Comparison between simulated moving bed and reverse flow chromatographic reactors for equilibrium limited reactions

A staged linear model, containing five parameters, is developed to compare equivalent simulated moving bed chromatographic reactors (SMBCR) and reverse flow chromatographic reactors (RFCR). A first order reversible reaction and linear adsorption equilibrium, with preferential adsorption of the reactant is assumed. The analysis uses simple, easily computable analytical solutions that rigorously represents the transients in the cyclic steady state for both the RFCR and the SMBR. A comparison between the two types of reactors is carried out to determine the maximum conversion attainable and the range of operation where these systems have advantages over conventional steady state reactors. It is found that the maximum conversion of both reactors is similar. The range of operation in terms of amount of catalyst and range of switching times favors the RFCR, while the conversion at low separation factors favors the SMBCR.     

TEOS as an improved alternative for chitosan beads cross‐linking: A comparative adsorption study

In this work the use of tetraethoxysilane (TEOS) for cross‐linking of chitosan hydrogel beads was studied at the level of 1 mmol TEOS per gram of chitosan. They were compared with glutaraldehyde and epichlorohydrin cross‐linked beads. The hydrogels were characterized by FTIR, SEM, water content, nitrogen content, and their point of zero charge. The performance of the anionic dye Remazol Black (RB) and the cationic Cd(II) adsorptions was assessed in order to characterize the sorbate–sorbent interaction. Adsorption experimental data were analyzed using two‐ and three‐parameter isotherm models along with the evaluation of mean adsorption energy and standard free energy. The adsorption was observed to be pH dependent. The uptake rate of RB and Cd(II) showed that the three type of beads followed a similar kinetic behavior. For both sorbates the TEOS cross‐linked beads showed the higher maximum adsorption capacity, followed by epichlorohydrin and glutaraldehyde cross‐linked beads. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41005.     

Neomycin Inhibition of (+)-7-Iso-Jasmonoyl-L-Isoleucine Accumulation and Signaling

The majority of plant defenses against insect herbivores are coordinated by jasmonate (jasmonic acid, JA; (+)-7-iso-jasmonoyl-L-isoleucine, JA-Ile)-dependent signaling cascades. Insect feeding and mimicking herbivory by application of oral secretions (OS) from the insect induced both cytosolic Ca²⁺ and jasmonate-phytohormone elevation in plants. Here it is shown that in Arabidopsis thaliana upon treatment with OS from lepidopteran Spodoptera littoralis larvae, the antibiotic neomycin selectively blocked the accumulation of OS-induced Ca²⁺ elevation and level of the bioactive JA-Ile, in contrast to JA level. Furthermore, neomycin treatment affected the downstream expression of JA-Ile-responsive genes, VSP2 and LOX2, in Arabidopsis. The neomycin-dependent reduced JA-Ile level is partially due to increased CYP94B3 expression and subsequent JA-Ile turn-over to12-hydroxy-JA-Ile. It is neither due to the inhibition of the enzymatic conjugation process nor to substrate availability. Thus, blocking Ca²⁺ elevation specifically controls JA-Ile accumulation and signaling, offering an insight into role of calcium in defense against insect herbivory.     

Inductively coupled probe for the measurement of partial discharges

Partial discharges are a transient phenomena whose measurement is remarkably important for electrical equipment diagnosis and maintenance. These discharges appear in the measurement circuit as very narrow current pulses of some nanoseconds. Therefore, discharge pulse detection is a particularly difficult problem, especially because they are superposed on the high voltage waveforms that cause them. In this paper, we present an inductively coupled probe able to measure this physical phenomenon by means of a very simple and inexpensive device that can be installed in the equipment under test. After modeling the probe, its response will be compared to that of commercial devices using both calibrated discharges and partial discharges occurring at real power.     

The Huynen-Fork Polarization Parameters in the Classification of Dielectric Mine-like Objects

We present a polarimetric approach that can be used to characterize subsurface targets by means of ground-penetrating radar. Several quantities related to the Huynen-fork parameters are basic to the study. These quantities are all expressible in terms of the elements of Sinclair matrix S which in turn, can be determined as functions of frequency by an application of the method-of-moment (MoM)—which is briefly reviewed here—to a mine-like object buried at various depths in a soil of specified dielectric and moisture properties. The quantities in question are the Stokes parameters, the elevation, azimuth, and polarizability angles, as well as the polarization ratios and the scattering eigenvalues which optimize the backscattered power. Some of these quantities are studied here and displayed in various graphs. These frequency dependent graphs exhibit useful symmetry properties. The plots of the polarizability angle (β) vs. frequency seem to remain invariant with target depth, and exhibit resonance features that are later shown to agree well with other standard methods to estimate resonances such as Prony method. A simple analysis of the early-time resonances thus estimated is used to obtain acceptable mine dimensions. The agreement found implies that polarimetric techniques, such as present one, can also be used in the arsenal of techniques yielding target-ID clues.     

Approximate Expressions to Evaluate the Performance in Butene-1 Purification Units

1 INTRODUCTIONSelective hydrogenatioll of small amounts of butynes and butadiene is industrially employedfor obtaining high purity butene-l used as co-monomer in the production of linear low-densitypolyethyene.For this purpose,the content of vinylacetylene.butyne-l and 1,3-butadiene presentin the process stream should be reduced to a few tens of ppm.     

Development, formulation, and effectiveness testing of a silicone-based barrier-type hand cream

We report the development, design, and results of effectiveness and acceptability testing of a hydrating, nutritive, barrier-type hand cream designed for severely damaged skin (including skin damaged by dermatological problems). We tested different silicone derivatives and a water-in-oil (W/O) silicone emulsifier to produce organoleptic qualities that would increase consumer acceptance of this type of W/O emulsion. Pharmacotechnical and effectiveness tests were done to check the stability and preservation of the formulas, their usefulness in improving dry skin, and acceptance by users. The results of pharmacotechnical testing were optimal. Although no active principle aimed specifically at dermatological problems was present in the final formulas, users reported notable subjective improvements in cracking and scaling.     

Differential near-field scanning optical microscopy

We theoretically and experimentally illustrate a new apertured near-field scanning optical microscopy (NSOM) technique, termed differential NSOM (DNSOM). It involves scanning a relatively large (e.g., 0.3-2 mum wide) rectangular aperture (or a detector) in the near-field of an object and recording detected power as a function of the scanning position. The image reconstruction is achieved by taking a two-dimensional derivative of the recorded power map. Unlike conventional apertured NSOM, the size of the rectangular aperture/detector does not determine the resolution in DNSOM; instead, the resolution is practically determined by the sharpness of the corners of the rectangular aperture/detector. Principles of DNSOM can also be extended to other aperture/detector geometries such as triangles and parallelograms.