Mode discrimination criterion for effective differential amplification in Yb-doped fiber design for high power operation

The mode discrimination criterion for single mode operation, usually considered in fiber amplifiers designed for high power operation, has been investigated and tested on three di erent fiber designs, a large pitch fiber and two symmetry free photonic crystal fibers. To have a significant collection of results, parameters like pump configuration, pump power, and amplifier length have been varied. The analysis has been carried out through the use of a custom numerical tool provided with e cient thermal and spatial amplification models. From the obtained results, it is possible to observe that the mode discrimination criterion is helpful but not strictly necessary to pledge an e ective single mode operation through di erential amplification. This fact extends the possibility for the study, as well as for the optimization, of di erent fiber designs. The use of advanced numerical analysis, which takes into consideration amplification along with thermally influenced modes guidance, becomes extremely useful for an e ective fiber design

Fe 3 O 4 nanoparticles for complex targeted delivery and boron neutron capture therapy

Magnetic Fe 3 O 4 nanoparticles (NPs) and their surface modification with therapeutic substances are of great interest, especially drug delivery for cancer therapy, including boron-neutron capture therapy (BNCT). In this paper, we present the results of boron-rich compound (carborane borate) attachment to previously aminated by (3-aminopropyl)-trimethoxysilane (APTMS) iron oxide NPs. Fourier transform infrared spectroscopy with Attenuated total reflectance accessory (ATR-FTIR) and energy-dispersive X-ray analysis confirmed the change of the element content of NPs after modification and formation of new bonds between Fe3O4 NPs and the attached molecules. Transmission (TEM) and scanning electron microscopy (SEM) showed Fe3O4 NPs’ average size of 18.9 nm. Phase parameters were studied by powder X-ray diffraction (XRD), and the magnetic behavior of Fe 3 O 4 NPs was elucidated by Mössbauer spectroscopy. The colloidal and chemical stability of NPs was studied using simulated body fluid (phosphate buffer-PBS). Modified NPs have shown excellent stability in PBS (pH = 7.4), characterized by XRD, Mössbauer spectroscopy, and dynamic light scattering (DLS). Biocompatibility was evaluated in-vitro using cultured mouse embryonic fibroblasts (MEFs). The results show us an increasing of IC50 from 0.110 mg/mL for Fe 3 O 4 NPs to 0.405 mg/mL for Fe 3 O 4 -Carborane NPs. The obtained data confirm the biocompatibility and stability of synthesized NPs and the potential to use them in BNCT. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant No AP05130947 “Setting the stage for boron neutron capture therapy of cancer in the Republic of Kazakhstan”) and Nazarbayev University “Social Policy Grant” (project title: “Research and development of the new Nano-Optical Sensor based on Polymer Optical Fiber for Near-Field Scanning Optical Microscopy”, PI: Kanat Dukenbayev). The authors also gratefully acknowledge the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (NoK4-2018-036, P02-2017-2-4), implemented by a governmental degree dated 16th of March 2013, No 211. The work was partially supported by Act 211 Government of the Russian Federation, contract No 02.A03.21.0011. This work was partially supported by the Ministry of Education and Science of the Russian Federation (Government task in SUSU 5.5523.2017/8.9)

Symmetry-free Tm-doped photonic crystal fiber with enhanced mode area

Thulium-doped fiber lasers have recently attracted a growing interest because of the possibility to combine emission around 2 $\mu$m with the high beam quality and compactness provided by the fiber medium. A key factor for power scaling of these devices, especially if operation in the short-and ultrashort-pulse regime is desired, is the availability of active fibers capable of joining large effective area and robust single-mode guiding. The strong thermo-optic effect originating from the large quantum defect of Tm ions hinders the possibility to easily find a design with such features, strongly improving the confinement of high-order modes and shrinking the mode area of the fundamental one. In this paper, a rod-type double-cladding photonic crystal fiber with inner cladding properly designed without any mirror symmetry in the cross-section is presented, and its guiding properties are thoroughly analyzed by means of numerical simulations, taking into account the effects of thermally-induced refractive index change. The results have shown that, with a careful choice of the structural parameters, the proposed fiber is capable of ensuring effective high-order mode suppression and effective area up to 3800 2 when operating under heat load of about 300 W/m

Distributed 2D temperature sensing during nanoparticles assisted laser ablation by means of high-scattering fiber sensors

The high demand in effective and minimally invasive cancer treatments, namely thermal ablation, leads to the demand for real-time multi-dimensional thermometry to evaluate the treatment effectiveness, which can be also assisted by the use of nanoparticles. We report the results of 20-nm gold and magnetic iron oxide nanoparticles-assisted laser ablation on a porcine liver phantom. The experimental set-up consisting of high-scattering nanoparticle-doped fibers was operated by means of a scattering–level multiplexing arrangement and interrogated via optical backscattered reflectometry, together with a solid-state laser diode operating at 980 nm. The multiplexed 2-dimensional fiber arrangement based on nanoparticle-doped fibers allowed an accurate superficial thermal map detected in real-time

Aortic valve replacement with right thoracotomy in a patient with sternal metastasis from renal carcinoma.

We present a clinical case of severe aortic stenosis in a 73-year-old patient symptomatic for dispnoea class NYHA III-IV. At the physical examination the patient presented a single sternal metastasis of renal carcinoma involving the sternum. Oncological stability prompted us to perform aortic valve replacement. In order to avoid median sternotomy and its complications due to the presence of sternal metastasis we successfully performed aortic valve replacement through a right minithoracotomy

Aortic valve replacement with right thoracotomy in a patient with sternal metastasis from renal carcinoma.

We present a clinical case of severe aortic stenosis in a 73-year-old patient symptomatic for dispnoea class NYHA III-IV. At the physical examination the patient presented a single sternal metastasis of renal carcinoma involving the sternum. Oncological stability prompted us to perform aortic valve replacement. In order to avoid median sternotomy and its complications due to the presence of sternal metastasis we successfully performed aortic valve replacement through a right minithoracotomy

A Case of Type I Debranching Complicated by Anastomotic Pseudoaneurysm: Do Not Ask Too Much of the Ascending Aorta.

Treatment of aortic arch aneurysm with standard open surgery is technically demanding, and associated morbidity and mortality are not insignificant. In high-risk patients, hybrid procedures with debranching and reimplantation or bypass of the aortic arch vessel followed by thoracic endovascular aortic repair (TEVAR) in the aortic arch represent a valid alternative to open surgery. However, when the ascending aorta is mildly dilated, the risk of retrograde dissection increases sharply. Here,we report a case of thoracic aortic aneurysm, with normal ascending aorta diameter, treated with Type I debranching and anterograde TEVAR complicated by anastomotic pseudoaneurysm and acute endocarditis, treated ultimately with ascending aortic repair and aortic valve replacement