Zeolites for Cleaner Processes: Alkylation of isobutane and n-butene

Large pore beta zeolite with straight and zig-zag channels and USY zeolite with super cages have shown potential to replace toxic and hazardous mineral acids as catalysts in alkylation processes. However, due to rapid deactivation of these zeolites, their acceptance in industrial alkylation has been delayed. In this study we seek a deeper understanding of the kinetics, transport, and sorption of organic molecules used in alkylation processes in nano-porous zeolites. A six lump kinetic model that considers the key reactions for the zeolite catalyzed alkylation process is presented. The influence of different reactions and rate limiting steps on catalyst, and reactor performance is examined by coupling an appropriate reactor scale model, that accounts for different back-mixing on the reactor scale, with a zeolite particle model, which accounts for the diffusion inside the zeolite pores, the alkylation reactions, and zeolite deactivation. Single pulse TAP experiments are employed for obtaining estimates of intra-particle diffusion coefficients and better insight into adsorption-desorption dynamics and equilibria for species in beta and USY zeolite. This technique provides a unique way of directly estimating transport and sorption processes at extremely low surface coverage, in the absence of an inert carrier stream, with no external mass transfer resistance, and with a negligible thermal effect. The results of this study suggest that higher alkylate yield and longer zeolite activity are achieved by increasing the intrinsic hydride transfer rate and the ratio of isobutane to n-butene: P/ O) concentration in the vicinity of the catalyst. For a given P/O feed ratio, achieving close to plug flow for isobutane and high back-mixing for n-butene further enhances local P/O ratio and yield. Furthermore, optimal zeolite catalyst design should consider the egg shell type of Br├╕nsted acid site distribution and a low silicon to alumina: Si/ Al) ratio. It is suggested that the ideal zeolite morphology should feature characteristics of both beta and USY zeolites. Specifically, it should have straight and zig-zag channels with an average pore diameter of 0.74 nm, for decreasing the deactivation rate. Further, to enhance the formation of 2,2,4-trimethylpentane it should have small cages in between these channels, with average pore diameter less than 1.2 nm but more than 0.74 nm

An Efficient Two-phase Clocked Sequential Multiply -Accumulator unit for Image blurring

The multiply-accumulator (MAC) unit is the basic integral computational block in every digital image and digital signal processor. As the demand grows, it is essential to design these units in an efficient manner to build a successful processor. By considering this into account, a power-efficient, high-speed MAC unit is presented in this paper. The proposed MAC unit is a combination of a two-phase clocked modified sequential multiplier and a carry-save adder (CSA) followed by an accumulator register. A novel two-phase clocked modified sequential multiplier is introduced in the multiplication stage to reduce the power and computation time. For image blurring, these multiplier and adder blocks are subsequently incorporated into the MAC unit. The experimental results demonstrated that the proposed design reduced the power consumption by 52% and improved the computation time by 4% than the conventional architectures. The developed MAC unit is implemented using 180nm standard CMOS technology using CADENCE RTL compiler, synthesized using XILINX ISE and the image blurring effect is analyzed using MATLAB

Enhancement of basolateral amygdaloid neuronal dendritic arborization following Bacopa monniera extract treatment in adult rats

OBJECTIVE: In the ancient Indian system of medicine, Ayurveda, Bacopa monniera is classified as Medhya rasayana, which includes medicinal plants that rejuvenate intellect and memory. Here, we investigated the effect of a standardized extract of Bacopa monniera on the dendritic morphology of neurons in the basolateral amygdala, a region that is concerned with learning and memory. METHODS: The present study was conducted on 2¹/2-month-old Wistar rats. The rats were divided into 2-, 4- and 6-week treatment groups. Rats in each of these groups were further divided into 20 mg/kg, 40 mg/kg and 80 mg/kg dose groups (n = 8 for each dose). After the treatment period, treated rats and age-matched control rats were subjected to spatial learning (T-maze) and passive avoidance tests. Subsequently, these rats were killed by decapitation, the brains were removed, and the amygdaloid neurons were impregnated with silver nitrate (Golgi staining). Basolateral amygdaloid neurons were traced using camera lucida, and dendritic branching points (a measure of dendritic arborization) and dendritic intersections (a measure of dendritic length) were quantified. These data were compared with the data from the age-matched control rats. RESULTS: The results showed an improvement in spatial learning performance and enhanced memory retention in rats treated with Bacopa monniera extract. Furthermore, a significant increase in dendritic length and the number of dendritic branching points was observed along the length of the dendrites of the basolateral amygdaloid neurons of rats treated with 40 mg/kg and 80 mg/kg of Bacopa monniera (BM) for longer periods of time (i.e., 4 and 6 weeks). CONCLUSION: We conclude that constituents present in Bacopa monniera extract have neuronal dendritic growth-stimulating properties

Biofilm and MBL production among imipenem resistant Pseudomonas aeruginosa and Acinetobacter species

Pseudomonas aeruginosa and Acinetobacter species are the primary cause of nosocomial infections. The advent of Metallo-beta-lactamase (MBL) and biofilm-producing bacterial strains poses a serious threat to reserve drugs such as carbapenem. The objective of this study was to determine the rate of MBL and biofilm production among imipenem resistant P. aeruginosa (IRPA) and imipenem resistant Acinetobacter spp. (IRAS) isolates. A total of 79 P. aeruginosa and 117 Acinetobacter spp. were isolated from various clinical specimens of patients from July 2016 to January 2017 at Manipal Teaching Hospital, Pokhara. MBL in IRPA and IRAS isolates were detected by Combined disc test and E-test. Biofilm production in imipenem resistant isolates was carried out by Microtitre plate assay. Fifteen (19%) P. aeruginosa and 57 (48.7%) Acinetobacter spp. were imipenem resistant isolates. MBL producers were found among 53.3% of IRPA and 38.6% of IRAS, whereas 100% of IRPA and 82.5% of IRAS were biofilm producers. All the biofilm producer IRPA isolates were Extensively Drug-Resistant (XDR), and a larger proportion of XDR IRAS strains were of high biofilm-producing phenotype. However, the majority of imipenem resistant (80% of IRPA and 49.1% of IRAS) and MBL producing (63%) isolates were weak biofilm formers. The study demonstrated the high capability of IRPA and IRAS to form a biofilm, which was strongly related to higher drug resistance. Nonetheless, imipenem resistant and MBL producer isolates showed an analogous association with the degree of biofilm formation. These MBL cum biofilm producer isolates were better susceptible to polymyxin B and ampicillin-sulbactam. DOI: http://dx.doi.org/10.5281/zenodo.419547

An Efficient Two-phase Clocked Sequential Multiply -Accumulator unit for Image blurring

The multiply-accumulator (MAC) unit is the basic integral computational block in every digital image and digital signal processor. As the demand grows, it is essential to design these units in an efficient manner to build a successful processor. By considering this into account, a power-efficient, high-speed MAC unit is presented in this paper. The proposed MAC unit is a combination of a two-phase clocked modified sequential multiplier and a carry-save adder (CSA) followed by an accumulator register. A novel two-phase clocked modified sequential multiplier is introduced in the multiplication stage to reduce the power and computation time. For image blurring, these multiplier and adder blocks are subsequently incorporated into the MAC unit. The experimental results demonstrated that the proposed design reduced the power consumption by 52% and improved the computation time by 4% than the conventional architectures. The developed MAC unit is implemented using 180nm standard CMOS technology using CADENCE RTL compiler, synthesized using XILINX ISE and the image blurring effect is analyzed using MATLAB

An Efficient Two-phase Clocked Sequential Multiply -Accumulator Unit for Image Blurring

The multiply-accumulator (MAC) unit is the basic integral computational block in every digital image and digital signal processor. As the demand grows, it is essential to design these units in an efficient manner to build a successful processor. By considering this into account, a power-efficient, high-speed MAC unit is presented in this paper. The proposed MAC unit is a combination of a two-phase clocked modified sequential multiplier and a carry-save adder (CSA) followed by an accumulator register. A novel two-phase clocked modified sequential multiplier is introduced in the multiplication stage to reduce the power and computation time. For image blurring, these multiplier and adder blocks are subsequently incorporated into the MAC unit. The experimental results demonstrated that the proposed design reduced the power consumption by % and improved the computation time by % than the conventional architectures. The developed MAC unit is implemented using standard CMOS technology using CADENCE RTL compiler, synthesized using XILINX ISE and the image blurring effect is analyzed using MATLAB

A Novel ASIC Implementation of Two-Dimensional Image Compression Using Improved B.G. Lee Algorithm

A 2D Discrete Cosine Transform and Inverse Discrete Cosine Transform using the B.G. Lee algorithm, incorporating a signed error-tolerant adder for additions, and a signed low-power fixed-point multiplier to perform multiplications are proposed and designed in this research. A novel Application Specific Integrated Circuit hardware implementation is used for the 2D DCT/IDCT computation of each 8 × 8 image block by optimizing the input data using the concepts of pipelining. An enhanced speed in processing and optimized arithmetic computations was observed due to the eight-stage pipeline architecture. The 2D DCT/IDCT of each 8 × 8 image segment can be quickly processed in 34 clock cycles with a substantially reduced level of circuit complexity. The B.G. Lee algorithm has been implemented using signed error-tolerant adders, signed fixed-point multipliers, and shifters, reducing computational complexity, power, and area. The Cadence Genus tool synthesized the proposed architecture with gpdk-90 nm and gpdk-45 nm technology libraries. The proposed method showed a significant reduction of 31.01%, 12.17%, and 21.11% in power, area, and PDP in comparison to the existing image compression architectures. An improved PSNR of the reconstructed image was also achieved compared to existing designs

Onychomycosis due to Candida parapsilosis in a Child with Ventricular Septal Defect: An Unusual Predisposition

Candida parapsilosis is emerging as a potential pathogen for onychomycosis. A 4-year-old male child with perimembranous ventricular septal defect (VSD) was admitted with features of cystitis and was treated with broad spectrum antibiotics. Two weeks later, he developed yellowish discoloration of nails of both hands. The sloughed out nail, on microscopy, showed numerous yeast forms that were identified as Candida parapsilosis by both phenotypic and genotypic methods. Antifungal sensitivity testing of the isolate was performed by microbroth dilution method in accordance with CLSI guidelines. Patient was successfully treated with topical amphotericin B and oral fluconazole. Thus, one should have a high index of suspicion of C. parapsilosis onychomycosis, especially when the patient is in the paediatric age group, presenting with unusual predisposing condition like congenital heart disease, and is on broad spectrum antibiotics