Contact Laser Research Articles

Surface treatment of carbon fiber reinforced polymer for adhesive bonding with pioneer epoxy using atmospheric pressure plasma jet

A recent technique used in surface preparation for adhesive bonding is plasma treatment. In the Philippines, one of the most accessible brands of adhesive is Pioneer epoxy adhesive and, currently, there has been no existing research on the effect of plasma treatment with this adhesive. Thus, this research aims to investigate the effects of plasma pretreatment on the adhesive bonding of carbon fiber-reinforced epoxy adherents with the Pioneer epoxy adhesive. To achieve this, carbon fiber-reinforced polymers (CFRPs) samples were first plasma treated using an atmospheric pressure plasma jet (APPJ) for 0, 1, 2, and 3 min. Then, these were used to form the joint systems with three different adherent combinations. The samples were characterized using the lap shear test, contact angle measurements, optical microscope, laser microscope, and Raman spectroscopy. The result shows that the surface free energy and roughness of the CFRP increase with increasing plasma treatment time. However, the roughness is contributed by the introduction of impurities, which can weaken the bonding. Thus, when the CFRP has adhered using Pioneer epoxy adhesive, the lap shear stress (LSS) of the treated CFRP proves to be lower than that of untreated samples, with a statistically significant p-value of 0.0069. From Tukey’s honestly significant difference (HSD) test, it is concluded that plasma treating the adherent weakens the adhesive bonding of the CFRP and Pioneer adhesive joint system instead of improving it. Potential explanations for this result include the introduction of impurities by the APPJ and the presence of Mercaptan polymer in the epoxy.

Initial Experience of Contact Laser Vaporization of the Prostate Using the New Type of Fiber for Benign Prostatic Hyperplasia in a Single Institution.

The objective of this study is to evaluate our initial experience with contact laser vaporization of the prostate (CVP) using the new type of fiber for benign prostatic hyperplasia (BPH). We retrospectively evaluated 43 patients in whom CVP was performed using the new type of fiber from October 2020 to December 2021 at our institution. Total International Prostate Symptom Score (IPSS), IPSS voiding, IPSS storage, IPSS postmicturition, quality of life (QOL) index, maximum urinary flow rate (Qmax), and postvoid residual urine (PVR) were evaluated preoperatively and at 1, 3, 6, and 12 months postoperatively. Prostate volume was assessed preoperatively and at 12 months postoperatively. Complications were also evaluated. Total IPSS, IPSS voiding, IPSS postmicturition, QOL index, and PVR showed significant improvement at 1 month postoperatively. IPSS storage showed significant improvement at 3 months postoperatively (p = 0.001), and Qmax showed significant improvement at 6 months postoperatively (p = 0.021). The preoperative prostate volume was 87.8 (65.0-116.7) ml and significantly decreased to 80.5 (42.6-97.4) ml at 12 months postoperatively (p = 0.002). The complications were acute prostatitis (9.3%) and temporary urinary retention (7.0%). CVP using the new type of fiber was found to be a minimally invasive surgical procedure. There were no severe complications, and the short-term outcomes were favorable.

Low-threshold limaçon-shaped micro-cavity semiconductor lasers with an approximate ring-shaped top contact

Based on the whispering gallery mode (WGM) characteristics in the limaçon-shaped micro-cavity, we designed a micro-cavity laser with an approximate ring-shaped top electrical contact, which theoretically realized the annular current injection and low temperature rise features in the active gain region. Then we fabricated micro-cavity lasers with approximate ring-shaped top contact at different ring widths and compared them with conventional full disk-shaped top contact lasers, and observed a lower operating injection threshold current as a consequence of this relatively straightforward and feasible technique. The threshold current density of the approximate ring-shaped top contact laser is ∼0.41 kA/cm2, which is 16% lower than that of the conventional laser. Furthermore, we obtain a maximum light output peak power of 133 mW with directional emission at a far-field divergence angle of ∼38° at a full width of half maximum (FWHM).

A case of rapidly progressive prostate cancer with bone and lymph node metastasis after contact laser vaporization for benign prostatic hyperplasia

IntroductionProstate cancer is incidentally diagnosed in 6%–11% of benign prostatic hyperplasia surgeries.Case presentationA 79‐year‐old man was diagnosed with benign prostatic hyperplasia. The prostate volume was 54.5 mL, and the prostate‐specific antigen level was 7.121 ng/mL. Magnetic resonance imaging and prostate biopsy were not performed. He then underwent contact laser vaporization of the prostate. After 3 months, gross hematuria occurred, and the prostate‐specific antigen level was 62.495 ng/mL. Cystoscopy and magnetic resonance imaging revealed prostate cancer with bladder invasion. Prostate biopsy and transurethral resection were performed, revealing adenocarcinoma with a Gleason score of 5 + 5. The patient was diagnosed with prostate cancer T4N1M1b, and triplet therapy was initiated. After 6 months, the prostate‐specific antigen level was 0.037 ng/mL, and the metastases had shrunk.ConclusionVaporization for high‐grade prostate cancer can lead to rapid progression. Therefore, screening for prostate cancer before benign prostatic hyperplasia surgery is important.

Features of the Clinical Course of Urolithiasis in Combatants

The objective: to analyze the course of urolithiasis in patients who are combatants and military personnel who were not in the combat zone. Materials and methods. An analysis of the treatment results of 62 patients with urolithiasis, who underwent treatment and subsequent observation at the urological department of the State Institution “Main Medical Center of the Ministry of Internal Affairs of Ukraine” from 2014 to 2023, was conducted. All patients were divided into 2 groups. In the first group (n=30), there were patients who were active employees of the Ministry of Internal Affairs of Ukraine and did not participate in combat actions. In the second group (n=32), there were servicemen of the National Guard of Ukraine who were brought to the hospital directly from the active combat zone. Results. During the treatment, spontaneous passage of the calculus was observed in 12 (19.3%) patients, with 5 (16.6%) patients in the first group and 7 (21.8%) patients in the second group. Remote shock wave lithotripsy was performed in 15 (50%) patients in the first group and 7 (28.12%) patients in the second group. Contact laser ureterolithotripsy ranked second among surgical interventions – 10 (33.3%) patients in the first group and 13 (40.6%) patients in the second group. Percutaneous nephrolithotripsy was performed only in 1 patient in the second group. Open lithotomy was performed in 2 (3.2%) patients, specifically in 2 patients in the second group. Conclusions. Analyzing and comparing the data of both groups, it was found that there is no significant difference in the course, clinical manifestations, and treatment of patients with urolithiasis who are active participants in combat actions and patients with urolithiasis who are active employees of the Ministry of Internal Affairs of Ukraine.

Impact of hydrophobically modified cellulose nanofiber on the stability of Pickering emulsion containing insect protein.

Cellulose nanofiber (CNF) is an ideal Pickering emulsion stabilizer because of its high aspect ratio and flexibility. CNF was hydrophobically modified by dodecenyl succinic anhydride and used to stabilize the simulated food emulsion system containing insect protein. The prepared dodecenyl succinate nanofiber (D-CNFs) was characterized by contact angle and laser particle size analyzer. The stability of the emulsion system under different conditions was characterized by zeta potential and appearance observation. Lastly, in vitro digestion simulation experiments were carried out to investigate whether the addition of D-CNFs had an effect on the digestion and absorption of oil. The modification process for dodecenyl succinic anhydride to CNFs was that the system temperature was 40 °C, the system pH value was 8.5 and the reaction time was 6 h. The water contact angle of the modified CNFs increased to 83.2 ± 0.9°. D-CNFs were introduced into the simulated food emulsion system containing insect protein. The increase in the concentration of D-CNFs in the aqueous phase promoted the stability of the simulated emulsion system. Increasing the ratio of insect protein was not conducive to the stability of the emulsion. The final fat digestibility of the emulsion with D-CNFs was lower than that of the emulsion without D-CNFs. Overall, the analysis and characterization results show the potential of the modified CNF as a food simulant emulsion stabilizer containing insect protein, which can be used for the development of specific functional foods. © 2024 Society of Chemical Industry.

Pros and Cons of (NH4)2S Solution Treatment of p-GaN/Metallization Interface: Perspectives for Laser Diode.

The impact of wet treatment using an (NH4)2S-alcohol solution on the interface state of the p-GaN/Ni/Au/Pt contact system and laser diode processing was investigated. Sulfur wet cleaning resulted in reduced surface roughness and contact resistivity. The lowest specific contact resistance (ρc < 1 × 10-4 Ω·cm2) was achieved with samples treated with an (NH4)2S-isopropanol solution, whereas the highest resistivity (ρc = 3.3 × 10-4 Ω·cm2) and surface roughness (Ra = 16 nm) were observed in samples prepared by standard methods. Annealing the contact system in an N2 + O2 + H2O atmosphere caused degradation through species inter-diffusion and metal-metal solid solution formation, irrespective of the preparation method. Standard prepared substrates developed a thin GaN-Au intermediate layer at the interface after heat treatment. Enhanced adhesion and the absence of GaN decomposition were observed in samples additionally cleaned with the (NH4)2S-solvent solution. Complete oxidation of nickel to NiO was observed in samples that underwent additional sulfur solution treatment. The intensity of metal species mixing and nickel oxidation was influenced by the metal diffusion rate and was affected by the initial state of the GaN substrate obtained through different wet treatment methods.

Impact of Surface Pretreatment on the Corrosion Resistance and Adhesion of Thin Film Coating on SS316L Bipolar Plates for Proton-Exchange Membrane Fuel Cell Applications.

Coated SS316L is a potential alternative to the graphite bipolar plates (BPPs) used in proton-exchange membrane fuel cells (PEMFCs) owing to their low manufacturing cost and machinability. Due to their susceptibility to corrosion and passivation, which increases PEMFC ohmic resistance, protective and conductive coatings on SS316L have been developed. However, coating adhesion is one of the challenges in the harsh acidic environment of PEMFCs, affecting the performance and durability of BPPs. This study compares mechanical polishing and the frequently adopted chemical etchants for SS316L: Adler's, V2A, and Carpenter's etchant with different etching durations and their impact on the wettability, adhesion, and corrosion resistance of a Nb-coated SS316L substrate. Contact angle measurements and laser microscopy revealed that all etching treatments increased the hydrophobicity and surface roughness of SS316L substrates. Ex situ potentiodynamic and potentiostatic polarization tests and interfacial contact resistance analysis revealed high corrosion resistance, interfacial conductivity, and adhesion of the Nb-coated SS316L substrate pretreated with V2A (7 min) and Adler's (3 min) etchant. Increased hydrophobicity (contact angle = 101°) and surface roughness (Ra = 74 nm) achieved using V2A etchant led to the lowest corrosion rate (3.3 µA.cm-2) and interfacial resistance (15.4 mΩ.cm2). This study established pretreatment with V2A etchant (a solution of HNO3, HCl, and DI water (1:9:23 mole ratio)) as a promising approach for improving the longevity, electrochemical stability, and efficiency of the coated SS316L BPPs for PEMFC application.

Evaluation of learning curves for contact laser vaporization of the prostate using the 980 nm diode laser for benign prostatic hyperplasia.

We investigated the background of patients who underwent contact laser vaporization of the prostate (CVP) surgery and the learning curve of the operators. A total of 207 patients who underwent CVP surgery for benign prostatic hyperplasia between August 2018 and March 2023 were included in this study. Patient background, perioperative results, pre- and postoperative urinary flow tests, and complications were collected retrospectively. We enrolled 12 doctors who were divided into expert (five doctors) and novice (seven doctors) groups based on the number of TURP experiences before CVP. The median patient age was 73 years (51-92 years) and prostate volume was 56 cc (15-190 cc) with no difference between the expert and novice groups. Complications included urinary retention (eight cases), hematuria (four), urinary tract infection (four), intraoperative perforation (two), and postoperative stricture (one). Both cases of intraoperative perforation occurred in the novice group. The expert group had a significantly shorter operative time (38 vs. 66 min) and a higher operative efficacy of prostate volume divided by operative time (1.43 vs. 0.88 cc/min). Postoperatively, IPSS, quality of life scores, and postvoid residual urine volume decreased, and maximal flow rate increased; however, there was no significant difference between the groups. The expert group showed stable operative time and operative efficacy after about five to eight cases, while the novice group showed stable after about 15 cases. Our findings suggest that CVP was safely performed at our hospital, and operators with limited experience in TURP can achieve stable perioperative results.

Interrelations between factors in the development of inflammatory changes in the urinary tract in the comprehensive treatment of patients with urolithiasis

The aim of the work is to analyze the scientific literature data on the principles and state of rational antibiotic therapy use according to factors for the development of inflammatory changes in the urinary tract with the identification of the latter in the complex therapy for urolithiasis, taking into account the peculiarities of contact laser lithotripsy. The article presents the results of analytical processing of professional publications on current principles of rational antibiotic therapy in the surgical treatment for urolithiasis, taking into account factors that may influence the development of inflammatory changes in the urinary tract. It has been revealed that there is currently no clear understanding about chances of developing infectious processes during the treatment for urolithiasis of various localization, as well as the advisability and duration of using antibiotics in the comprehensive treatment of the disease. At the same time, antibiotic overuse has resulted in phenomena of resistance, side effects, and a number of other complicating factors needed to be addressed. Conclusions. An analysis of present approaches to antibacterial therapy, considering its rationality at different treatment stages, has been conducted concluding that clear criteria and indicators for the use of drugs have not been specified, but these data serve only as recommendations and have not been thoroughly examined. Data on searching for a solution to problematic aspects are also provided.

Efficacy and safety of Vibegron for the treatment of residual overactive bladder symptoms after laser vaporization of the prostate: A single-center prospective randomized controlled trial (VAPOR TRIAL).

This study aimed to evaluate the efficacy and safety of Vibegron for the treatment of residual overactive bladder (OAB) symptoms after laser vaporization of the prostate (photo-selective vaporization of the prostate, contact laser vaporization of the prostate, and thulium laser vaporization). This randomized, open-label, parallel-group, single-center superiority trial with a 12-week observation (jRCTs071190040) enrolled male patients with OAB aged 40 years or older who had undergone laser vaporization of the prostate for not less than 12 weeks and not more than 1 year earlier. Patients were allocated to receive Vibegron 50 mg once daily or follow-up without treatment for 12 weeks. Forty-seven patients were enrolled between January 2020 and March 2023. The median age (interquartile range) was 75.5 (72.5-78.5) years for the Vibegron group and 76.5 (71.0-81.0) years for the control group. The intergroup difference in the mean change (95% confidence interval) in the 24-hour urinary frequency at 12 weeks after randomization was -3.66 (-4.99, -2.33), with a significant decrease for the Vibegron group. The Overactive Bladder Symptom Score, International Prostate Symptom Score, IPSS storage score, and Overactive Bladder Questionnaire score significantly improved for the Vibegron group. Voided volume per micturition also increased for the Vibegron group. The administration of 50 mg of Vibegron once daily for 12 weeks showed significant improvement compared with follow-up without treatment in bladder storage (OAB) symptoms after laser vaporization of the prostate for symptomatic benign prostatic hyperplasia.

Initial Experience of Contact Laser Vaporization of the Prostate (CVP) for Benign Prostate Hyperplasia Patients With Hemorrhagic Risk.

Introduction: Since contact laser vaporization of the prostate (CVP) was approved by the Japanese insurance system in 2016, the use of a 980 nm diode laser system for CVP has become widespread for treating benign prostate hyperplasia (BPH) patients. Our institute has been implementing CVP for BPH since 2018, treating a total of 93 patients, including 28 with a risk of hemorrhage. This study examines the safety and efficacy of CVP treatment for BPH patients with a hemorrhagic risk. Patient and Methods: A total of 93 BPH patients with lower urinary tract symptoms (LUTS) underwent CVP between February 2018 and September 2022. All patients were on medications for BPH and were refractory to these medications. The median (mean ± SD) age was 72 (72.9±6.27), and the prostate volume was 64 (68.9±32.5). IPSS, QOL index, and OABSS scores for patients not requiring catheterization were 22 (22.1±6.38), 5 (5.24±0.74), and 6 (7±3.29), respectively. The CVP treatment was performed using a 980 nm diode laser. Of the 93 patients, 28 (30.1%) had a hemorrhage risk. This group included 13 (14.0%) who were continuously receiving anticoagulant and/or antiplatelet agents, 13 (14.0%) who temporarily stopped these medications, and 2 (2.1%) who had a hemorrhage risk due to low platelet counts (< 5.0 × 104/μL). Results: Postoperatively, 15 (16.1%) patients, including 11 who were catheterized preoperatively, needed temporary catheterization after CVP treatment. Of these, 14 had their catheters successfully removed. The IPSS score significantly decreased from 22 (22.1±6.38) to 8 (9.02±6.07) (p < 0.0001). In patients with hemorrhagic risk on anticoagulant and/or antiplatelet agents, the change in hemoglobin level before and after surgery was 0.6 g/dL, a difference that was not significant. Two of the 15 patients with hemorrhagic risk experienced hemorrhage 23 and 26 days postoperatively and underwent transurethral coagulation. Other perioperative complications classified as Clavien-Dindo Grade 2 or higher occurred in 4 (4.3%) patients. Conclusion: CVP treatment appears to be acceptable for BPH patients with hemorrhagic risk. In this study, late-onset hemorrhage occurred approximately 1 month postoperatively. Close postoperative follow-up is required.

Robot-assisted transurethral holmium ureterolithotripsy

Introduction. Currently, transurethral laser ureterolithotripsy is the standard treatment for ureteral stones. It allows you to achieve complete stone fragmentation in one-stage. We were interested in the possibility of performing ureterolithotripsy using a robotic assistant. In fact, robotic systems in medicine and surgery are becoming more and more relevant every year.Objective. To evaluate the possibilities of robot-assisted transurethral laser ureterolithotripsy, to study its effectiveness and duration in comparison with holmium lithotripsy in standard surgery, as well as to conduct a study and expert evaluation of the symptoms of surgeon fatigue in standard lithotripsy and robot-assisted lithotripsy.Materials &amp; methods. The study was conducted in 2022 and consisted of two stages. The first stage involved the development and testing of a robotic lithotripsy technique using simulators, including the author's fixation device for the ureteroscope. This device allowed to tightly fix the instrument in the "robotic arm", while maintaining the full range of necessary movements. During the second stage (clinical), the results of holmium ureterolithotripsy in standard and robotic surgeries were studied. Patients with ureterolithiasis were divided into two groups: 14 patients — standard lithotripsy and 13 patients — robotic assisted lithotripsy. The selection criteria were the presence of a single ureteral stone accessible to a semi-rigid ureteroscope.Results. According to the results of the study, robot-assisted transurethral holmium ureterolithotripsy has the greatest advantages in terms of the fatigue indicators of the surgeon during surgery. So, no significant difference was found in fragmentation time (1 gram of stone). In standard ureterolithotripsy this indicator was 63.8 min/g, and in robot-assisted ureterolithotripsy it was 57.8 min/g (p &lt; 0.1). When comparing the surgeon's fatigue scores, a significant difference between the two groups was determined. Thus, during standard surgery, the surgeon rated the shoulder numbness score at 3.50 points, while during robot-assisted surgery at 0.17 points (p &lt; 0.01).Conclusion. The study showed that transurethral contact laser ureterolithotripsy with the use of robotic assistant does not increase the surgery time, but the surgeon's fatigue factor is significantly reduced. This may indirectly contribute to reducing the risk of intra- and postoperative complications.

Preparation of epoxy resin elastic particles and their application in oil well cement

AbstractTo solve the problem of high brittleness and easy cracking of cement stone, epoxy resin powder elastic particles (HEEP) were developed to improve the elasticity of cement stone. HEEP was prepared from epoxy resin and trimeric anhydride by solution polymerization. The surface wettability and particle size of HEEP were analyzed by contact angle test and laser particle size analysis respectively. Mechanical performance tests, scanning electron microscope (SEM) analysis and x‐ray diffraction analysis were conducted on the cement stone containing HEEP. The results showed that HEEP was the target product, with a hydrophilic surface and a water contact angle of 75.2° on the HEEP surface. The particle size distribution of HEEP was uniform, and the median particle size was 36.5 μm. The initial decomposition temperature of HEEP was 300°C, indicating a good thermal stability. The stress–strain curve showed that when the HEEP dosage was 3%, 6%, and 9%, the elastic modulus of the cement stone was 6.382, 4.017, and 3.148 GPa, respectively. Compared with the blank cement without HEEP, the elastic modulus was reduced by 28.3%, 54.9%, and 64.6%, respectively. This showed that HEEP could effectively improve the elasticity of cement stone. In addition, the compressive strength and flexural strength of cement stone containing HEEP can meet the requirements of on‐site applications. SEM analysis of cement stone showed that HEEP was well filled in cement stone. When the cement stone was subjected to complex stress, HEEP could effectively buffer and disperse the stress, thereby enhancing the resistance of cement stone to external force impact.

Drone Photogrammetry for Accurate and Efficient Rock Joint Roughness Assessment on Steep and Inaccessible Slopes

The roughness of rock joints exerts a substantial influence on the mechanical behavior of rock masses. In order to identify potential failure mechanisms and to design effective protection measures, the accurate measurement of joint roughness is essential. Traditional methods, such as contact profilometry, laser scanning, and close-range photogrammetry, encounter difficulties when assessing steep and inaccessible slopes, thus hindering the safety and precision of data collection. This study aims to assess the feasibility of utilizing drone photogrammetry to quantify the roughness of rock joints on steep and inaccessible slopes. Field experiments were conducted, and the results were compared to those of 3D laser scanning in order to validate the approach’s procedural details, applicability, and measurement accuracy. Under a 3 m image capture distance using drone photogrammetry, the root mean square error of the multiscale model-to-model cloud comparison (M3C2) distance and the average roughness measurement error were less than 0.5 mm and 10%, respectively. The results demonstrate the feasibility and potential of drone photogrammetry for joint roughness measurement challenges, providing a useful tool for practitioners and researchers pursuing innovative solutions for assessing rock joint roughness on precipitous and hazardous slopes.

Pulsed exposure mode of the 445 nm semiconductor laser in phonosurgery: an experimental study

The study presents the results of an experimental study devoted to the choice of the most optimal mode of pulsed contact laser exposure of semiconductor laser with a wavelength of 445 nm in phonosurgery, which implies maximum preservation of anatomically and functionally significant structures of the larynx combined with a radical approach to the pathological process. From the standpoint of the mucoundular theory of voice formation, wave-like oscillations of the vocal folds are possible due to the mobility of the cover layer of the vocal fold (epithelium, superficial layer of the lamina propria) relative to its body (deep layer of the lamina propria, vocal muscle). Thus, any injury at the level of the integumentary layer is associated with the risk of excessive scarring and loss of the ability to wave-like sliding. Pig vocal folds, according to a number of authors, have a structure similar to human ones in terms of both histological structure and acoustic parameters, which justifies the rationality of their use as an experimental model. In a series of experiments using a 445 nm laser, contact pulsed impacts on a biological model were carried out with pulse durations of 10, 20, 50, and 100 ms, followed by evaluation of the following parameters based on the data of histological sections: the depth and width of the ablation crater, the width of the zone of lateral thermal damage. Thus, the most optimal for phonosurgical interventions modes of pulsed laser exposures with a wavelength of 445 nm are described.

Influence of microphone tilt angle on instability identification in micromilling of thin-walled Ti6Al4V

High speed micromilling is the most preferred manufacturing process to fabricate complex 3D featured thin-walled structures like stents, turbine blades, micro-fins, cabin parts etc., that are extensively used in bio-medical, energy, automobile and aerospace sectors. Fabricating thin-walled structures with high dimensional and geometrical accuracy requires chatter free machining parameters. Different sensors like accelerometer, current sensors, laser based sensors, vibration pick-ups etc. are available for capturing the vibration while machining thin-walled structures. Each sensor has its own advantages and disadvantages, like laser based sensors adds noise to response as chips fly past in the laser path and accelerometer captures deflection of both micro-cutting tool and thin-walled workpiece. Hence, In-process chatter identification is a challenging task in thin-wall micromilling. Also, the Filtering of signals to remove the noise from signals captured via contact type and laser based sensors results in loss of low-amplitude chatter data in high-speed micromilling. Consequently, there is a need of sensor, which functions similar to contact type with less or no loss in low-amplitude chatter data. The proposed work compares vibration signal captured using accelerometer and microphone at different tilt angles for radial milling of thin-walled Ti6Al4V at different radial immersion to analyse the effect of tilt-angle on chatter identification. The recorded signals from both accelerometer and microphone are analysed in time domain by estimation and comparison of statistical parameters, in frequency domain by analysing the distributed frequency and in time–frequency domain by analysing the energy of the signals. Complete characterization of the signals in time, frequency and time–frequency domain/methods indicated that microphone at 60° tilt angle can be used as an alternative sensor for chatter onset identification without loss in chatter data irrespective of cutting condition. Machined surface analysis of thin-walled structures complements the microphone as an effective chatter identification sensor.

Fragmentation and release of pristine and functionalized carbon nanotubes from epoxy-nanocomposites during accelerated weathering.

There is an increasing volume of nano-enabled materials in the market. Once composites containing nano-additives are disposed of, weathering could deteriorate their structures, releasing nanoparticles and risking exposure of humans and aquatic organisms. Composite degradation due to environmental aging continues, including structural deterioration resulting in cracking, fragmentation, and release of microplastics and nano-additives to the environment. This research aims to study the degradation and release of initially embedded nanomaterials (NMs) from composites and their toxicity. The molecular interaction of carbon nanotube (CNT)/polymer composites is critical for modifying the polymer properties. This study investigated the interactions of functional multiwalled carbon nanotube (MWCNT) composites which affect their release during accelerated weathering processes. Different epoxy-MWCNT composites were prepared by filling a polymer with pure MWCNTs and MWCNTs functionalized with acid () and amine () groups. The physical and chemical changes of aged composites were characterized by gravimetric analysis, contact angle measurements, FTIR, SEM, and laser confocal microscopy. A loss of hydrophobicity was observed for composite surfaces long before surface cracks materialized. Released polymer fragments and nanoparticles were analyzed in wash water using TEM, FTIR and Raman spectroscopy. The environmental risks for long-term use of CNT-polymer composites and the influence of fillers on the extent of chemical photodegradation depended on the combination of polymer and fillers. If nanoparticles are released from the matrix, the high surface-to-volume ratio and reactivity of NMs make them highly dynamic in environmental systems. Exposure to these released NMs could negatively affect human health and the environment. This study provides fragmentation and CNT particle release data that could describe how molecular-level interactions between functionalized CNTs and epoxy polymers affect the aging and release of CNTs. A toxicity assessment based on a reactive oxygen species (ROS) formation assay and MTS assay for cell viability and activity of the released polymer and CNT fragments and leachate showed moderate levels of cytotoxicity of released materials as compared to pristine epoxy plates.

EXPERIENCES OF CONTACT LASER VAPORIZATION OF THE PROSTATE (CVP) FOR TREATING BENIGN PROSTATIC HYPERPLASIA IN THE LOCAL HOSPITAL

(Objective) We started contact laser vaporization of the prostate (CVP) for treating benign prostatic hyperplasia at our hospital in July 2019. Forty-five patients were treated with CVP from July 2019 to April 2021. (Methods) Patients were assessed preoperatively and at one and three months after CVP treatment by using the International Prostate Symptom Score (IPSS), quality of life index (QOL index), peak urinary flow rate (Qmax), and postvoid residual urine volume (PVR). (Results) IPSS, QOL index, Qmax, and PVR significantly improved three months after CVP (p<0.05). Regarding adverse events, five patients developed early external urinary meatus strictures, two had postoperative bleeding, and three had temporary urinary retention. (Conclusions) In our hospital, elderly patients and patients who cannot discontinue an antithrombotic drug were treated by CVP for benign prostatic hyperplasia relatively safely.

Pain-related gamma band activity is dependent on the features of nociceptive stimuli: a comparison of laser and contact heat.

Painful contact heat and laser stimulation offer an avenue to characterize nociceptive pathways involved in acute pain processing, by way of evoked potentials. Direct comparisons of radiant laser and contact heat are limited, particularly in context of examining time-frequency responses to stimulation. This is important in light of recent evidence to suggest that gamma band oscillations (GBOs) represent a functionally heterogeneous measure of pain. The purpose of the current study was to investigate differences in GBOs generated in response to laser and contact heat stimulation of the nondominant forearm. Following intensity matching to pain ratings, evoked electroencephalography (EEG) responses to laser and contact heat stimulation were examined in the time-frequency domain in the same participants (19 healthy adults) across two sessions. At ∼200 ms, both contact heat and laser stimulation resulted in significant, group-level event-related synchronization (ERS) in the low gamma band (i.e., 30-60 Hz) in central electrode locations (Cc, Cz, Ci). Laser stimulation also generated ERS in the 60-100 Hz range (i.e., high gamma), at ∼200 ms, while contact heat led to a significant period of desynchronization in the high gamma range between 400 and 600 ms. Both contact heat and laser GBOs were stronger on the central electrodes contralateral to the stimulated forearm, indicative of primary somatosensory cortex involvement. Based on our findings, and taken in conjunction with previous studies, laser and contact heat stimulation generate characteristically different responses in the brain, with only the former leading to high-frequency GBOs characteristic of painful stimuli.NEW & NOTEWORTHY Despite matching pain perception between noxious laser and contact heat stimuli, we report notable differences in gamma band oscillations (GBO), measured via electroencephalography. GBOs produced following contact heat more closely resembled that of nonnoxious stimuli, while GBOs following laser stimuli were in line with previous reports. Taken together, laser and contact heat stimulation generate characteristically different responses in the brain, with only the former leading to high-frequency GBOs characteristic of painful stimuli.