Over the years, conventional cancer treatments, such as chemotherapy with only a limited specificity for tumors, have undergone significant improvement. Moreover, newer therapies such as immunotherapy have undergone a revolution to stimulate the innate as well as adaptive immune responses against the tumor. However, it has been found that tumors can be selectively colonized by certain bacteria, where they can proliferate, and exert direct oncolytic effects as well as stimulating the immune system. Bacterial-mediated cancer therapy (BMCT) is now one example of a hot topic in the antitumor field. Salmonella typhimurium is a Gram-negative species that generally causes self-limiting gastroenteritis in humans. This species has been designed and engineered in order to be used in cancer-targeted therapeutics. S. typhimurium can be used in combination with other treatments such as chemotherapy or radiotherapy for synergistic modification of the tumor microenvironment. Considerable benefits have been shown by using engineered attenuated strains for the diagnosis and treatment of tumors. Some of these treatment approaches have received FDA approval for early-phase clinical trials. This review summarizes the use of Salmonella bacteria for cancer therapy, which could pave the way towards routine clinical application. The benefits of this therapy include an automatic self-targeting ability, and the possibility of genetic manipulation to produce newly engineered attenuated strains. Nevertheless, Salmonella-mediated anticancer therapy has not yet been clinically established, and requires more research before its use in cancer treatment.
The recognition of flow regimes is very important in the application of spouted beds. In this paper, two‐dimensional computer simulations of a slot‐rectangular spouted bed using FLUENT commercial software were utilised to construct flow regime maps. Two‐phase gas–solid flows in the bed were simulated with computational fluid dynamics (CFD) using the two‐phase Eulerian–Eulerian granular model. The numerical simulations were applied to predict different flow regimes. The constructed flow regime map for a bed containing solid particles with a diameter of 1.44 mm was in good agreement with the experimental map previously reported elsewhere. With this successful numerical mapping, a flow regime map for particles with a diameter of 3.77 mm was constructed for various superficial gas velocities and static bed heights. The map was composed of six distinct flow patterns, that is fixed bed, internal jet, jet‐in‐fluidised‐bed, spouting, incoherent spouting and slugging. The slugging flow regime occurred at large values for the static bed height and air inlet velocity, while the spouting regime arose by increasing the air inlet velocity at low values of static bed height. Unlike the spouting regime, large pressure drop fluctuations were observed in the incoherent spouting regime.
The effect of manganese addition on decreasing hot crack susceptibility of submerged arc welding in microalloyed steels is well understood, but its increment should not cause unsuitable changes in metallurgical and mechanical properties of weld metal. Therefore, since weld metal Mn content in SAW process is mainly controlled by welding wire composition, the aim of this investigation is to study the effect of wire Mn content on the microstructure, mechanical properties and hot crack susceptibility of helical linepipes weld metal. In this regard, three different wires with 0.88, 1.05 and 1.54 wt% of Mn content were selected and welding was performed in both experimental and production process condition of X70 helical linepipes. As a result, 1.26, 1.44 and 1.67 wt% of Mn in weld metal was obtained respectively. Metallographical examinations using optical and scanning electron microscopy showed that, increasing the amount of Mn in weld metal, decrease the grain size of all phases (acicular ferrite, primary ferrite and ferrite with aligned second phase). Moreover, in the expense of increasing acicular ferrite, the volume fraction of primary ferrite (mostly grain boundary ferrite) and ferrite with aligned second phase decreased. Also, the results of mechanical properties indicated that the higher the amount of Mn, the higher the strength and hardness of weld metal, but in the case of impact toughness and tensile elongation, an optimum level was observed and lower toughness in the highest Mn content weld metal is attributed to the increasing hardenability and thus formation of martensite/retained austenite islands and grain boundary carbides in coincident sites of acicular ferrite grains. Moreover, analyzes in more than 1000m helical linepipes weld metal length showed that increasing weld metal Mn content up to 1.4wt%, reduced the possibility of hot crack formation from total percentage of 0.005 to around 0.001.
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