11,858 research outputs found
Poesías de Andrés Bello
No full textLa h. de grab. calc.: "B. Maura d" y g" 1881", retrato de Andrés Bello ; centenario de su nacimientoA f. de grav. calc.:"B. Maura d. y g. 1881", retrato do auto
Efficient Lewis Acid Systems for the A3 Coupling reaction
No full textEfficient Lewis Acid Systems for the A3 Coupling reaction
Cimarelli C., a Navazio F.,a Rossi F. V.a, Del Bello F., Marcantoni E.a
aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected]
Propargylamines are an attractive class of molecules because of their particular molecular skeleton, that contains an amine group located in β-position to an alkyne moiety suitable for many chemical transformations. In recent years they received a growing interest as key intermediates for several biologically active compound, natural products and also different heterocycles.[1,2]
Our goal was the development of green and simple methodologies for the synthesis of secondary propargylamines by Lewis acid catalyzed or promoted A3 reaction among aldehydes, alkynes and primary amines, that are in general less applied in such reactions because of their lower reactivity. In particular, we studied two different pathway: the CuSO4/NaI system in one pot fashion and the CeCl3/CuI system in one pot/two steps way (Scheme 1).
Scheme 1. CeCl3·7H2O/CuI and CuSO4/NaI catalyzed A3 reaction.
Heptahydrated CeCl3 is reported to be an excellent catalyst for many useful organic transformation as the synthesis of imines. Its efficacy as Lewis acid is enhanced in the presence of inorganic iodides/iodide salt and being cooper the transition metal of choice for A3 reactions, CuI was used.[3]
Also the CuSO4/NaI couple has revealed to be an interesting Lewis acid system as an alternative to CeCl3/CuI system which allow the formation of CuI in situ by quantitative spontaneous reaction that takes place in few seconds.[4]
Typically CuSO4/NaI catalysed reactions are faster than CeCl3·7H2O/CuI reactions, but suffer of some disadvantages, such as lower yields, and a narrower applicability. Both reaction conditions have been applied to different aldehydes (aromatic and aliphatic) and to chiral starting materials, the amine in general has no effect on the reaction outcome.
The relevant Glaser coupling drawback observed in the CuSO4/NaI system conditions has been suppressed by adding some benzoic acid, and has not been observed with the CeCl3/CuI system.
References:
1) Lauder, K.; Toscani, A.; Scalacci, N.; Castagnolo, D. Chem. Rev. 2017, 117, 14091.
2) Peshkov, V. A.; Pereshivko, O. P.; Van der Eycken, E. V. Chem. Soc. Rev. 2012, 41, 3790.
3) G. Bartoli, E. Marcantoni, M. Marcolini, L. Sambri, Chem. Rev. 2010, 110, 6104.
4) Bailey, A. D.; Cherney, S. M.; Anzalone, P. W.; Anderson, E. D.; Ernat, J. J.; Mohan, R. S. Synlett 2006, 215
De bello Judaico. Llatí
No full textMs. il·luminatTítol obtingut de la rúbrica (f. 1r)Col·lació: Vitel·la, f. i (pergamí actual) 245 (f. 245 en blanc) + f. i (pergamí actual) ; foliació moderna a llapis ; reclams verticals cada deu fullsComposició: Escrit a línia tirada a 31 líniesEscriptura: Humanística antiquaDecoració: La decoració d'aquest còdex està formada per huit orles de tipus arquitectònic en or i colors amb miniatures, corresponents al pròleg i als set llibres que componen l'obra. En la primera i segona apareixen els escuts dels sobirans de Nàpols. En les caplletres miniades, la inicial està sostinguda per éssers mitològics com faunes, tritons, centaures, etc. En els títols alternen les línies en or, blau i granat. Títols dels fronstispicis i miniatures atribuïdes a Bartolomeo Sanvito (Ruysschaert)Enquadernació: Pell sobre fusta, amb unes palmetes en daurat com motiu ormamental, cants daurats. En el segle XVI estava enquadernat en vellut carmesíOrigen: Escrit a Roma, ca. 1475 (G. Toscano)Signatura anterior: Ms. 819Signatura actual: València, Universitat de València. Biblioteca Històrica, BH Ms. 836Catalogat des del manuscrit original. Lectura i identificació de textos pel Prof. Francisco M. Gimeno Blay; bibliografia, documentació i normalització per M. Cruz Cabeza Sánchez-Albornoz i Silvia Villaplana TraverEl còdex transcriu els set llibres de l'obra de Josep Flavi "De bello judaico" escrita en grec, encara que la primera redacció, perduda actualment, fou escrita en arameu. Narra la història del poble jueu des d'Herodes el Gran fins la destrucció de Jerusalem1. f.1r-3v: "[rúbr.] Flavii Iosephi prologus incipit De bello Iudaico. Quoniam bellum quod omnium maximum quæ nostra ... [text] faciam hoc ordine quo capitula sunt gesta"2. f. 4r-57r: "[rúbr.] Incipit liber primus Iosephi De bello Iudaico. [text] Cum potentes iudeorum inter se dissidere[n]t ... regis ipsius mandata sepultum est. Et hic q[uod] Herod[is] finis fuit. [rúbr.] Explicit l[ibe]r primus"3. f. 57r-103v: "[rúbr.] Iosephi incipit li[ber] II De bello Iudaico. [text] Turbarum novarum pri[n]cipium fuit Archelao Romam proficisce[n]di necessitas ... ; [f. 103r: text] collecto milite vicos presidiis tueretur et Idumee quide[m] res ita se habebant. ; [103v: rúbr.] Explicit l[ibe]r secundus"4. f. 103v-132r: "[rúbr.] Iosephi incipit tertius De bello Iudaico. [text] Per oniam [sic] autem urbi res apud Iudeam no[n] prosper[e] gestas accepit ... ; [f. 131v: text] Capti sunt autem VI iduum septembrum die. ; [f. 132r: rúbr.] Explicit lib[er] tertius"5. f. 132r-149v: "[rúbr.] Iosephi incipit lib[er] IIII De bello Iudaico. [text] Quicu[m]que aute[m] iudei iotapatis excisis a romanis defecerant ... virtute[m] tantu[m] licuisse vitiis flententem [sic]. [rúbr.] Explicit lib[er] quartus"6. f. 149v-167r: "[rúbr.] Iosephi incipit quintus De bello Iudaico. [text] Anano quide[m] et l[e]su huiusmodi finis venit ... ; [f. 166v: text] decreto ap[u]d se alias militum copias congregare. ; [167r: rúbr.] Explicit lib[er] quintus"7. f. 167r-198v: "[rúbr.] Iosephi incipit sextus De bello Iudaico. [text] Titus eo modo quo prediximus emensa ultra Egiptu[m] Syria usq[ue] solitudinem Cesaream venerat ... ; [f. 198r: text] Factum enim eos reddiderat certos [sic] quod iam et ipsis erat et civitati. ; [198v: rúbr.] Explicit lib[er] VI"8. f. 198v-244v: "[rúbr.] Iosephi incipit lib[er] VII De bello Iudaico. [text] Clades quide[m] Hierosolimorum in peius cotidie procedebant cum et seditiosi magis accenderentur adversis ... De veritate autem confidenter dicer[e] no[n] pigebit q[uo]d solu[m] per o[mn]ia que scripsi habuerunt coniecturam. Finis"Ex-libris Universitatis, p. 200-201, n. 40Llat
Práctica empresarial alcaldía de Bello Antioquia
No full textEl presente informe corresponde a la práctica empresarial profesional realizada en la empresa ALCALDÍA del MUNICIPIO DE BELLO ANTIOQUIA, como aspirante al título de ingeniero civil de la Universidad Cooperativa de Colombia, materializando en este documento todos los procesos y actividades establecidas por la empresa para el desarrollo del contrato como practicante.
ALCALDIA del MUNICIPIO DE BELLO. Es una organización publica, que contribuye al desarrollo urbano y social en el municipio de Bello, fomentando el desarrollo sostenible, con talento humano competente, administrando con eficiencia los recursos y prestando eficazmente los servicios para mejorar la calidad de vida de su población. El informe describe las actividades realizadas en el periodo de 4 meses, donde se estuvo vinculada como practicante de la empresa, auxiliar de ingeniería civil en el marco del programa “por una eficiente planeación territorial y fiscal”, de la dirección administrativa de catastro adscrita a la secretaria de hacienda del municipio de Bello. Adicionalmente, se presentan aspectos relacionados con el desempeño, mencionando fortalezas demostradas, dificultades superadas, bases teóricas para la práctica, sugerencias y conclusiones sobre la práctica realizada.Resumen. --
Introducción. --
1. Objetivos. --
1.1 General. --
1.2 Específicos. --
2. Descripción de actividades desarrolladas en la práctica empresarial. --
2.1 Reseña histórica del centro (empresa) de prácticas. --
2.2 Descripción del área de la empresa donde se efectuó la práctica. --
2.3 Organigrama general de la entidad. --
2.4 Funciones de los practicantes. --
2.5 Actividades realizadas. --
3. Fundamentos teóricos o ingenieriles para el desarrollo de la práctica. --
4. Logros formativos obtenidos en la práctica. --
5. Fortalezas demostradas en la práctica empresarial. --
6. Limitaciones o debilidades en la práctica empresarial. --
7. Aportes relevantes de aprendizaje como futuros profesionales de la ingeniería. --
8. Propuesta académica para los futuros practicantes o para los profesionales. --
Conclusiones y recomendaciones. --
Bibliografia. --
Lista de [email protected]
Brain potential evoked by spinal cord stimulation from D-Wave catheter at the end of resection of spinal cord tumors
No full textIntroduction
IntraOperative NeuroMonitoring (IONM) in spinal cord tumour surgery relies mostly onto the assessment of the integrity of the motor pathways, with Transcranial Motor Evoked Potentials, with the possible adjunct of Somatosensory Evoked Potentials from peripheral nerve stimulation.
In a few patients subjected to IONM during spinal cord tumour resection, we also recorded Brain Potentials (BP) from direct stimulation of the spinal cord, delivered through the epidural D wave catheter inserted caudally to the tumour. The BP was obtained at the end of resection and it was not used for IONM.
Materials and Methods
In three adult patients operated for dorsal spinal cord tumours (two intramedullary tumours, one extramedullary intradural tumour), the IONM was conducted with muscle MEP+D wave recording. PTN SEPs were obtained at intervals. At the end of resection, the D-wave catheter distal to the lesion was used for delivering direct spinal cord stimulation, with recording from Cz-C3'. A square wave pulse lasting 200-500 microseconds, intensity 9-10 mA, was used for stimulation and 10 sweeps were averaged on a 30 ms time base. Filter setting was 15-1500 Hz.
Result
A robust negative wave (BP) was recorded in the two patients with intramedullary tumours, peaking 6.2 ms (D3 stimulation), 6.1 ms (D1 stimulation), respectively. D wave peak latencies, recorded from the same catheter just before BP, were 5.4 ms and 4.6 ms, respectively. In the third patient (extramedullary meningioma) we could not record any reliable BP from D8 stimulation.
Conclusions
An ascending Brain Potentials could be evoked by direct spinal cord stimulation from the electrode recording distal corticospinal D wave in two adult subjects. Its peak latency was longer than D wave in both cases. This technique may be an adjunct to SEP from peripheral nerve stimulation. More experience is needed to assess its generators and its reliability for IONM
High-Detail Fault Segmentation: Deep Insight into the Anatomy of the 1983 Borah Peak Earthquake Rupture Zone (Mw 6.9, Idaho, USA)
No full textFollowing observations made in a survey campaign along the Lost River Fault (Idaho, USA) in 2019, we integrate both original and previously published data to obtain a detailed segmentation of the fault sections that failed in the 1983 Borah Peak earthquake (Mw 6.9). The earthquake ruptured the topographic surface with an oblique-normal faulting mechanism, activating two SW-dipping fault segments (Thousand Springs and Warm Springs) and a branching SSW-dipping fault (Arentson Gulch Fault) and producing coseismic surface ruptures with up to 3m of vertical separation. We augment the 1983 earthquake description by interpreting high-resolution topography and fault mapping. We use quality vertical separation data, rupture zone width measurements, and fault slip data to analyze major and minor structural-geometric complexities, highlighting a partition of the deformation and a fault segmentation into four detail levels (i.e., segments, sections, subsections, and sectors). Our work provides new details of the 1983 Borah Peak earthquake, constraints for paleoseismic and seismotectonic studies, and a methodological approach applicable in other areas of the world. Our fault-slip data show variations along faultstrike that we interpret as kinematic partitioning. In 1983, the main southern segment had a large rupture zone width, while the northern segment localized the deformation. The distributed ruptures accommodate a large portion of the rupture length (~19.5 km versus 31 km for the main rupture) and displacement (~66%). 83% of the surface faulting and 80% of the displacement are located at the hanging wall of the main rupture. There is a strong correlation between vertical separation, rupture zone width, rupture position (footwall or hanging wall), and fault geometry. We highlight the control of the obliquity and kinematic partitioning in the surface expression of the earthquake propagation. We interpret the coseismic (i.e., 1983) and long-term (i.e., Quaternary) behavior, showing that the two activated segments had similar cumulated behaviors in distributing the deformation between synthetic and antithetic ruptures, despite the different geometries. Our results have implications for fault rupture behavior with application to rupture hazard. © 2022. Simone Bello et al. Exclusive Licensee GeoScienceWorld. Distributed under a Creative Commons Attribution License (CC BY 4.0
Presencia de Serotipos de Aggregatibacter actinomycetemcomitans y su susceptibilidad antibiótica en pacientes de la Clínica Facultad de Odontología de la Universidad Andrés Bello
No full textTesis (Cirujano Dentista, especialización en Periodoncia)Aggregatibacter actinomycetemcomitans posee 6 serotipos distintos (a-f), diferenciados estructuralmente, que se distribuyen en proporciones diferentes según el lugar geográfico y raza. Existen estudios que sugieren que ciertos serotipos poseen mayor capacidad para producir enfermedad, mientras que otros tipos son menos patogénicos, incluso encontrándose en personas sin enfermedad. Estudios han revelado que el Aggregatibacter posee diferentes susceptibilidades a antibióticos. En este estudio se pretende localizar los serotipos mas prevalentes de Aggregatibacter actinomycetemcomitans y su susceptibilidad antibiótica.
El estudio fue realizado en un total de 50 pacientes que acudieron para diagnóstico y tratamiento periodontal, en las clínicas de pre y post grado de periodoncia de la Facultad de Odontología de la Universidad Andrés Bello.
Se realizaron muestras de 3 sitios diferentes con sacos de profundidad de 5mm o superiores por cada paciente, y se realizaron examenes de PCR para consignar el serotipo y antibiogramas para medir la suceptibilidad antibiotica de los serotipos encontrados.
Del total de pacientes examinados el 28% fueron positivos para Aggregatibacter actinomycetemcomitans, mientras que el 30% de los pacientes con periodontitis fueron positivos para Aggregatibacter actinomycetemcomitans.
Del total de pacientes con periodontitis cronica el 23% presentaron Aggregatibacter actinomycetemcomitans. El 80% de los pacientes con periodontitis agresiva fueron positivos para Aggregatibacter actinomycetemcomitans, mientras que el 20% de todos los pacientes sanos fueron positivos para este microorganismo.
Del total de pacientes que se aisló exitosamente Aggregatibacter actinomycetemcomitans el 29% correspondió al serotipo b, 57% correspondió al serotipo c y 14% no se pudo serotipificar. No se observaron los serotipos a, d, e y f en las muestras aisladas para este estudio.
Se observó un 100% de sensibilidad antibiótica de todos los serotipos aislados para Metronidazol y Amoxicilina. Un 86% de todos los serotipos fue sensible a Ciprofloxacino, Eritromicina y Tetraciclinas. Un 86% de todos los serotipos fue resistente a Clindamicina
Elemental abundances and isotopic composition of Italian limestones: Glimpses into the evolution of the Tethys
No full textBiogenic limestones from three sections (north, central, and south) across peninsular Italy have been analysed for major and trace elements and Nd, Pb, and Sr isotopic ratios. These data are used to monitor the evolution of the Tethys Ocean from the Triassic through to the Miocene. Limestones’ major, trace, and REE elements contents are consistent with their formation in seawater with little sign of crustal, volcanic, or hydrothermal input. V/Cr and Ce/Ce* ratios indicate their deposition in oxygenated waters. Rb-Sr-Ba discrimination diagram, consistent with the immobile trace element distribution, indicates that limestone deposition took place in either marginal or open ocean environments. Ages based on stratigraphy are in good agreement with the chronostratigraphic Sr curves implying that the Tethys ocean, throughout its history, was in contact with the open, global, ocean system. Although the isotopic values of Sr and Nd are relatively restricted, Pb is extremely variable and highly radiogenic. High Pb isotope ratios characterise limestones deposited during the rifting of the southern Tethyan ocean in the Lower Jurassic and in the Lower Cretaceous, suggesting stronger crustal inputs in small basins. The weighted average, present-day, isotope values (AIL = average Italian limestone) for the Italian limestones, excluding anomalous samples, are 87Sr/86Sr = 0.70785, 143Nd/144Nd = 0.51227, and 206Pb/204Pb = 18.94, 207Pb/204Pb = 15.69, 208Pb/204Pb = 38.66. These values are useful in monitoring the fate of limestones during orogenesis and the role that they may have played in magma genesis. © 2023 The Author(s
Synergistic effects of micro-abrasion–corrosion of UNS S30403, S31603 and S32760 stainless steels
No full textIn this study, the synergistic effects of abrasion and corrosion on UNS S30403, S31603 and S32760 stainless steels have been investigated using a micro-abrasion test rig. The stainless steel samples have been studied under both pure abrasion (PA) and abrasion–corrosion (AC) conditions simulated by using silicon carbide based slurries in either distilled water or 3.5% sodium chloride solutions. Tests have been conducted at various abrasive concentrations (0.006–0.238 g/cm3) and at 38 and 180m sliding distance to enable the interactions between abrasion and corrosion to be better understood. Wear mode identification and regime mapping was used to establish the dominant wear mechanism at the different slurry concentrations. The synergistic effect has been quantified and related to the material composition and the grooving or rolling abrasive wear mechanisms present. The synergistic levels were typically positive and have been discussed in terms of their dependence on the integrity of the passive films and the repassivation kinetics. The three-body abrasion–corrosion rates for all steels were found to be 14 times higher than two-body
abrasion–corrosion rates. S30403 shows weak repassivation performance with electrochemical activity being proportional to mechanical activity. S31603 showed a constant electrochemical activity over a variety of mechanical conditions, indicating a stronger repassivation performance than S30403. S32760 has the best repassivation performance with negative synergistic characteristics until abrasion rate are such that depassivation
occurs and the electrochemical activity is then comparable to the other steels
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