Contact-Mediated Nucleation of Subcooled Droplets in Melt Emulsions: A Microfluidic Approach

The production of melt emulsions is mainly influenced by the crystallization step, as every single droplet needs to crystallize to obtain a stable product with a long shelf life. However, the crystallization of dispersed droplets requires high subcooling, resulting in a time, energy and cost intensive production processes. Contact-mediated nucleation (CMN) may be used to intensify the nucleation process, enabling crystallization at higher temperatures. It describes the successful inoculation of a subcooled liquid droplet by a crystalline particle. Surfactants are added to emulsions/suspensions for their stabilization against coalescence or aggregation. They cover the interface, lower the specific interfacial energy and form micelles in the continuous phase. It may be assumed that micelles and high concentrations of surfactant monomers in the continuous phase delay or even hinder CMN as the two reaction partners cannot get in touch. Experiments were carried out in a microfluidic chip, allowing for the controlled contact between a single subcooled liquid droplet and a single crystallized droplet. We were able to demonstrate the impact of the surfactant concentration on the CMN. Following an increase in the aqueous micelle concentrations, the time needed to inoculate the liquid droplet increased or CMN was prevented entirely.

First report of Pseudomonas savastanoi pv. nerii on oleander in the Czech Republic

The bacterium Pseudomonas savastanoi pv. nerii was identified as the causal agent of parenchymatous galls on leaves of potted oleander plants grown at Brno, Moravia, in 2004. The plants had originated from cuttings made from firm shoots of a supposedly asymptomatic plant grown in and introduced from the Mediterranean region. The Biolog GN microplate system was used to identify the isolated bacterial strains. Successful inoculation of Nerium oleander seedlings proved the pathogenicity of the isolates. This is the first record of P. savastanoi pv. nerii in the Czech Republic. :

Undesirable Graphite Morphologies Incidence in Inoculated Grey Irons

Successful inoculation is not guaranteed and effects may even be deleterious. The main risks are the appearance of types B and D graphite, associated with ferrite and/or carbides due to lack of control of undercooling during eutectic solidification. Alternatively coarse type C graphite in hypo to eutectic grey irons may result from inadequate or excessive inoculation. Sulphur and aluminium content in a molten iron are considered to be the main factors to control the degree of eutectic undercooling, graphite morphology and inoculation efficiency. Thermal conditions, such as superheating, inoculation and pouring temperature play an important role in controlling these effects. Cooling rates due to different mould materials and casting thickness were also considered. In order to resolve individual problems, different inoculant systems have to be considered, such as Sr-FeSi, Ca-FeSi, Ti,Ca-FeSi, Zr,Ca-FeSi, Ba,Ca-FeSi, RE-FeSi (Ca). The present paper made a synthesis of other published papers by the authors, but also added many original un-published results.

Influence of diazotrophic inoculations on nitrogen nutrition of rice

An experiment was conducted in microplots (7 by 7m) to investigate the effect of 2 non-symbiotic N2-fixing bacteria [Azotobacter (strain CS1) and Azospirillum (strain CM4)] in the presence of 50 kg N/ha on the performances of the diazotrophs with respect to nitrogen accretion and its transformation in the rhizosphere soils of rice (Oryza sativa L. cv. IR-36). In most cases, a successful inoculation of the diazotrophs was recorded, with the proliferation of Azotobacter and Azospirillum, either alone or in combination, in the rhizosphere soils, and nitrogenase activity (C2H2 reduction) of the microbes was present in rice roots. The uninoculated soil receiving 100 kg N/ha recorded the highest amount of total nitrogen, non-hydrolysable organic nitrogen, available nitrogen, and hydrolysable organic nitrogen content in the rhizosphere soils, resulting in greater yield of the crop. Inoculation of the diazotrophs substantially increased different fractions of nitrogen content in the rhizosphere soils, and the increase in total nitrogen, non-hydrolysable organic nitrogen, and hydrolysable organic nitrogen was greater due to Azotobacter than either Azospirillum or a combination of Azotobacter and Azospirillum. Total and mineral nitrogen content increased at maximum tillering to flowering stages of the crop, followed by a decline at maturity, whereas, hydrolysable organic nitrogen decreased with a concomitant increase in non-hydrolysable fraction with the age of the crop.

Experimental Rodent Models of Brainstem Tumors

Despite recent advances in surgical technology, resection is not an option for many brainstem tumors. Experimental models have played essential roles in examining new approaches to therapy. The objective of the present study was to generate models by determining coordinates for safe inoculation into the brainstem of mice and rats, and to establish whether the implantation of heterotopic cells would create reproducible survival curves. Morbidity and survival studies were used to map stereotactic coordinates allowing successful inoculation of tumor cells. Survival studies were used to investigate the time course of tumor growth. Tumor location was examined by light microscopy and magnetic resonance imaging. Mice survived injections of 2 μL of saline at interaural, lateral, and depth coordinates of −2.5, 1.0, and 3.5 mm and −1.5, 1.0, and 3.5 mm. Rats survived injections at interaural, lateral, and depth coordinates of −2.0, 2.0, and 7.0 mm and −3.0, 0, and 7.0 mm. Median survival of mice challenged with 5 × 105 EMT6 and 104 B16 tumor cells was 11 and 10 days, respectively. Median survival for rats challenged with 104 9L and F98 cells was 14 and 13 days, respectively. The present study demonstrates a feasible approach to preparing models of brainstem tumors. Limitations of these models are discussed.

Bacterial Symbiont Transmission in the Wood-Boring Shipworm Bankia setacea (Bivalvia: Teredinidae)

ABSTRACT The Teredinidae (shipworms) are a morphologically diverse group of marine wood-boring bivalves that are responsible each year for millions of dollars of damage to wooden structures in estuarine and marine habitats worldwide. They exist in a symbiosis with cellulolytic nitrogen-fixing bacteria that provide the host with the necessary enzymes for survival on a diet of wood cellulose. These symbiotic bacteria reside in distinct structures lining the interlamellar junctions of the gill. This study investigated the mode by which these nutritionally essential bacterial symbionts are acquired in the teredinid Bankia setacea. Through 16S ribosomal DNA (rDNA) sequencing, the symbiont residing within the B. setaceagill was phylogenetically characterized and shown to be distinct from previously described shipworm symbionts. In situ hybridization using symbiont-specific 16S rRNA-directed probes bound to bacterial ribosome targets located within the host gill coincident with the known location of the gill symbionts. These specific probes were then used as primers in a PCR-based assay which consistently detected bacterial rDNA in host gill (symbiont containing), gonad tissue, and recently spawned eggs, demonstrating the presence of symbiont cells in host ovary and offspring. These results suggest that B. setacea ensures successful inoculation of offspring through a vertical mode of symbiont transmission and thereby enables a broad distribution of larval settlement.