Nanosecond Picosecond
Mostrando 1-12 de 12 artigos, teses e dissertações.
-
1. Nd:YAG picosecond and nanosecond lasers in enamel and dentin: morphological and chemical analysis / Lasers de Nd:YAG nos regimes de nano e de picossegundos em esmalte e em dentina-análises morfológica e química
Vários experimentos têm demonstrado que pulsos ultra curtos no domínio de subpicossegundos promovem uma combinação de efeitos termomecânicos que superam algumas das objeções ao uso de um laser como instrumento removedor. Usando os parâmetros apropriados de operação, lasers com pulsos ultra curtos podem se comportar melhor do que instrumentos conve
Publicado em: 2000
-
2. Picosecond molecular motions in bacteriorhodopsin from neutron scattering.
The characteristics of internal molecular motions of bacteriorhodopsin in the purple membrane have been studied by quasielastic incoherent neutron scattering. Because of the quasihomogeneous distribution of hydrogen atoms in biological molecules, this technique enables one to study a wide variety of intramolecular motions, especially those occurring in the p
-
3. Characterizing semilocal motions in proteins by NMR relaxation studies
The understanding of protein function is incomplete without the study of protein dynamics. NMR spectroscopy is valuable for probing nanosecond and picosecond dynamics via relaxation studies. The use of 15N relaxation to study backbone dynamics has become virtually standard. Here, we propose to measure the relaxation of additional nuclei on each peptide plane
The National Academy of Sciences.
-
4. Large-amplitude picosecond anisotropy decay of the intrinsic fluorescence of double-stranded DNA.
The conformational flexibility of the DNA double helix is of great interest because of its potential role in protein recognition, packaging into chromosomes, formation of photodefects, and interaction with drugs. Theory finds that DNA is very flexible; however, there is a scarcity of experimental results that examine intrinsic properties of the DNA bases for
-
5. Human myoglobin recognition of oxygen: Dynamics of the energy landscape
Femtosecond to nanosecond dynamics of O2 rebinding to human WT myoglobin and its mutants, V68F and I107F, have been studied by using transient absorption. The results are compared with NO rebinding. Even though the immediate environment around the heme binding site is changed by the mutations, the picosecond geminate rebinding of oxygen is at most minimally
National Academy of Sciences.
-
6. Nanosecond Motions in Proteins Impose Bounds on the Timescale Distributions of Local Dynamics
We elucidate the physics of protein dynamical transition via 10–100-ns molecular dynamics simulations at temperatures spanning 160–300 K. By tracking the energy fluctuations, we show that the protein dynamical transition is marked by a crossover from nonstationary to stationary processes that underlie the dynamics of protein motions. A two-timescale func
The Biophysical Society.
-
7. Effect of disordered hemes on energy transfer rates between tryptophans and heme in myoglobin.
Our recent linear dichroism study of heme transitions (Gryczynski, Z., E. Bucci, and J. Kusba. 1993. Photochem. Photobiology. in press) indicate that heme cannot be considered a planar oscillator when it acts as an acceptor of radiationless excitation energy transfer from tryptophan. The linear nature of the heme absorption transition moment in the near-UV r
-
8. Crosslinking of progesterone receptor to DNA using tuneable nanosecond, picosecond and femtosecond UV laser pulses.
UV laser crosslinking is a potentially powerful tool to investigate transient DNA-protein interactions and binding kinetics in intact cells. As the processes underlying UV laser crosslinking are not fully understood, we have performed a study of the influence of laser pulses with different physical parameters on crosslinking of the progesterone receptor to a
-
9. Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy.
Time-resolved vibrational spectra are used to elucidate the structural changes in the retinal chromophore within the K-590 intermediate that precedes the formation of the L-550 intermediate in the room-temperature (RT) bacteriorhodopsin (BR) photocycle. Measured by picosecond time-resolved coherent anti-Stokes Raman scattering (PTR/CARS), these vibrational d
-
10. Molecular dynamics study of unbinding of the avidin-biotin complex.
We report molecular dynamics simulations that induce, over periods of 40-500 ps, the unbinding of biotin from avidin by means of external harmonic forces with force constants close to those of AFM cantilevers. The applied forces are sufficiently large to reduce the overall binding energy enough to yield unbinding within the measurement time. Our study comple
-
11. Picosecond kinetics of fluorescence and absorbance changes in photosystem II particles excited at low photon density
Oxygen-evolving photosystem II particles (from Synechococcus) with about 80 chlorophyll molecules per primary electron donor (P680) were used for a correlated study of picosecond kinetics of fluorescence and absorbance changes, detected by the single-photon-timing technique and by a pump-probe apparatus, respectively. Chlorophyll fluorescence decays were bie
-
12. Effect of lesions on the dynamics of DNA on the picosecond and nanosecond timescales using a polarity sensitive probe
This paper explores the effects of structural modifications on the fast dynamics of DNA and the ability of time-resolved Stokes shift spectroscopy to measure those changes. The time-resolved Stokes shift of a synthetic coumarin base-pair replacement within an oligomer is measured between 40 ps and 40 ns. Comparisons are made between 17mers without modificati
Oxford University Press.