Production of Nanoparticles in Thermal Plasmas: A Model Including Evaporation,Nucleation, Condensation,and Fractal Aggregation

In this work a coupled model for the production of nanoparticles in an inductively coupled plasma reactor is proposed. A Lagrangian approach is used to describe the evaporation of precursor particles and an Eulerian model accounting for particle nucleation, condensation, and fractal aggregation. The models of the precursor and nanoparticles are coupled with the magneto-hydrodynamic equations describing the plasma. The purpose of this study is to develop a model for the synthesis of particles in a thermal plasma reactor, which can be used to optimize industrial reactors. The growth of aggregates is considered by introducing a power law exponent D _f. Results are compared qualitatively and quantitatively with existing experimental data from plasma reactors at a relatively large laboratory scale. The results obtained from the model confirm the previously observed importance of the quench strategy in defining the morphology of the nanoparticles.     

High Explosives Mixtures Detection Using Fiber Optics Coupled: Grazing Angle Probe/Fourier Transform Reflection Absorption Infrared Spectroscopy

Fourier Transform Infrared Spectroscopy operating in Reflection–Absorption mode has been demonstrated as a potential spectroscopic technique to develop new methodologies for detection of chemicals deposited on metallic surfaces. Mid-IR transmitting optical fiber bundle coupled to an external Grazing Angle Probe and an MCT detector together with a bench Michelson interferometer have been used to develop a highly sensitive and selective methodology for detecting traces of organic compounds on metal surfaces. The methodology is remote sensed, in situ and can detect surface loading concentrations of nanograms/cm² of most target compounds. It is an environmentally friendly, solvent free technique that does not require sample preparation. In this work, the ever-important task of high explosives detection, present as traces of neat crystalline forms and in lab-made mixtures, equivalent to the important explosive formulation Pentolite, has been addressed. The sample set consisted of TNT, PETN (both pure samples) and the formulation based on them: Pentolite, present in various loading concentrations. The spectral data collected was subjected to a number of statistical pre-treatments, including first derivative and normalization transformations to make the data more suitable for the analysis. Principal Components Analysis combined with Linear Discriminant Analysis allowed the classification and discrimination of the target analytes contained in the sample set. Loading concentrations as 220 ng/cm² were detected for each explosive in neat form and the in the simulated mixture of Pentolite.     

Non-dairy probiotic products

There is evidence documenting the beneficial health effects of probiotic microorganisms. Also, many studies have reported that the best matrices to deliver probiotic are dairy fermented products. However, recently several raw materials have been extensively investigated to determine if they are suitable substrates to produce novel non-dairy probiotic microorganisms, and it has been found that traditional fermented foods may contain viable probiotic microorganisms. Numerous such examples can be found in the text. Therefore, the aim of this review was to investigate the utilization of probiotics in new and traditional non-dairy products with probiotic potential. It was found that while cereals have been extensively investigated to develop new probiotic foods; further research about the probiotic beneficial effects of traditional fermented products is needed.     

Poly(hexylacrylate)Core‐poly(ethyleneglycol methacrylate)Shell nanogels as fillers for poly(2‐hydroxyethyl methacrylate) nanocomposite hydrogels

The preparation of poly(hexylacrylate)_core‐poly(ethyleneglycol methacrylate)_shell (PHA‐co‐PEGMA) nanogels, to be used as fillers in nanocomposite hydrogels, is reported. Stable nanogels with particle sizes between 90–300 nm were obtained varying the conditions of synthesis. The synthesis recipe of the nanogels could be easily scaled up. Purified and dispersed nanogels in aqueous solution were used as soft fillers for poly(2‐hydroxyethyl methacrylate) (PHEMA) hydrogels, crosslinked with ethylene glycol dimethacrylate (EGDMA). The obtained nanocomposite hydrogels exhibit a larger swelling capacity and a higher thermal stability in comparison with the non‐filled PHEMA hydrogels. Young, storage, and lost moduli, increase largely, in the better case up to 72.5% in the swollen state; while in the dry state the storage modulus increase up to 4.7 fold with a very low load on nanogels (0.64 wt%); resulting in biomaterials with improved properties with potential applications in medical devices. POLYM. ENG. SCI., 59:170–181, 2019. © 2018 Society of Plastics Engineers     

ZnBr2‐catalyzed chemical effects in poly(acrylonitrile‐ co‐butadiene)

The excellent chemical properties and resistance to oil of poly(acrylonitrile‐co‐butadiene), or nitrile–butadiene rubber (NBR), has led to the extensive use of these elastomers as O‐ring material in the oil extraction industry. The degradation of NBR gaskets is known to occur during the well completion and oil extraction process when they are exposed to bromide fluids such as ZnBr₂‐based completion fluid. Samples of NBR, polyacrylonitrile, and polybutadiene were exposed to ZnBr₂‐based completion fluid and analyzed by attenuated total reflectance (ATR) and diffuse reflectance IR. These analyses showed that the ZnBr₂ completion fluid promoted the hydrolysis of the nitrile group to form amides and carboxylic groups. The carbon–carbon double bonds in NBR were unaffected after short exposure to ZnBr₂‐based completion fluid but were quickly hydrated in acidic bromide mixtures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1250–1257, 2003     

Residence time distribution in spouted bed drying of maltodextrin solutions on a bed of inert particles

Residence time distributions (RTD) for aqueous maltodextrin solutions were determined in two kinds of spouted bed dryers: (1) conventional spouted bed (CSB) 0.305 m diameter with a bed of polypropylene beads and (2) spout‐fluid bed 0.143 m diameter with draft tube submerged in a bed of FEP® pellets (S‐FBDT). RTD, mean residence time t_m, and spread of the distribution σ², were determined at different drying temperatures, spouting velocities, bed depths, spraying pressures, and feed concentrations. Average values of t_m and σ² were 6.5 min and 26.6 min² for the CSB and 6.9 min and 36 min² for the S‐FBDT, respectively, for all operating conditions except spraying pressure. RTD curves were well represented by the response of an ideal stirred tank with a superimposed bypass of 15% on average for the CSB and 7% on average for the S‐FBDT dryer for all operating conditions. Increase in spraying pressure produced a reduction of t_m and an increase in the bypass fraction of the product in both dryers. © 2011 Canadian Society for Chemical Engineering     

Antibiotic resistance and tolerance to simulated gastrointestinal conditions of eight hemolytic Bacillus pumilus isolated from pulque,a traditional Mexican beverage

Food Science and Biotechnology - Traditional fermented sap beverages from two provinces of Mexico were studied for the isolation of pathogenic bacteria from these beverages. Eight strains of...     

Transmembrane TNF and Its Receptors TNFR1 and TNFR2 in Mycobacterial Infections

Tumor necrosis factor (TNF) is one of the main cytokines regulating a pro-inflammatory environment. It has been related to several cell functions, for instance, phagocytosis, apoptosis, proliferation, mitochondrial dynamic. Moreover, during mycobacterial infections, TNF plays an essential role to maintain granuloma formation. Several effector mechanisms have been implicated according to the interactions of the two active forms, soluble TNF (solTNF) and transmembrane TNF (tmTNF), with their receptors TNFR1 and TNFR2. We review the impact of these interactions in the context of mycobacterial infections. TNF is tightly regulated by binding to receptors, however, during mycobacterial infections, upstream activation signalling pathways may be influenced by key regulatory factors either at the membrane or cytosol level. Detailing the structure and activation pathways used by TNF and its receptors, such as its interaction with solTNF/TNFRs versus tmTNF/TNFRs, may bring a better understanding of the molecular mechanisms involved in activation pathways which can be helpful for the development of new therapies aimed at being more efficient against mycobacterial infections.