scholarly journals Enhancement of the Anti-Stokes Fluorescence of Hollow Spherical Carbon Nitride Nanostructures by High Intensity Green Laser

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2529
Author(s):  
Pavel V. Zinin ◽  
Tayro E. Acosta-Maeda ◽  
Anupam K. Misra ◽  
Shiv K. Sharma
Keyword(s):  
High Intensity ◽  
Fluorescence Spectra ◽  
Carbon Nitride ◽  
Laser Intensity ◽  
Pulsed Laser ◽  
Green Laser ◽  
Spherical Nanoparticles ◽  
Spherical Carbon ◽  
High Level ◽  
Anti Stokes

Fluorescence spectra of graphitic (g-C3N4) and spherical (s-C3N4) modifications of carbon nitride were measured as a function of green pulsed (6 ns-pulse) laser intensity. It was found that the intensity of the laser increases the maximum of the fluorescence shifts towards the anti-Stokes side of the fluorescence for s-C3N4 spherical nanoparticles. This phenomenon was not observed for g-C3N4 particles. The maximum of the anti-Stokes fluorescence in s-C3N4 nanoparticles was observed at 480 nm. The ratio of the intensity of the anti-Stokes peak (centered at 480 nm) to that of the Stokes peak (centered at 582 nm) was measured to be I484/582 = 6.4 × 10−3 at a low level of intensity (5 mW) of a green pulsed laser, whereas it rose to I484/582 = 2.27 with a high level of laser intensity (1500 mW).

scholarly journals High-Intensity Focused Ultrasound Circular Cyclocoagulation in Glaucoma: A Step Forward for Cyclodestruction?

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Rodolfo Mastropasqua ◽  
Vincenzo Fasanella ◽  
Alessandra Mastropasqua ◽  
Marco Ciancaglini ◽  
Luca Agnifili
Keyword(s):  
High Intensity ◽  
Ciliary Body ◽  
Focused Ultrasound ◽  
Current Knowledge ◽  
High Intensity Focused Ultrasound ◽  
High Rate ◽  
Dose Effect ◽  
Computer Assisted ◽  
Refractory Glaucoma ◽  
High Level

The ciliary body ablation is still considered as a last resort treatment to reduce the intraocular pressure (IOP) in uncontrolled glaucoma. Several ablation techniques have been proposed over the years, all presenting a high rate of complications, nonselectivity for the target organ, and unpredictable dose-effect relationship. These drawbacks limited the application of cyclodestructive procedures almost exclusively to refractory glaucoma. High-intensity focused ultrasound (HIFU), proposed in the early 1980s and later abandoned because of the complexity and side effects of the procedure, was recently reconsidered in a new approach to destroy the ciliary body. Ultrasound circular cyclocoagulation (UC3), by using miniaturized transducers embedded in a dedicated circular-shaped device, permits to selectively treat the ciliary body in a one-step, computer-assisted, and non-operator-dependent procedure. UC3 shows a high level of safety along with a predictable and sustained IOP reduction in patients with refractory glaucoma. Because of this, the indication of UC3 was recently extended also to naïve-to-surgery patients, thus reconsidering the role and timing of ciliary body ablation in the surgical management of glaucoma. This article provides a review of the most used cycloablative techniques with particular attention to UC3, summarizing the current knowledge about this procedure and future possible developments.

X-RAY PHOTOELECTRON SPECTROSCOPY STUDIES ON THE BONDING PROPERTIES OF AMORPHOUS CARBON NITRIDE FILMS SYNTHESIZED BY PULSED LASER DEPOSITION WITH DIFFERENT SUBSTRATE TEMPERATURES

2005 ◽  
Vol 12 (02) ◽  
pp. 185-195
Author(s):  
M. RUSOP ◽  
T. SOGA ◽  
T. JIMBO
Keyword(s):  
Pulsed Laser Deposition ◽  
Amorphous Carbon ◽  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Measurement Techniques ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
X Ray ◽  
Amorphous Carbon Nitride ◽  
Substrate Temperatures

Amorphous carbon nitride films ( a-CN x) were deposited by pulsed laser deposition of camphoric carbon target with different substrate temperatures (ST). The influence of ST on the synthesis of a-CN x films was investigated. The nitrogen-to-carbon (N/C) and oxygen-to-carbon (O/C) atomic ratios, bonding state, and microstructure of the deposited a-CN x films were characterized by X-ray photoelectron spectroscopy and were confirmed by other standard measurement techniques. The bonding states between C and N , and C and O in the deposited films were found to be significantly influenced by ST during the deposition process. The N/C and O/C atomic ratios of the a-CN x films reached the maximum value at 400°C. ST of 400°C was proposed to promote the desired sp 3-hybridized C and the C 3 N 4 phase. The C–N bonding of C–N , C=N and C≡N were observed in the films.

Carbon nitride coherently grown on Si (111) substrates by pulsed laser irradiation

2000 ◽  
Author(s):  
G. Barucca ◽  
Guiseppe Majni ◽  
Paolo Mengucci ◽  
Gilberto Leggieri ◽  
Armando Luches ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Carbon Nitride ◽  
Pulsed Laser ◽  
Pulsed Laser Irradiation

High-Intensity Focused Ultrasound Scattering at Mammal Vertebrae

2020 ◽  
Author(s):  
David Sanford ◽  
Christoph Schaal
Keyword(s):  
High Intensity ◽  
Laboratory Experiments ◽  
Energy Deposition ◽  
Focused Ultrasound ◽  
Complex Geometry ◽  
Ex Vivo ◽  
Pulsed Laser ◽  
High Intensity Focused Ultrasound ◽  
Focal Region ◽  
Homogeneous Media

Abstract High-intensity focused ultrasound (HIFU) is used clinically to heat cells therapeutically or to destroy them through heat or cavitation. In homogeneous media, the highest wave amplitudes occur at a predictable focal region. However, HIFU is generally not used in the proximity of bones due to wave absorption and scattering. Ultrasound is passed through the skull in some clinical trials, but the complex geometry of the spine poses a greater targeting challenge and currently prohibits therapeutic ultrasound treatments near the vertebral column. This paper presents a comprehensive experimental study involving shadowgraphy and hydrophone measurements to determine the spatial distribution of pressure amplitudes from induced HIFU waves near vertebrae. First, a bone-like composite plate that is partially obstructing the induced waves is shown to break the conical HIFU form into two regions. Wave images are captured using pulsed laser shadowgraphy, and hydrophone measurements over the same region are compared to the shadowgraphy intensity plots to validate the procedure. Next, shadowgraphy is performed for an individual, clean, ex-vivo feline vertebra. The results indicate that shadowgraphy can be used to determine energy deposition patterns and to determine heating at a specific location. The latter is confirmed through additional temperature measurements. Overall, these laboratory experiments may help determine the efficacy of warming specific nerve cells within mammal vertebrae without causing damage to adjacent tissue.

Selection of Single Harmonic Emission Peak for Producing Isolated Attosecond Pulse via Chirped-UV Combined Field

2019 ◽  
Vol 75 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hang Liu ◽  
Li-Qiang Feng
Keyword(s):  
High Intensity ◽  
Laser Field ◽  
Laser Intensity ◽  
Potential Method ◽  
Emission Peak ◽  
Harmonic Emission ◽  
Low Intensity ◽  
Isolated Attosecond Pulse ◽  
Intensity Laser ◽  
Selection Of

AbstractA potential method to produce isolated attosecond pulses (IAPs) by using low-intensity chirped-UV combined field has been investigated. The results can be separated into three parts. First, by properly introducing the mid-chirp or down-chirp of the low-intensity laser field, the harmonic cutoff can be extended and achieve the referenced value, which is produced from the high-intensity referenced field. Moreover, the spectral continuum is contributed by a single harmonic emission peak, which is beneficial to produce IAPs. However, the harmonic yield is very low due to the lower driven laser intensity. Second, by properly adding a UV pulse, the harmonic yield can be enhanced and achieve the referenced value due to the UV resonance ionisation. The intensity of the combined field is lower than that of the referenced field, which reduces the experimental requirements for producing high-intensity spectral continuum. Third, with the introduction of the positive or negative inhomogeneous effect of the mid-chirped combined field or down-chirped combined field, respectively, the similar harmonic cutoff and harmonic yield can also be obtained but with a much lower driven laser intensity. Finally, by superposing the harmonics on the spectral continuum, the IAPs with the durations of sub-38 as can be obtained.

Pulsed laser deposition of carbon nitride thin films from graphite targets

Carbon ◽  
1998 ◽  
Vol 36 (5-6) ◽  
pp. 771-774 ◽  
Author(s):  
Y. Suda ◽  
T. Nakazono ◽  
K. Ebihara ◽  
K. Baba ◽  
S. Aoqui
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Carbon Nitride ◽  
Pulsed Laser ◽  
Laser Deposition

scholarly journals Composition and chemical bonding of pulsed laser deposited carbon nitride thin films

2000 ◽  
Vol 88 (7) ◽  
pp. 4365 ◽  
Author(s):  
E. Riedo ◽  
F. Comin ◽  
J. Chevrier ◽  
A. M. Bonnot
Keyword(s):  
Thin Films ◽  
Chemical Bonding ◽  
Carbon Nitride ◽  
Pulsed Laser
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