876 resultados para CYCLIC LOADING
Resumo:
The goal of the thesis was to gain understanding of organizational buying behavior and its effect from the selling perspective and to generate base for verifying customer value propositions for Actiw Oy. The first objective was to discover the current buying decision criteria of current customers to understand the buying motives which had led to the investment initially. Second objective was to understand how the buying decision criteria and customer experiences can be turned into customer value propositions. Research was done with 16 customer interviews, which were focused on obtaining the information on the buying center and the value of the solution. Thesis goes through the main theories of OBB and the theory behind customer value management. Based on customer interviews, the currently used customer value propositions were tested and categorized into points-of-parities and points-ofdifferences. The interviews confirmed customer behavior in new task and modified rebuy situations and also gave confirmation to the internally done customer value propositions. Main finding of the study was, that as the value propositions are possible to present more specifically to each new case instead of using all benefits at the same time.
Resumo:
The objective of the present research was to evaluate the usefulness of anti-cyclic citrullinated peptide (anti-CCP) antibodies and the IgM rheumatoid factor (IgM RF) test for the differential diagnosis of leprosy with articular involvement and rheumatoid arthritis (RA). Anti-CCP antibodies and IgM RF were measured in the sera of 158 leprosy patients (76 with and 82 without articular involvement), 69 RA patients and 89 healthy controls. Leprosy diagnosis was performed according to Ridley and Jopling classification criteria and clinical and demographic characteristics of leprosy patients were collected by a standard questionnaire. Leprosy patients with any concomitant rheumatic disease were excluded. Serum samples were obtained from all participants and frozen at _20°C. Measurement of anti-CCP antibodies and IgM RF were performed by ELISA, using a commercial second-generation kit, and the latex agglutination test, respectively. Anti-CCP antibodies and IgM RF were detected in low frequencies (2.6 and 1.3%, respectively) in leprosy patients and were not associated with articular involvement. Among healthy individuals both anti-CCP antibodies and IgM RF were each detected in 3.4% of the subjects. In contrast, in the RA group, anti-CCP antibodies were present in 81.2% and IgM RF in 62.3%. In the present study, both anti-CCP antibodies and IgM RF showed good positive predictive value for RA, helping to discriminate between RA and leprosy patients with articular involvement. However, anti-CCP antibodies were more specific for RA diagnosis in the population under study.
Resumo:
Our objective was to determine whether the presence of the human leukocyte antigen HLA-DRB1 locus is associated with production of anti-cyclic citrullinated peptide antibodies (anti-CCP Abs) and to what extent they are associated with increased susceptibility to and severity of rheumatoid arthritis (RA) in Egyptian patients. Twenty-nine RA patients gave informed consent to participate in a case-control study that was approved by the Ain Shams University Medical Ethics Committee. RA disease activity and severity were determined using the simplified disease activity index and Larsen scores, respectively. We used a wide scale national study on the pattern of HLA typing in normal Egyptians as a control study. Anti-CCP Abs and HLA-DRB1 typing were determined for all subjects. The alleles most strongly associated with RA were HLA-DRB1 [*01 , *04 and *06] (41.4%). RA patients with serum anti-CCP Ab titers above 60 U/mL had a significantly higher frequency of HLA-DRB1*01 (58.3%) and HLA-DRB1*04 alleles (83.3%). Significant positive correlations were found between serum and synovial anti-CCP Ab titer, RA disease activity, and severity (r = 0.87, 0.66 and 0.63, respectively; P < 0.05). HLA-DRB1 SE+ alleles [*01 and *04] were highly expressed among Egyptian RA patients. The presence of these alleles was associated with higher anti-CCP Ab titer, active and severe RA disease. Early determination of HLA-DRB1 SE+ alleles and serum anti-CCP Ab could facilitate the prediction of the clinical course and prognosis of RA when first evaluated leading to better disease control.
Resumo:
In this study, finite element analyses and experimental tests are carried out in order to investigate the effect of loading type and symmetry on the fatigue strength of three different non-load carrying welded joints. The current codes and recommendations do not give explicit instructions how to consider degree of bending in loading and the effect of symmetry in the fatigue assessment of welded joints. The fatigue assessment is done by using effective notch stress method and linear elastic fracture mechanics. Transverse attachment and cover plate joints are analyzed by using 2D plane strain element models in FEMAP/NxNastran and Franc2D software and longitudinal gusset case is analyzed by using solid element models in Abaqus and Abaqus/XFEM software. By means of the evaluated effective notch stress range and stress intensity factor range, the nominal fatigue strength is assessed. Experimental tests consist of the fatigue tests of transverse attachment joints with total amount of 12 specimens. In the tests, the effect of both loading type and symmetry on the fatigue strength is studied. Finite element analyses showed that the fatigue strength of asymmetric joint is higher in tensile loading and the fatigue strength of symmetric joint is higher in bending loading in terms of nominal and hot spot stress methods. Linear elastic fracture mechanics indicated that bending reduces stress intensity factors when the crack size is relatively large since the normal stress decreases at the crack tip due to the stress gradient. Under tensile loading, experimental tests corresponded with finite element analyzes. Still, the fatigue tested joints subjected to bending showed the bending increased the fatigue strength of non-load carrying welded joints and the fatigue test results did not fully agree with the fatigue assessment. According to the results, it can be concluded that in tensile loading, the symmetry of joint distinctly affects on the fatigue strength. The fatigue life assessment of bending loaded joints is challenging since it depends on whether the crack initiation or propagation is predominant.
The role of cyclic nucleotides in modulation of crayfish neuromuscular junctions by a neuropeptide /
Resumo:
DF2, a heptapeptide, is a member of the family of FMRFamide-like peptides and has been shown to increase the amount of transmitter released at neuromuscular junctions of the crayfish, Procambarus clarkit Recent evidence has shown that protein kinase C (PKC), calcium/calmodulin-dependent protein kinase II (CaMKII) and the cAMPdependent protein kinase (PKA) play a role in the neuromodulatory pathway of DF2. The involvement of these kinases led to the prediction that a G-protein-coupled receptor (GPCR) is activated by DF2 due to the role that each kinase plays in traditional GPCR pathways seen in other organisms and in other cells. G-proteins can also act on an enzyme that generates cyclic guanosine monophosphate (cGMP) which mediates its effects through a cGMP-dependent protein kinase (PKG). This thesis addresses the question of whether or not DF2's effects on synaptic transmission in crayfish are mediated by the cyclic nucleotides cAMP and cGMP. The effects of DF2 on synaptic transmission were examined using deep abdominal extensor muscles of the crayfish Procambarus clarkii. An identified motor neuron was stimulated, and excitatory post-synaptic potentials (EPSPs) were recorded in abdominal extensor muscle LI . A number of activators and inhibitors were used to determine whether or not cAMP, PKA, cGMP and PKG mediate the effect of this peptide. Chemicals that are known to activate PKA (Sp-cAMPS) and/or PKG (8-pCPTcGMP) mimic and potentiate DF2's effect by increasing EPSP amplitude. Inhibitors of either PKA (Rp-cAMPS) or PKG (Rp-8-pCPT-cGMPS) block a portion of the increase in EPSP amplitude induced by the peptide. When both kinase inhibitors are applied simultaneously, the entire effect of DF2 on EPSPs is blocked. The PKG inhibitor blocks the effects of a PKG activator but does not alter the effect of a PKA activator on EPSP amplitude. Thus, the PKG inhibitor appears to be relatively specific for PKG. A trend in the data suggests that the PKA inhibitor blocks a portion of the response elicited by the PKG activator. Thus, the PKA inhibitor may be less specific for PKA. Phosphodiesterase inhibitors, which are known to inhibit the breakdown of cAMP (IBMX) and/or cGMP (mdBAMQ), potentiate the effect of the peptide. These results support the hypothesis that cAMP and cGMP, acting through their respective protein kinase enzymes, mediate the ability of DFi to increase transmitter output.
Resumo:
The purpose of this thesis is to investigate some open problems in the area of combinatorial number theory referred to as zero-sum theory. A zero-sequence in a finite cyclic group G is said to have the basic property if it is equivalent under group automorphism to one which has sum precisely IGI when this sum is viewed as an integer. This thesis investigates two major problems, the first of which is referred to as the basic pair problem. This problem seeks to determine conditions for which every zero-sequence of a given length in a finite abelian group has the basic property. We resolve an open problem regarding basic pairs in cyclic groups by demonstrating that every sequence of length four in Zp has the basic property, and we conjecture on the complete solution of this problem. The second problem is a 1988 conjecture of Kleitman and Lemke, part of which claims that every sequence of length n in Zn has a subsequence with the basic property. If one considers the special case where n is an odd integer we believe this conjecture to hold true. We verify this is the case for all prime integers less than 40, and all odd integers less than 26. In addition, we resolve the Kleitman-Lemke conjecture for general n in the negative. That is, we demonstrate a sequence in any finite abelian group isomorphic to Z2p (for p ~ 11 a prime) containing no subsequence with the basic property. These results, as well as the results found along the way, contribute to many other problems in zero-sum theory.
Resumo:
(A) In recent years, considerable amount of effort has contributed towards enhancing our understanding of the new photoswitch, cyclic azobenzene, particularly from the theoretical point of view. However, the challenging part with this system was poor efficiency of its synthesis from 2,2’- dinitrodibenzyl and lack of effective methods for further modification which would be useful to incorporate this system into biomolecules as a photoswitch. We report the synthesis of cyclic azobenzene and analogues from 2,2’-dinitrodibenzyl, which would allow for further incorporation of this cyclic azobenzene into biomolecules. Reaction of 2,2’-dinitrodibenzyl with zinc metal powder in the presence of triethylammonium formate buffer (pH-9.5) gave a cyclic azoxybenzene, 11,12-dihydrodibenzo[c,g][1,2]diazocine-5-oxide. The latter compound was converted into cyclic azobenzene analogues (bromo-, chloro-, cyano-, and carboxyl) through subsequent transformations. The carboxylic acid analogue was reacted with D-threoninol to give the corresponding amide, which readily undergoes photo-isomerization upon illumination with light. Upon illumination with light at 400 nm, approximately 70% of cis- isomer of amide was isomerized to trans- isomer. It was observed that cis- to trans- isomerization reached the maximum steady state of light transmission after approximately 40 min, whereas the trans- to cis- isomerization approximately acquired in 2 h to regain full recovery of light transmission. Cyclic azobenzene phosphoramidite was synthesized from DMT-protected D-threoninol linked cyclic azobenzene. (B) In recent years, there has been considerable interest invested towards the synthesis of azobenzene analogues for incorporation into proteins. Among the many azobenzene analogues, the synthesis of bi-functional cyclic azobenzene analogues for the incorporation into proteins is relatively new. In this thesis, we report the synthesis of a cyclic azobenzene biscarboxylic acid from 4-(bromomethyl)benzonitrile. (C) Azobenzene has been widely used in the field of polymer science to study the surface morphology and surface properties of polymers. In this thesis, we report the incorporation of cyclic azobenzene into a commercial polymer 2- (hydroxyethyl)methacrylate. Samples collected after 24 h from the reaction solution showed approximately 9% of incorporation of cyclic azobenzene into polymer compared to samples collected after 10 h, which showed approximately 6% incorporation.
Resumo:
In the past few years, interest in signaling networks involving 3ʹ, 5ʹ -cyclic diguanylic acid (c-di-GMP) has increased dramatically. Evidence started to emerge that connects c-di-GMP to the regulation of a range of biological processes in bacteria, such as bacterial biofilm formation, virulence, extracellular polysaccharide synthesis, however, much remains to be explored in the signaling pathways that involve this secondary messenger. This molecule has also been shown to be a very powerful immunostimulating agent and potent mucosal vaccine adjuvant.
Resumo:
(A) Most azobenzene-based photoswitches require UV light for photoisomerization, which limit their applications in biological systems due to possible photodamage. Cyclic azobenzene derivatives, on the other hand, can undergo cis-trans isomerization when exposed to visible light. A shortened synthetic scheme was developed for the preparation of a building block containing cyclic azobenzene and D-threoninol (cAB-Thr). trans-Cyclic azobenzene was found to thermally isomerize back to the cis-form in a temperature-dependent manner. cAB-Thr was transformed into the corresponding phosphoramidite and subsequently incorporated into oligonucleotides by solid phase synthesis. Melting temperature measurement suggested that incorporation of cis-cAB into oligonucleotides destabilizes DNA duplexes, these findings corroborate with circular dichroism measurement. Finally, Fluorescent Energy Resonance Transfer experiments indicated that trans-cAB can be accommodated in DNA duplexes. (B) Inverse Electron Demand Diels-Alder reactions (IEDDA) between trans-olefins and tetrazines provide a powerful alternative to existing ligation chemistries due to its fast reaction rate, bioorthogonality and mutual orthogonality with other click reactions. In this project, an attempt was pursued to synthesize trans-cyclooctene building blocks for oligonucleotide labeling by reacting with BODIPY-tetrazine. Rel-(1R-4E-pR)-cyclooct-4-enol and rel-(1R,8S,9S,4E)-Bicyclo[6.1.0]non-4-ene-9-ylmethanol were synthesized and then transformed into the corresponding propargyl ether. Subsequent Sonogashira reactions between these propargylated compounds with DMT-protected 5-iododeoxyuridine failed to give the desired products. Finally a methodology was pursued for the synthesis of BODIPY-tetrazine conjugates that will be used in future IEDDA reactions with trans-cyclooctene modified oligonucleotides.
Resumo:
Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and 150°C using a low temperature curing accelerator system. Composites were also prepared using a conventional accelerator system and cured at 150°C. The swelling behavior of these composites at varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent uptake decreased, due to the superior solvent resistance of the fibre and good fibre-rubber interactions. The bonding agent improved the swelling resistance of the composites due to the strong interfacial adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V,) was found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre composite showed a lower percentage swelling than untreated one for both systems showing superior rubber-fibre interactions.
Resumo:
A series of short-isora-fiber-reinforced natural rubber composites were prepared by the incorporation of fibers of different lengths (6, 10, and 14 mm) at 15 phr loading and at different concentrations (10, 20, 30, and 40 phr) with a 10 mm fiber length. Mixes were also prepared with 10 mm long fibers treated with a 5% NaOH solution. The vulcanization parameters, processability, and stress-strain properties of these composites were analyzed. Properties such as tensile strength, tear strength, and tensile modulus were found to be at maximum for composites containing longitudinally oriented fibers 10 mm in length. Mixes containing fiber loadings of 30 phr with bonding agent (resorcinol-formaldehyde [RF] resin) showed mechanical properties superior to all other composites. Scanning electron microscopy (SEM) studies were carried out to investigate the fiber surface morphology, fiber pullout, and fiber-rubber interface. SEM studies showed that the bonding between the fiber and rubber was improved with treated fibers and with the use of bonding agent.
Resumo:
Composite magnetic materials have the unique advantage of property modification for tailoring devices for various applications. Rubber ferrite composites (RFCs) prepared by incorporating ferrites in rubber matrixes have the advantage of easy mouldability and flexibility. RFCs containing various loadings of nickel zinc ferrite (NZF) (Ni1 xZnxFe2O4) in a natural rubber matrix have been prepared. The cure characteristics and the mechanical properties of these composites were evaluated. The effect of loading on the cure characteristics and tensile properties were also evaluated. It is found that the loading dependence on the cure time and mechanical properties exhibit an identical pattern.
Resumo:
The identification of compositional changes in fumarolic gases of active and quiescent volcanoes is one of the most important targets in monitoring programs. From a general point of view, many systematic (often cyclic) and random processes control the chemistry of gas discharges, making difficult to produce a convincing mathematical-statistical modelling. Changes in the chemical composition of volcanic gases sampled at Vulcano Island (Aeolian Arc, Sicily, Italy) from eight different fumaroles located in the northern sector of the summit crater (La Fossa) have been analysed by considering their dependence from time in the period 2000-2007. Each intermediate chemical composition has been considered as potentially derived from the contribution of the two temporal extremes represented by the 2000 and 2007 samples, respectively, by using inverse modelling methodologies for compositional data. Data pertaining to fumaroles F5 and F27, located on the rim and in the inner part of La Fossa crater, respectively, have been used to achieve the proposed aim. The statistical approach has allowed us to highlight the presence of random and not random fluctuations, features useful to understand how the volcanic system works, opening new perspectives in sampling strategies and in the evaluation of the natural risk related to a quiescent volcano