| 1. |
- Bertani, Stefano, et al.
(author)
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Stretching-tunable external-cavity laser locked by an elastic silicone grating
- 2006
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In: Optics Express. - 1094-4087. ; 14:25, s. 11982-11986
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Journal article (peer-reviewed)abstract
- We demonstrate wavelength locking of a diode laser at 760 nm with feedback from an elastic transmission grating in the Littrow configuration. The laser was in a single longitudinal mode with a side-mode suppression of 20 dB. By stretching the grating the laser could be tuned over a few nm. The grating was fabricated in a silicone elastomer ( polydimethylsiloxane) by a moulding technique, and coated by a thin layer of Ti and Au to achieve an increased diffraction efficiency needed for efficient locking.
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| 2. |
- Ek, Patrik, et al.
(author)
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Electrospray ionization mass spectrometry from discrete nanoliter-sized sample volumes
- 2010
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In: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 24:17, s. 2561-2568
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Journal article (peer-reviewed)abstract
- We describe a method for nanoelectrospray ionization mass spectrometry (nESI-MS) of very small sample volumes. Nanoliter-sized sample droplets were taken up by suction into a nanoelectrospray needle from a silicon microchip prior to ESI. To avoid a rapid evaporation of the small sample volumes, all manipulation steps were performed under a cover of fluorocarbon liquid. Sample volumes down to 1.5 nL were successfully analyzed, and an absolute limit of detection of 105 attomole of insulin (chain B, oxidized) was obtained. The open access to the sample droplets on the silicon chip provides the possibility to add reagents to the sample droplets and perform chemical reactions under an extended period of time. This was demonstrated in an example where we performed a tryptic digestion of cytochrome C in a nanoliter-sized sample volume for 2.5h, followed by monitoring the outcome of the reaction with nESI-MS. The technology was also utilized for tandem mass spectrometry (MS/MS) sequencing analysis of a 2 nL solution of angiotensin I.
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| 3. |
- Hartmann, Michael, et al.
(author)
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Non-contact protein microarray fabrication using a procedure based on liquid bridge formation
- 2009
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In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 393:2, s. 591-598
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Journal article (peer-reviewed)abstract
- Contemporary microarrayers of contact or noncontact format used in protein microarray fabrication still suffer from a number of problems, e. g. generation of satellite spots, inhomogeneous spots, misplaced or even absent spots, and sample carryover. In this paper, a new concept of non-contact sample deposition that reduces such problems is introduced. To show the potential and robustness of this pressure-assisted deposition technique, different sample solutions known to cause severe problems or to be even impossible to print with conventional microarrayers were accurately printed. The samples included 200 mg mL(-1) human serum albumin, highly concentrated sticky cell adhesion proteins, pure high-salt cell-lysis buffer, pure DMSO, and a suspension of 5-mu m polystyrene beads. Additionally, a water-immiscible liquid fluorocarbon, which was shown not to affect the functionality of the capture molecules, was employed as a lid to reduce evaporation during microarray printing. The fluorocarbon liquid lid was shown to circumvent hydrolysis of water-sensitive activated surfaces during long-term deposition procedures.
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| 4. |
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| 5. |
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| 6. |
- Stjernström, Mårten, et al.
(author)
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Diode-pumped solid state laser light sources for confocal laser scanning fluorescence microscopy
- 2008
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In: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 20:3, s. 160-164
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Journal article (peer-reviewed)abstract
- Diode-pumped solid-state lasers (DPSSLs) have been integrated as light sources in confocal laser scanning microscopy (CLSM). The standard argon ion laser at 488 rim is compared with a DPSSL operating at 473 run in terms of noise and CLSM image characteristics. The equally high fluorescence image quality together with the many advantageous characteristics inherent to solid-state lasers suggest that excitation using a DPSSL is favored. The application of a dual-line DPSSL emitting at 491 and 532 nm for high resolution CLSM fluorescence imaging is shown for the first time.
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| 7. |
- Sudirman, Azizahalhakim, et al.
(author)
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A fiber optic system for detection and collection of micrometer-size particles
- 2014
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In: Optics Express. - 1094-4087. ; 22:18, s. 21480-21487
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Journal article (peer-reviewed)abstract
- An optical fiber containing longitudinal holes adjacent to the core has been used to detect and collect fluorescent particles from a solution. Excitation light was launched through the fiber and fluorescence signal was guided back to a detector system. As a proof of principle, green and red fluorescent polystyrene beads were detected and selectively collected from a water solution containing a mixture of red and green fluorescent beads.
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| 8. |
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| 9. |
- Uemura, Suguru, et al.
(author)
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Picoliter droplet formation on thin optical fiber tips
- 2006
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:24, s. 10272-10276
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Journal article (peer-reviewed)abstract
- In this paper, we present experimental results on how minute droplets are formed on fiber optic end faces. Results show that reproducible picoliter volumes can be generated when fibers are retracted from an aqueous phase contained under an inert fluorinated immiscible liquid, with a coefficient of variation (CV) of 0.7-2.3%. The droplet formation was analyzed as a function of the fiber diameter, retraction speed, and wettability. Experiments reveal a volume-determining critical equilibrium contact angle between 60 and 75, defining the onset of fiber end-face dewetting. The dynamics of the droplet snap-off progression was characterized using high-speed imaging in order to explain the observed wettability-volume dependency.
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| 10. |
- Villanueva, Walter, et al.
(author)
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Microdroplet deposition under a liquid medium
- 2007
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 23:3, s. 1171-1177
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Journal article (peer-reviewed)abstract
- An experimental and numerical study of the factors affecting the reproducibility of microdroplet depositions performed under a liquid medium is presented. In the deposition procedure, sample solution is dispensed from the end of a capillary by the aid of a pressure pulse onto a substrate with pillar-shaped sample anchors. The deposition was modeled using the convective Cahn-Hilliard equation coupled with the Navier-Stokes equations with added surface tension and gravity forces. To avoid a severe time-step restriction imposed by the fourth-order Cahn-Hilliard equation, a semi-implicit scheme was developed. An axisymmetric model was used, and an adaptive finite element method was implemented. In both the experimental and numerical study it was shown that the deposited volume mainly depends on the capillary-substrate distance and the anchor surface wettability. A critical equilibrium contact angle has been identified below which reproducible depositions are facilitated.
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