Filter Feeding and Carbon and Nitrogen Assimilation of a Freshwater Bivalve (Unio douglasiae) on a Toxic Cyanobacterium (Microcystis aeruginosa)

We investigated the possible intake of toxic cyanobacteria (Microcystis aeruginosa) as a nutrient resource for a filter-feeder bivalve (Unio douglasiae) based on the measurement of feeding and assimilation rates of carbon and nitrogen in a limited space with no current for 72 h using 13C and 15N dual isotope tracers. With high clearance rates, the unionid rapidly removed Microcystis cells within 24 h, but only a small amount of carbon and nitrogen were incorporated into the tissues. Even with the low assimilation rates, the mussels showed more favorable uptake of carbon than of nitrogen from toxic Microcystis water, and of tissues, the gills and gut accumulated more carbon and nitrogen than the muscle and mantle. Collectively, our findings indicate that although Unio douglasiae effectively uptake toxic Microcystis cells, they can assimilate only low amounts of nutrients into tissues within three days, despite a non-flowing system.

Formulation, Development and Evaluation of in-situ Periodontal Gel Containing Ofloxacin

In-situ gel forming formulations are a novel concept of providing drugs to individuals as a liquid dosage form yet achieving sustained release of the drug for the required duration. Different polymer based distribution schemes have been created that can boost the residence time of the product at the drug absorption location. These formulations exist as a flowing system before administration and at the physiological environment it gets converted into viscoelastic gel. The available therapies are to minimize the bacterial infection and to regenerate the damage done by infection and inflammation. The therapies involve systemic therapy, conventional therapy, as well as local therapy. Aim of the present work was to formulate in-situ gel of ofloxacin and it is evaluated for antibacterial activity and stability and it showed good antibacterial activity for both gram positive and gram negative microorganisms and was stable at refrigerated temperature over three months. The results indicated that the formulation could be utilized to maintain the localized drug concentration for a longer period and increase patient compliance with lesser adverse effects.

Dental Plaque Biofilm: Development, Pathogenicity and Analysis

Biofilms are communities of microorganisms which are found attached to a surface. They develop on both biotic and abiotic surfaces and could act as a source of infection. The development of biofilms is a complex process and it involves several steps such as initial adhesion, reversible binding of bacteria to the solid surface, production of exopolysaccharide matrix, irreversible binding to the surface, maturation of biofilm structure, disintegration and dispersion of organized structure and the formation of new habitats. The biofilm exhibits unique properties of protecting host defences and desiccation, persistence in the flowing system, heterogeneity, spatial organization and resistance to antimicrobial agents through its ability to influence gene expression and phenotype. Quorum sensing, a means of the cell to cell communication is closely interconnected to the development of biofilm formation and inhibition. The dental plaque is the most common and well known oral biofilm. The preponderance of biofilm-associated diseases and its resistance in eradication has potentiated the need for further research in this field. Hence, the purpose of the review is to enlighten the importance of dental plaque as a biofilm, its properties, pathogenicity and analysis of biofilm. Keywords: Biofilms, Dental Plaque, Microbiome, Quorum sensing.

Never Change a Flowing System? The Effects of Retrograde Flow on Isolated Perfused Lungs and Vessels

Retrograde perfusion may occur during disease, surgery or extracorporeal circulation. While it is clear that endothelial cells sense and respond to changes in blood flow, the consequences of retrograde perfusion are only poorly defined. Similar to shear stress or disturbed flow, retrograde perfusion might result in vasomotor responses, edema formation or inflammation in and around vessels. In this study we investigated in rats the effects of retrograde perfusion in isolated systemic vessels (IPV) and in pulmonary vessels of isolated perfused lungs (IPL). Anterograde and retrograde perfusion was performed for 480 min in IPV and for 180 min in the IPL. Perfusion pressure, cytokine levels in perfusate and bronchoalveolar lavage fluid (BALF), edema formation and mRNA expression were studied. In IPV, an increased perfusion pressure and initially also increased cytokine levels were observed during retrograde perfusion. In the IPL, increased edema formation occurred, while cytokine levels were not increased, though dilution of cytokines in BALF due to pulmonary edema cannot be excluded. In conclusion, effects of flow reversal were visible immediately after initiation of retrograde perfusion. Pulmonary edema formation was the only effect of the 3 h retrograde perfusion. Therefore, further research should focus on identification of possible long-term complications of flow reversal.

Interaction of Liquid Lead Bismuth and Materials in Spallation Target

Material choices for liquid lead bismuth spallation target are some of austenitic stainless steel, ferrite martensitic steel and cold-worked austenitic stainless steel. In order to ensure materials resistance to irradiation and corrosion as well as compatibility with lead bismuth, it is appropriate to lower the incident proton current density and the process temperature, in which temperature range engineering design can control to work, especially in ADS (Accelerator-Driven nuclear transmutation System) concept. The lower limit temperature is determined from the physical melting temperature and the engineering efficiency of the steam generator involved in process control. The material related issues for liquid lead bismuth are mass loss by impinging secondary flow, wettability at the device interface for ultrasonic waves application, detachable control of the slag in the flowing system, stabilized electrical resistance between the material and the liquid lead bismuth interface. Electromagnetic fluid analyses show how flow rate relates electrical resistivity of flow channel material.

Fundamentals and Sources of Magnetic Nanocomposites and Their Sorption Properties

Over the years, adsorption has been the most widely applied technique for pollutants remediation in conventional water and wastewater treatment regimes with commendable results. Consequently, multiple adsorbents have been synthesized, characterized and tested for various pollutants sequestration such as; heavy metals, dyes, pharmaceutically active ingredients, among others, in aqueous media. Unfortunately, most of the sorbents face many inherent limitations such as high production cost, difficult separation of adsorbent from solution, and complex synthesis processes. Therefore, an efficient adsorbent that would be sustainably adopted for industrial application in wastewater treatment requires, among other properties, a simple and efficient recovery step from a continuous flowing system. The regenerated adsorbent must also possess near original properties after several cycles of reuse thereby resulting to low capital investment. To address this challenge, studies conducted in the past few years incorporating magnetism in both natural and synthetic sorbents to improve their removal from water via magnetic separation have yielded stupendous results compared to conventional technologies. This chapter concisely discusses synthesis methods and adsorption capacities and mechanisms of selected magnetic nanocomposite adsorbents under diverse physicochemical conditions for removal of cations, dyes and organic pollutants from wastewater. Magnetic nanocomposites present eco-friendly properties and are potential alternatives for application in water purification processes subject to commercial viability evaluation before practical use.