Highly Damage-Resistant Thin Film Saturable Absorber Based on Mechanically Functionalized SWCNTs

Thin-film saturable absorbers (SAs) are extensively used in mode-locked fiber laser due to the robust and simple application methods that arise because SAs are alignment-free and self-standing. Single-walled carbon nanotubes (SWCNTs) are the most suitable low dimensional material uesd for SAs because of their high nonlinearity and the wavelength control of absorption based on tube diameters. The most challenging problem with the use of CNT-based thin film SAs is thermal damage caused during high power laser operation, which mainly occurs due to aggregation of CNTs. We have demonstrated improved thermal damage resistance and enhanced durability of a film-type SA based on functionalization of SWCNTs, which were subjected to a mechanical functionalization procedure to induce covalent structural modifications on the SWCNT surface. Increased intertube distance was shown by X-ray diffraction, and partial functionalization was shown by Raman spectroscopy. This physical change had a profound effect on integration with the host polymer and resolved aggregation problems. A free-standing SA was fabricated by the drop casting method, and improved uniformity was shown by scanning electron microscopy. The SA was analyzed using various structural and thermal evaluation techniques (Raman spectroscopy, thermogravimetric analysis, etc.). Damage tests at different optical powers were also performed. To the best of our knowledge, a comprehensive analysis of a film-type SA is reported here for the first time. The partially functionalized SWCNT (fSWCNT) SA shows significant structural integrity after intense damage tests and a modulation depth of 25.3%. In passively mode-locked laser operation, a pulse width of 152 fs is obtained with a repetition rate of 77.8 MHz and a signal-to-noise ratio of 75 dB. Stable operation of the femtosecond fiber laser over 200 h verifies the enhanced durability of the fSWCNT SA.

Comparison of Operative Outcomes Between Monopolar and Bipolar Coagulation in Hepatectomy: A Propensity Score-Matched Analysis in a Single Center

Background: Various hemostatic devices have been utilized to reduce blood loss during hepatectomy. Nonetheless, a comparison between monopolar and bipolar coagulation, particularly their usefulness or inferiority, has been poorly documented. The aim of this study is to reveal the characteristics of these hemostatic devices.Methods: A total of 264 patients who underwent open hepatectomy at our institution from January 2009 to December 2018 were included. Monopolar and bipolar hemostatic devices were used in 160 (monopolar group) and 104 (bipolar group) cases, respectively. Operative outcomes and thermal damage to the resected specimens were compared between these groups using propensity score matching according to background factors. Multivariate logistic regression analysis was performed to identify predictive factors for postoperative complications.Results: After propensity score matching, 73 patients per group were enrolled. The monopolar group had significantly lower total operative time (239 vs. 275 min; P=0.013) and intraoperative blood loss (487 vs. 790 mL; P<0.001). However, the incidence rates of ascites (27.4% vs. 8.2%; P=0.002) and grade ≥3 intra-abdominal infection (12.3% vs. 2.7%; P=0.028) were significantly higher in the monopolar group. Thermal damage to the resected specimens was significantly longer in the monopolar group (4.6 vs. 1.2 mm; P<0.001). Use of monopolar hemostatic device was an independent risk factor for ascites (odds ratio, 5.626, 95% confidence interval 1.881–16.827; P=0.002) and severe intra-abdominal infection (odds ratio, 5.905, 95% confidence interval 1.096–31.825; P=0.039).Conclusions: Although monopolar devices have an excellent hemostatic ability, they might damage the remnant liver. The use of monopolar devices can be one of the factors that increase the frequency of complications.

Experimental justification for prompt neutralization of traumatic action of thermal exo- and endogenous damage factors (morphological features)

Objective: morphological substantiation of efficiency of prompt neutralization of traumatic action of exogenous and endogenous damage factors in burn injuries in experimental conditions. After simulating the burns on 60 rats, the traumatic hyperthermic damage factors in the main group were immediately neutralized by a gauze napkin soaked in water. Depending on its duration, the animals were divided into subgroups. Such applications were not performed on the control group. The study involved histological examination of tissues. Animals of the main groups had the presence of histologically confirmed skin appendages with a formed scar of connective tissue without signs of inflammation. In animals of the control group there were no skin appendages, which indicates a deeper thermal damage to tissues and the impossibility of self-epithelialization of wounds. These results confirm the importance and necessity of prompt neutralization of the traumatic effect of damage factors as the main elements of burn depth formation.

Scanner-Assisted CO2 Laser Fissurectomy: A Pilot Study

Introduction: Surgery for chronic anal fissure is challenging for every proctologist. Solving the pain by guaranteeing rapid and effective healing is the objective, but what is the price to pay today in functional terms? Though this result is nowadays partially achievable through interventions that include the execution of an internal sphincterotomy among the procedures, it is necessary to underline the high rate of patients who can present faecal incontinence. The aim of this study is to explore the effectiveness of scanner-assisted CO2 laser fissurectomy.Methods: From April 2021 to September 2021, all consecutive patients who affected by chronic anal fissure suitable for surgery, meeting the inclusion and exclusion criteria, were evaluated. All planned data were recorded before surgery, then at 24 h, 1 week, and 1 month follow-up. A scanner-assisted CO2 laser was used in this study to achieve a smooth and dried wound with a minimal tissue thermal damage, to ensure good postsurgical pain control, rapid and functional, elastic and stable healing, and to prevent potential relapses. Paracetamol 1 g every 8 h was prescribed for the first 24 h and then continued according to each patient's need. Ketorolac 15 mg was prescribed as rescue.Results: Mean pain intensity ≤3, considered as the principal endpoint, was recorded in 26 out of the 29 patients who enrolled in the study with a final success rate of 89.7% at 1-month follow-up. Pain and anal itching showed a statistically significant reduction while bleeding, burning, and maximum pain, and REALIS score showed a reduction too at the end of the follow-up period. Reepithelisation proved to be extremely fast and effective: 22 of 29 (75.9%) showed a complete healing and 5 showed a partial reepithelisation at 1-month follow-up.Discussion: Outcomes of this study showed that it is undoubtedly necessary to change the surgical approach in case of anal fissure. The internal sphincterotomy procedure must be most of all questioned, where the availability of cutting-edge technological tools must be avoided and offered only in selected cases. Scanner-assisted CO2 laser showed great results in terms of pain control and wound healing, secondary to an extremely precise ablation, vaporisation, and debridement procedures with minimal lateral thermal damage.

To the Question about the Methods Used in Combustiology Practice to Assess the Condition of Patients and Predict General and Local Complications

The aim. The article is devoted to the methods used in combustiology practice to assess the condition of patients and predict general and local complications. Results. With severe thermal trauma, there is a risk of developing life-threatening conditions in the victims, in particular, sepsis and multiple organ failure. Informative for assessing the course of burn disease is a modified scale of physiological disorders, which takes into account the syndrome of systemic inflammatory response, endogenous intoxication during periods of toxemia and septicotoxemia, and concomitant pathology. The development of intoxication in severe burn injuries requires determining the degree of severity of the process and its assessment in dynamics. The toxicity of blood plasma is studied by the resistance of red blood cell membranes in the acid hemolysis reaction, indicators of the red blood cell intoxication index, and the content of universal markers of intoxication, in particular, medium-weight molecules. Methods for biosensor indication of cytotoxic factors have also been developed. Assessment of the severity of the condition of victims with burns and monitoring the effectiveness of therapy is carried out taking into account the level of procalcitonin and presepsin. To determine the effect of the wound process on the formation of early sepsis in patients with burns in the capillary zone of thermal damage, the content of homocysteine, endothelin and nitric oxide is studied. To assess the severity of the condition of burn patients and predict the development of complications, the values of integral hematological indices are informative. Reliable data on the depth of a burn wound are obtained using thermotopometry and pH measurement of burn wounds, the method of magnetic resonance imaging. In order to assess violations and dynamics of blood supply restoration in the area of thermal damage, the method of laser Doppler flowmetry and optical tissue oximetry is used. Determination of interstitial pressure in burns of the extremities and intra-abdominal pressure in common burns is a way to predict the development of compartment syndrome. To monitor the patient's glycemic status, it is proposed to determine the level of glycosylated hemoglobin. Microbiological research data is used to predict the risk of developing general complications of burn disease, as well as – together with cytological data and methods for determining the maturity of granulation tissue – to assess the readiness of granulating wounds for autodermoplasty. Conclusion. The development of new effective ways to predict and prevent the development of complications in burns is promising

Comparative ex vivo Investigations on the Cutting Quality of the CO2 Laser and the Diode Pumped Er:YAG Laser

Objectives: A sufficient histological evaluation is a key pillar in oncological treatment, especially in situations of cancer of unknown primary. CO2 laser technology is used in clinical routine of soft tissue surgery because of its cutting quality and availability. Diode pumped solid state Er(bium):YAG laser systems promise a higher cutting efficiency and minor thermal damages. The aim of this study was to compare both laser systems with respect to their suitability for cutting soft tissue.Methods: A setup was realized which enables comparable experiments with the clinical CO2 laser (AcuPulse 40ST DUO, Lumenis) and the Er:YAG laser system (DPM 40, Pantec Biosolutions AG). Fresh mucosal samples of porcine tongues were used to determine the influence of laser power and sample velocity on cutting depth and thermal damage width for both lasers. In addition, for the Er:YAG laser, the influence of the pulse repetition rate was examined additionally. For analysis, images of histological sections were taken.Results: In all experiments, the Er:YAG laser shows a significantly higher cutting depth (P &lt; 0.0001) and less thermal damage width (P &lt; 0.0001) than the CO2 laser. For example, at an average power of 7.7 W and a sample velocity of 5 mm/s the Er:YAG laser shows a mean cutting depth of 1.1 mm compared to the CO2 laser with 500 μm. While the Er:YAG laser shows a mean thermal damage width of 70 μm compared to 120 μm. Furthermore, the Er:YAG enables the adjustment of the cutting depth and thermal damage width by varying the irradiation parameters. A decrease of the repetition rate leads to a reduction of thermal damage. For example, a repetition rate of 100 Hz results in a thermal damage width of 46 μm compared to 87 μm at 800 Hz at an average power of 7.7 W and a cutting velocity = 5 mm/s while a homogenous cutting quality can be achieved.Conclusions: In conclusion, the results of these ex vivo experiments demonstrate significant advantages of the diode pumped Er:YAG laser system for soft tissue ablation compared to the CO2 laser, in particular regarding cutting efficiency and thermal damage width.

A Comparative Modeling Study of Thermal Mitigation Strategies in Irreversible Electroporation Treatments

Irreversible electroporation (IRE), otherwise known as non-thermal pulsed field ablation (PFA), is an attractive focal ablation modality due to its ability to destroy aberrant cells with limited disruption of extracellular tissue architecture. Despite its non-thermal cell death mechanism, application of electrical energy results in Joule heating that, if ignored, can cause undesired thermal injury. Engineered thermal mitigation (TM) technologies including phase change materials (PCMs) and active cooling (AC) have been reported and tested in isolated preliminary studies to limit the risk of thermal damage, but their performance compared to one another is relatively unknown. Further, the effects of pulsing paradigm, electrode geometry, PCM composition, and chosen active cooling parameters have not been examined. Here, we develop a computational model of conventional bipolar and monopolar probes with solid, PCM-filled, or actively cooled cores and simulate clinical IRE treatments in pancreatic tissue. We find that probes with integrated PCM cores can be tuned to drastically limit thermal damage compared to traditional solid probes. Actively cooled probes, on the other hand, provide even more control over thermal effects within the probe vicinity and can altogether eliminate thermal damage. In practice, these differences in performance are tempered by the increased time, expense, and effort necessary to use actively cooled probes compared to traditional solid probes or those containing a PCM core.