Dealumination–aging pattern of REUSY zeolites contained in fluid cracking catalysts

The evolution of the properties of a REUSY zeolite contained in a fluid cracking catalyst was investigated under laboratory steam deactivation procedures and in age fractions of the corresponding equilibrium catalyst (Ecat). The aging pattern, defined by the evolution of the zeolite surface area (ZSA) related to the decrease of the unit cell size (UCS), was similar between lab-steamed zeolites and Ecat fractions. A sharp drop in ZSA occurred at ca. 2.430 nm UCS. A study done by FT-IR spectroscopy suggested that zeolite dealumination initially took place more extensively on the sodalite cages and double six-member rings (D6R) of the structure and that the final collapse of the zeolite framework occurred through destruction of the 12-member rings (12M). This can be explained by a crystal fracture and break down process and disassembling of the sodalite cages in the faujasite structure. NH₃ microcalorimetry showed that strong acid sites in faujasites are destroyed by steam aging, but this effect does not lead to a reduction in the cracking activity of the Ecat form. The microactivity test (MAT) showed that the specific activity declined sharply at 2.430 nm UCS. Differences in product selectivity were related to the extent of damage of the zeolite, extra-framework alumina and mesoporosity. While further aging canceled the effect attributed to extra-framework alumina differences attributed to mesoporosity increased.     

Implementation of RNS-Based Distributed Arithmetic Discrete Wavelet Transform Architectures Using Field-Programmable Logic

Currently there are design barriers inhibiting the implementation of high-precision digital signal processing (DSP) objects with field programmable logic (FPL) devices. This paper explores overcoming these barriers by fusing together the popular distributed arithmetic (DA) method with the residue number system (RNS) for use in FPL-centric designs. The new design paradigm is studied in the context of a high-performance filter bank and a discrete wavelet transform (DWT). The proposed design paradigm is facilitated by a new RNS accumulator structure based on a carry save adder (CSA). The reported methodology also introduces a polyphase filter structure that results in a reduced look-up table (LUT) budget. The 2C-DA and RNS-DA are compared, in the context of a FPL implementation strategy, using a discrete wavelet transform (DWT) filter bank as a common design theme. The results show that the RNS-DA, compared to a traditional 2C-DA design, enjoys a performance advantage that increases with precision (wordlength).     

Heavy Metals Bioremediation from Polluted Water by Glass-Ceramic Materials

The objective of this research was to study the removal of cadmium and lead from an aqueous solution through a biological treatment. For this purpose a glass-ceramic material was manufactured from industrial and urban wastes. Biofilms of microorganisms found in wastewater were developed on its surface, and continuous tests were conducted in the presence and absence of the biofilm to analyze the glass-ceramic's ability to remove the heavy metals from an aqueous environment. The results suggest that this bioremediation process, developed on an industrial scale, could represent an alternative to the chemical processes currently used.     

Major abdominal surgery and the clearance of lipid emulsions

Reaction of bacterial adhesins with complementary receptors on the surfaces of mucosal respiratory, gastrointestinal and genitourinary cells leads to bacterial adhesion to the human body. This is the first step in the sequence of events leading to infection. It has been observed that subinhibitory concentrations (sub-MICs) of some antibiotics are able to reduce bacterial adhesion. The pharmacokinetic curves of antibiotics show that these sub-MICs are present in tissues during a typical course of therapy. This study investigated the ability of sub-MICs of seven macrolides and four fluoroquinolones to reduce adhesiveness of Staphylococcus aureus to human buccal cells. The literature generally reports data for only one antibiotic at a time. To obtain an overall view of the findings of eleven antibiotics together, the data have been normalized according to the molecular weight of each antibiotic and the dose-effect curves determined.     

Quasi-analytical static solution for the generalized boxed coplanar waveguide

A quasi-analytical method for computing the quasi-static-TEM parameters of the generalized coplanar waveguide (GCPW) is reported. The structure is assumed to be enclosed in a rectangular frame and embedded in a layered medium. Essentially, the method is an analytically enhanced spectral domain formulation. Its application leads to virtually exact results in very short CPU times, making it suitable for CAD purposes. Although the method is somewhat more time consuming than conformal mapping approaches, it is a useful alternative because of its exactness and ability to deal with multilayer structures. © 1994 John Wiley & Sons, Inc.     

Influence of total surface area of core material on yield of deposited coacervate

The neuronal cytoskeleton is one of the most profoundly altered organelles in late life neuro-degenerative disorders that are characterized by progressive impairments in cognitive abilities. The elucidation of the protein building blocks of these organelles as well as advances in understanding how these proteins become altered in Alzheimer's disease (AD) and other less common dementing illnesses, i.e., diffuse Lewy body disease (DLBD) or the Lewy body variant of AD (LBVAD), will provide insights into the molecular basis of these disorders. Within, we review evidence that normal adult human tau is abnormally phosphorylated and converted into the subunits of AD paired helical filaments (PHFs), and that Lewy bodies (LBs) represent accumulation of altered neurofilament (NF) triplet subunits. Although the precise biological consequences of PHF and LB formation in neurons is unknown, growing evidence suggests that the formation of PHFs and LBs from normal neuronal cytoskeletal proteins could have deleterious effects on neuronal function and survival. Finally, insights into the composition of PHFs and LBs could lead to the development of novel strategies for the timely and accurate diagnosis of AD, DLBD and the LBVAD.