Gas-phase reactions of methylene chloride and methylene chloride-trichloroethylene mixture with methane in tubular flow reactor and atmospheric pressure

Reactions of methylene chloride diluted in methane and Argon and a mixture of methylene chloride + trichloroethylene diluted in methane and argon are studied in three flow reactors of different surface to volume ratios 4, 10.5, and 16 mm ID , atmospheric pressure and over a temperature range of 750-1000 °C. Experiments were conducted isothermally, ±5 °C over central 80% of oven length using a three zone oven. Argon was added as a diluent in order to limit carbon (s) formation. The concentration ratios of methylene chloride/methane/argon and methylene chloride/trichloroethylene/methane/argon was held constant at 1:4:10 and 1:1:40:40 respectively, throughout the study. An on line gas chromatograph and GC/MS spectrometer were used for analysis of reactor products. Acetylene, ethylene, benzene, chloromethane, and HC1 were observed as the major products, for temperatures above 750 °K and residence times of 0.08 to 2 secs. First order plug flow model was utilized to analyze the experimental data. In addition the homogeneous and wall rate constants were decoupled and separately evaluated. The following overall rate equations were found to fit the reaction systems studied. Methylene Chloride in CH2C12/CH4/Ar : k = 1.166E09 * Exp(-44.85/RT) (1/sec) Methylene chloride in C2HCl3/CH2Cl2/CH4/Ar : k = 8.11E08 * Exp(-43.2/RT) (1/sec) Trichloroethylene in C2HCl3/CH2Cl2/CH4/Ar : k = 1.13E05 * Exp(-30.67/RT) (1/sec) A detailed kinetic reaction mechanism was developed and used to model the reaction systems and fit the experimentally determined product distribution. Fundamental principles in Transition State Theory and Quantum RRK theory were used in developing reaction rate constants for the model. A mechanism composed of 68 elementary reactions for CH2Cl2/CH4 system and another one with 72 reactions for mixture of C2HCl3+CH2C12/CH4 system were found to reproduce experimental results. A rate constant for : CH2Cl2 ----\u3e CH2Cl + Cl of k = 1.88*1016*Exp(-82.8/RT) chlorine elimination from methylene chloride was found to dominate HC1 elimination by 5 orders of magnitude with rate constants and Ea\u27s was determined for this elementary reaction over our experimental conditions. The important initial reactions in C2HCl3/CH2Cl2/CH4 system were determined as: C2HC13 ----\u3e C2Cl2 + HCl k = 7.1*1013*Exp(-77.61/RT) C2HCl3 ----\u3e C2HCl2. + Cl. k = 1.74*1015*Exp(-92.1/RT) CH2Cl2 ----\u3e CH2C1. + Cl. k = 1.88*1016*Exp(-82.8/RT) QRRK analysis and regression of rate constants against experimental data have lead to rate constants for the reactions: CH2Cl + CH2Cl (1)\u3c----\u3e(-1) [C2H4C12]4 ---\u3e C2H3C12+H (2) ---\u3e C2H4C1+Cl (3) ---\u3e C2H3Cl+HC1 (4) ---\u3e C2H4C12 STABILIZED CH3 + CH2Cl (1)\u3c----\u3e\u3c----\u3e(-1) [C2H5Cl]# ---\u3e C2H4Cl+H (2) ---\u3e C2H5+Cl (3) ---\u3e C2H4+HC1 (4) ---\u3e C2H5C1 STABILIZED CH3 + C2Cl2 (1)\u3c----\u3e(-1) [C3H3Cl2]# ---\u3e C3H3Cl+ Cl (2) ---\u3e C3H3C12 STABILIZED C2HCl3 + CH3 (1)\u3c----\u3e(-1) [C3H4Cl3]# ---\u3e C3H4Cl2+Cl (2) ---\u3e C3H4Cl3 STABILIZED The CHEMKIN computer code was incorporated to model the kinetic schemes and good agreement was obtained between calculated and experimental resutls

Oil-Polluted Water Treatment Using Nano Size Bagasse Optimized- Isotherm Study

The preliminary studies were conducted in order to evaluate the ability and behavior of sugarcane bagasse (generated as waste material from sugar mill) to remove oil by-products from aqueous. In this work adsorption experiments were carried out in a batch reactor to obtain adsorption isotherms of oil by-product on sugarcane bagasse. The capacity of sugarcane bagasse to adsorb oil by-product from aqueous solutions was evaluated at different pH, adsorbent dose and initial concentration. Equilibrium isotherms were analyzed by Langmuir isotherm equations. Compare the result and Langmuir isotherm shown that adsorption of oil by-product on a sugarcane bagasse is favorable. The concentration which was reviewed in this study was much closed to concentration in the industrial water disposal effluents and Langmuir isotherm did describe well the adsorption behavior obtained for these systems

Bacterial cellulose production, properties and applications with different culture methods – A review

© 2019 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlyBacterial cellulose (BC) is an organic compound produced by certain types of bacteria. In natural habitats, the majority of bacteria synthesize extracellular polysaccharides, such as cellulose, which form protective envelopes around the cells. Many methods are currently being investigated to enhance cellulose growth. The various celluloses produced by different bacteria possess different morphologies, structures, properties, and applications. However, the literature lacks a comprehensive review of the different methods of BC production, which are critical to BC properties and their final applications. The aims of this review are to provide an overview of the production of BC from different culture methods, to analyze the characteristics of particular BC productions, to indicate existing problems associated with different methods, and to choose suitable culture approaches for BC applications in different fields. The main goals for future studies have also been discussed here

Wideband Directional Coupler for Millimeter Wave Application based on Substrate Integrated Waveguide

Recently, Substrate Integrated Waveguide (SIW) techniques have been noticed for millimeter wave devices in microwave applications. In this paper, we are developing a wide band directional 3 dB coupler with a phase of 90̊ phase delay in the range of 30-40 GHz based on periodic vias and multi hole structure. For achieving this wide bandwidth multi-section coupler is designed based on the theoretical modeling and the simulation result is compared with HFSS and CST with  two different  numerical  methods show good performance with low insertion and return loss, broad operational bandwidth and high isolation. A fractional bandwidth is about 28.5 %

Optimality conditions for approximate solutions of set-valued optimization problems in real linear spaces

In this paper, we deal with optimization problems without assuming any topology. We study approximate efficiency and Q- Henig proper efficiency for the setvalued vector optimization problems, where Q is not necessarily convex. We use scalarization approaches based on nonconvex separation function to present some necessary and sufficient conditions for approximate (proper and weak) efficient solutions.Publisher's Versio

Designing an appropriate adaptive controller for synchronizing a bi-oscillator heart model with time delay

In this paper, synchronization of heart follower oscillator which has lower frequency AV with heart leader oscillator which has dominant frequency SA will be studied. It can be seen if two nodes SA and AV are not synchronized, different types of cardiac blocking arrhythmias occur. Thus, in this paper, beside putting voltage to node SA, by applying time delay in bi-oscillator model of heart system and designing appropriate controller via linear and adaptive methods, we try to prevent blocking arrhythmias of heart. Finally, we apply Lyapanuv stability theorem for ensuring convergence

New insights into the viscoelastic and failure mechanical properties of the elastic fiber network of the inter-lamellar matrix in the annulus fibrosus of the disc

Published by Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NCND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Sept 2020) in accordance with the publisher’s archiving policyThe mechanical role of elastic fibers in the inter-lamellar matrix (ILM) is unknown; however, it has been suggested that they play a role in providing structural integrity to the annulus fibrosus (AF). Therefore, the aim of this study was to measure the viscoelastic and failure properties of the elastic fiber network in the ILM of ovine discs under both tension and shear directions of loading. Utilizing a technique, isolated elastic fibers within the ILM from ovine discs were stretched to 40% of their initial length at three strain rates of 0.1% s−1 (slow), 1% s−1 (medium) and 10% s−1 (fast), followed by a ramp test to failure at 10% s−1. A significant strain-rate dependent response was found, particularly at the fastest rate for phase angle and normalized stiffness (p < 0.001). The elastic fibers in the ILM demonstrated a significantly higher capability for energy absorption at slow compared to medium and fast strain rates (p < 0.001). These finding suggests that the elastic fiber network of the ILM exhibits nonlinear elastic behavior. When tested to failure, a significantly higher normalized failure force was found in tension compared to shear loading (p = 0.011), which is consistent with the orthotropic structure of elastic fibers in the ILM. The results of this study confirmed the mechanical contribution of the elastic fiber network to the ILM and the structural integrity of the AF. This research serves as a foundation for future studies to investigate the relationship between degeneration and ILM mechanical properties

Ultrastructural organization of elastic fibres in the partition boundaries of the annulus fibrosus within the intervertebral disc

© 2017 Acta Materialia Inc. Published by Elsevier Ltd. This manuscript version is made available under the CC-BY-NCND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Dec 2017) in accordance with the publisher’s archiving policyThe relationship between elastic fibre disorders and disc degeneration, aging and progression of spine deformity have been discussed in a small number of studies. However, the clinical relevance of elastic fibres in the annulus fibrosus (AF) of the disc is poorly understood. Ultrastructural visualization of elastic fibres is an important step towards understanding their structure-function relationship. In our previous studies, a novel technique for visualization of elastic fibres across the AF was presented and their ultrastructural organization in intra- and inter-lamellar regions was compared. Using the same novel technique in the present study, the ultrastructural organization of elastic fibres in the partition boundaries (PBs), which are located between adjacent collagen bundles, is presented for the first time. Visualization of elastic fibres in the PBs in control and partially digested (digested) samples was compared, and their orientation in two different cutting planes (transverse and oblique) were discussed. The ultrastructural analysis revealed that elastic fibres in PBs were a well-organized dense and complex network having different size and shape. Adjacent collagen bundles in a cross section (CS) lamella appear to be connected to each other, where elastic fibres in the PBs were merged in parallel or penetrated into the collagen bundles. There was no significant difference in directional coherency coefficient of elastic fibres between the two different cutting planes (p = .35). The present study revealed that a continuous network of elastic fibres may provide disc integrity by connecting adjacent bundles of CS lamellae together. Compared to our previous studies, the density of the elastic fibre network in PBs was lower, and fibre orientation was similar to the intra-lamellar space and inter-lamellar matrix. Statement of Significance A detailed ultrastructural study in the partition boundaries of the annulus fibrosus within the disc revealed a well-organized elastic fibre network with a complex ultrastructure. The continuous network of elastic fibres may provide disc integrity by connecting adjacent bundles of cross section lamellae together. The density of the elastic fibre network in PBs was lower, and fibre orientation was similar to the intra-lamellar space and the inter-lamellar matrix

New findings confirm the viscoelastic behaviour of the inter-lamellar matrix of the disc annulus fibrosus in radial and circumferential directions of loading

© 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (March 2018) in accordance with the publisher’s archiving policyWhile few studies have improved our understanding of composition and organization of elastic fibres in the inter-lamellar matrix (ILM), its clinical relevance is not fully understood. Moreover, no studies have measured the direct tensile and shear failure and viscoelastic properties of the ILM. Therefore, the aim of this study was, for the first time, to measure the viscoelastic and failure properties of the ILM in both the tension and shear directions of loading. Using an ovine model, isolated ILM samples were stretched to 40% of their initial length at three strain rates of 0.1%s−1 (slow), 1%s−1 (medium) and 10%s−1 (fast) and a ramp test to failure was performed at a strain rate of 10%s−1. The findings from this study identified that the stiffness of the ILM was significantly larger at faster strain rates, and energy absorption significantly smaller, compared to slower strain rates, and the viscoelastic and failure properties were not significantly different under tension and shear loading. We found a strain rate dependent response of the ILM during dynamic loading, particularly at the fastest rate. The ILM demonstrated a significantly higher capability for energy absorption at slow strain rates compared to medium and fast strain rates. A significant increase in modulus was found in both loading directions and all strain rates, having a trend of larger modulus in tension and at faster strain rates. The finding of no significant difference in failure properties in both loading directions, was consistent with our previous ultra-structural studies that revealed a well-organized (±45°) elastic fibre orientation in the ILM. The results from this study can be used to develop and validate finite element models of the AF at the tissue scale, as well as providing new strategies for fabricating tissue engineered scaffolds. Statement of significance While few studies have improved our understanding of composition and organization of elastic fibres in the inter-lamellar matrix (ILM) of the annulus in the disc no studies have measured the direct mechanical failure and viscoelastic properties of the ILM. The findings from this study identified that the stiffness of the ILM was significantly larger at faster strain rates, and energy absorption significantly smaller, compared to slower strain rates. The failure properties of the ILM were not significantly different under tension and shear