Evolution, and functional analysis of Natural Resistance-Associated Macrophage proteins (NRAMPs) from Theobroma cacao and their role in cadmium accumulation

The presence of the toxic metal cadmium (Cd2+) in certain foodstuffs is recognised as a global problem, and there is increasing legislative pressure to reduce the content of Cd in food. The present study was conducted on cacao (Theobroma cacao), the source of chocolate, and one of the crops known to accumulate Cd in certain conditions. There are a range of possible genetic and agronomic methods being tested as a route to such reduction. As part of a gene-based approach, we focused on the Natural Resistance-Associated Macrophage Proteins (NRAMPS), a family of proton/metal transporter proteins that are evolutionarily conserved across all species from bacteria to humans. The plant NRAMP gene family are of particular importance as they are responsible for uptake of the nutritionally vital divalent cations Fe2+, Mn2+, Zn2+, as well as Cd2+. We identified the five NRAMP genes in cacao, sequenced these genes and studied their expression in various organs. We then confirmed the expression patterns in response to variation in nutrient cation availability and addition of Cd2+. Functional analysis by expression in yeast provided evidence that NRAMP5 encoded a protein capable of Cd2+ transport, and suggested this gene as a target for genetic selection/modification

Analysis of enhanced flame speed in the transition droplet sizes for n-alkane aerosols generated by electrospray

PresentationFire and explosion incidents related to aerosol occur occasionally throughout the industries. However, its hazards are relatively overlooked due to the misconception of that liquids are safe below their flash point. As well as scarcity of data stems from the difficulty of aerosol generation by a well-controlled manner. In this research, n-alkane aerosols were produced from an improved electrospray device, and their flame speeds were measured to verify the transition range. When droplet sizes fell into this range, the flame speed would be enhanced and pose greater threats to people and surroundings. Theoretic simulation and empirical equation were performed to predict the trend of flame propagation. Application of convective droplet evaporation improved the theoretic simulation but still failed to recognize the transition range. On the other hand, the empirical equation provided a good fitting and explained possible reason for the trend. It should notice that the transition droplet size range is not a fixed range for aerosols. Therefore, process design and operation should consider the potential generation of aerosol size and location of transition range to reduce the hazards. By understanding the flammability of aerosol, the associated risk can be managed to an acceptable level

Stable smectic phase in suspensions of polydisperse colloidal platelets with identical thickness

6 pages, 6 figures.-- PACS nrs.: 61.30.Eb, 64.70.M−, 81.16.Dn, 82.70.Dd.-- ArXiv pre-print available at: http://arxiv.org/abs/0909.2625We report the nematic and smectic ordering in an aqueous suspension of monolayer α-Zirconium phosphate platelets possessing a high polydispersity in diameter but uniform thickness. We observe an isotropic-nematic transition as the platelet volume fraction increases, followed by the formation of a smectic, an elusive phase that has been rarely seen in discotic liquid crystals. The smectic phase is characterized by x-ray diffraction high-resolution transmission electron microscopy, and optical microscopy. The phase equilibria in this highly polydisperse suspension are rationalized in terms of a theoretical approach based on density-functional theory.Acknowledgment is made to the donors of ACS Petroleum Research Fund (Grant No. 45303-G7) and to the Dow Chemical Co. This work has been partly financed by start-up funds from Texas Engineering Experimental Station and Texas A&M University, by Grants No. NANOFLUID, No. MOSAICO, and No. S-0505/ESP-0299 from Comunidad Autónoma de Madrid (Spain), and Grants No. FIS2005-05243-C02-01, No. FIS2007-65869-C03-01, No. FIS2008-05865-C02-02, and No. FIS2007-65869-C03-C01 from Ministerio de Educación y Ciencia (Spain).Publicad

Modeling the blanketing and warming effect of high expansion foam used for LNG vapor risk mitigation

PresentationNatural Gas is a cleaner energy when compared to other sources like oil or coal. Its consumption has been drastically increasing over the past few years and is projected to increase further. Liquefying natural gas is an effective way of easily storing and transporting it because of the high ratio of liquid to vapor densities. However, a leak of liquefied natural gas (LNG) can result in the formation of a huge vapor cloud, which poses a potential risk. This cryogenic vapor cloud has the potential to ignite and can migrate downwind near ground level because of a density greater than air. NFPA recommends the use of high expansion foam to mitigate the vapor hazard due to LNG. The primary objective of this paper is to study the effects of heat transfer mechanisms like convection and radiation on foam breakage to be able to accurately quantify the amount of foam required to mitigate the vapor risk of LNG spills

Formation and Control of Fluidic Species

This invention generally relates to systems and methods for the formation and/or control of fluidic species, and articles produced by such systems and methods. In some cases, the invention involves unique fluid channels, systems, controls, and/or restrictions, and combinations thereof. In certain embodiments, the invention allows fluidic streams (which can be continuous or discontinuous, i.e., droplets) to be formed and/or combined, at a variety of scales, including microfluidic scales. In one set of embodiments, a fluidic stream may be produced from a channel, where a cross-sectional dimension of the fluidic stream is smaller than that of the channel, for example, through the use of structural elements, other fluids, and/or applied external fields, etc. In some cases, a Taylor cone may be produced. In another set of embodiments, a fluidic stream may be manipulated in some fashion, for example, to create tubes (which may be hollow or solid), droplets, nested tubes or droplets, arrays of tubes or droplets, meshes of tubes, etc. In some cases, droplets produced using certain embodiments of the invention may be charged or substantially charged, which may allow their further manipulation, for instance, using applied external fields. Non-limiting examples of such manipulations include producing charged droplets, coalescing droplets (especially at the microscale), synchronizing droplet formation, aligning molecules within the droplet, etc. In some cases, the droplets and/or the fluidic streams may include colloids, cells, therapeutic agents, and the like

Modelling Ice and Wax Formation in a Pipeline in the Arctic Environment

PresentationIn the Arctic environment, fluid temperature in pipeline can drop below the freezing point of water, which causes wax and ice to form on pipeline surface. Solid formation on pipeline surface can lead to flow assurance and process safety issues, such as blockage of pipeline, pipeline component failure, and the release of hazardous liquid. The blockage of pipeline can cause additional burden or failure to pumping system. Remediating the plugging requires shutdown of pipeline operation, which cause tremendous cost and delay to the entire production system. Ice and wax deposition in pipeline is a slow process. Pigging operation can be used to remove the deposits on pipeline surface. However, if deposition is too thick, pipeline blockage can still occur. In order to prevent pipeline blockage, ice and wax deposition rates are required to be estimated. This paper investigates ice and wax deposition rates in a 90 km pipeline. A fundamental model for both ice and wax deposition is proposed using first principles of heat and mass transfer. The interaction between water and wax is analysed

A new device for the generation of microbubbles

In this paper we present a new method for the production of bubble-liquid suspensions (from now on BLS) composed of micron-sized bubbles and with gas to liquid volume ratios larger than unity. We show that the BLS gas fraction ʎ=Qg and Q1 , being Qg and Q1 the flow rates of gas and liquid, respectively, is controlled by a dimensionless parameter which accounts for the ratio of the gas pressure inside the device to the liquid viscous pressure drop from the orifices where the liquid is injected to the exit, where the BLS is obtained. This parameter permits the correct scaling of the BLS gas volume fraction of all the experiments presented

Increasing entropy for colloidal stabilization

Stability is of paramount importance in colloidal applications. Attraction between colloidal particles is believed to lead to particle aggregation and phase separation; hence, stability improvement can be achieved through either increasing repulsion or reducing attraction by modifying the fluid medium or by using additives. Two traditional mechanisms for colloidal stability are electrostatic stabilization and steric stabilization. However, stability improvement by mixing attractive and unstable particles has rarely been considered. Here, we emphasize the function of mixing entropy in colloidal stabilization. Dispersion stability improvement is demonstrated by mixing suspensions of attractive nanosized titania spheres and platelets. A three-dimensional phase diagram is proposed to illustrate the collaborative effects of particle mixing and particle attraction on colloidal stability. This discovery provides a novel method for enhancing colloidal stability and opens a novel opportunity for engineering applications