The paper discusses work completed at Cardinal River Coals in Canada to improve the existing oil analysis condition-monitoring program being undertaken for wheel motors. Oil analysis results from a fleet of 55 haul truck wheel motors were analyzed along with their respective failures and repairs over a nine-year period. Detailed data cleaning procedures were applied to prepare data for modeling. In addition, definitions of failure and suspension were clarified depending on equipment condition at replacement. Using the proportional-hazards model (PHM) approach, the key condition variables relating to failures were found from among the 19 elements monitored, plus sediment and viscosity. Those key variables were then incorporated into a decision model that provided an unambiguous and optimal recommendation on whether to continue operating a wheel motor or to remove it for overhaul on the basis of data obtained from an oil sample. Wheel motor failure implied extensive planetary gear or sun gear damage necessitating the replacement of one or more major internal components in a general overhaul. The decision model, when triggered by incoming data, provided both a recommendation based on an optimal decision policy as well as an estimate of the unit's remaining useful life (RUL). By optimizing the times of repair as a function both of age and condition data a 20-30% potential savings in overhaul costs over existing practice was identified.
The preparation and DNA binding characteristics of a structural analog of Hoechst 33258 bearing two pyridinic nitrogen atoms are described. The 1H NMR signals of the complex formed between the new ligand 1 and decadeoxyribonucleotide d(CATGGCCATG)2 were assigned by employing one- and two-dimensional NMR techniques. Intermolecular nuclear Overhauser effects (NOE) between the ligand and the DNA receptor fragment confirm that the ligand binds in the minor groove of the DNA, interacting with the centrally located 5'-GGCCA segment. In contrast to the steric clash between the benzimidazole rings of the parent Hoechst 33258 molecule and the guanine 2-NH2 groups, which renders it G.C avoiding and thus A.T base pair preferring, the ligand 1 described here overcomes these unfavorable interactions and instead exhibits a marked preference of G.C base pairs. This behavior appears to arise from additional stabilization due to H-bonding with the guanine 2-NH2 groups. Although a ligand-induced distortion at the binding site is qualitatively assessable, the overall B-type conformation of the DNA fragment is retained upon complexation. The structural conclusions drawn from the NOE-NMR evidence were confirmed by molecular mechanics and molecular modeling studies.
The paper reports the development of an optimal maintenance program based on vibration monitoring of critical bearings on machinery in the food processing industry. Statistical analysis of vibration data is undertaken using the software package EXAKT to establish the key vibration signals that are necessary for risk estimation. Once the risk curve is identified using a proportional hazards model, cost data are then blended with risk to identify the optimal maintenance program. The structure of the decision making software EXAKT is also presented. Concludes that perhaps the most important benefit of the study was the realization by maintenance management that it is possible to identify key measurements for examination at the time of vibration monitoring – thus possibly saving on inspection costs.
. Can. J. Chem. 54, 3517 (1976).The acyclic amido radicals generated from the corresponding N-bromo.AT-iert-alkylamides reacted like ,?'-radicals, rather than 0-radicals, and preferentially abstracted a 6-hydrogen of the alkyl chain, rather than a r-iiydrogen of the acyl chain. On the basis that, in these amido radicals, the conforn~ation of the transition state of the hydrogen transfer is a five-membered ring and the stereoelectronic requiren~ent for the transfer demands a colinear arrangement of the radical containing orbital and the C-PI bond, the results are satisfactorily rationalized by the n electron configuration of the amido radicals. It is also established that the chain length of these N-bromoamide photodecompositions increases as the intran~olecular hydrogen transfer of the corresponding amido radicals becomes easier; the hydrogen abstraction step must be the rate determining step in the chain reaction. The spontaneous formations of r-iminolactones from r-bromoamides indicate that the intramolecular nucleopliilic displacement by the 0-center of the amido group is facilitated since its transition state conformation readily accommodates the stereoelectronic requirements for the nucleophilic substitution. A colinear approach of thep-orbital of the more nucleophilic N-center to the rear side of the yC-Br bond is shown to be prohibitively strained. Chem. 54, 3517 (1976).Les radicaux amido acycliques, gknCrCs B partir des N-bromo N-tert alkylamides correspondantes, reagissent comrne les radicaux N-alkyles plutBt que comme des radicaux 0-alkyles; ils rkagissent prCf6rentiellement pour enlever un hydrogkne en 6 de la chaine aIkylCe plut6t qu'un hydrogkne en 7 de la chaine acylCe. En faisant l'hypothbse que, dans ces radicaux amido, la conformation de 1'Ctat de transition du transfert d'hydrogene est un cycle a cinq membres et que les conditioils stCrCoClectroniques pour le trarsfert demandent un arrangement colinCaire de l'orbitale contenant le radical et du lien C-H, on peut rationaliser d'une fason satisfaisante les resultats par la configuration Clectronique IT des radicaux amido. On a aussi Ctabli que la longueur de la chaine de ces photodkcompositions de N-bromoamides augmente B mesure que le rransfert d'hydrogbne intramolCculaire des radicaux arnido correspondants devient plus facile; I'6tape de l'enlkvement de l'hydrogene doit &tre l'ktape dCterminante dans la reaction en chaine.Les reactions spoi~tanCes de formation de r-iminolactones B partir de r-bromoan~ides indiquent que le dkplacement nuclCophile intramolCculaire par l'intermediaire du centre oxygCnC du groupe amido est facilite puisque la conformation de son Ctat de transition accommode facilement les demandes stCrCoClectrorliques de la substitution nuclCopbile. La tension provoquCe par une approche colineaire de l'orbitale p du centre azote, qui est plus nuclkophile, vers la face arrikre du lien -y-C-Br est prohibitive.[Traduit par le journal]In recent. years, the existence of anlido radi-(81, and reaction patterns (9-13). These results cal...
The location, orientation and dynamics of a thiazole-containing analogue of distamycin 1 bound to the decadeoxyribonucleotide d-[CGCAATTGCG]2 have been studied by non-exchangable and imino proton NMR resonances of the 1:1 complex. Using NOE difference, COSY and NOESY experiments, lexitropsin (1) was located in the minor groove of DNA at 5'-CAAT sequence. This was concluded by an intermolecular NOE between the ligand and a minor groove A4H2 proton. The NOE cross-correlations in the NOESY map confirmed that the DNA decamer duplex in the 1:1 complex remains in a right-handed B-conformation similar to that in the free decamer. Experiments on non-exchangeable and exchangeable proton NMR resonances placed the N-formylamino terminus of drug 1 on the 5'-C3 nucleotide, while the rest of the molecule extends onto the 5'-AAT sequence. The structural evidence for sequence preferential binding at 5'CAAT rather than 5'AATT suggests this reflects an attempt on the part of the sterically demanding inward directed sulfur of the thiazole to minimize compression by moving part of the molecule to the somewhat wider CG base site. The lack of evidence for a 2:1 drug:DNA complex, in contrast to distamycin, is in accord with this interpretation. The lexitropsin 1 was found to be in an exchange between the equivalent 5'-CAAT sites at a rate of approximately 35S-1 with a delta G degree of 65 +/- 5 kJ mol-1 at 303 K. The experimental data suggests a slide-swing mechanism for this exchange process.
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