Modelling the Effect of Process Parameters on the Wet Extrusion and Spheronisation of High-Loaded Nicotinamide Pellets Using a Quality by Design Approach

Open access articleThe aim of the present study was to develop an alternative process to spray granulation in order to prepare high loaded spherical nicotinamide (NAM) pellets by wet extrusion and spheronisation. Therefore, a quality by design approach was implemented to model the effect of the process parameters of the extrusion-spheronisation process on the roundness, roughness and useable yield of the obtained pellets. The obtained results were compared to spray granulated NAM particles regarding their characteristics and their release profile in vitro after the application of an ileocolon targeted shellac coating. The wet extrusion-spheronisation process was able to form highly loaded NAM pellets (80%) with a spherical shape and a high useable yield of about 90%. However, the water content range was rather narrow between 24.7% and 21.3%. The design of experiments (DoE), showed that the spheronisation conditions speed, time and load had a greater impact on the quality attributes of the pellets than the extrusion conditions screw design, screw speed and solid feed rate (hopper speed). The best results were obtained using a low load (15 g) combined with a high rotation speed (900 m/min) and a low time (3–3.5 min). In comparison to spray granulated NAM pellets, the extruded NAM pellets resulted in a higher roughness and a higher useable yield (63% vs. 92%). Finally, the coating and dissolution test showed that the extruded and spheronised pellets are also suitable for a protective coating with an ileocolonic release profile. Due to its lower specific surface area, the required shellac concentration could be reduced while maintaining the release profil

Biting midges (Ceratopogonidae: Diptera) present in aquatic macrophytes from wetlands of Marchantaria Island, Iranduba, Central Amazonia, Brazil

Ceratopogonidae (Diptera) are easily found in both aquatic and semi-aquatic sites under various environmental conditions, where their immature stages develop in areas of nutrient richness. Material was collected from six wetland areas in Ilha da Marchantaria, Iranduba, Amazonas, between July and October 2010 and February and June 2011 throughout the Amazon River’s cycle (receding and flooding stages), in aquatic macrophytes Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata. The collections produced 431 immature individuals: 191 (44.3%) in E. crassipes, 125 (29%) in P. stratiotes and 115 (26.7%) in S. auriculata. After development in the laboratory 16 species were identified belonging to the following genera: Alluaudomyia Kieffer, Bezzia Kieffer, Dasyhelea Kieffer, Forcipomyia Meigen, Heteromyia Say, Neobezzia Wirth and Ratanaworabhan, Palpomyia Meigen, Paryphoconus Enderlein and Stilobezzia Kieffer. Aquatic macrophytes are excellent substrates for immature Ceratopogonidae, which are important because of their value to the balance of biodiversity in ceratofauna in wetlands.Fil: Torreias, Sharlene R. S.. Laboratório de Citotaxonomia e Insetos Aquáticos , Coordenação de Biodiversidade – CBio, Instituto Nacional de Pesquisas da Amazônia – INPA; BrasilFil: Ferreira Keppler, R. L.. Laboratório de Citotaxonomia e Insetos Aquáticos , Coordenação de Biodiversidade – CBio, Instituto Nacional de Pesquisas da Amazônia – INPA; BrasilFil: Ronderos, Maria Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentin

Clec9a-mediated ablation of conventional dendritic cells suggests a lymphoid path to generating dendritic cells In Vivo

Conventional dendritic cells (cDCs) are versatile activators of immune responses that develop as part of the myeloid lineage downstream of hematopoietic stem cells. We have recently shown that in mice precursors of cDCs, but not of other leukocytes, are marked by expression of DNGR-1/CLEC9A. To genetically deplete DNGR-1-expressing cDC precursors and their progeny, we crossed Clec9a-Cre mice to Rosa-lox-STOP-lox-diphtheria toxin (DTA) mice. These mice develop signs of age-dependent myeloproliferative disease, as has been observed in other DC-deficient mouse models. However, despite efficient depletion of cDC progenitors in these mice, cells with phenotypic characteristics of cDCs populate the spleen. These cells are functionally and transcriptionally similar to cDCs in wild type control mice but show somatic rearrangements of Ig-heavy chain genes, characteristic of lymphoid origin cells. Our studies reveal a previously unappreciated developmental heterogeneity of cDCs and suggest that the lymphoid lineage can generate cells with features of cDCs when myeloid cDC progenitors are impaired

A systematic study of the residence time of flour in a vibrating apparatus used for thermal processing

AbstractThe dry heat treatment of flour is well established for the production of cake flour for high ratio cakes. This study investigates a new tubular apparatus in which flour is conveyed by vibrations through a helical pipe. Residence time distributions (RTDs) of flour were characterised for various processing conditions and the development of the residence time in extended operation was analysed.A method was developed to accurately determine the RTDs, which could be approximated by normal distributions. The width of the distributions is a critical factor for the accuracy of a thermal process and was identified for different processing conditions. The distributions were narrow, with variations of ±1% at most.In some cases, the residence time increased over 3.5h of machine run-time by 7.7%–13.9%. To explain this phenomenon, several hypotheses have been tested. The machine performance was constant with time and no influence of ambient temperature or humidity could be found. It was furthermore shown that changes in the bulk material passing through the apparatus were not the cause of the increase. However, electrostatic charging of the material was observed.Two things led to a reduction in residence time: i) cleaning the pipe with a cleaning pig and water and ii) time, during which the machine is not running. It was suggested that a thin layer of particles inside the pipe in combination with electrostatics effects could be the reason for the residence time increase. Frequent cleaning can therefore allow relatively uniform behaviour and control of residence time.Industrial relevanceThis work investigates the potential application of a novel, vibrating device for the dry heat treatment of flour as a replacement for chlorination in the production of cake flour. Since chlorination was banned in the EU in the year 2000, there is an industrial interest for alternative treatments and equipment to produce flour for high ratio cakes

Atmospheric constraints on global emissions of methane from plants

We investigate whether a recently proposed large source of CH4 from vegetation can be reconciled with atmospheric measurements. Atmospheric transport model simulations with and without vegetation emissions are compared with background CH4, delta C-13-CH4 and satellite measurements. For present - day CH4 we derive an upper limit to the newly discovered source of 125 Tg CH4 yr(-1). Analysis of preindustrial CH4, however, points to 85 Tg CH4 yr(-1) as a more plausible limit. Model calculations with and without vegetation emissions show strikingly similar results at background surface monitoring sites, indicating that these measurements are rather insensitive to CH4 from plants. Simulations with 125 Tg CH4 yr(-1) vegetation emissions can explain up to 50% of the previously reported unexpectedly high CH4 column abundances over tropical forests observed by SCIAMACHY. Our results confirm the potential importance of vegetation emissions, and call for further research

Processing of barley grains in a continuous vibrating conveyor

AbstractA novel tubular industrial apparatus for the surface pasteurization of particles has been studied. Particles are conveyed through a helical pipe by vibrations created by off-balance motors. The residence time of barley grains was characterized. The behaviour of the system was a function of motor angle and motor speed. The residence time could vary up to 21% during one experiment of 2 h (20°, 740 rpm). However, ranges of processing conditions were identified that produce stable operation and thus effective pasteurization of product. In some cases, residence time increased by up to 7% of the initial value over consecutive experiments (40°, 710 rpm). Some reasons for this phenomenon have been proposed and tested. The formation of a powder layer inside the pipe has been proven to affect the residence time of barley grains. A simple model for pasteurization of particles has been developed to characterise the impact of variation in residence time on microbial inactivation

A heterochromatic histone methyltransferase lowers nucleosome occupancy at euchromatic promoters

H3K9me3 (histone H3 modified with tri-methylation at lysine 9) is a hallmark of transcriptional silencing and heterochromatin. However, its global effects on the genome, including euchromatin, are less well understood. Here we develop Formaldehyde-Assisted Identification of Regulatory Elements (FAIRE) for C. elegans to examine the chromatin configuration of mutants that lack virtually all H3K9me3, while leaving H3K9me1 and H3K9me2 intact. We find that nucleosomes are mildly disrupted, and levels of H3K9me2 and H3K27me3 rise in mutant embryos. In addition to these expected changes, the most dramatic change occurs in euchromatin: many regions encompassing transcription start sites (TSSs) gain an average of two nucleosomes in mutants. The affected regions normally lack H3K9me3, revealing a locus non-autonomous role for H3K9me3. Affected TSSs are associated with genes that are active in epithelia and muscles, and implicated in development, locomotion, morphogenesis and transcription. Mutant embryos develop normally under ideal laboratory conditions but die when challenged, with defects in morphogenesis and development. Our findings reveal that H3K9me3 protects transcription start sites within euchromatin from nucleosome deposition. These results may be relevant to mammals, where diseases that disrupt the nuclear lamina and heterochromatin can alter epithelial and muscle gene expression