A CFD-VOF based model to address intensive photobioreactor design

The design and optimization of photobioreactors for intensive microalgal cultures are key issues to increase process performance. A model to assess the photosynthetic performance of tubular, bubble column and flat photobioreactors is presented. The model has coupled microalgal light distribution, photosynthesis kinetics and gas-liquid hydrodynamics. A lumped kinetic parameter model of photosynthetic unit (PSU) has been adopted for photosynthetic reactions. The dynamics of a microalgal cell has been described according to the gas-liquid flow of a bubble column. The flow field induced by liquid turbulence and bubbles uprising throughout the photobioreactor have been simulated with ANSYS-FLUENT. A representative domain of the flat photobioreactor has been selected by adopting proper periodic boundary conditions. Turbulence dispersion fields have been assessed by numerical simulations for several bubble size. A random-walk model developed in MATLAB has been adopted to microalgal cells to assess the irradiance experienced by the PSU-cell in the photobioreactors. The photobioreactor performances - expressed in terms of global photosynthesis rate – have been assessed. Irradiance level and biomass concentration have been changed in the range of operating conditions typically adopted for known processes

Spontaneous immunogenicity of ribosomal P0 protein in patients with benign and malignant breast lesions and delay of mammary tumor growth in P0-vaccinated mice

A common carboxyl-terminal epitope (C-22 P0) of the ribosomal P proteins (P0, P1 and P2) was shown to elicit autoantibodies in systemic lupus erythematosus (SLE) and in head and neck cancer patients. In this report we provide evidence for the in vivo immunogenicity of the P0 protein in breast cancer patients. Using recombinant P proteins, we demonstrated that sera from breast carcinoma patients (8/75) displayed significant reactivity to P0 protein when compared with healthy donor sera (0/45). Four out of the eight sera showed simultaneous reactivity to all P proteins. Breast benign tumor (3/17) and mammary hyperplasia (3/17) patient sera also showed significant reactivity to P proteins, thus suggesting that the occurrence of P protein autoantibodies might reveal mammary cell cycle dysregulation. Patient sera reacting with all P proteins recognized C-22 P0. Anti-P0 autoantibodies did not correlate with prognostic parameters of breast carcinomas. High level expression of C-22 P0 was found in mammary carcinomas compared with normal adjacent epithelium and benign lesions. To determine the antitumor activity of P0 as an immunogen, BALB-neuT transgenic mice displaying age-related breast cancer progression were vaccinated using xenogeneic P0 at the stage of mammary atypical hyperplasia. P0 vaccination significantly delayed the onset of mouse mammary tumors that overexpressed C-22 P0. Sera from P0 vaccinated mice recognized C-22 P0. Evidence for immunity to the P0 protein, its overexpression in carcinomas and its peculiar surface localization on cancer cells, along with its antitumor activity as an immunogen might be relevant for the use of P0 protein in monitoring cancer progression and in planning immunotherapeutic strategies

Autophagy induction extends lifespan and reduces lipid content in response to frataxin silencing in C. elegans

Severe mitochondria deficiency leads to a number of devastating degenerative disorders, yet, mild mitochondrial dysfunction in different species, including the nematode Caenorhabditis elegans, can have pro-longevity effects. This apparent paradox indicates that cellular adaptation to partial mitochondrial stress can induce beneficial responses, but how this is achieved is largely unknown. Complete absence of frataxin, the mitochondrial protein defective in patients with Friedreich's ataxia, is lethal in C. elegans, while its partial deficiency extends animal lifespan in a p53 dependent manner. In this paper we provide further insight into frataxin control of C. elegans longevity by showing that a substantial reduction of frataxin protein expression is required to extend lifespan, affect sensory neurons functionality, remodel lipid metabolism and trigger autophagy. We find that Beclin and p53 genes are required to induce autophagy and concurrently reduce lipid storages and extend animal lifespan in response to frataxin suppression. Reciprocally, frataxin expression modulates autophagy in the absence of p53. Human Friedreich ataxia-derived lymphoblasts also display increased autophagy, indicating an evolutionarily conserved response to reduced frataxin expression. In sum, we demonstrate a causal connection between induction of autophagy and lifespan extension following reduced frataxin expression, thus providing the rationale for investigating autophagy in the pathogenesis and treatment of Friedreich's ataxia and possibly other human mitochondria-associated disorders

Natural humoral immune response to ribosomal P0 protein in colorectal cancer patients

Tumor associated antigens are useful in colorectal cancer (CRC) management. The ribosomal P proteins (P0, P1, P2) play an important role in protein synthesis and tumor formation. The immunogenicity of the ribosomal P0 protein in head and neck, in breast and prostate cancer patients and the overexpression of the carboxyl-terminal P0 epitope (C-22 P0) in some tumors were reported

The use of temozolomide for the treatment of malignant tumors: clinical evidence and molecular mechanisms of action

Temozolomide (TMZ) is a monofunctional methylating agent which is spontaneously activated in aqueous solution into the dacarbazine metabolite 5-(3-methyl-1-triazeno)imidazole-4-carboxamide. This drug has been approved for the treatment of metastatic melanoma and glioblastoma multiforme, the latter in combination with radiotherapy. Furthermore, clinical trials have been performed to assess the activity of TMZ, alone or in combination, on brain metastatic solid tumors and leukaemias. This review will report clinical evidence on the use of TMZ for the treatment of different types of cancer; it also considers current knowledge on TMZ's molecular mechanisms of action of and discusses relevant patents relating to the same drug

Solids flow structures in a two-dimensional riser of a circulating fluidized-bed

A two-dimensional riser with transparent walls has been successfully opernted in a CFB loop. Solids flow structures have been investigated through the glass front wall by means of a motion analysis system. Slugs and gaspercolated plugs are observed in the dense and dilute regions of the riser respectively. Particle aggregates in the riser have elongated shapes and are not dispersed but are structured as solids streaks flowing in converging and diverging branches. The latter appear like small slugs extending on a fraction of the riser width only. © 1989, The Society of Chemical Engineers, Japan. All rights reserved

Break-up of cylindrical clusters of solid particles under gravity flow in a 2-dimensional column

A 0.012 m x 0.12 m two-dimensional column has been used to study gravitational motion and break-up of 0.032 m diameter cylindrical clusters of solid particles. Clusters were analysed by means of a KODAK SPIN PHYSICS SP2000 Motion Analysis System. Shape deformations, volume expansions and surface perturbations have been estimated for clusters of various solids at different distances from the point of release. Aspect and expansion ratios, times for onset of surface perturbations, and also cluster fall-velocities have been measured. Depending on the nature of the solids, three types of cluster have been considered: undeformable clusters, gas-impermeable clusters and gas-permeable clusters. Particle-to-particle forces are considered responsible for compacting solids of undeformable clusters. Two dimensionless numbers have been developed for the case of gas-impermeable clusters: the first is related to the aspect ratios of the cluster, whereas the second is related to the time needed for the appearance of surface perturbations on the cluster front. It has been suggested that the ratio of particle to cluster size controls expansion and break-up of gas-permeable clusters

Solids flow structures in a two-dimensional riser of a circulating fluidized bed

A two-dimensional riser with transparent walls has been successfully opernted in a CFB loop. Solids flow structures have been investigated through the glass front wall by means of a motion analysis system. Slugs and gaspercolated plugs are observed in the dense and dilute regions of the riser respectively. Particle aggregates in the riser have elongated shapes and are not dispersed but are structured as solids streaks flowing in converging and diverging branches. The latter appear like small slugs extending on a fraction of the riser width only. © 1989, The Society of Chemical Engineers, Japan. All rights reserved