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Uro ◽  
2022 ◽  
Vol 2 (1) ◽  
pp. 13-20
Author(s):  
Yazeed Barghouthy ◽  
Mariela Corrales ◽  
Alba Sierra ◽  
Hatem Kamkoum ◽  
Camilla Capretti ◽  
...  

Introduction: With advances in endoscopic treatment of upper tract urothelial carcinoma (UTUC) lesions, the recommended upper limit of lesion size amenable to laser ablation was set to 2 cm. However, this limit is based on expert opinion only, and debate still exists regarding this definition. Objective: To determine the maximal size of the tissue, for which total endoscopic ablation with laser energy is achievable, from a laser performance perspective. Materials and Methods: Simulating endoscopic surgery conditions, renal tissue blocks from pork kidneys in growing size from 1 cm3 to 3 cm3 were totally ablated with Ho:YAG laser (1 J, 10 Hz). The time to ablation was recorded for each tissue mass. Following the ablation, each sample was inspected microscopically by an expert pathologist to determine the extent to which the tissue was destroyed. Results: Time to ablation ranged from 16.4 min for a 1 cm3 mass, to 69.7 min for a 3 cm3 mass. Histologic evaluation after laser ablation showed that ablation was achieved in all tissue masses, and no “unaffected” tissue was present, even for lesions with a size of 3 cm3. Conclusions: This study showed that laser ablation can be achieved for tumor lesions up to a size of 3 cm3. The results of this study can contribute to the debate regarding the limits of endoscopic management of UTUC lesions and strengthen the recommended upper limit of 2 cm3 for endoscopic treatment of tumor lesions.


2022 ◽  
Author(s):  
Adawiya Haider ◽  
Ghalib Ali ◽  
Mohammed Haider ◽  
Amer Dheyab ◽  
Amin Thamir

Abstract Pulsed Laser Deposition (PLD) technique was performed to deposit the pure Titanium oxide (TiO2) nanoparticles on the glass substrate of temp. (100 - 400°C), using the doubled frequency of Nd: YAG laser wavelength of 532nm at (10) Hz rate, 10 nanosecond duration pulses and a constant laser energy 800 mJ. The optical measurements obtained by UV-Vis transmittance on deposited TiO2 films indicate the highest transparency in the visible wavelength region with an average transmittance of 80%. Estimated the relationship between the refractive index of TiO2 thin films with substrate temperature was n = 2.49 at 400 oC. Moreover, the calculated empirical relation between the energy gap and refractive index have similar to the work results.


Author(s):  
Sylwia Ryszczyńska ◽  
Tomasz Grzyb

Abstract Recently, the up-converting (UC) materials, containing lanthanide (Ln3+) ions have attracted considerable attention because of the multitude of their potential applications. The most frequently investigated are UC systems based on the absorption of near-infrared (NIR) radiation by Yb3+ ions at around 975-980 nm and emission of co-dopants, usually Ho3+, Er3+ or Tm3+ ions. UC can be observed also upon excitation with irradiation with a wavelength different than 975-980 nm. The most often studied systems capable of UC without the use of Yb3+ ion are those based on the properties of Er3+ ions, which show luminescence resulting from the excitation at 808 or 1532 nm. However, also other Ln3+ ions are worth attention. Herein, we focus on the investigation of the UC phenomenon in the materials doped with Ho3+ ions, which reveal unique optical properties upon the NIR irradiation. The SrF2 NPs doped with Ho3+ ions in concentrations from 4.9% to 22.5%, were synthesized by using the hydrothermal method. The structural and optical characteristics of the obtained SrF2:Ho3+ NPs are presented. The prepared samples had crystalline structure, were built of NPs of round shapes and their sizes ranged from 16.4 to 82.3 nm. The NPs formed stable colloids in water. Under 1156 nm excitation, SrF2:Ho3+ NPs showed intense UC emission, wherein the brightest luminescence was recorded for the SrF2:10.0%Ho3+ compound. The analysis of the measured lifetime profiles and dependencies of the integral luminescence intensities on the laser energy allowed proposing the mechanism, responsible for the observed UC emission. It is worth mentioning that the described SrF2:Ho3+ samples are one of the first materials for which the UC luminescence induced by 1156 nm excitation was obtained.


2022 ◽  
Author(s):  
Yunze Li ◽  
Dongzhe Zhang ◽  
Bo Zhao ◽  
Weilong Cong

Abstract Inconel 718 has been widely used in aerospace, nuclear and marine industries due to excellent high-temperature mechanical properties and corrosion resistance. In recent years, laser directed energy deposition (DED) become a competitive method in the fabrication of Inconel 718 coatings. Compared with other surface coating processes, laser DED has the advantage of extremely fine-grained structures, strong metallurgical bonding, and high density. However, the hardness and wear resistance of Inconel 718 coatings still need to be improved. To further improve these properties, ceramic reinforced Inconel 718 coatings have been investigated. Compared with ex-situ ceramic reinforcements, the in-situ synthesized reinforcements have the advantage of refined ceramic particle size, uniform distribution, and low thermal stress. B4C was a preferable additive material to fabricate in-situ synthesized multi-component ceramic reinforced Inconel 718 coatings. The addition of B4C could form a large number of borides and carbides as ceramic reinforcements. In addition, the in-situ reactions between Inconel 718 and B4C could release heat during the fabrication, thereby promoting the melting of material powders. However, there are currently no investigations on the in-situ synthesis mechanisms, microstructure, and mechanical properties of laser DED fabricated B4C-Inconel 718 coatings. In this study, the effects of B4C on the properties of Inconel 718 coatings were investigated. Results show that Ni3B, NbB, and Cr3C2 phases were formed. With the addition of B4C, the size of Laves phase was refined and the porosity was decreased. The hardness and wear resistance of B4C reinforced coatings were improved by about 34% and 28%, respectively.


2022 ◽  
Author(s):  
Shankar Ghosh ◽  
Anurag Chauhan ◽  
Rohan Pattankar

2022 ◽  
Vol 29 (1) ◽  
pp. 013301
Author(s):  
E. Eftekhari-Zadeh ◽  
M. S. Blümcke ◽  
Z. Samsonova ◽  
R. Loetzsch ◽  
I. Uschmann ◽  
...  

Author(s):  
Jung-Hae Cho

The pulsed photoangiolytic 532-nm potassium-titanyl-phosphate (KTP) laser has emerged in recent years as an efficacious treatment modality for vocal fold lesions. It also has broadened the indications for other laryngeal laser surgery. Features of KTP laser that it is a fiber-based delivery system and its energy is selectively absorbed by oxyhemoglobin make it suitable for office-based laryngeal procedures. An office-based KTP laser surgery provides an alternative management option for benign laryngeal diseases and can be performed comfortably under flexible endoscopic guidance which is placed through the nose of a fully awake patient. Office-based laryngeal surgery with a KTP laser can alleviate the need for general anesthesia. However, there are some limitations to apply due to reduced visual precision and the fact that the vocal folds are moving during procedures. Clinicians should carefully weigh the advantages and disadvantages of office-based procedures before a treatment option is selected. Patient selection and standardized laser energy parameters may help in decreasing complications and improving the treatment results.


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