426 research outputs found
Incorporating shrinkage effects in FE modeling of prestressed concrete bridge
No full textRight from the inception of the implementation of prestressed concrete in the bridge construction field, it has been very popular. Even though this type of bridges has big advantages, cracking is a major problem. The cracking event, due to its detrimental effects on the structure is the most objectionable problem. In cracking shrinkage plays a very significant role. This implies that the study of shrinkage is essential to study the phenomenon of cracking. Due to many variables responsible for deck cracking, it is very difficult to study the overall effect of these variegated factors taken in the consideration at a time. This thesis aims to confluence as many such aspects as possible in a single plane of consideration with the help of Finite Element software namely ABAQUS. The goal of this research is to study shrinkage, shrinkage effects, and factors affecting the shrinkage and ultimately to incorporate the shrinkage effects in Finite Element Modeling. Here the study is constrained to Prestressed Concrete Bridge. Thus, the research is carried to incorporate the shrinkage effects in FE Modeling of Prestressed Concrete Bridge. This is a difficult task as many finite element programs do not have pre-programmed methods for simulating the time dependent properties of concrete. Therefore, it is necessary to develop these methods. This study concentrates on trying to simulate the behavior of a simple span bridge as a means of developing the basic analytical method. In the research Abaqus has been selected and the selection has been justified for the purpose of analyzing time dependent effects in bridges. A parametric study has been carried out with a view to identifying the effects of various parameters of shrinkage in a structure. The effects of the parameters such as length of the span, girder spacing, deck thickness and modulus of elasticity of girder have been analyzed with the help of bridges modeled in Abaqus. The parametric study concludes that shrinkage strain increases with increase in length and spacing of girder. The shrinkage strain decreases with increase in compressive strength of girder and deck thickness.M.S.Includes bibliographical referencesby Dhara Puran
Behavioral Subtyping in Object-Oriented Languages
No full textdata types, modules, packages; F.3.1 [Logics and Meanings of Programs] Specifying and Verifying and Reasoning about Programs --- logics of programs, pre- and post-conditions, theory A version of this technical report is published as the author's doctoral dissertation. c fl Copyright 1997 by Krishna Kishore Dhara All rights reserved. Department of Computer Science 226 Atanasoff Hall Iowa State University Ames, Iowa 50011-1040, USA ii TABLE OF CONTENTS 1. INTRODUCTION : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.1 Problem : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.1.1 Reasoning problem and behavioral subtyping : : : : : : : : : : 2 1.1.2 Aliasing and behavioral subtyping : : : : : : : : : : : : : : : : 4 1.2 Overview of the solutions : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.2.1 Different notions of behavioral subtyping : : : : : : : : : : : : 6 1.2.2 Semantic conditions : : : : : : : : : : : : : : : : : : : : : : : : 7 1.2.3 "..
Normalised solutions for p-Laplacian equations with Lp-supercritical growth
No full textFor N >= 3 and 2 < p < N, we find normalised solutions to the equation -Delta pu + (1 +V(x))|u|(p-2)u +lambda u =|u|(q-2)u in R-N |u| 2 = rho in the mass supercritical and Sobolev sub critical case, that is q E (pN+2/N , Np/ N-p ), at least if rho > 0 is small enough. The function V is an element of L-N/p(R-N), which plays the role of potential, is assumed to be non-positive and vanishing at infinity. Moreover, we will prove the compactness of the embedding of the space of radial functions W (1,p) (rad)(R-N ) subset of L-q(R-N) for p is an element of (1, N) and q E (pN+2/N , Np/N-p)
Di-, Tetra-, and Polynuclear Copper(II) Complexes : active Catalysts for Oxidation of Toluene and Benzene
No full textThree copper(II) complexes with a binucleating N 2O donor ligand, [Cu 2(L 1)(μ 2-pz)(CH 3COO) 2] (1), [Cu 4(L 1) 2(μ 4- O)(μ 2-CH 3COO) 2(μ 1,1-N 3)(N 3)] (2), and [Cu 2(L 2) (μ 1,1-N 3)(μ 1,3-N 3) 2] ∞ (3) [pz = pyrazolato, HL 1 = 2,6-bis(morpholinomethyl)-4-tert-butylphenol and HL 2 = 2,6-bis(morpholinomethyl)-4-methylphenol] have been synthesized and characterized by elemental analysis, FTIR and UV/Vis spectroscopy, and X-ray crystallography. X-ray crystallographic studies revealed that a series of di-, tetra-, and polynuclear complexes have been formed by varying the bridging ligand, counteranion, and reaction conditions. These show effective catalytic properties for the hydrogen peroxide oxidation of toluene and benzene
Selective fluorescence zinc ion sensing and binding behavior of 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol: Biological application
No full textZinc ion fluorescence sensing and the binding properties of 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol (HL) have been investigated. It displays high selectivity for Zn2+ and can be used as zinc ion-selective luminescent probe for biological application under physiological conditions. The increase in emission in the presence of Zn2+ is accounted for by the formation of hexanuclear complex [Zn6(L) 2(OH)2(CH3COO)8] characterized by X-ray crystallography. An approximately 6-fold Zn2+-selective chelation-enhanced fluorescence response in HEPES buffer (pH 7.4) is attributed due to the strong coordination of Zn(II) that would impose rigidity and hence decrease the nonradiative decay of the excited state. By incubation of cultured living cells (B16F10 mouse melanoma and A375 human melanoma) with HL, intracellular Zn2+ concentration could be monitored
Arterial flow based transfer function and ascending aorta pressure waveform estimation
No full textHypertension has been recognized as a leading cause of cardiovascular diseases. It is principally determined by the amount of the blood ejected by the heart and the properties of the receiving arteries. There is a strong correlation of a reduction in large artery compliance and high blood pressure. Thus, it is important to identify the causative factors that contribute to the severity of hypertension in terms of blood pressure, flow and mechanical properties of arteries. Numerous methods have been used to measure peripheral arterial blood pressure. As pressure waveform travels away from heart, it is amplified because of increased elastic stiffness which gives rise to wave reflections. As a result, peripheral pressure cannot accurately describe cardiovascular events. On the other hand, central aortic pressure is a much better predictor, but it can only be measured directly with an invasive catheter. For this reason, several pressure-based generalized transfer function methods have been proposed. In this thesis, a novel flow-based generalized transfer function is established. This new method is tested using carotid flow waveform as an input to predict ascending aortic flow. Additionally a three element windkessel model was used to predict ascending aortic pressure. Results show good correspondence of predicted ascending aortic flow and pressure. The present approach can be effectively applied in clinical situations where either peripheral arterial flow or ascending aortic flow noninvasively obtained by Doppler ultrasound can be used to obtain ascending aortic pressure. The derived aortic pressure waveform can then be further analyzed in terms of large artery compliance and systolic pressure augmentation, both critical in determining the severity of hypertension.M.S.Includes bibliographical referencesby Dhara Zal
Synthesis, crystal structure, magnetic property and DNA cleavage activity of a new tereplithalate-bridged tetranuclear copper(II) complex
No full textA new terephthalate-bridged tetranuclear copper(II) complex has been synthesized and structurally characterized by X-ray crystallography: [Cu4(L)2(tp)(dmf)2] (1) (H3L = 1,3-bis(salicylideneamino)propan-2-ol, tp = terephthalate and dmf = N,N’-dimethylformamide). The dinucleating pentadentate character of the ligand (H3L) and the desired pair-of-dimers arrangement, through the incorporation of the bridging terephthalate moiety, is clearly evident from the structure of 1. The copper atoms are coordinated in a slightly distorted square pyramidal arrangement within each dinucleating half of the complex and are bridged mono-atomically by the secondary alkoxo oxygen of the ligand and di-atomically by the terephthalate moiety. The apical position is occupied by the oxygen atom of the dmf. The structure of 1 reveals a short intramolecular Cu–Cu separation (ca. 3.1 Å), in combination with long intramolecular copper separations (ca. 11 Å). The variable temperature-dependent susceptibility measurement (2–300 K) of 1 reveals a dominant ferromagnetic coupling, 2J = 18.70 cm-1. Complex 1 binds to double-stranded CT (calf-thymus) DNA giving a Kapp value of 1.25 × 107 M-1 and displays efficient cleavage of supercoiled pUC19 DNA in the presence of H2O2 following a hydroxyl radical pathway
Developing E. coli-E. coli co-cultures to overcome barriers of heterologous tryptamine biosynthesis
No full textTryptamine is an alkaloid compound with demonstrated bioactivities and is also a precursor molecule to many important hormones and neurotransmitters. The high efficiency biosynthesis of tryptamine from inexpensive and renewable carbon substrates is of great research and application significance. In the present study, a tryptamine biosynthesis pathway was established in a metabolically engineered E. coli-E. coli co-culture. The upstream and downstream strains of the co-culture were dedicated to tryptophan provision and conversion totryptamine, respectively. The constructed co-culture was cultivated using either glucose or glycerol as carbon source for de novo production of tryptamine.The manipulation of the co-culture strains’ inoculation ratio was adapted to balance the biosynthetic strengths of the pathway modules for bioproduction optimization. Moreover, a biosensor-assisted cell selection strategy was adapted to improve the pathway intermediate tryptophan provision by the upstream strain, which further enhanced the tryptamine biosynthesis. The resulting biosensor-assisted modular co-culture produced 194mg/L tryptamine with a yield of 0.02 g/g glucose using shake flask cultivation.The findings of this work demonstrate that the biosensor-assisted modular co-culture engineering offers a new perspective for conducting microbial biosynthesis.Peer reviewe
Expedient synthesis of l-heptose derived septacidin building blocks from l-glucose
No full textInternational audienceBacterial natural products containing heptosides such as septacidin represent interesting scaffolds for the development of drugs to combat antimicrobial resistance. However, very few synthetic strategies have been reported to grant access to these derivatives. Here, we have devised a synthetic pathway to l-glycero-l-glucoheptoside, a key building block en route to septacidin, directly from l-glucose. Importantly, we show that carbon homologation at C6, encompassing oxidation of the C6-OH followed by methylenation, is significantly influenced by the nature of the C4-moiety. In order to observe the effect of various patterns, namely azide (N3), p-methoxybenzyloxy (OPMB), and benzyloxy (OBn), a thorough analysis was conducted on the corresponding l-glucosides. The results unveiled a distinct trend where the efficiency of methylenation followed the trend OBn > OPMB > N3. Finally, the C6-alkene was dihydroxylated in the presence of osmium tetroxide to yield the expected l/d-glycero-l-glucoheptosides. The lead building block, which features a C-4 azide, was delivered as a phenyl thioglycoside. Added to the suitable masking of the 6,7-diol, this combination enables further functionalization to achieve versatile compounds of biological interest. The study insights into the interplay between substitution at C-4 and carbon homologation at C-6 provide valuable guidance for future endeavors in the synthesis of these carbohydrate molecules
Additions to the Dehm collection of Siwalik hominoids, Pakistan: descriptions and interpretations
No full text- …
