Browsing by Author "Rodríguez, J."
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- ItemAño Internacional de Aristóteles : recordando los aportes a la medicina y a la biología humana de este gran polímata(2016) Cortés M.; Rodríguez, J.; Rodríguez, M.; Del Río, J.; Vigil Portales, María del Pilar
- ItemEffect of Modified Atmosphere Packaging and Maturity on Susceptibility to Mealiness and Flesh Browning of Peach Cultivars(2002) Zoffoli Guerra, Juan Pablo; Balbontín, S.; Rodríguez, J.The susceptibility of mealiness and flesh browning physiological disorders was evaluated after 3, 5 and 6 weeks on ripe `Sweet September,' `September Sun,' `Ryan Sun' and `Rosario Red' peach (Prunus persica (L.) Batsch) cultivars harvested at three maturities and stored under modified atmosphere packaging ((MAP) experimental bag P2UC 965 (Chile)). High incidence (>40%) of mealiness was detected in all the cultivars even at 3 weeks of storage at 0 degreesC. `Sweet September,' `September Sun' and `Rosario Red' were most susceptible to mealiness in more mature fruit. MAP reduced the incidence of meatiness after 3 weeks of storage to acceptable commercial level (<20%) only in `Sweet September' cultivar for the three maturities evaluated. Total control of flesh browning was obtained with MAP in all the maturity levels evaluated, but was not controlled on `Rosario Red' cultivar. High concentration of carbon dioxide was attained with MAP. This information suggests that MAP gives only partial control to physiological disorders of peaches, with mealiness symptoms being the most difficult to control.
- ItemEffect of sulfur dioxide and modified atmosphere packaging on blueberry postharvest quality(2016) Rodríguez, J.; Zoffoli, Juan Pablo
- ItemFirst report of diaporthe novem causing postharvest rot of kiwifruit during controlled atmosphere storage in Chile(The American Phytopathological Society, 2014) Díaz, G. A.; Latorre Guzmán, Bernardo; Jara, S.; Ferrada, E.; Naranjo, P.; Rodríguez, J.; Zoffoli Guerra, Juan PabloChile is considered the third major exporter of kiwifruits (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson) worldwide after Italy and New Zealand (1). The genus Diaporthe Nitschke (anamorph: genus Phomopsis) has been reported as causing postharvest rot in kiwifruit (4). During the current study, 1,400 fruits arbitrarily collected from seven controlled atmosphere (CA) rooms after 90 days of storage conditions (2% O2, 5% CO2) determined that 21.5% of the fruit were affected by decay and 0.86% developed symptoms different than those caused by Botrytis cinerea, the main postharvest pathogen associated to kiwifruit. Symptoms were soft rot with brown skin that started at the stem-end and in severe cases affected the entire fruit. Internally, affected fruit showed browning and watery tissues. Twelve affected fruits were surface disinfested (75% ethanol) and small pieces of internal rotten tissues were placed on acidified potato dextrose agar (APDA) for 7 days at 20°C. Twelve isolates were obtained, and four of them were identified morphologically and molecularly as Diaporthe ambigua, a species that has been previously described causing rot in stored kiwifruits in Chile (2). However, eight other flat, white to grayish colonies with sparse dirty-white aerial mycelium at the edge of the dish were obtained (3). Black pycnidia contained unicellular, hyaline, biguttulate, oval to cylindrical alpha conidia, with obtuse ends of (7.9) 6.7 (5.3) × (2.9) 2.5 (2.1) μm (n = 30). These isolates were tentatively identified as a Diaporthe sp. The species identification was determined by sequencing comparison of the internal transcribed spacer (ITS1-5.8S-ITS2) region of the rDNA (GenBank Accession Nos. KJ210020 to 24, KJ210027, and KJ210033) and a portion of beta-tubulin (BT) (KJ210034 to 38, KJ210041, and KJ210047) using primers ITS4-ITS5 and Bt2a-Bt2b, respectively. BLAST analyses showed 99 to 100% identity with D. novem J.M. Santos, Vrandecic & A.J.L Phillips reference ex-type (KC343156 and KC344124 for ITS and BT, respectively) (3). Eighteen mature kiwifruits cv. Hayward were inoculated using a sterile cork borer on the surface of the fruit and placing 5-mm agar plugs with mycelial of D. novem (DN-1-KF). An equal number of fruits treated with sterile agar plugs were used as negative controls. After 30 days at 0°C under CA, all inoculated fruit showed rot symptoms with lesions 7.8 to 16.4 mm in diameter. The same D. novem isolate was inoculated with 30 μl of a conidial suspension (106 conidia/ml) on the surface of 18 ripe kiwifruits that were previously wounded and non-wounded as described above. An equal number of wounded and non-wounded fruits, treated with 30 μl sterile water, were used as negative controls. All inoculated wounded fruits developed rot symptoms with necrotic lesions of 14.1 to 20.2 mm of diameter after 14 days at 25°C. Inoculated non-wounded and negative control fruits remained symptomless. Koch's postulates were fulfilled by re-isolating D. novem only from the symptomatic fruits. To our knowledge, this is the first report of rot caused by D. novem on kiwifruit during cold storage in Chile and worldwide. Therefore, both Diaporthe species appears to be associated to Diaporthe rot of kiwifruit in Chile.
- ItemNew Methodology for Analysis and Diagnosis of Sympathetic Interaction of Inrush Currents in Power Transformers for Detecting Abnormal Operating Conditions(IEEE, 2007) Martin, J. S.; Pontt, J.; Rodríguez, J.; Dixon Rojas, JuanThis paper presents a methodology for fast detection and identification of abnormal conditions in electrical systems. Modeling and simulation of most common operations of the system are simulated to create a database containing several patterns of performance under different abnormal operation conditions. The methodology has been tested to identify abnormal operating condition caused by sympathetic interaction of inrush currents in power transformers. Experimental validation of this method was allowing good current pattern identification and a good performance of the methodology was reached.
- ItemPostharvest factors that influence the effectiveness of modified atmosphere packaging of kiwifruit(2007) Zoffoli Guerra, Juan Pablo; Rodríguez, J.; Levy, N.Harvest maturity of kiwifruit and the time at which fruit were packed into a modified atmosphere bag, were the two factors used to study the effectiveness of MAP (modified atmosphere packaging) technology, using fruit from two orchards. Fruit were harvested at four times, over a range of soluble solids from 5.8% to 9.8%, firmness 76 N to 62.3 N and dry matter 15.9% to 18.4%. Fruit were packed into a modified atmosphere bags after 0, 30 and 60 days of storage at 0 degrees C and MAP was evaluated after 30 and 60 days at 0 degrees C plus a ripening period at 20 degrees C. A perforated bag was included as control. Independent of harvest maturity, the best results of MAP were obtained with fruit packed immediately after harvest. A delay period of thirty days reduced fruit softening only for the subsequent 30 days of storage. MAP was ineffective in maintaining fruit firmness when fruit were packed after being held 60 days at 0 degrees C. The time to reach the eating ripening stage (<9 N) during 20 degrees C shelf life was extended with the modified atmosphere bag. Fruit from both orchards behaved similarly in response to the MAP technology.
- ItemRecomendaciones para el diagnóstico y tratamiento antimicrobiano de la neumonía bacteriana adquirida en la comunidad en pediatría(2019) Cofré, J.; Pavez, D.; Pérez Pérez, Regina Elizabeth; Rodríguez, J.
- ItemRecomendaciones para el diagnóstico y tratamiento antimicrobiano de la otitis media aguda en pediatría(2019) Rodríguez, J.; Pavez, D.; Pérez Pérez, Regina Elizabeth; Cofré, J.
- ItemTrapezoidal Current Mode for Bidirectional High Step Ratio Modular Multilevel dc-dc Converter(IEEE, 2019) Pineda Fornerod, Cristian Andres; Pereda Torres, Javier Eduardo; Neira Castillo, Sebastian Felipe; Bravo, P.; Rodríguez, J.; García, C.High voltage direct current (HVDC) transmission systems and low voltage direct current (LVDC) networks are becoming popular due to their advantages and present feasibility, mainly pushed by the advance in power electronics. However, one of the main drawbacks of dc networks is the lack of a dc-dc converter that performs as the ac transformer in terms of efficiency, reliability and high-step voltage ratio, specially in medium and high voltage. Modular multilevel converters are an attractive alternative because they can manage medium and high dc voltages with standard semiconductor devices, and they can achieve high efficiency with soft switching modulation, such as resonant, trapezoidal or triangular currents usually used in double active bridges (DAB). This paper proposes a novel generalized trapezoidal current mode applied to high step ratio Modular Multilevel dc-dc Converters. The proposed modulation increases the efficiency and achieves bidirectional control of the power, soft-switching and a natural balance of the voltage in the capacitors. The simulation results show the bidirectional operation and the capacitor voltage balance of the converter under different operating conditions with high efficiency (98.2%).
- ItemTrayectorias de la periurbanización en Morelia, México : segregación espacial desde un enfoque relacional(2020) Rodríguez, N.; Vieyra, A.; Méndez Lemus, Y.; Hidalgo, Rodrigo; Alvarado Peterson, Voltaire Christian; Rodríguez, J.