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202 results on '"Wolf, J. M."'

4. Room Temperature Operation of a Buried Heterostructure Photonic Crystal Quantum Cascade Laser

Author

Peretti, R., Liverini, V., Wolf, J. M., Bonzon, C., Süess, M. J., Lourdudoss, S., Metaferia, W., Beck, M., and Faist, J.

Subjects
Physics - Optics
Abstract

High power single mode quantum cascade lasers with a narrow far field are important for several applications including surgery or military countermeasure. Existing technologies suffer from drawbacks such as operation temperature and scalability. In this paper we introduce a fabrication approach that potentially solves simultaneously these remaining limitations. We demonstrate and characterize deep etched, buried photonic crystal quantum cascade lasers emitting around a wavelength of 8.5 {\mu}m. The active region was dry etched before being regrown with semi-insulating Fe:InP. This fabrication strategy results in a refractive index contrast of 10% allowing good photonic mode control, and simultaneously provides good thermal extraction during operation. Single mode emission with narrow far field pattern and peak powers up to 0.88 W at 263 K were recorded from the facet of the photonic crystal laser, and lasing operation was maintained up to room temperature. The lasing modes emitted from square photonic crystal mesas with a side length of 550{\mu}m, were identified as slow Bloch photonic crystal modes by means of three-dimensional photonic simulations and measurements.

Published
2015
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45. Characterization of retroviral infectivity and superinfection resistance during retrovirus-mediated transduction of mammalian cells

Author

Liao, J, primary, Wei, Q, additional, Fan, J, additional, Zou, Y, additional, Song, D, additional, Liu, J, additional, Liu, F, additional, Ma, C, additional, Hu, X, additional, Li, L, additional, Yu, Y, additional, Qu, X, additional, Chen, L, additional, Yu, X, additional, Zhang, Z, additional, Zhao, C, additional, Zeng, Z, additional, Zhang, R, additional, Yan, S, additional, Wu, T, additional, Wu, X, additional, Shu, Y, additional, Lei, J, additional, Li, Y, additional, Zhang, W, additional, Wang, J, additional, Reid, R R, additional, Lee, M J, additional, Huang, W, additional, Wolf, J M, additional, and He, T-C, additional

Published
2017
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46. Biological control of potato soft rot caused by Dickeya solani and the survival of bacterial antagonists under cold storage conditions.

Author

Hadizadeh, I., Peivastegan, B., Hannukkala, A., Wolf, J. M., Nissinen, R., and Pirhonen, M.

Subjects
POTATO diseases & pests, BIOLOGICAL pest control agents, SEED potatoes, ERWINIA, PHYTOPATHOGENIC microorganisms
Abstract

Dickeya and Pectobacterium are responsible for causing blackleg of plants and soft rot of tubers in storage and in the field, giving rise to losses in seed potato production. In an attempt to improve potato health, biocontrol activity of known and putative antagonists was screened using in vitro and in planta assays, followed by analysis of their persistence at various storage temperatures. Most antagonists had low survival on potato tuber surfaces at 4 °C. The population dynamics of the best low‐temperature tolerant strain and also the most efficient antagonist, Serratia plymuthica A30, along with Dickeya solani as target pathogen, was studied with TaqMan real‐time PCR throughout the storage period. Tubers of three potato cultivars were treated in the autumn with the antagonist and then inoculated with D. solani. Although the cell densities of both strains decreased during the storage period in inoculated tubers, the pathogen population was always lower in the presence of the antagonist. The treated tubers were planted in the field the following growing season to evaluate the efficiency of the bacterial antagonist for controlling disease incidence. The potato endophyte S. plymuthica A30 protected potato plants by reducing blackleg development on average by 58.5% and transmission to tuber progeny as latent infection by 47–75%. These results suggest that treatment of potato tubers with biocontrol agents after harvest can reduce the severity of soft rot disease during storage and affect the transmission of soft rot bacteria from mother tubers to progeny tubers during field cultivation. [ABSTRACT FROM AUTHOR]

Published
2019
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47. Development of an in vitro protocol to screen Clavibacter michiganensis subsp. michiganensis pathogenicity in different Solanum species.

Author

Mohd Nadzir, M. M., Vieira Lelis, F. M., Thapa, B., Ali, A., Visser, R. G. F., Heusden, A. W., and Wolf, J. M.

Subjects
CLAVIBACTER michiganensis, TOMATO diseases & pests, WILT diseases, GREEN fluorescent protein, BIOFLUORESCENCE
Abstract

Clavibacter michiganensis subsp. michiganensis (Cmm) is a quarantine organism in Europe and in many other countries. It is one of the most severe bacterial pathogens affecting tomato. Screening tomato plants for their resistance level to Cmm requires a large amount of space under quarantine conditions and is therefore costly. This project developed a new inoculation protocol on in vitro tomato plants to facilitate a more economic and higher throughput disease screening. A new method using the PathoScreen system was tested to localize green fluorescent protein‐tagged Cmm in planta and to quantify the pathogen based on the percentage of corrected GFP (cGFP%). The system was sensitive in detecting the GFP‐tagged Cmm in the shoots, but in the roots a high autofluorescence masked detection and thus sensitivity of the assay. The in vitro protocol was tested on several wild relatives of tomato, which were previously screened in a greenhouse assay. The correlation between wilt symptoms in vitro and wilt symptoms in the greenhouse was overall moderate (r = 0.6462). The protocol worked well in differentiating the two parents that were used in the mapping studies. This study shows that the in vitro protocol can be efficiently used for resistance breeding in many tomato genotypes. [ABSTRACT FROM AUTHOR]

Published
2019
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48. Room temperature operation of a deep etched buried heterostructure photonic crystal quantum cascade laser

Author

Peretti, R., Liverini, V., Süess, M. J., Liang, Y., Vigneron, P. B., Wolf, J. M., Bonzon, C., Bismuto, A., Metaferia, W., Balaji, Manavaimaran, Lourdudoss, Sebastian, Gini, E., Beck, M., Faist, J., Peretti, R., Liverini, V., Süess, M. J., Liang, Y., Vigneron, P. B., Wolf, J. M., Bonzon, C., Bismuto, A., Metaferia, W., Balaji, Manavaimaran, Lourdudoss, Sebastian, Gini, E., Beck, M., and Faist, J.

Abstract

High power single mode quantum cascade lasers with a narrow far field are important for several applications including surgery or military countermeasure. Existing technologies suffer from drawbacks such as operation temperature and scalability. In this paper we introduce a fabrication approach that potentially solves simultaneously these remaining limitations. We demonstrate and characterize deep etched, buried photonic crystal quantum cascade lasers emitting around a wavelength of 8.5 μm. The active region was dry etched before being regrown with semi-insulating Fe:InP. This fabrication strategy results in a refractive index contrast of 10% allowing good photonic mode control, and simultaneously provides good thermal extraction during operation. Single mode emission with narrow far field pattern and peak powers up to 0.88 W at 263 K were recorded from the facet of the photonic crystal laser, and lasing operation was maintained up to room temperature. The lasing modes emitted from square photonic crystal mesas with a side length of 550μm, were identified as slow Bloch photonic crystal modes by means of three-dimensional photonic simulations and measurements. (Figure presented.)., QC 20161207

Published
2016
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49. Buried heterostructure photonic crystal quantum cascade laser : Towards 2D large-area single-mode operation

Author

Liang, Y., Peretti, R., Liverini, V., Süess, M. J., Vigneron, P. -B, Wolf, J. M., Bonzon, C., Bismuto, A., Lourdudoss, Sebastian, Metaferia, W., Balaji, M., Gini, E., Beck, M., Faist, J., Liang, Y., Peretti, R., Liverini, V., Süess, M. J., Vigneron, P. -B, Wolf, J. M., Bonzon, C., Bismuto, A., Lourdudoss, Sebastian, Metaferia, W., Balaji, M., Gini, E., Beck, M., and Faist, J.

Abstract

We demonstrate a buried-heterostructure photonic-crystal quantum cascade laser operating at room temperature. The large-area coherent lasing enabled an output peak power of 0.88 W at 263 K with single-mode behavior and narrow far field pattern., Conference code: 134228; Export Date: 22 May 2017; Conference Paper; Correspondence Address: Liang, Y.; Institute for Quantum Electronics, ETH ZürichSwitzerland; email: liangyo@phys.ethz.ch. QC 20170607

Published
2016
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