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Toxic Effects and Biodistribution of Ultrasmall Gold Nanoparticles *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Gunter Schmid, Wolfgang G. Kreyling, Ulrich Simon
Another method, characterizing the Au55 core in Au55(PPh3)12Cl6, is to study the relaxation behavior of excited electrons and to compare it with other AuNPs [79]. Femtosecond laser spectroscopy is the corresponding technique. The relaxation time depends on the electron–phonon coupling and on the electron surface collision of electrons. The experimental results concerning the femtosecond laser spectroscopy of AuNPs of different sizes are shown in Fig. 15.13 [79]. Weakening of the electron-phonon coupling dominates in large particles slowing down electronic relaxation (see Fig. 15.13, 15 nm particle). The 1.4 nm Au55 nucleus is characterized by strong surface collisions, making relaxation faster. In the case of the 0.7 nm AuNP (Au13), the extremely slow relaxation behavior arises from the fact that the electrons are strictly located in the Au-Au bonds.
The eye and orbit
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
In the last three decades, eye surgery has become a microsurgical specialty. Cataract surgery has been transformed by changes in local anaesthesia, implants, phacoemulsification and small-incision surgery, which allows compressible/fold- able silicone or acrylic implants to be inserted through a 2-mm incision. The implant power can be more accurately measured by new formulae and the use of A-scan ultrasonography or laser wavefront biometry, and multifocal and accommodative lenses are now available. An even more recent advance in cataract surgery is the development of femtosecond laser technology, which allows extremely controlled corneal incisions, lens capsule opening and lens fragmentation to be achieved automatically together with the facility to adjust the shape of the cornea at the time of surgery to improve visual outcome for some patients. The extent to which this technology improves long-term visual outcomes remains to be seen.
Patterned Sapphire and Chip Separation Technique in InGaN-Based LEDs
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
To study laser scribing, samples was grown on 430-μm-thick 2-in. (0001) sapphire substrates using MOCVD under the same growth conditions [62]. The layer structures for LEDs with a total thickness of about 6 μm consist of undoped GaN/Si-doped n-GaN, five pairs of InGaN/GaN MQW, and Mg-doped p-GaN. Devices of 260 μm × 670 μm dimensions were fabricated by a normal side view LED chip process using ITO transmittance for p-contact and Cr/Au metals for n-contact. After that, the sapphire substrate was thinned to about 80 μm thickness by using backside lapping and polishing. Two lasers, with nanosecond and femtosecond laser pulses, were used to scribe grooves on the back of the thinned sapphire substrates. The nanosecond pulse laser has a wavelength of 355 nm, a repetition rate of 50 kHz, a pulse duration of 30 ns, and an output power of 0.4 W. The corresponding values of the femtosecond pulse laser are 1045 nm, 100 kHz, 150 fs, and 0.45 W. During the laser scan, the wafer chuck moves 18 mm/s for nanosecond laser and 400 mm/s for femtosecond laser, respectively.
Long-Term Follow-Up of a 150° Arc-Length Intrastromal Corneal Ring Segment Implantation in Post-LASIK Ectasia
Published in Current Eye Research, 2023
Lucía Ibares-Frías, Luis Fernández-Vega-Cueto, Belén Alfonso-Bartolozzi, Aranzazu Poo-López, David Madrid-Costa, José F. Alfonso
A single 150° arc-length Ferrara-type ICRS (AJL Ophthalmic, Spain) was implanted in all eyes. The optical diameter of the ICRS was 6.0 mm (AFR6) with a base of 0.8 mm. An experienced surgeon (J.F.A.) performed all the surgeries using a femtosecond laser, according to our standard procedure.16–19 We programmed the laser software to create a tunnel diameter of 5.8 mm (inner) and 6.8 mm (outer). An incision was performed at the steepest meridian, and the ICRS was implanted and positioned on the flattest meridian. Preoperative medication included 0.3% ciprofloxacin three times daily for the three days before surgery. Postoperative medication comprised antibiotics (ciprofloxacin, 0.3%) and steroid eye drops (dexamethasone, 0.1%) three times daily for 2 weeks. Subsequently, the dose was tapered off over the following 2 weeks.
Sterile Excimer Laser Shaped Allograft Corneal Inlay for Hyperopia: One-year Clinical Results in 28 Eyes
Published in Current Eye Research, 2021
Cafer Tanriverdi, Ayse Ozpinar, Sezer Haciagaoglu, Aylin Kilic
Refractive lenticules made of human tissue implantation were enounced as a tissue additive method in 1966 by Barraquer,14 but they have fallen out of favor because of the difficulties associated in the recovery of human donor tissue and the poor refractive predictability due to the lack of process control at that time.12,15 Here, hyperopia tissue addition procedures steepen the anterior corneal surface and optical power of the cornea without creating a significant transition zone in the periphery known from laser ablation procedures.16,17 Recently, some authors reported that femtosecond laser technology facilitates alternative solutions for tissue additive procedures. For example, the extracted lenticule in SMILE for myopia was implanted into an intrastromal layer in a patient with hyperopia to cause steepening of the anterior corneal curvature.18 The postoperative refractive correction after allograft SMILE lenticule implantation remains unclear. Sun et al.19 reported that transplanting an autologous lenticule by SMILE for hyperopia might be safe, effective, and stable, but the predictability of the procedure must be improved.
Isolated Capsulorhexis Flap Technique in Femtosecond Laser-Assisted Cataract Surgery to Protect the Corneal Endothelial Cells
Published in Journal of Investigative Surgery, 2019
Shaowei Li, Xu Chen, Jun Zhao, Man Xu, Zhouxing Yu
Decompensation of corneal endothelial cells (CECs) is one of the most serious complications in cataract surgery which often presented with cornea edema and loss transparency, resulted in pseudophakic bullous keratopathy that led to corneal transplantation required.(1) This affliction occurs especially in cases with low CEC counts preoperatively, such as Fuchs endothelial dystrophy or previous ocular surgeries. All surgeons try to reduce the loss of corneal endothelial cells in these cases, to ensure a less traumatic surgical procedure and decrease complication rates(2,3). The chop technique, ophthalmic viscoelastic devices (OVD) and the higher-efficacy phacoemulsification platform had been developed to minimize damage to the CECs(4–6). Femtosecond laser techniques have become popular in recent years and have been used in cataract surgery to perform lens fragmentation, anterior capsulotomy, and self-sealing corneal incisions(7).