The stability of slugs in fluidised beds of fine particles: A theory based on particle pick-up from the wake

A theory for slug stability in fluidised beds of fine particles is developed based on the idea of gas circulation inside bubbles.Data on the intensity of circulation inside gas slugs in liquids are reported and an analogy is drawn with slugs in fluidised beds; this information is coupled with data on gas pick-up velocity for flow over granular beds, to yield a simple criterion for slug stability. A test of this criterion is provided by comparison with data on the stability of freely slugging beds.An X-ray study of slugs in fluidised beds at various pressures is also described that gives further support to the predictions of the theory.     

Surface topography and tribological properties of coatings prepared from microparticle size polyurethane dispersions studied by atomic force microscopy

The surface topography and mechanical properties of coatings prepared using large particle size polyurethane dispersions (PUD) are investigated using atomic force microscopy (AFM) imaging, AFM-based force measurements, and friction force microscopy. PUD coatings, which are prepared from dispersions containing particles of micron size, have surface roughness of 250–300 nm and waviness of 2.5–3 μm resulting from the particle size. The surface moduli of the PUD coatings are varied by tuning the ratio of hard-to-soft segmentation in the polyurethanes and are found to be between 40 and 100 MPa. The friction coefficient obtained in the study is found to be correlated with both the surface modulus of the coatings and the adhesion between the probe and the samples and is well in line with the perceived feel of an experienced human panel. The data are very well behaved and clearly show the utility of this technique in characterizing these types of surfaces.     

Cottonseed oil and meal utilization

For five consecutive years world-wide production of cottonseed has set new highs, and cottonseed is more valuable as a source of food, feed, and fiber than ever before. However this paper is primarily concerned with the utilization of cottonseed oil and meal in the United States. During the three-year period, 1963–65, U.S. farmers received about $300 million annually for 6.18 million tons of cottonseed. Annual U.S. crushings were 5.79 million tons, having produced 1.94 billion pounds of crude oil valued at $222 million, 2.72 million tons of meal valued at $174 million, and 1,609,700 running bales of linters valued at $41.2 million. Retail value of cottonseed products is estimated to have been $1.1 billion annually. Changes in the U.S. cottonseed industry include shifts westward, to fewer and larger extraction plants and to the use of new and improved extraction techniques which involve solvents and high-speed expellers. The cottonseed extraction industry has a payroll of $38.2 million and consists of 188 oil mills in about 14 states, employing 8,400 people. Cottonseed oil accounted for 11.5% of total 1965 U.S. factory consumption of 12.7 billion pounds of fats and oils. Some 62% was used in salad or cooking oil, 27% in baking or frying fats, and 8% in margarine. During the 1960–65 period, usage increased in salad or cooking oils, in baking or frying fats, and in inedible products but decreased in margarine, mellorine, and other edible products. Increases exceeded decreases, and total consumption of cottonseed oil in edible and inedible products increased from 1.28 billion lb. to 1.47 billion lb. Practically all of the 2.76 million tons of cottonseed meal produced in the three-year period beginning October 1963 was used for feed. Relatively insignificant amounts were used as fertilizer on farms of cotton growers. Cattle, sheep, horse, and mule rations consumed 1.88 million tons, poultry rations 440 thousand tons, and swine rations 350 thousand tons. Cottonseed meal in cattle rations has had a downward trend since the early 1950’s although usage in poultry and swine rations has increased. It is estimated that 1.52 million tons were used by feed manufacturers in the preparation of mixed feeds during the 1964–65 season, representing a steady increase over the past two decades and a 54% increase over 1962–63. Domestic use of cottonseed flour has not changed appreciably during the past few years.     

Functionalized-radiolabeled hydroxyapatite/tenorite nanoparticles as theranostic agents for osteosarcoma

Hydroxyapatite (HA) nanoparticles (NPs) doped with different radioisotopes for use as theranostic systems play an important role in scientific research nowadays due to their ability to simultaneously act in the treatment and diagnosis of various types of cancers. In this work, we describe the synthesis and characterization of a hydroxyapatite/tenorite nanocomposite functionalized with folic acid, representing a nanotheranostic material with potential for application as an agent in positron emission tomography imaging systems and to act specifically in the treatment and diagnosis of osteosarcoma. ⁶⁴Cu and ³²P were produced by nuclear activation in the TRIGA reactor at CDTN. The obtained samples were characterized by XRD with Rietveld refinement, XAFS, SEM, BET, TGA, FTIR, CHN, ICP-AES, XPS and gamma spectroscopy. We investigated how CuO grows in HA NPs, the stability of the interactions between CuO and HA constituents and the interactions between folic acid and the surface of the HA NPs. The results indicate the formation of a second phase (tenorite) besides hydroxyapatite, and that the interactions between the two phases are stable, resulting in a nanocomposite. Furthermore, the activation of ⁶⁴Cu and ³²P inside the HA matrix, through the exposition to a neutron flux, produces a theranostic material of interest for biological tests.     

Concomitant use of liquid–liquid batch and continuous plug flow reactors for kinetic model discrimination. Application to the Rh/TPPTS catalysed reduction of the C–C double bond in dimethylitaconate

The biphasic catalytic reduction of the C–C double bond of dimethylitaconate with a water soluble rhodium/triphenylphosphinetrisulphonated sodium salt (TPPTS) complex is investigated. Kinetic studies in a well-mixed batch reactor provide kinetics parameters and an activation energy of 71 kJ mol⁻¹ but cannot discriminate between a first order or a complex kinetic model within the range of substrate concentration where the approximation of linear liquid/liquid partition is respected. Catalytic tests in the centrifugal partition chromatograph (CPC) reactor under steady-state operations in chemical regime and plug flow mode allow discriminating the kinetic models, the complex kinetic rate law being preferred.     

Valorization of Beef Tallow by Lipase-Catalyzed Interesterification with High Oleic Sunflower Oil

Although beef tallow (BT) has been considered a hard low-trans fat convenient to be used in several bakery applications, it has some undesirable characteristics like fatty acid composition, crystallization behavior, graininess formation and poor plastic range. This work studied the modification of BT by blending at different percentages with high oleic sunflower oil (HOSFO) followed by the enzyme-catalyzed interesterification of the blends. The reduction in the solid fat content achieved by the simple blending was enhanced by the interesterification process, as a result of the increase in the concentration of the diunsaturated monosaturated type triacylglycerols. Interesterification strongly impacted too on the crystallization behavior of the blends, since products showed more homogeneous and regular crystals than the starting mixture. Results show that lipase catalyzed interesterification of BT with HOSFO offers a useful tool for the design of fats with adjustable physicochemical properties, improved with respect to that of the starting fats.     

Application of power addition as modelling technique for flow processes: Two case studies

In many of the continuum processes typically found in chemical engineering, the functional dependency of the dependent variable is only known for large and small values of the independent variable. Exact solutions in the transitional regime are often obscure for various reasons (e.g. narrow band within which the transition from one regime to the other occurs, inadequate knowledge of the physics in this area, etc.). An established method for the matching of limiting solutions is reviewed and subsequently applied. The method regards the known solutions as asymptotes and proposes addition to a power of such asymptotes. It yields a single, adjustable correlating equation that is applicable over the entire domain. This procedure circumvents the introduction of ad hoc curve fitting measures for the different regions and subsequent, unwanted discontinuities in piece-wise fitted correlative equations for the dependent variables. Experimental data of two diverse processes, namely flow in a straight-through diaphragm valve and the fluidisation of a packed bed, are analysed as case studies. Empirical results are investigated for possible asymptotic bounds whereafter power addition is applied to the functional dependencies. The outcome is compared to those of the empirical models and the results discussed. The procedure is revealed to be highly useful in the summarising and interpretation of experimental data in an elegant and simplistic manner. It may also, in general, aid the setup of experimental apparatus for investigation of continuum processes.