damnificus has been implicated in significant losses in catfish aquaculture since the late 1990s. The complex life cycle sequentially involves the American white pelican Pelecanus erythrorhynchos, the marsh rams horn snail Planorbella trivolvis, and Channel Catfish Ictalurus punctatus. Research supports anecdotal reports from the industry, suggesting that the hybrid of Channel Catfish×Blue Catfish I. furcatus is less susceptible to disease agents that have been historically prohibitive to Channel Catfish production, namely the gram-negative bacteria Edwardsiella ictaluri and Flavobacterium columnare, as well as the myxozoan parasite Henneguya ictaluri. This current research compared the susceptibility of Channel Catfish, Blue Catfish, and their hybrid cross to an experimental challenge by B. damnificus. Fish were exposed to 0, 100, 200, and 400 B. damnificus cercariae per fish, and the numbers of metacercariae per fish were determined 14 d postchallenge. Metacercariae were recovered from all challenged fish. There were no significant differences among fish groups challenged with the same dose, suggesting Channel and Blue Catfish and their hybrid are comparably susceptible to B. damnificus infection. As such, it is recommended that producers raising hybrid catfish remain diligent in controlling populations of the snail intermediate host to prevent production losses attributed to B. damnificus, especially when loafing pelicans have been observed at the aquaculture operation.

Received October 22, 2013; accepted January 5, 2014     

植物提取物饲料添加剂在水产养殖上的应用

植物提取物饲料添加剂的英文词并不统一,常见的使用词类包括:lant extract(植物提取物)、Nutraceuticals(天然药物)、Phytobiotics(阳生素)、Essential oil(植物精油)、Herbs(草药)、Chinese Tra-ditional Medicine(中草药)等.植物提取物类饲料添加剂在过去的十几年中已经广泛市场化而用于动物生产.抗生素类产品已经在人类和畜禽动物的疾病预防与控制中得到广泛的使用,而抗生素类产品在水产养殖过程中的应用却造成了一定的副面效应,这主要是与水产动物的给药方式有关.水产养殖迫切需要一种非抗生素的促长剂来提高水产动物的生长率、饲料转化率,同时能增强其抗应激能力和降低死亡率等.鉴此,近些年来众多科学家和从业者一直试图尝试采用新的技术措施,以求促进鱼虾生长和提高存活率,同时减少疾病的发生,并保持环境友好.使用植物提取物添加剂可能会为缓解这种后抗生素时代的尴尬提供有益的帮助.文章综述了植物提取物添加剂在水产动物养殖中的研究和应用概括.