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Artigos de revistas sobre o assunto "MDA phage"
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Dymova, Maya Alexandrovna, Yaroslav Alexandrovich Utkin, Maria Denisovna Dmitrieva, Elena Vladimirovna Kuligina e Vladimir Alexandrovich Richter. "Modification of a Tumor-Targeting Bacteriophage for Potential Diagnostic Applications". Molecules 26, n.º 21 (29 de outubro de 2021): 6564. http://dx.doi.org/10.3390/molecules26216564.
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Background: Tumor-targeting bacteriophages can be used as a versatile new platform for the delivery of diagnostic imaging agents and therapeutic cargo. This became possible due to the development of viral capsid modification method. Earlier in our laboratory and using phage display technology, phages to malignant breast cancer cells MDA-MB 231 were obtained. The goal of this study was the optimization of phage modification and the assessment of the effect of the latter on the efficiency of phage particle penetration into MDA-MB 231 cells. Methods: In this work, we used several methods, such as chemical phage modification using FAM-NHS ester, spectrophotometry, phage amplification, sequencing, phage titration, flow cytometry, and confocal microscopy. Results: We performed chemical phage modification using different concentrations of FAM-NHS dye (0.5 mM, 1 mM, 2 mM, 4 mM, 8 mM). It was shown that with an increase of the modification degree, the phage titer decreases. The maximum modification coefficient of the phage envelope with the FAM–NHS dye was observed with 4 mM modifying agent and had approximately 804,2 FAM molecules per phage. Through the immunofluorescence staining and flow cytometry methods, it was shown that the modified bacteriophage retains the ability to internalize into MDA-MB-231 cells. The estimation of the number of phages that could have penetrated into one tumor cell was conducted. Conclusions: Optimizing the conditions for phage modification can be an effective strategy for producing tumor-targeting diagnostic and therapeutic agents, i.e., theranostic drugs.
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Brown, D. J., E. J. Threlfall, M. D. Hampton e B. Rowe. "Molecular characterization of plasmids in Salmonella enteritidis phage types". Epidemiology and Infection 110, n.º 2 (abril de 1993): 209–16. http://dx.doi.org/10.1017/s0950268800068126.
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SUMMARYPlasmids in selected type strains of 26 of the Salmonella enteritidis phage types have been characterized by restriction enzyme fingerprinting and by DNA–DNA hybridization with oligonucleotide probes for Salmonella plasmid virulence (Spv) genes. With one exception, the fingerprints of the 38 MDa plasmids studied were homogeneous but there was heterogeneity in the fingerprints of 59 MDa plasmids found in 4 of the type strains. However all 38 MDa and 59 MDa plasmids were related as was a 45 MDa plasmid identified in the type strain of phage type 19. A 3·5 kb fragment homologous to SpvC was conserved in Hind III digests of all 38 MDa and 59 MDa plasmids, and in the related 45 MDa plasmid. In contrast a 65 MDa plasmid found in the type strain of phage type 10 was not related to these three plasmid molecular weight groups and did not carry the SpvC gene.
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van Passel, Mark W. J., Arie van der Ende e Aldert Bart. "Plasmid Diversity in Neisseriae". Infection and Immunity 74, n.º 8 (agosto de 2006): 4892–99. http://dx.doi.org/10.1128/iai.02087-05.
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ABSTRACT Horizontal gene transfer constitutes an important force in prokaryotic genome evolution, and it is well-known that plasmids are vehicles for DNA transfer. Chromosomal DNA is frequently exchanged between pathogenic and commensal neisseriae, but relatively little is known about plasmid diversity and prevalence among these nasopharyngeal inhabitants. We investigated the plasmid contents of 18 Neisseria lactamica isolates and 20 nasopharyngeal Neisseria meningitidis isolates. Of 18 N. lactamica strains, 9 harbored one or more plasmids, whereas only one N. meningitidis isolate contained a plasmid. Twelve plasmids were completely sequenced, while five plasmid sequences from the public databases were also included in the analyses. On the basis of nucleic acid sequences, mobilization, and replicase protein alignments, we distinguish six different plasmid groups (I to VI). Three plasmids from N. lactamica appeared to be highly similar on the nucleotide level to the meningococcal plasmids pJS-A (>99%) and pJS-B (>75%). The genetic organizations of two plasmids show a striking resemblance with that of the recently identified meningococcal disease-associated (MDA) phage, while four putative proteins encoded by these plasmids show 25% to 39% protein identity to those encoded by the MDA phage. The putative promoter of the gene encoding the replicase on these plasmids contains a polycytidine tract, suggesting that replication is subjected to phase variation. In conclusion, extensive plasmid diversity is encountered among commensal neisseriae. Members of three plasmid groups are found in both pathogenic and commensal neisseriae, indicating plasmid exchange between these species. Resemblance between plasmids and MDA phage may be indicative of dissemination of phage-related sequences among pathogenic and commensal neisseriae.
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Kozarsky, Phyllis E., David Rimland, Pamela M. Terry e Kaye Wachsmuth. "Plasmid Analysis of Simultaneous Nosocomial Outbreaks of Methicillin-Resistant Staphylococcus aureus". Infection Control 7, n.º 12 (dezembro de 1986): 577–81. http://dx.doi.org/10.1017/s0195941700065413.
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AbstractA large outbreak of infections caused by methicillin and aminoglycoside resistant Staphylococcus aureus provided the opportunity to evaluate mechanisms of resistance and compare the usefulness of typing systems. Between January 1979 and December 1980, 63 patients developed infections with S aureus resistant to multiple antibiotics, including methicillin and tobramycin. All isolates had an identical antibiogram and were phage type 47/54/75/77/83A. Beginning in January 1981, a superimposed outbreak caused by S aureus of the same phage type but with a resistance pattern now including gentamicin occurred. The two strains contained different aminoglycoside inactivating enzymes. The initial strain contained a single plasmid of 21.5 mDa molecular weight, whereas the subsequent strain which had acquired gentamicin resistance contained this plasmid plus a heavier one of 33 mDa. Plasmid analysis complements the analysis of antibiograms and phage types and aids in defining epidemiologic patterns of transmission.
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Pertics, Botond Zsombor, Tamás Kovács e György Schneider. "Characterization of a Lytic Bacteriophage and Demonstration of Its Combined Lytic Effect with a K2 Depolymerase on the Hypervirulent Klebsiella pneumoniae Strain 52145". Microorganisms 11, n.º 3 (6 de março de 2023): 669. http://dx.doi.org/10.3390/microorganisms11030669.
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Klebsiella pneumoniae is a nosocomial pathogen. Among its virulence factors is the capsule with a prominent role in defense and biofilm formation. Bacteriophages (phages) can evoke the lysis of bacterial cells. Due to the mode of action of their polysaccharide depolymerase enzymes, phages are typically specific for one bacterial strain and its capsule type. In this study, we characterized a bacteriophage against the capsule-defective mutant of the nosocomial K. pneumoniae 52145 strain, which lacks K2 capsule. The phage showed a relatively narrow host range but evoked lysis on a few strains with capsular serotypes K33, K21, and K24. Phylogenetic analysis showed that the newly isolated Klebsiella phage 731 belongs to the Webervirus genus in the Drexlerviridae family; it has a 31.084 MDa double-stranded, linear DNA with a length of 50,306 base pairs and a G + C content of 50.9%. Out of the 79 open reading frames (ORFs), we performed the identification of orf22, coding for a trimeric tail fiber protein with putative capsule depolymerase activity, along with the mapping of other putative depolymerases of phage 731 and homologous phages. Efficacy of a previously described recombinant K2 depolymerase (B1dep) was tested by co-spotting phage 731 on K. pneumoniae strains, and it was demonstrated that the B1dep-phage 731 combination allows the lysis of the wild type 52145 strain, originally resistant to the phage 731. With phage 731, we showed that B1dep is a promising candidate for use as a possible antimicrobial agent, as it renders the virulent strain defenseless against other phages. Phage 731 alone is also important due to its efficacy on K. pneumoniae strains possessing epidemiologically important serotypes.
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Tonin, Patricia N., e Robert B. Grant. "Genetic and physical characterization of trimethoprim resistance plasmids from Shigella sonnei and Shigella flexneri". Canadian Journal of Microbiology 33, n.º 10 (1 de outubro de 1987): 905–13. http://dx.doi.org/10.1139/m87-157.
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Analysis of six Shigella flexneri and four S. sonnei isolates with trimethoprim (Tp) resistance from clinical cases in Ontario has shown that, in all isolates, the Tp resistance is mediated by gene(s) on conjugative, multiple antibiotic-resistance plasmids. The physical and genetic characterization of these plasmids revealed that there are three different Tp resistance plasmids. One group, composed of all six S. flexneri plasmids, consists of plasmids which are about 70 megadaltons (MDa) and inhibit the fertility of an Escherichia coli Hfr strain (Fi+). A representative member of this group, pPT4, demonstrates a weak incompatibility reaction with IncFI plasmid R455-2. Another group, three of the four S. sonnei plasmids, contains plasmids which are about 43 MDa, Fi−, and mediate propagation of phage PRD1. The third group, the remaining S. sonnei plasmid, is 53 MDa,fi+, mediates propagation of phages fd and MS2, and is incompatible with IncFII plasmid R100. These plasmids also have been differentiated by restriction endonuclease fragment profiles. Analysis of pPT4 has revealed that the Tp resistance of this plasmid is transposable. The transposon, Tn536, is different from previously described Tp resistance transposons; it is 16 MDa, and in addition to Tp, it encodes resistance to mercuric chloride ions, spectinomycin, streptomycin, and sulfonamides.
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Petrenko, Valery A., James W. Gillespie, Hai Xu, Tiffany O’Dell e Laura M. De Plano. "Combinatorial Avidity Selection of Mosaic Landscape Phages Targeted at Breast Cancer Cells—An Alternative Mechanism of Directed Molecular Evolution". Viruses 11, n.º 9 (26 de agosto de 2019): 785. http://dx.doi.org/10.3390/v11090785.
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Low performance of actively targeted nanomedicines required revision of the traditional drug targeting paradigm and stimulated the development of novel phage-programmed, self-navigating drug delivery vehicles. In the proposed smart vehicles, targeting peptides, selected from phage libraries using traditional principles of affinity selection, are substituted for phage proteins discovered through combinatorial avidity selection. Here, we substantiate the potential of combinatorial avidity selection using landscape phage in the discovery of Short Linear Motifs (SLiMs) and their partner domains. We proved an algorithm for analysis of phage populations evolved through multistage screening of landscape phage libraries against the MDA-MB-231 breast cancer cell line. The suggested combinatorial avidity selection model proposes a multistage accumulation of Elementary Binding Units (EBU), or Core Motifs (CorMs), in landscape phage fusion peptides, serving as evolutionary initiators for formation of SLiMs. Combinatorial selection has the potential to harness directed molecular evolution to create novel smart materials with diverse novel, emergent properties.
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Binkin, N., G. Scuderi, F. Novaco, G. L. Giovanardi, G. Paganelli, G. Ferrari, O. Cappelli et al. "Egg-relatedSalmonella enteritidis, Italy, 1991". Epidemiology and Infection 110, n.º 2 (abril de 1993): 227–37. http://dx.doi.org/10.1017/s095026880006814x.
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SUMMARYIn recent years,Salmonella enteritidishas become an increasingly important public health problem in Italy. In some parts of the country, the fraction of total human salmonella isolates accounted for byS. enteritidishas risen from 3–4% in the mid-1980s to more than 30% in 1990. Between 1090 and 1991. the number of reportedS. enteritidisoutbreaks increased more than sixfold. The 33 outbreaks reported in 1991 occurred in seven contiguous regions in northern and central Italy and were clustered in time between June and October: in the majority, products containing raw or undercooked shell eggs were implicated. Five of the egg-related outbreaks that occurred within a 30 kilometre radius over a 7-week period were investigated in detail. A phage type 1 strain containing a 38·9 MDa plasmid appeared responsible for three of the outbreaks, while in the remaining two a phage type 4 strain, also with a 38·9 MDa plasmid was isolated. Efforts are being made to enhance epidemiological surveillance and laboratory evaluation, and the use of pasteurized eggs has been recommended for high-risk populations.
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Harnett, N., S. McLeod, Y. AuYong, J. Wan, S. Alexander, R. Khakhria e C. Krishnan. "Molecular characterization of multiresistant strains ofSalmonella typhifrom South Asia isolated in Ontario, Canada". Canadian Journal of Microbiology 44, n.º 4 (1 de abril de 1998): 356–63. http://dx.doi.org/10.1139/w98-012.
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Two hundred and fourteen isolates of Salmonella typhi submitted to our laboratory between 1992 and 1996 were tested for susceptibility to 20 antimicrobial agents. Forty-eight of the 214 isolates (22.4%), recovered from individuals who had travelled in South Asia, were multiresistant. Forty-four of the 48 isolates were resistant to ampicillin, chloramphenicol, tetracycline, streptomycin, sulfamethoxazole, trimethoprim, cotrimoxazole, ticarcillin, and piperacillin; the other four isolates were resistant to four to six agents. Forty-two of the multiresistant isolates belonged to Vi phage type E1, two isolates from the Punjab State belonged to phage type A, another from the Punjab State belonged to phage type E3, one isolate from Pakistan belonged to type M1, and one isolate from India belonged to type J1. Plasmids from 45 of 48 isolates showed a temperature-sensitive mechanism of transfer to Escherichia coli K-12 strains, characteristic of HI incompatibility group plasmids. The majority of plasmids had an estimated molecular weight of 120 MDa and encoded both citrate utilization and mercury resistance. Plasmids from three isolates had an estimated molecular weight of 112-115 MDa; one of these isolates encoded citrate utilization but not mercury resistance. Analysis of isolates by pulsed-field gel electrophoresis after digestion with XbaI and SpeI indicated that the majority of multiresistant isolates shared a common restriction profile, while four isolates had unique patterns.Key words: typing, multiresistant, Salmonella typhi.
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Stanley, J., A. P. Burnens, E. J. Threlfall, N. Chowdry e M. Goldsworthy. "Genetic relationships among strains ofSalmonella enteritidisin a national epidemic in Switzerland". Epidemiology and Infection 108, n.º 2 (abril de 1992): 213–20. http://dx.doi.org/10.1017/s0950268800049694.
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SUMMARYA collection ofSalmonella enteritidisstrains isolated in Switzerland (1965–90) was characterized. The phage type and plasmid profile of isolates were compared with the copy number and insertion loci of the DNA insertion element IS200. Three clonal lines ofS. enteritidiswere identified by IS200profile; the various phage types were subtypes reproducibly associated with one of these lines. All human and poultry isolates contained a 38 Mda plasmid which hybridized with a mouse virulence-associated gene probe. InS. enteritidis, the IS200profile is a race-specific molecular marker of the chromosome, and may be particularly applicable for studying the epidemiology of less common serovars.
Teses / dissertações sobre o assunto "MDA phage"
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Mouville, Clémence. "Interaction entre les pili de type IV et le phage filamenteux MDA : impact potentiel sur la virulence de Neisseria meningitidis". Electronic Thesis or Diss., Université Paris Cité, 2024. http://www.theses.fr/2024UNIP5235.
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Neisseria meningitidis (Nm) est une bactérie commensale du nasopharynx humain qui traverse quelques fois la barrière nasopharyngée et se propage dans la circulation sanguine jusqu'à atteindre les méninges. Un bactériophage filamenteux appelé MDA (Meningococcal Disease Associated) est associé aux infections invasives à méningocoques chez les jeunes adultes. Le MDA semble augmenter l'incidence de la maladie en augmentant la colonisation bactérienne au point d'entrée. L'objectif de ce travail a été de comprendre le mécanisme moléculaire précis de l'infection de Nm par le MDA. L'étude des mutants des gènes impliqués dans la machinerie des pili de type IV (PT4) a montré que l'entrée du phage nécessite un PT4 rétractable. Ce résultat est cohérent avec la littérature sur les phages Ff ou CTX qui interagissent directement avec l'extrémité du pilus. Mais aucune preuve de l'interaction du MDA avec l'extrémité du pilus n'a été trouvée. L'interaction possible entre la fibre du pilus et la capside du phage a été examinée. Comme PilE, la piline majeure, est sujette à variation antigénique, des variants de PilE qui diminuent l'entrée du phage ont été identifiés. L'infection par le phage se produit dans des populations de bactéries exprimant des séquences de PilE spécifiques. Par imagerie, nous avons montré que les pili et les MDA s'associaient ensemble. Une analyse de la charge des acides aminés de PilE et celle de la capside soutient l'hypothèse d'une interaction variable selon le variant de PilE. Finalement, il a été montré que les P4T avec un potentiel électrostatique positif favorisaient l'infection par le phage et permettaient, de plus, une forte adhésion des Nm aux cellules humaines. L'inverse est observé pour les P4T chargés négativement. Ce travail présente également les premières caractérisations de la machinerie de sécrétion du phage. Des études préliminaires avaient montré que dans un biofilm formé sur cellules épithéliales, Nm produisaient soit des pili, soit des phages, mais pas les deux en même temps. Nous avons montré que la sécrétion du phage nécessitait PilQ, PilW et TsaP de la machinerie des P4T. Les analyses bio-informatiques suggèrent que l'ORF8 du phage, qui aurait une activité ATPase, s'associerait avec l'ORF11 pour former un complexe qui interagirait avec la sécrétine bactérienne PilQ. Ce modèle est soutenu par des tests d'interaction par double-hybride. Cette interaction mobiliserait les PilQ de la bactérie, les rendant inaccessible à la machinerie de piliation. La surexpression d'ORF8 entraine une inhibition de la piliation. Ces données permettent d'établir un nouveau modèle d'interaction entre les phages filamenteux et les P4T, ce qui pourrait participer à la sélection des souches pathogènes de NmNeisseria meningitidis (Nm) is a commensal bacterium of the human nasopharynx that sometimes crosses the nasopharyngeal barrier and spreads through the bloodstream to reach the meninges. A filamentous bacteriophage called MDA (Meningococcal Disease Associated) is associated with invasive meningococcal disease in young adults. MDA appears to increase the incidence of the disease by increasing bacterial colonization at the point of entry. The aim of this work was to understand the precise molecular mechanism of infection of Nm by MDA. The study of mutants of genes involved in the type IV pili (T4P) machinery showed that phage entry requires a retractable T4P. This result is consistent with the literature on Ff or CTX phages, which interact directly with the pilus tip. However, no evidence was found for MDA interacting with the T4P tip. The possible interaction between the pilus fiber and the phage capsid was investigated. Since PilE, the major pilin, is subject to antigenic variation, variants of PilE that reduce phage entry were identified. Phage infection occurs in populations of bacteria that express specific PilE sequences. Using imaging, we showed that pili and MDA associate with each other. An analysis of the amino acid charge of the pilin and that of the capsid supports the hypothesis of a variable interaction depending on the PilE variant. Finally, it was shown that T4P with a positive electrostatic potential favored phage infection and allowed the bacteria to adhere strongly to human cells. The opposite is observed for negatively charged T4P. This work also presents the first characterizations of the phage secretion machinery. Previous studies had shown that in a biofilm formed on epithelial cells, Nm produce either pili or phages, but not both at the same time. We showed that phage secretion requires PilQ, PilW and TsaP of the pili machinery. Bioinformatic analyses suggest that phage ORF8, which has ATPase activity, associates with ORF11 to form a complex that interacts with the bacterial secretin PilQ. This model is supported by two-hybrid interaction assays. This interaction would mobilize the bacterial PilQ, making them inaccessible to the piliation machinery. Overexpression of ORF8 inhibits piliation. These data provide a new model for the interaction between filamentous phages and T4P, which could be involved in the selection of pathogenic strains of Nm
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Kolb, Johann. "Calibration and test tools for MCAO system : application to the ESO demonstrator MAD". Paris 6, 2005. http://www.theses.fr/2005PA066599.
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Gimeno, Pascal. "Caractérisation d'échantillons de 3,4-méthylènedioxyméthamphétamine (MDMA) par analyse en chromatographie gazeuse - spectrométrie de masse des impuretés de synthèse". Lyon 1, 2003. http://www.theses.fr/2003LYO1T002.
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La 4e de couverture indique : "Ce travail présente une méthode d'analyse qualitative et semi-quantitative des impuretés de synthèse de la 3,4-méthylènedioxyméthamphétamine (MDMA) par chromatographie gazeuse couplée à la spectrométrie de masse (GC/MS). L'identification des impuretés trouvées dans des échantillons de saisie a été réalisée par ionisation en impact électronique (Ei) suivie d'une détection en mode full scan. La majorité des impuretés d'intérêt a ensuite été confirmée par une analyse en ionisation chimique positive (CI+) suivi d'une fragmentation MS-MS de l'ion moléculaire obtenu. Des études ont été réalisées afin d'optimiser cette méthode par détermination des différents paramètres d'influence sur l'extraction (pH, solvants, concentration des extraits,. . . ). De plus, afin de vérifier les voies de synthèse susceptibles d'être utilisées par les laboratoires clandestins, différentes synthèses organiques de MDMA ont été réalisées. Les impuretés trouvées dans les précurseurs (safrole, isosafrole,. . . ), intermédiaires (MDP2P, b-nitroisosafrole,. . . ) et le produit final (MDMA) sont présentées, en prêtant une attention toute particulière à leur origine chimique. Enfin, des résultats de comparaison d'échantillons de saisie, à partir de leur profil d'impuretés dans un objectif de rapprochement (profiling) sont également donnés. "
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Wilburn, Kaylee Marie. "Isolation and Characterization of Broad Host Range Phage that infect P. aeruginosa Pathogens". Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1594224687661359.
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Sidi-Boumedine, Réda. "Etude des systèmes gaz acide - Alcanolamine - Eau : Mesures couplées de composition de la phase liquide et de solubilité". Paris, ENMP, 2003. http://www.theses.fr/2003ENMP1144.
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L'absorption des gaz acides (CO2, H2S) par des solutions aqueuses d'alcanolamines est un procédé couramment employé au sein de l'industrie du traitement des gaz. Le dimensionnement et l'optimisation de ce type de procédé nécessitent l'utilisation d'un outil thermodynamique permettant une représentation réaliste des équilibres liquide-vapeur de ces systèmes d'électrolytes. Néanmoins, les données de solubilité sur lesquelles sont ajustés les paramètres des modèles sont le plus souvent incohérentes. De plus, malgré leur importance pour la modélisation, il n'existe de données expérimentales de composition de la phase liquide. Nous avons donc conçu un dispositif expérimental basé sur la spectroscopie infrarouge (IR) permettant la mesure couplée de la solubilité du CO2 et de la teneur en CO2 moléculaire et en carbamate dans la phase liquide des systèmes CO2 / Alcanolamine / H2O. Cinq solutions de DEA, de MDEA et d'un mélange de ces deux amines ont été considérées. Afin d'obtenir une base de données fiable, complète et cohérente, nous avons entrepris des mesures complémentaires de solubilité du CO2 et du H2S dans les mêmes solutions aqueuses d'alcanolamines. Finalement, la base de données comprenant les nouvelles données de solubilité et de composition de la phase liquide se caractérise par des pressions partielles de gaz allant de 0,1 à 4600 kPa et des températures variant de 298,15 à 373,15 K. Elle a par la suite été régressée pour l'ajustement des paramètres du modèle EOS-électrolyte basé sur une équation d'état développée au laboratoire. Cette modélisation a pour particularité de tenir compte, pour la première fois, de la composition de la phase liquideThe absorption of the acid gases (CO2, H2S) by aqueous solutions of alkanolamines is a well-known gas sweetening process. The design and the optimization of this process require the use of a thermodynamic tool permitting a realistic representation of the vapor-liquid equilibrium of these electrolytes systems. Nevertheless, the solubility data used for the determination of models' parameters are, the most often, incoherent. Moreover, experimental data of speciation do not exist, although they are important for the modelling. We conceived an experimental device based on the infrared spectroscopy (IR) permitting the measurement of both CO2 solubility and molecular CO2 and carbamate speciation in the liquid phase of the CO2 / Alkanolamine / H2O systems. Five solutions of DEA, MDEA and a mixture of these two amines have been considered. In order to get a reliable, complete and coherent database, we undertook complementary measurements of the CO2 and H2S solubility in the same aqueous solutions of alkanolamines. Finally, the database obtained during this work, contains the new solubility and speciation data, and is characterized by gas partial pressures going from 0. 1 to 4600 kPa and temperatures varying from 298. 15 to 373. 15 K. This database has been regressed for the determination of the EOS-Electrolyte model parameters based on an equation of state developed in the laboratory. The originality of this modelling is to be the first one which considers speciation data
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Wang, Jiong. "Analytical studies on the force-induced phase transitions in slender shape memory alloy cylinders layers /". access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ma-b23750546f.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves [214]-224)
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Jacq, Sylvie. "Décodage itératif des codes produits : "turbo-codes en blocs", et évaluations de leurs performances pour des modulations MDP et MAQ sur canal de Gauss et de Rayleigh". Limoges, 1996. http://www.theses.fr/1996LIMO0056.
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Rosa, Wesley de Oliveira. "Síntese e caracterização de géis para cromatografia de exclusão por tamanho via reticulação de Acetato de Celulose com 4,4' - Difenilmetano Diisocianato (MDI)". Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8327.
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The need to obtain biomaterials in order to reduce environmental impacts has been the focus of research groups in recent years, and cellulose, a dominant component at most forms of plants is a promising resource because of its abundance. In order to improve the ability processing, the chemical modification of cellulose has been widely studied. Among the most important reactions of cellulose are: etherification, esterification, acetylation and oxidation; being cellulose acetate, viscose, nitrocellulose and cellulose ethers, the main cellulose derivatives. The chemical modification with isocyanates presents some unique properties, such as absence of by-products and chemical stability of the urethane group. In this work we were synthesized gels obtained by modified cellulose acetate (CA) with a degree of substitution (DS) 2,5 by crosslinking, with 4,4' - Diphenylmethane diisocyanate (MDI) in stoichiometry of 1:1, in homogeneous by varying the humidity and the homogenization time. For characterization were used the following techniques and tests: vibrational infrared absorption spectroscopy (Fourier Transform Spectrometer - FTIR), size exclusion Chromatography (SEC), molecular absorption spectrophotometry UV-VIS, density determining of the gels by pycnometry, determination of the coefficient swelling, determination of cross-links by Flory-Rehner theory, thermogravimetry (TG) and scanning electron microscopy (SEM). Crosslink density results showed that the gel synthesized in the absence of moisture suffered greater crosslinking with an average number of repeat units between the crosslinking points of about 1000 times lower. The potential applications of these gels were tested, by using than as stationary phase in size exclusion chromatography, having been assessed its efficiency in the fractionation and separation of natural and synthetic polymers. Results showed the effectiveness of the gel as stationary phase on separation of polymers, opening up a range of opportunities, taking into consideration the simplicity of the process and lower costs attributed to it.
A necessidade de se obter biomateriais na tentativa de reduzir impactos ambientais tem sido o foco de grupos de pesquisa nos últimos anos e, a celulose, um componente dominante na maioria das formas de plantas, é um recurso promissor devido à sua abundância. A fim de melhorar a capacidade de processamento, a modificação química da celulose tem sido amplamente estudada. Dentre as reações mais importantes da celulose estão: eterificação, esterificação, acetilação e oxidação; sendo o acetato de celulose, viscose, nitrocelulose e éteres de celulose, os principais derivados da celulose. A modificação química com isocianatos apresenta algumas propriedades únicas, como ausência de produtos secundários e estabilidade química do grupo uretano. Nesse trabalho foram sintetizados géis obtidos por meio da modificação de Acetato de Celulose (AC) com grau de substituição (GS) 2,5 através da reticulação com 4,4' - Difenilmetano Diisocianato (MDI), na estequiometria 1:1, em meio homogêneo, variando a umidade e o tempo de homogenização. Para caracterização foram utilizadas as seguintes técnicas e ensaios: espectroscopia vibracional de absorção no infravermelho por Transformada de Fourier (FTIR), cromatografia de exclusão por tamanho (SEC), espectrofotometria de absorção molecular UV-VIS, determinação de densidade dos géis por picnometria, determinação do coeficiente de intumescimento, determinação de ligações cruzadas pela teoria de Flory-Rehner, termogravimetria (TG) e microscopia eletrônica de varredura (MEV). Resultados da densidade de ligações cruzadas mostraram que o gel sintetizado na ausência de umidade sofreu uma maior reticulação, com um número médio de unidades de repetição entre os pontos de reticulação cerca de 1000 vezes menor. As aplicações potenciais desses géis foram testadas como fase estacionária em cromatografia de exclusão por tamanho, tendo sido avaliada sua eficiência no fracionamento e separação de polímeros naturais e sintéticos. Resultados mostraram a eficácia do gel como fase estacionária na separação de polímeros, abrindo uma gama de oportunidades, levando-se em consideração a simplicidade do processo e os baixos custos a ele atribuídos.
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Koot, Dwayne Jonathan. "Strategic pre-clinical development of Riminophenazines as resistance circumventing anticancer agents". Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/24163.
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Cancer is responsible for upward of 13% of human deaths. Contemporary chemotherapy of disseminated cancer is often thwarted by dose limiting systemic toxicity and by multi-drug resistance (MDR). Riminophenazines are a novel class of potential anticancer agents that possess a potent multi-mechanistic antineoplastic action. Apart from their broad action against intrinsic, non-classical resistance, Riminophenazines inhibit the action of Pgp and hypothetically all ABC transporters demonstrating their great utility against classical MDR. Considering that combination chemotherapy is the norm, the vision directing R&D efforts was that Riminophenazines could be used with benefit within many standard chemotherapeutic regimes. The strategic intent of this project was to attain improved therapeutic benefit for patients through gains in both pharmaco dynamic and pharmacokinetic specificity for cancer cells over what is currently available. Tactically, this was driven through the use of synergistic Fixed-Ratio Drug Combinations (FRDC) encapsulated within tumour-targeting Nanoparticulate Drug Delivery Systems (NDDS). Long-term aims of this R&D project were to: 1) Screen FRDC of clofazimine (B663) and the lead derivative (B4125) with etoposide, paclitaxel and vinblastine for synergistic drug interactions in vitro. 2) Design, assemble and characterize a novel nanoparticulate, synergistic, anticancer co-formulation. 3) Evaluate the in vivo safety and efficacy of the developed product/s in accordance with international regulatory guidelines. Using the median effect and combination index equations, impressive in vitro synergistic drug interactions (CI<1) were shown for various FRDC of the three standard chemotherapeutics tested (etoposide, paclitaxel and vinblastine) in combination with either B663 or B4125 against MDR neoplastic cell cultures. Considering in vitro results and with the view to advance quickly to clinical studies, the already approved clofazimine (B663) was elected as the combination partner for paclitaxel (PTX). Considering the potency and wide action of PTX, a novel coformulation (designed to circumvent drug resistance) has the potential to greatly impact upon virtually all cancer types, particularly if selectively delivered through innovative delivery systems and loco-regional administration. A passively tumour targeting, micellular NDDS system called Riminocelles™ that encapsulates a synergistic FRDC of B663 and PTX has been designed, assembled using thin film hydration methods and characterized in terms of drug loading, particle size, zeta potential, CMC and drug retention under sink conditions. An acute toxicity and a GLP repeat dose toxicity study confirmed Riminocelles to be well tolerated and safe at clinically relevant dosages whilst Taxol® (QDx7) produced statistically significant (P<0.05) weight loss within 14 days. The same study demonstrated statistically significant (P<0.05) tumour growth delays superior to that of Taxol at an equivalent PTX dosage of 10 mg/kg. Importantly, all components (amphiphiles and drugs) used in assembly of Riminocelles are already individually approved for medicinal use - this promotes accelerated development towards advanced clinical trials and successful registration. Although these results are very promising (outperforming Taxol), this system was however found in a pharmacokinetic study to suffer from in vivo thermodynamic instability due to the high concentration (abundance) of albumin present in plasma. For this reason, in vivo longevity within circulation, permitting passive tumour accumulation was not fully realized. A second NDDS called the RiminoPLUS™ imaging system was additionally developed. This lipopolymeric nanoemulsion system has successfully entrapped Lipiodol® Ultra fluid (an oil based contrast agent) within the hydrophobic core of a monodisperse particle population with a size of roughly 100 nm and a stability of one week. This formulation is therefore thought capable of CT imaging of tumour tissue and drug targeting after either intravenous or loco-regional injection. In vivo proof of the imaging concept is warranted. The results of this study serve to highlight the great potential of in vitro optimized synergistic FRDC against drug resistant cancers. Lipopolymeric micelles are an effective way to formulate multiple hydrophobic drugs for intravenous administration and present a means by which cancer can be readily targeted; provided that the delivery system possess the prerequisite in vivo stability and surface attributes. Further experiments exploring synergistic drug and biological combinations as well as “intelligent” NDDS actively guided through specific molecular recognition are called for.Thesis (PhD)--University of Pretoria, 2012.
Pharmacology
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Ulbricht, David, Jan Pippel, Stephan Schultz, René Meier, Norbert Sträter e John T. Heiker. "A unique serpin P1′ glutamate and a conserved β-sheet C arginine are key residues for activity, protease recognition and stability of serpinA12 (vaspin)". Portland Press, 2015. https://ul.qucosa.de/id/qucosa%3A33439.
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SerpinA12 (vaspin) is thought to be mainly expressed in adipose tissue and has multiple beneficial effects on metabolic, inflammatory and atherogenic processes related to obesity. KLK7 (kallikrein 7) is the only known protease target of vaspin to date and is inhibited with a moderate inhibition rate. In the crystal structure, the cleavage site (P1-P1′) of the vaspin reactive centre loop is fairly rigid compared with the flexible residues before P2, possibly supported by an ionic interaction of P1′ glutamate (Glu379) with an arginine residue (Arg302) of the β-sheet C. A P1′ glutamate seems highly unusual and unfavourable for the protease KLK7. We characterized vaspin mutants to investigate the roles of these two residues in protease inhibition and recognition by vaspin. Reactive centre loop mutations changing the P1′ residue or altering the reactive centre loop conformation significantly increased inhibition parameters, whereas removal of the positive charge within β-sheet C impeded the serpin–protease interaction. Arg302 is a crucial contact to enable vaspin recognition by KLK7 and it supports moderate inhibition of the serpin despite the presence of the detrimental P1′ Glu379, which clearly represents a major limiting factor for vaspin-inhibitory activity. We also show that the vaspin-inhibition rate for KLK7 can be modestly increased by heparin and demonstrate that vaspin is a heparin-binding serpin. Noteworthily, we observed vaspin as a remarkably thermostable serpin and found that Glu379 and Arg302 influence heat-induced polymerization. These structural and functional results reveal the mechanistic basis of how reactive centre loop sequence and exosite interaction in vaspin enable KLK7 recognition and regulate protease inhibition as well as stability of this adipose tissue-derived serpin.
Livros sobre o assunto "MDA phage"
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Bilanin, Jeanne E. A staffing levels study for the Maryland Aviation Administration (MAA), phase II. College Park, Md: Institute for Governmental Service, University of Maryland System, 1991.
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Gardner, Brian M. A staffing levels study for the Maryland Aviation Administration (MAA), phase III. College Park, Md. (Suite 2101, Woods Hall, College Park 20742-7421): Institute for Governmental Service, University of Maryland System, 1991.
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Authority, Massachusetts Water Resources, ed. MDC-MWRA long range water supply study and environmental impact report-2020: Phase II report. [Boston]: Massachusetts Water Resources Authority, 1990.
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DeLeonardis, Lisa. A phase II archaeological investigation of the cultural resources associated with the Carroll-Caton House courtyard, 18BC6, Baltimore, Maryland: Report. Baltmore, Md. (802 E. Lombard St., Baltimore): The Center, 1995.
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Padma-ye-śes, Dbal-śul. Gnas chen Phag-mo-ri'i ngo sprod mdor bsdus: Dag snang 'o mtsho 'phel ba'i zla zer. Zhang-kang: Zhang-kang gyi ling dpe skrun khang, 2007.
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Bonito, Arthur J., Nancy D. Berkman e May Kuo. Analysis of Medicare beneficiary knowledge data using the Medicare Current Beneficiary Survey (MCBS): Phase 3.2 : final report. Research Triangle Park, N.C: RTI International, Health, Social, and Economics Research, 2003.
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Berkman, Nancy D. Analysis of Medicare beneficiary knowledge data using the Medicare Current Beneficiary Survey (MCBS): Phase 3.1 : final report. Research Triangle Park, N.C: RTI, 2002.
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Anderson, Wayne L. Analysis of the 1998 Medicare Current Beneficiary Survey for use in monitoring the National Medicare Education Program: Phase two report. Research Triangle Park, NC: Research Triangle Institute, 2000.
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Padma-tshe-dbaṅ-rgyal-po, Bstan-gñis-gliṅ-pa. Rdo rje phag moʼi zab khrid kyi skor: A collection of revelations focussing upon the practice of Vajravārāhī in mystical union with Hayagrīva. Thimphu, Bhutan: National Library of Bhutan, 1985.
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United States. Congress. Senate. Committee on Labor and Human Resources. Chlorofluorocarbon propellants in the atmosphere, inhalers, and regulation: Hearing before the Committee on Labor and Human Resources, United States Senate, One Hundred Fifth Congress, second session, on examining the federal role in the implementation of Title VI of the Clean Air Act as it relates to the use of chlorofluorocarbons (CFC) in metered-dose inhalers (MDI), and an advance notice of proposed rulemaking to phase out essential-use exemptions for CFC-based MDI's, April 2, 1998. Washington: U.S. G.P.O., 1998.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "MDA phage"
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Onida, Francesco, e Yves Chalandon. "Myelodysplastic/Myeloproliferative Neoplasms". In The EBMT Handbook, 685–94. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-44080-9_76.
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AbstractThe myelodysplastic syndrome-myeloproliferative neoplasms (MDS/MPNs) are a heterogeneous group of hematologic malignancies characterized by dysplastic and myeloproliferative clinical, laboratory, and morphological overlapping features, both in marrow and in blood. MDS/MPNs include chronic myelomonocytic leukemia (CMML), MDS/MPN with neutrophilia, MDS/MPN with SF3B1 mutation (in its absence with ringed sideroblasts) and thrombocytosis (MDS/MPN-SF3B1-T), and MDS/MPN not otherwise specified (MDS/MPN-NOS). Prognosis of MDS/MPN is highly variable, being dismal in the majority of patients with CMML, MDS/MPN with neutrophilia and MDS/MPN-NOS. In the absence of disease-modifying treatment options, allo-HCT represents the only curative option for eligible patients. With regard to allo-HCT indication in CMML patient, a number of prognostic systems have been developed over the years. As far as pre-transplant phase, in high-risk patients with MDS/MPN and low blast count (<10%), upfront transplantation is the most frequently preferred strategy. In patients with high blast count, pre-transplant treatment with HMAs, or combination of HMAs with other new agents in clinical trials may be considered. In case of rising leukocytosis and/or organ infiltration, hydroxyurea is the drug of choice. In MDS/MPN patients, the choice of conditioning regimen depends on many different conditions, the major ones being comorbidities, patient age, disease phase at transplant, type of donor, and HSC source. In general, myeloablative regimens may be advisable in young patients without comorbidities aiming to reduce the relapse risk, while reduced-intensity regimens are preferred for patients with older age or comorbidities. As disease recurrence represents the major cause of transplant failure in MDS/MPN, there is a growing interest toward possible post-transplant treatment strategies, both as preemptive and as prophylactic modalities.
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Pinto, Mónica, Lidia Fuentes, Luis Fernández e Juan A. Valenzuela. "Using AOSD and MDD to Enhance the Architectural Design Phase". In Lecture Notes in Computer Science, 360–69. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-05290-3_48.
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Rosenberger, W. F., L. M. Haines e I. Perevozskaya. "Constrained Bayesian Optimal Designs for Phase I Clinical Trials: Continuous Dose Space". In mODa 6 — Advances in Model-Oriented Design and Analysis, 225–33. Heidelberg: Physica-Verlag HD, 2001. http://dx.doi.org/10.1007/978-3-642-57576-1_25.
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Zhou, Zongwei, Yibo Xue, Junda Liu, Wei Zhang e Jun Li. "MDH: A High Speed Multi-phase Dynamic Hash String Matching Algorithm for Large-Scale Pattern Set". In Information and Communications Security, 201–15. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-77048-0_16.
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Hoffmann, Stefan R. K., Christine A. Deillon e Bernd Gutte. "Solid Phase Synthesis of Seleno-Methionine Peptides by tBoc/Bzl and Fmoc/tBu Protection Strategy Suitable for the Crystallographic Phase Determination by Multi-Wavelength Anomalous Diffraction (MAD)". In Peptides: The Wave of the Future, 166–67. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0464-0_74.
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Passie, Torsten. "Rise of a Recreational Drug". In The History of MDMA, editado por Andrew Dennis, 27—C3N127. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198867364.003.0004.
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Abstract This chapter provides an overview of the early, rather unknown, phase of MDMA as a recreational drug. MDMA was first detected by scientists in a forensic laboratory in 1970, and then a few more times up until 1976. A previously unknown document of the United States DEA has been used to describe these early detections. The evidence shows that up until 1976, the distribution of MDMA was rather limited and MDMA was initially produced as a ‘legal alternative for MDA’, which had been scheduled in 1970. Mention is made of a 1970 science fiction novel by the prominent writer Stanislav Lem, which seemed to describe the effects of MDMA, as well as of new documentation suggesting that the American drug chemist Alexander Shulgin had synthesized MDMA in 1975. A description of the American drug guru Timothy Leary’s first experiences with MDMA in 1978 is also given. There were two ‘hotspots’ for MDMA use during the 1970s: initially in the Midwest, and from 1976 onwards in Oregon and California.
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Elayoni Emmanuel, Igomu. "Challenges of Phage Therapy as a Strategic Tool for the Control of Salmonella Kentucky and Repertoire of Antibiotic Resistance Genes in Africa". In Bacteriophages in Therapeutics. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95329.
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Salmonella Kentucky ST198 (S. Kentucky ST198) is the most ubiquitous multidrug resistant (MDR) strain posing the greatest threat to public health, livestock and food industry in Africa. The reinvention of bacteriophage (Phage) as a non-antibiotic alternative only gives a glimmer of hope in the control of MDR strains of Salmonellae. S. Kentucky ST198 posses’ chromosomal and plasmid factors capable of been co-opted into phage mediated transduction and co-transduction of antibiotic resistance genes (ARGs) as well as cross-serovar transduction of ARGs. Phage DT104, DT120 and P-22 like prophages like PDT17 and ES18 together have been shown to be capable of transducing and co-transducing the classical ACSSuT resistance phenotype identified in most S. Kentucky ST198 strain on the continent. Also, the institution of fluoroquinolones and third generation cephalosporin for salmonellosis treatment in animals or human infected by S. Kentucky ST198 strain resistant to these drugs can induce Salmonella phage transduction of kanamycin between different Salmonella serovars if present. This review highlights possible risk associated with the use of known Salmonella phages in the control of S. Kentucky ST198 and the need for chromosomal and plasmid tracking of genes prior to the institution of phage therapy on the continent.
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Yan, Wei, Subhankar Mukhopadhyay, Kenneth Kin Wah To e Sharon Shui Yee Leung. "Potential of Inhaled Bacteriophage Therapy for Bacterial Lung Infection". In Bacteriophages [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96660.
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Phage therapy as a promising alternative antimicrobial to treat multidrug resistant (MDR) bacteria related lung infections, has drawn significant attention in clinical trials and bench-scale study in the recent decade, and the therapeutic effect of local delivery of phage has been demonstrated by several clinical reports. This book chapter discusses the current clinical development of inhaled phage therapy followed by the advancement of phage formulation designs for respiratory delivery of phage using various inhalation devices and their in vivo efficacy. The development of combination therapy of phage and antibiotics to combat MDR bacteria associated lung infections is also covered to reflect the current clinical practice. Lastly, we also share our insights on the challenges of advancing inhaled phage therapy and potential directions for future research.
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Kalra, Aakanksha, Sakshi Piplani e Ravi Ranjan Kumar Niraj. "Current Therapeutic Options and Challenges for MDR". In Current Developments in the Detection and Control of Multi Drug Resistance, 66–78. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815049879122010009.
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Multiple-Drug Resistance (MDR) against many antibiotics and other therapeutic agents is a major concern for health care providers and researchers in the field. Due to tremendous rise in MDR cases, researchers are in search of potent therapeutic options or alternatives to overcome MDR. Here, in this chapter, we will discuss the current status of the common as well as advanced methods which have been developed so far for the treatment of MDR and also the challenges and opportunities in each of those methods. This chapter discusses common methods used for the treatment of MDR, i.e., major antibiotics used for the treatment of MDR bacteria and synergistic approaches by the combination of different antibiotics. Along with common treatments used against MDR bacteria, this chapter also discusses current treatments like anti microbial peptides, anti-virulence compounds, phage therapy and drug repurposing approaches for MDR treatment.
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Doublie, S., e C. W. Carter. "Preparation of Selenomethionyl Protein Crystals". In Crystallization of Nucleic Acids and Proteins, 311–18. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780199632459.003.0014.
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Abstract For many years multiple isomorphous replaccement (MIR) has been the method of choice for phase determination. In most cases MIR is reliable, but occasionally it fails: heavy-atom binding may not occur, or if it does it may lead to loss of isomorphism. Use of Multiwavelength Anomalous Dispersion (MAD) has been introduced to circumvent these two problems (I, 2). On the one hand, the MAD method exploits the presence of anomalous scatterers, such as Cu or Fe in metalloproteins, or any of the heavy-metal derivatizing agents. On the other hand, all measurement relevant to determining a single phase can be made on the same crystal o isomorphism is exact, and electron density maps are of very high quality (3, 4). Thus, the MAD method will likely become a preferred method for phase determination.
Trabalhos de conferências sobre o assunto "MDA phage"
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Zdańkowski, Piotr, Maksymilian Chlipała, Mikołaj Rogalski e Maciej Trusiak. "Bedrosian theorem problem in quantitative phase imaging". In Digital Holography and Three-Dimensional Imaging, M3A.2. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/dh.2024.m3a.2.
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In this study we highlight the significance of the Bedrosian theorem, stating that strong sample-induced amplitude variations can impact the result of the phase demodulation, challenging the often-overlooked assumptions in phase reconstruction.
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Berguiga, Lotfi, Théo Girerd, Fabien Mandorlo, Cécile Jamois, Taha Benyattou e Lydie Ferrier. "Young’s interference hologram generated with a spatial light modulator for nanophotonic sensor". In Digital Holography and Three-Dimensional Imaging, M4A.5. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/dh.2024.m4a.5.
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A new method of phase interrogation of photonic sensors is proposed. The method relies on the Young’s interference experiment generated by holography with a DMD. Phase variations have been measured for photonic crystal temperature sensor.
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Silva, Alejandro, Miguel Arocena, Ariel Fernández e Julia R. Alonso. "Quantitative Phase Microscopy of hypoxic epithelial cells using the Transport of Intensity Equation". In Digital Holography and Three-Dimensional Imaging, M3A.3. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/dh.2024.m3a.3.
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Quantitative Phase Imaging of epithelial cells under different levels of hypoxia can be achieved by acquiring a multifocus stack with a 3D printed microscope and using the Transport of Intensity Equation. Experimental results are provided.
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Pandey, Dhruvam, Viren S. Ram e Rajshekhar Gannavarpu. "Neural network based subspace analysis for estimation of phase derivatives from noisy interferograms". In Digital Holography and Three-Dimensional Imaging, M2A.2. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/dh.2024.m2a.2.
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This article introduces a robust phase derivative estimation method using deep learning-assisted subspace analysis. Simulation results validate the performance of the proposed approach under severe noise conditions.
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Guadagnini, Jacopo, e Gabriele De Zaiacomo. "Multidisciplinary Design Optimisation for Missionisation of Re-entry Vehicles: Preliminary Mission Design and Mission Capabilities Evaluation of Winged Re-Entry Vehicles Case Study". In ESA 12th International Conference on Guidance Navigation and Control and 9th International Conference on Astrodynamics Tools and Techniques. ESA, 2023. http://dx.doi.org/10.5270/esa-gnc-icatt-2023-126.
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The work presented in this paper is part of the European H2020 ASCenSIon program. In this context, the overall purpose of this research is the definition and development of a Mission Analysis and GNC missionisation tool for autonomous re-entry vehicles. In recent years, space agencies and private firms are investing in reusable spacecraft and launch vehicles to make space access and in-orbit studies more economically and environmentally sustainable. The re-flight capability, requested by a reusable space system, motivates the need for a dedicated missionisation tool. The objective of missionisation is, indeed, the minimization of the tailoring effort during the mission design phase of each flight. One approach, which can address this aim, is to provide solutions for re-entry vehicles that are qualified for multiple missions. For this reason, a crucial step for missionisation is the computation of the set of missions that a vehicle can perform concerning its design parameters. The focus of this paper is on the preliminary mission design and the evaluation of the mission capabilities of a winged re-entry vehicle by means Multidisciplinary Design Optimization (MDO) approach available within the proposed MA and GNC missionisation tool. One of the key challenges in missionizing a re-entry vehicle is the need to balance the trade-offs between a broad set of system and mission requirements and constraints to obtain robust trajectories. The missionisation in this context is, indeed, a complex and challenging task that requires a thorough understanding of the multidisciplinary aspects of the system and mission design. For this reason, the paper reports the Multidisciplinary Design Analysis (MDA) framework with an overview of the set of disciplines embedded in the tool. For this scenario, the disciplines deal with weight, geometry, and aerodynamic estimation, evaluation of the static longitudinal equilibrium and stability, computation of the aerothermal-mechanical domain, and range capability. The disciplines numerically quantify the related performance and assess the feasible space domain concerning the design variables. Then, the MDA problem is exploited by the optimization routine to optimize the design variables while maximizing targeted performance. The MDO is a crucial feature because allows for the simultaneous optimization of multiple design parameters and objectives to ensure the overall performance and feasibility of the re-entry vehicle. By using this technique, the goal is to evaluate different design options to perform trade-off studies and identify the optimal design, especially when a multi-objectives approach is considered and nondominated optimal Pareto solutions are obtained. Within the MDO process, indeed, the solution space domain is explored through the variation of the design parameters. In this research, metamodeling techniques have been adopted to reduce the computational cost. One of the main challenges faced by MDO concerns, indeed, the efficiency in solving the optimization problem due to the relatively expensive evaluation of the MDA. In particular, in this work, the MDA has been integrated with the DEIMOS Space proprietary tool (EDLS/GNC Sizing and Analysis Too) ESAT, which employs Radial Basis Functions (RBFs) to create a surrogate model of the original problem. The metamodel is built by evaluating the MDA in different design points (samples). Consequently, the metamodel predicts the performance at any point of the domain space by interpolating the outputs of the known points. ESAT, then, uses the metamodel to perform the optimization and create performance maps. One of the drawbacks of adopting a surrogate model is given by the flaw in the accuracy of the solution, especially if a large number of design parameters is taken into account and a limited number of sample points is used. To validate the optimization process, the obtained results for the scenario analysed in this paper are compared with the outcomes achieved by solving the original problem with a Multi-Objective Particle Swarm Optimization (MOPSO) algorithm. The solutions are critically discussed both in terms of accuracy and computational time. The results obtained within the case study reported in this paper show that the proposed multidisciplinary tool embedding an MDO process is a powerful tool for enhancing the missionisation of re-entry vehicles. In particular, the MDA-MDO framework is essential for efficiently missionizing re-entry vehicles, providing a solution qualified for multiple missions. The MDO, indeed, handles the trade-offs between several solutions by considering a broad set of mission and system requirements, and it ensures that the final design is optimized across all relevant disciplines.
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Boda, Z., G. Pfliegler, I. Tornai, M. Udvardy, J. Hársfalvi e K. Rak. "LONG-TERM COUMAROL PLUS SMALL DOSE ASA THERAPY IN PATIENTS WITH PROSTHETIC HEART VALVE. SOME QUESTIONS OF LABORATORY CONTROL". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643268.
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Thromboembolism in patients with prosthetic heart valves remains a major time-related problem (Sullivan 1971, Dale 1976, Chesebro 1983). Patients receiving anticoagulant plus antiplatelet agent have the lowest incidence of thromboembolism but the risk of bleeding is not negligible. The laboratory control of combined therapy is unsolved.This study considers the thromboembolic prophylaxis of 38 patients with prosthetic heart valve. Cou-marol treatment was combined with ASA (1 000 mg/week, 36 months follow up).Prothrombin ratio was used in control of the oral anticoagulant therapy. Malondialdehyde production was measured parallel with the so-called malondialdehyde-ratio (MDA-ratio = malondialdehyde level of patient/ control plasma). MDA-ratio, platelet aggregation, thromboxane and prostacycline metabolites were studied 48 hours after 500 mg ASA intake. The average of MDA-ratio was 0.42 ± 0.23 (from 137 measurements). The therapeutic range of MDA-ratio is 0.7 - 0.2. Value below 0.2 means overdosed, over 0.7 means an ineffective ASA therapy. Normal first and second phase platelet aggregation was observed in 23 % of cases when MDA-ratio was below 0.5. Only in 4 % of patients with MDA-ratio over 0.7 was found an abnormal platelet aggregation. The mean prothrombin ratio was 1.59 ± 0.22.No gastrointestinal bleeding or thromboembolism was observed during the 36 months follow up. Contrary to the literary data (Chesebro 1983) coumarol plus small dose ASA did not result excessive bleeding and can be suggested for patients with prosthetic heart valve. Examination of both the prothrombin and the malondialdehyde ratio with study of platelet aggregation is recommended as laboratory control.
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De Maria, S., A. Liati e M. Monti. "Oxygen Removal in Water Injection: A Life-Cycle Cost Comparison Between Vacuum Degassing and Membrane Deaeration Technologies". In SPE Water Lifecycle Management Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/218995-ms.
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Abstract This paper aims at making an overall comparison based on life-cycle costs (LCC) between vacuum degassing and membrane deaeration, the two main technologies for removing oxygen from injection water in the energy upstream sector. Traditional degassing technology based on vacuum towers (VT), where oxygen is stripped from liquid water falling on random packing under vacuum conditions, has been compared with membrane deaeration (MDA), a potentially emerging technology in which oxygen moves from the liquid phase through a gas-permeable membrane toward an oxygen-depleted gas stream. The comparison was made based on real projects carried out using vacuum degassing on a wide range of capacities and equivalent membrane deaeration (MDA) configurations obtained by simulating the replacement of the towers and their ancillaries with membrane deaeration. The two deaeration systems were compared in terms of performance, costs/life-cycle costs assessment (LCC), and general characteristics at different operating capacities to identify under which conditions each technology may be preferable. While MDA is already widely applied in several industrial applications, it has still not found its way into the "injection water" market. The study helps identify the conditions under which MDA might be beneficial, in terms of life-cycle costs to the Upstream O&G sector.
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Abdellatif, Lasbahani, Mostafa Chhiba e Oussama Mjihil. "Deals with integrating of security specifications during software design phase using MDA approach". In ICC '17: Second International Conference on Internet of Things, Data and Cloud Computing. New York, NY, USA: ACM, 2017. http://dx.doi.org/10.1145/3018896.3065835.
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Yang, Hedong, e Clark C. Guest. "Binary phase-only filters with improved discrimination: maximized amplitude difference method". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.thq2.
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A new design method, the maximized amplitude difference (MAD) method, is developed to improve the discrimination of binary phase-only filters (BPOFs). In this approach, we construct an energy function that represents the weighted difference between the amplitude of the autocorrelation peak caused by the target signal and that of the cross-correlation peak caused by the nontarget signal. The weight determines the suppression level of the crosscorrelation peak. The best phases for each of the two peaks are determined through a fast deterministic search algorithm. A BPOF that minimizes the energy function is encoded by assigning each filter pixel according to the projections of the spectral components of the target and the nontarget signals onto the phasors representing the two peaks. For the examples used in the numerical studies, a 7.0 dB increase of the ratio of the autocorrelation peak intensity to the cross-correlation peak intensity has been achieved. For a given suppression level of the cross-correlation peak, the MAD method also maximizes the intensity difference between the two peaks. The MAD method is also compared with the simulated annealing method through numerical studies. The two methods generate almost identical filters, but the MAD method is much faster.
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Tarbell, T. D., D. S. Acton e Z. A. Frank. "Phase Diversity Wavefront Sensing and Image Reconstruction on the MDI instrument at L1". In Adaptive Optics. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/adop.1996.awd.4.
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The Michelson Doppler Imager (MDI) is a spectral imaging experiment on the ESA-NASA Solar and Heliospheric Observatory spacecraft (SOHO-see Domingo et al., 1995). SOHO was launched in December, 1995, and reached its final orbit about the Earth-Sun Lagrangian point L1 in mid-February, 1996. This point, about 1.5×l06 km towards the Sun, is where the Earth’s and Sun’s gravity balance, allowing a nearly stable orbit ideal for continuous observations of the Sun and solar wind. MDI is collecting the observational data for the Solar Oscillations Investigation (SOI), a study of the interior structure of the Sun as inferred from the normal modes of oscillation seen on its surface (“heliosesmology”). Since launch, MDI has been collecting images showing the Doppler velocity, continuum intensity, and magnetic field on the solar surface with high spatial and temporal resolution. SOI/MDI were developed jointly by Stanford University and Lockheed Martin Advanced Technology Center, supported by NASA (see Scherrer et al., 1995). The Principal Investigator is Prof. P. Scherrer of Stanford.
Relatórios de organizações sobre o assunto "MDA phage"
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Vaucher, Gail, Jeffrey Swanson, John Raby, Theresa Foley, Sandra Harrison, Robert Brice, Sean D'Arcy e Edward Creegan. Meteorological Sensor Array (MSA) - Phase I Volume 1 (Proof of Concept" Overview)". Fort Belvoir, VA: Defense Technical Information Center, setembro de 2014. http://dx.doi.org/10.21236/ada608929.
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Vaucher, Gail, e Robert Edmonds. Meteorological Sensor Array (MSA)-Phase I. Volume 3 (Pre-Field Campaign Sensor Calibration). Fort Belvoir, VA: Defense Technical Information Center, julho de 2015. http://dx.doi.org/10.21236/ada622325.
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Dinovitzer, Aaron. PR-214-153739-WEB ERW Fatigue Life Integrity Management Improvement - Phase III. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), agosto de 2019. http://dx.doi.org/10.55274/r0011614.
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Tuesday, September 17, 2019 11:00 a.m ET PRESENTER: Aaron Dinovitzer, MA Sc., MBA, PEng, BMT Canada HOST: Mark Piazza, Colonial Pipeline Company MODERATOR: John Lynk, PRCI CLICK THE BUY/DOWNLOAD BUTTON TO ACCESS THE WEBINAR REGISTRATION LINK Join the PRCI Integrity and Inspection Technical Committee as they present research results that set out to evaluate the level of conservatism inherent to current state-of-practice procedures using full-scale fatigue testing. Learning outcomes/benefits of attending: - Understand the sources of conservatism, and how to improve the accuracy of, fatigue life estimation techniques for ERW or EFW pipes containing manufacturing process induced crack-like features. - Learn about an improved estimation method of remaining pipe fatigue life estimates that better agree with actual operational experience. This can reduce conservatism in engineering fatigue life estimates over currently used techniques. - Since fatigue life estimates are used to identify inspection intervals and assessing the life of features in a pipeline system, reducing unnecessary conservatism will avoid the cost of unnecessary inspections, pressure tests and repairs before fatigue life is expended. Who should attend? - Pipeline integrity and risk personnel, engineers and management Recommended pre-reading: PR-214-153739-R01 ERW Fatigue Life Integrity Management Improvement - Phase III Register anyway to automatically receive a link to the webinar recording to view on-demand at your convenience. After registering, you will receive a confirmation email containing information about joining the webinar.
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Miller. L51699 Diverless Pipeline Repair Clamp Phase III. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), agosto de 1993. http://dx.doi.org/10.55274/r0010218.
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Offshore oil and gas developments are underway for water depths beyond which divers can function. The economic lifelines of these projects are the pipelines which will transport the products to shore. In preparation for the day when one of these pipelines will require repair because of a leak, the Pipeline Research Committee of Pipeline Research Council International, Inc. is funding research directed at developing diverless pipeline repair capabilities. This Report summarizes the results of the third and final phase of this project. Phase III work included design, manufacture, and dry testing of 1) a one-half scale model of a 12"� repair clamp, 2) a full-scale bolt test fixture to demonstrate boltcontainment and startup under realistic misalignment of the clamp halves, and 3) a full-scale one-way cylinder for end seal activation. Engineering drawings for a 12" - 900# (324 mm, 15.3 mPa) diverless repair clamp package were also produced, and are provided with this report in Appendix B. Phase III also included a study commissioned from Oceaneering directed at defining the interfaces of the clamp package and the ROV, including suggested procedures for deployment and positioning of the clamp package on the pipeline. Issues regarding bolt make-up by the ROV were also studied in detail and limitations in bolting capability were outlined.
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McNealy. L52295 Fundamentals and Performance Improvements of ILI Technologies for Mechanical Damage Inspection. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), maio de 2008. http://dx.doi.org/10.55274/r0010677.
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The objective of this effort is to assist the pipeline industry in selecting ILI technologies that are best suited for detecting and sizing the types of mechanical damage that may pose integrity concerns, and/or are required to be addressed by the existing Regulatory Rules. The practical need is driven by both the recent changes in Regulatory requirements, vis-à-vis mechanical damage, and the latest developments of ILI technologies aiming to detect and size such damage. Based on the information provided by the six participating ILI vendors, and taking fulladvantage of extensive previous work, this report presents the results of Phase I of the Project, including updated capabilities and deficiencies of the current MD ILI technologies, performance claims, and supporting validation data. In addition, this Phase 1 report details the fundamental approaches embodied within each technology then analyzes validation data and derives performance conclusions from available data. Finally, this report identifies further testing to be conducted within Phase II of the Project.
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Jinawath, Supatra. Fabrication of porous calcium phosphates. Chulalongkorn University, 2002. https://doi.org/10.58837/chula.res.2002.29.
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The starting materials for this experiment were monocalcium phosphate monohydrate, dicalcium phosphate dihydrate and anhydrous dicalcium phosphate synthesized in-house from the by-product of a local bone-gelatin manufacture. Porous calcium phosphates comprising hydroxyapatite either as a single phase or a composite containing traces of its congeners. i.e., β-TCP were fabricated in the forms of granules and compacts. The characteristics of typical compacts produced were 37 v % apparent porosity with interconnected pores of diameter 1-30 µm, and flexural and compressive strengths of 17.51 and 78.13 MPa, respectively. Effects of fabrication parameters on the properties of the products were also studied. In addition, coralline hydroxyapatite-converted coral with preservation of its 200-µm-pore architecture, was also successfully produced. Keywords: Coralline hydroxyapatite, hydrothermal synthesis, porous calcium phosphates.
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Gurung, Bijan, J. Hutchinson, Brian Peterson, J. Beeco, Sharolyn Anderson, Damon Joyce, Bijan Gurung et al. Exploring spatial patterns of overflights at Olympic National Park. National Park Service, 2024. http://dx.doi.org/10.36967/2304991.
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This study explored spatial patterns of overflights at Olympic National Park (OLYM). Overflights were analyzed from July 27th, 2021 to January 2nd, 2023 using Automatic Dependent Surveillance-Broadcast (ADS-B) data with a total of 525 days of data. Data were collected using data loggers that were deployed at Blyn (located outside of OLYM), Hurricane Ridge, and Hoh Rain Forest. The first phase of analysis focused on all overflights and found a high concentration of overflights above the northeastern portion of OLYM, and definitive flight corridors were identified across the park. The second phase of analysis focused on low-level overflights that fly below 10,500 ft mean sea level (MSL) and fly within 10 miles of the OLYM boundary. Phase 2 figures display four figures based on seasons and show a concentration of flights between 6,001?10,500 ft MSL except in and around the Port Angeles area where there is a concentration of flights in the 0?6,000 ft MSL altitudinal range. The third phase of analysis selected all low-level overflights below 2,500 ft above ground level (AGL) and within 0.5-mile of the OLYM boundary. Kernel density analysis was conducted using waypoints segmented into 500 ft above ground level (AGL) altitude intervals from 0?2,500 ft AGL. The altitude interval with the highest density of overflights was ?0?500 ft AGL?. Kernel density hot spots were observed along the flight corridor and over Port Angeles. Also, overflights flown by known air tour operators and park administration were shown. Overflight patterns of air tour operators mostly follow the recommended air tour route. Lastly, overflights intersecting with Olympic Military Operations Area (MOA) were identified and mapped. This information can be used for planning and management purposes and this study serves as a resource for future research that intends to use more advanced analytics.
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Author, Unknown. PR-328-6352-R01 LaserScan Mapping and Reporting of Plain Dents in Support of PRCI - Phase 2. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), setembro de 2007. http://dx.doi.org/10.55274/r0012169.
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As part of the PRCI sponsored project (MD 1-2), ten defects were introduced on a three-meter section of a 30-inch pipe. Detailed mapping of all the defects was performed using a 3D LaserScan system by Applus RTD. The objective of the scan was to get a detailed, high resolution, high density, three-dimensional representation of the defects and to provide some critical metrics about the defects.
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Tangpasuthadol, Varawut, e Amarawan Intasiri. Silica reinforement of natural rubber by sol-gel process in latex. Chulalongkorn University, 2005. https://doi.org/10.58837/chula.res.2005.32.
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Beside carbon black, silica powder is the other important filler used to reinforce various colored rubber products. In order to improve the compatibility between silica particles and rubber phase, this work has focused on preparing an NR composite, reinforced by silica generated inside the NR matrix or ‘in situ’. The silica particle was formed by a sol-gel process of tetraethoxysilane (TEOS) dispersed in NR latex. The latex used was concentrated latex having 60% rubber content, and already contained water and ammonia, two ingredients needed for the sol-gel reaction. The conversion of TEOS to silica was close to 100% and the particles size was about 44 nm in diameter, determined by TEM. The silica particles scattered evenly in the rubber. A statistical analysis method, named ‘two-level factorial design’, was used to study the influence of the amount of TEOS, ammonia, and gelation time on the mechanical properties of the composite. Silica content as high as 19% was prepared successfully. The composite had a tensile modulus of 3.7 MPa and a tear strength value of 41 N/nm. It was also found that the composite containing in situ silica had a higher tensile modulus and tear strength than a composite that was prepared by conventionally mixing with silica power.
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Botros, Geerligs e Given. L52187 Decompression Response of High-Pressure Natural Gas Pipelines Under Rupture or Blowdown Conditions. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), agosto de 2004. http://dx.doi.org/10.55274/r0010394.
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The Pipeline Research Council International, Inc. found that Scandpower has software that is capable of predicting the transient response of a pipeline segment transporting either conventional or enriched dense phase natural gas mixtures when subjected to a controlled blow down or an uncontrolled rupture event. Consequently PRCI expressed a desire to pursue an experimental work to provide the basis for evaluating the adequacy of the existing software and/or define further development if any. NOVA Research and Technology Corporation (NRTC) was awarded a contract to perform the experimental work and compare results with prediction by the OLGA 2000 software. The existing NPS 2 stainless steel decompression tube test rig at TCPL Gas Dynamic Test Facility (GDTF) in Didsbury, Alberta, Canada, has been expanded specifically for this project. The initial length of 30 meters was extended to 172 meters in order to simulate a longer length to diameter (L/D) ratio. Two sets of tests were conducted: one to simulate pipeline rupture and another to simulate controlled blowdown. Rupture was simulated by a rupture disc located at one end of the tube, while blowdown was affected by a typical blowdown stack and a reduce-bore ball valve. The test scope included three gas mixtures (conventional, medium rich and rich) and three initial pressures: 10, 14 and 20 MPa.