Magnesium Nanoparticle Synthesis from Powders via Pulsed Laser Ablation in Liquid for Nanocolloid Production

Magnesium nanoparticles of various mean diameters (53–239 nm) were synthesised in this study via pulsed laser ablation in liquid (PLAL) from millimetre sized magnesium powders within isopropyl alcohol. It was observed via a 3 × 3 full factorial design of experiments that the processing parameters can control the nanoparticle distribution to produce three size-distribution types (bimodal, skewed and normal). Ablation times of 2, 5, and 25 min where investigated. An ablation time of 2 min produced a bimodal distribution with the other types seen at higher periods of processing. Mg nanoparticle Ultraviolet–Visible spectroscopy (UV–Vis) absorbance at 204 nm increased linearly with increasing ablation time, indicating an increase in nanoparticle count. The colloidal density (mg/mL) generally increased with increasing nanoparticle mean diameter as noted via increasing UV–Vis absorbance. High laser scan speeds (within the studied range of 3000–3500 mm/s) tend to increase the nanoparticle count/yield. For the first time, the effect of scan speed on colloidal density, UV–Vis absorbance and nanoparticle diameter from metallic powder ablation was investigated and is reported herein. The nanoparticles formed dendritic structures after being drop cast on aluminium foil as observed via field emission scanning electron microscope analysis. Dynamic light scattering was used to measure the size of the nanoparticles. Magnesium nanoparticle inks show promise for use in the fabrication conductive tracks or thermal insulation in electronics.

Magnesium Nanoparticle Synthesis From Powders Via Pulsed Laser Ablation In Liquid For Wearables and Flexible Sensor Technologies

Magnesium nanoparticles of various mean diameters (53 – 239 nm) were synthesized herein via Pulsed Laser Ablation in Liquid (PLAL) from millimeter sized magnesium powders within iso-propyl alcohol. It was observed via a 3x3 full factorial DOE that the processing parameters can control the nanoparticle distribution to produce three size-distribution types (bimodal, skewed and normal). Ablation times of 2, 5, and 25 minutes where investigated. An ablation time of 2 minutes produced a bimodal distribution with the other types seen at higher periods of processing. Mg nanoparticle UV-Vis absorbance at 204 nm increased linearly with increasing ablation time, indicating an increase in nanoparticle count. The colloidal density (mg/ml) generally increased with increasing nanoparticle mean diameter as noted via increasing UV-vis absorbance. High la-ser scan speeds (within the studied range of 3000 - 3500 mm/s) tend to increase the nanoparticle count/yield. For the first time, the effect of scan speed on colloidal density, UV-vis absorbance and nanoparticle diameter from metallic powder ablation was investigated and is reported herein. The nanoparticles formed dendritic structures after being drop cast on aluminum foil as observed via FESEM analysis. Dynamic light scattering was used to measure the size of the nanoparticles. Magnesium nanoparticles have promising use in the fabrication of wearables, such as in conductive tracks or battery electrodes, owing to their low heat capacity, high melting point and bio-compatibility.

A tertiary centre experience comparing new temperature-controlled high-power short-duration ablation technology with standard radiofrequency and cryo-energy ablation

Introduction Pulmonary vein isolation (PVI) is an established treatment strategy for atrial fibrillation (AF). Radiofrequency (RF) ablation technology has evolved over the last decade with the very high-power short-duration (vHPSD) temperature-controlled ablation approach emerging as the latest development. The aim of this study was to determine the procedural efficacy, metrics and safety of vHPSD ablation with conventional power-controlled RF (PCRF) ablation and cryo-energy ablation (CRYO). Methods A prospective single tertiary centre analysis was performed on patients undergoing first time PVI ablation from 2019 to 2020. The population was divided in to 4 treatment arms; vHPSD, high-power short-duration (HPSD), PCRF and CRYO. Demographics, clinical and procedural metrics such as PVI duration, ablation time and sedation requirement were collated. Patients were monitored for perioperative complications. Results One hundred patients underwent ablation with 25 cases conducted in each arm. Complete PVI was attained in all study subjects. For the vHPSD group, PVI procedural duration, ablation and fluoroscopy times were 71.7±6.35 min, 9.21±0.76 min and 15.1±1.50 min respectively. The HSPD group exhibited total PVI, burn and fluoroscopy times of 90.2±5.59 min (p=0.03), 10.3±2.40 min (p<0.0001) and 34.1±1.67 min (p=0.1) respectively. In comparison, the PCRF group exhibited longer procedure duration, ablation and fluoroscopy times of 93.3±6.50 min (p=0.01), 15.2±1.73 min (p<0.0001), 37.8±2.47 min (p=0.870). Whereas procedural and fluoroscopy times of 96.3±7.1 min (p=0.01) and 18.8±1.31 (p=0.05) were observed in the cryo-ablation group. Procedural doses of morphine and midazolam for the vHPSD, HPSD, PCRF and CRYO group were 11.3 mg + 4.00 mg, 15.5 mg (p=0.0003) + 9.33 mg (p=0.0003), 15.7 mg (p=0.0002) + 8.03 mg (p=0.02), and 8.19 mg (p=0.01) + 4.84 mg (p=0.303) respectively. No adverse procedural events were recorded for the vHPSD while 2 pericardial effusions occurred in the PCRF group, 1 cardiac tamponade in the HPSD group and 2 transient ischaemic attacks in the CRYO group. Conclusion With the emergence of vHPSD RF ablation, preliminary findings indicate significant potential in reduction of procedural and ablation time. Further analysis is ongoing in order to ascertain longer-term efficacy and patient safety. FUNDunding Acknowledgement Type of funding sources: None. Intraprocedural outcomes Intraprocedural outcomes

Six-Year Follow-Up Outcomes of Catheter Ablation of Para-Hisian Accessory Pathways

Background: Ablation of para-hisian accessory pathways (APs) remains challenging due to anatomic characteristics, and a few studies have focused on the causes for recurrence of radiofrequency ablation of para-hisian APs.Objective: This retrospective single center study aimed to explore the risk factors for recurrence of para-hisian APs.Methods: One hundred thirteen patients who had para-hisian AP with an acute success were enrolled in the study. In the 6-year follow-up, 15 cases had a recurrent para-hisian AP. Therefore, 98 patients were classified into the success group, while 15 patients were classified into the recurrence group. Demographic and ablation characteristics were analyzed.Results: Gender difference was similar in two groups. The median age was 36.2 years old and was younger in the recurrence group. Maximum ablation power was significantly higher in the success group (29 ± 7.5 vs. 22.9 ± 7.8, p < 0.01). Ablation time of final target sites was found to be markedly higher in the success group (123.4 ± 53.1 vs. 86.7 ± 58.3, p < 0.05). Ablation time <60 s was detected in 12 (12.2%) cases in the success group and 7 (46.7%) cases in the recurrence group (p < 0.01). Occurrence of junctional rhythm was significantly higher in the recurrence group (25.5% vs. 53.3%, p < 0.05). No severe conduction block, no pacemaker implantation, and no stroke were reported. Junctional rhythm during ablation (OR = 3.833, 95% CI 1.083–13.572, p = 0.037) and ablation time <60 s (OR = 5.487, 95% CI 1.411–21.340, p = 0.014) were independent risk factors for the recurrence of para-hisian AP.Conclusions: With careful and accurate mapping, it is relatively safe to ablate para-hisian AP. If possible, proper extension of ablation time could reduce the recurrence rate of para-hisian APs.

Comparison of lesion characteristics between conventional and high-power short-duration ablation using contact force-sensing catheter in patients with paroxysmal atrial fibrillation

Background Transmural lesion creation is essential for effective atrial fibrillation (AF) ablation. Lesion characteristics between conventional energy and high-power short-duration (HPSD) setting in contact force-guided (CF) ablation for AF remained unclear. Methods Eighty consecutive AF patients who received CF with conventional energy setting (power control: 25–30 W, force–time integral = 400 g s, n = 40) or with HPSD (power control: 40–50 W, 10 s, n = 40) ablation were analyzed. Of them, 15 patients in each conventional and HPSD group were matched by age and gender respectively for ablation lesions analysis. Type A and B lesions were defined as a lesion with and without significant voltage reduction after ablation, respectively. The anatomical distribution of these lesions and ablation outcomes among the 2 groups were analyzed. Results 1615 and 1724 ablation lesions were analyzed in the conventional and HPSD groups, respectively. HPSD group had a higher proportion of type A lesion compared to conventional group (P < 0.01). In the conventional group, most type A lesions were at the right pulmonary vein (RPV) posterior wall (50.2%) whereas in the HPSD group, most type A lesions were at the RPV anterior wall (44.0%) (P = 0.04). The procedure time and ablation time were significantly shorter in the HPSD group than that in the conventional group (91.0 ± 12.1 vs. 124 ± 14.2 min, P = 0.03; 30.7 ± 19.2 vs. 57.8 ± 21 min, P = 0.02, respectively). At a mean follow-up period of 11 ± 1.4 months, there were 13 and 7 patients with recurrence in conventional and HPSD group respectively (P = 0.03). Conclusion Optimal ablation lesion characteristics and distribution after conventional and HPSD ablation differed significantly. HPSD ablation had shorter ablation time and lower recurrence rate than did conventional ablation.

Efficacy of liver cancer microwave ablation through ultrasonic image guidance under deep migration feature algorithm

Objective: To explore the therapeutic effects of ultrasound-guided microwave ablation and radio frequency ablation for liver cancer patients. Methods: Seventy-eight patients with microwave ablation were rolled into the experimental group and 56 patients with radio frequency ablation were in the control group. This study was conducted from March 1, 2019 to June 30, 2020 in our hospital. Based on Convolutional Neural Networks (CNN) and Migration feature (MF), a new ultrasound image diagnosis algorithm CNNMF was constructed, which was compared with AdaBoost and PCA-BP based on Principal component analysis (PCA) and back propagation (BP), and the accuracy (Acc), specificity (Spe), sensitivity (Sen), and F1 values of the three algorithms were calculated. Then, the CNNMF algorithm was applied to the ultrasonic image diagnosis of the two patients, and the postoperative ablation points, complications and ablation time were recorded. Results: The Acc (96.31%), Spe (89.07%), Sen (91.26%), and F1 value (0.79%) of the CNNMF algorithm were obviously larger than the AdaBoost and the PCA-BP algorithms (P<0.05); in contrast with the control group. The number of ablation points in the experimental group was obviously larger, and the ablation time was obviously shorter (P<0.05); the experimental group had one case of liver abscess and two cases of wound pain after surgery, which were both obviously less than the control group (four cases; five cases) (P<0.05) Conclusion: In contrast with traditional algorithms, the CNNMF algorithm has better diagnostic performance for liver cancer ultrasound images. In contrast with radio frequency ablation, microwave ablation has better ablation effects for liver cancer tumors, and can reduce the incidence of postoperative complications in patients, which is safe and feasible. doi: https://doi.org/10.12669/pjms.37.6-WIT.4885 How to cite this:Riaz A, Sughra U, Jawaid SA, Masood J. Measurement of Service Quality Gaps in Dental Services using SERVQUAL in Public Hospitals of Rawalpindi. Pak J Med Sci. 2021;37(6):1693-1698. doi: https://doi.org/10.12669/pjms.37.6-WIT.4885 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.