Compact 20-pass thin-disk multipass amplifier stable against thermal lensing effects and delivering 330 mJ pulses with M2 < 1.17

We report on an Yb:YAG thin-disk multipass amplifier delivering 100 ns long pulses at a central wavelength of 1030 nm with an energy of 330 mJ at a repetition rate of 100 Hz. The beam quality factor at the maximum energy was measured to be M2 < 1.17. The small signal gain is 21.7, and the gain at 330 mJ was measured to be 6.9. The 20-pass amplifier is designed as a concatenation of stable resonator segments in which the beam is alternately Fourier transformed and relay-imaged back to the disk by a 4f-imaging optical scheme stage. The Fourier transform propagation makes the output beam robust against spherical phase front distortions, while the 4f-stage is used to compensate the thermal lens of the thin-disk and to reduce the footprint of the amplifier.

Development of hybrid feature learner model integrating FDOSM for golden subject identification in motor imagery

Brain-computer interfaces (BCIs) based on motor imagery (MI) face challenges due to the complex nature of brain activity, nonstationary and high-dimensional properties, and individual variations in motor behaviour. The identification of a consistent "golden subject" in MI-based BCIs remains an open challenge, complicated by multiple evaluation metrics and conflicting trade-offs, presenting complex Multi-Criteria Decision Making (MCDM) problems. This study proposes a hybrid brain signal decoding model called Hybrid Adaboost Feature Learner (HAFL), which combines feature extraction and classification using VGG-19, STFT, and Adaboost classifier. The model is validated using a pre-recorded MI-EEG dataset from the BCI competition at Graz University. The fuzzy decision-making framework is integrated with HAFL to allocate a golden subject for MI-BCI applications through the Golden Subject Decision Matrix (GSDM) and the Fuzzy Decision by Opinion Score Method (FDOSM). The effectiveness of the HAFL model in addressing inter-subject variability in EEG-based MI-BCI is evaluated using an MI-EEG dataset involving nine subjects. Comparing subject performance fairly is challenging due to complexity variations, but the FDOSM method provides valuable insights. Through FDOSM-based External Group Aggregation (EGA), subject S5 achieves the highest score of 2.900, identified as the most promising golden subject for subject-to-subject transfer learning. The proposed methodology is compared against other benchmark studies from various key perspectives and exhibits significant novelty in several aspects. The findings contribute to the development of more robust and effective BCI systems, paving the way for advancements in subject-to-subject transfer learning for BCI-MI applications.

Detrimental effects of period-chirped gratings in pulse compressors

We present a comprehensive simulative and experimental investigation of how period-chirped pulse compression gratings affect the compressed pulses. A specifically developed ray-tracing tool was used for the simulative investigations. It is shown that the chirp creates a characteristic spatio-spectral error pattern, which leads to a degradation of the beam quality and an increase of the pulse duration. The experimental investigations, for which both a narrow-bandwidth continuous-wave and a pulsed laser beam were guided through a Treacy-compressor comprised of period-chirped gratings, confirm the simulation results and present methods on how to identify the chirp's characteristic error pattern in practice.

Expression of Concern: The controlled synthesis and DFT investigation of novel (0D)-(3D) ZnS/SiO2 heterostructures for photocatalytic applications

Expression of Concern for 'The controlled synthesis and DFT investigation of novel (0D)-(3D) ZnS/SiO2 heterostructures for photocatalytic applications' by Mohamed F. Sanad et al., RSC Adv., 2021, 11, 22352-22364, https://doi.org/10.1039/D1RA02284A.

Injection-seeded high-power Yb:YAG thin-disk laser stabilized by the Pound-Drever-Hall method

We demonstrate an injection-seeded thin-disk Yb:YAG laser at 1030 nm, stabilized by the Pound-Drever-Hall (PDH) method. We modified the PDH scheme to obtain an error signal free from Trojan locking points, which allowed robust re-locking of the laser and reliable long-term operation. The single-frequency pulses have 50 mJ energy (limited to avoid laser-induced damage) with a beam quality of M2 < 1.1 and an adjustable length of 55-110 ns. Heterodyne measurements confirmed a spectral linewidth of 3.7 MHz. The short pulse build-up time (850 ns) makes this laser suitable for laser spectroscopy of muonic hydrogen, pursued by the CREMA collaboration.

The educational value of ward rounds as a learning and teaching opportunity for house officers, medical officers, and registrars in Sudanese hospitals: a multi-center cross-sectional study

BACKGROUND

Ward rounds are a cornerstone in the educational experience of junior doctors and an essential part of teaching patient care. Here, we aimed to assess the doctors' perception of ward rounds as an educational opportunity and to identify the obstacles faced in conducting a proper ward round in Sudanese hospitals.

METHOD

A cross-sectional study was conducted from the 15^th to the 30^th of January 2022 among house officers, medical officers, and registrars in about 50 teaching and referral hospitals in Sudan. House officers and medical officers were considered the learners, while specialist registrars were considered the teachers. Doctors' perceptions were assessed using an online questionnaire, with a 5-level Likert scale to answer questions.

RESULTS

A total of 2,011 doctors participated in this study (882 house officers, 697 medical officers, and 432 registrars). The participants were aged 26.9 ± 3.2 years, and females constituted about 60% of the sample. An average of 3.1 ± 6.8 ward rounds were conducted per week in our hospitals, with 11.1 ± 20.3 h spent on ward rounds per week. Most doctors agreed that ward rounds are suitable for teaching patient management (91.3%) and diagnostic investigations (89.1%). Almost all the doctors agreed that being interested in teaching (95.1%) and communicating appropriately with the patients (94.7%) make a good teacher in ward rounds. Furthermore, nearly all the doctors agreed that being interested in learning (94.3%) and communicating appropriately with the teacher (94.5%) make a good student on ward rounds. About 92.8% of the doctors stated that the quality of ward rounds could be improved. The most frequently reported obstacles faced during ward rounds were the noise (70%) and lack of privacy (77%) in the ward environment.

CONCLUSION

Ward rounds have a special value in teaching patient diagnosis and management. Being interested in teaching/learning and having good communication skills were the two major criteria that make a good teacher/learner. Unfortunately, ward rounds are faced with obstacles related to the ward environment. It is mandatory to ensure the quality of both ward rounds' teaching and environment to optimize the educational value and subsequently improve patient care practice.

Simple spatially resolved period measurement of chirped pulse compression gratings

We present an easy-to-implement and low-cost setup for the precise measurement of the period chirp of diffraction gratings offering a resolution of 15 pm and reasonable scan speeds of 2 seconds per measurement point. The principle of the measurement is illustrated on the example of two different pulse compression gratings, one fabricated by laser interference lithography (LIL) and the other by scanning beam interference lithography (SBIL). A period chirp of 0.22 pm/mm² at a nominal period of 610 nm was measured for the grating fabricated with LIL, whereas no chirp was observed for the grating fabricated by SBIL, which had a nominal period of 586.2 nm.

Engineering S-scheme CuO/ZnO heterojunctions sonochemically for eradicating RhB dye from wastewater under solar radiation

In this research, S-scheme heterojunctions composed of different concentrations of CuO and ZnO nanoparticles are fabricated for eradicating rhodamine B dye under solar radiation. ZnO nanoparticles are designed through a facile sol-gel route employing Triton X-100. Spherical CuO nanoparticles of 15.2 nm and 1.5 eV band gap energy are deposited on ZnO nanoparticles in an ultrasonic bath of 300 W intensity. The physicochemical performance of the photocatalyst is explored by HRTEM, SAED, BET, XRD, DRS and PL. The in situ homogeneous growth of spherical CuO nanoparticles on ZnO active centers shifts the photocatalytic response to the deep visible region and enhances the efficiency of charge carrier separation and transportation. Among all heterojunctions, ZnCu10 containing 10 wt% CuO displays the best photocatalytic rate for expelling 93% of RhB dye within 240 min, which is twenty-fold higher than that of pristine ZnO and CuO. Reactive oxygen species are the predominant species in degrading the dye pollutant on the heterojunction surface, as shown from scrubber trapping experiments and PL spectrum of terephthalic acid. Coupling ZnO as an oxidative photocatalyst and CuO as a reductive photocatalyst generates an efficient S-scheme heterojunction with strong redox power in destructing various organic pollutants.

Engineering S-scheme Ag2CO3/g-c3N4 heterojunctions sonochemically to eradicate Rhodamine B dye under solar irradiation

The use of natural solar radiation is a low-cost significant technology for water pollution remediation and production of clean energy. In this work, S-scheme Ag₂CO₃/g-C₃N₄ heterojunctions were engineered for carefully eradicating Rhodamine B dye under natural sunlight irradiation. Solid thermal decomposition reactions generate g-C₃N₄ sheets by annealing urea at 520 °C. Ag₂CO₃ nanoparticles are directed and localized sonochemically to the active centers of g-C₃N₄ sheets. The physicochemical properties of the solid specimen were determined by PL, DRS, XRD, HRTEM, mapping, EDX, N₂-adsorption-desorption isotherm and XPS analyses. As elucidated by HRTEM, PL and DRS analyses, 5 wt% of spherical Ag₂CO₃ nanoparticles deposited on the g-C₃N₄ sheet surface and nearly equidistant from each other elevate the electron-hole separation efficiency and broaden the absorption capacity of photocatalysts. Rhodamine B dye was degraded at a rate of 0.0141 min^-1 by heterojunctions containing 5 wt% Ag₂CO₃ and 95 wt% g-C₃N₄, which is three-fold higher than that on pristine g-C₃N₄ nanosheets. Free radical scrubber experiments revealed the contribution of charge carriers and reactive oxygen species to the decomposition of RhB dye with a preferential role of positive holes and superoxide species. PL measurements of terephthalic acid and scrubber trapping experiments provide confirmatory evidence for charge diffusion via the S-scheme mechanism that accounts for the production of electron-hole pairs with strong redox power. This novel research work is contributory to manipulate the S-scheme heterojunction for efficient and low-cost wastewater treatment under natural solar irradiation.

Influence of Sapindus mukorossi extract in comparison to 17% EDTA as final root canal irrigant on the sealer penetration and microleakage of dentinal tubules

OBJECTIVE

The study evaluated the effect of Sapindus mukorossi (SM) extract as a final root canal irrigant on sealer penetration (SP) in dentinal tubules and microleakage.

MATERIALS AND METHODS

Samples were selected based on inclusion and exclusion criteria. An access opening in all samples was performed and the working length was decided using pro taper for canal finishing along with constant irrigation. Specimens were randomly divided into 3 groups. Group 1 was irrigated with 3 ml of 17% EDTA; group 2 was irrigated with SM irrigant and group 3 samples were irrigated with 0.9% saline. After obturation, samples were vertically placed in 1% methylene blue dye cut in half longitudinally, and viewed under a stereomicroscope. Analysis of SP in the dentinal tubule was assessed using scanning electron microscopy (SEM). For microleakage assessment, mean and standard deviation were reported and One-Way ANOVA was applied. SP was compared using Kruskal-Wallis' test. For inspecting the interaction between SM/EDTA and NaOCl, Fisher's exact test was applied. No statistically significant difference between microleakage in any of the tested groups was observed. The control group showed minimum leakage as compared to EDTA and SM.

RESULTS

The results displayed that there was no significant difference, (p=0.67), between dentinal tubule SP at 2 mm. A significant difference between dentinal tubule SP among groups at 5 mm was observed (p<0.05).

CONCLUSIONS

SM ethanolic extract showed comparable outcomes of smear layer removal and sealer penetration to 17% EDTA, as a final irrigant in root canal cleaning. Therefore, SM has the potential to be used as an adjuvant final irrigant in conjunction with NaOCl.

General mathematical model for the period chirp in interference lithography

We present a general analytical model for the calculation of the spatial distribution of the grating period, enabling the unification of all configurations of classical laser interference lithography (LIL) and scanning-beam interference lithography (SBIL) into one formalism. This is possible due to the consideration of Gaussian beams instead of point sources which allow for the accurate description of not only the laser's far-field but also its near-field. The proposed model enables the calculation of the grating period, the inclination and the slant of the grating lines on arbitrarily shaped substrates, originating from the interference of arbitrarily orientated and positioned Gaussian beams.

Quantitative investigation on a period variation reduction method for the fabrication of large-area gratings using two-spherical-beam laser interference lithography

Gratings produced by two-spherical-beam Laser Interference Lithography (LIL) will have a nonuniform period, and the associated period variation is larger with the increase of the substrate size. This work quantitatively investigates a noninvasive method for improving the period variation on 4-inch silicon wafers. By temporarily deforming the flexible silicon wafer using a customized concave vacuum chuck [J. Vac. Sci. Technol. B19(6), 2347 (2001)10.1116/1.1421558], we show that the fabricated gratings will have improved period uniformity, with the period variation reduced by 86% at the 1000 nm central grating period setting. This process is a simple and efficient way to achieve linear gratings without altering the LIL configuration with two spherical beams. We present experimental results on the impact of a concave vacuum chuck on the chirp reduction at different grating period settings. Then, we compare two different LIL configurations with different wavelength sources concerning their influence on the efficiency of period variation reduction. Finally, the flatness of the 4-inch silicon wafers due to the temporary bending process is verified using optical profilometry measurements.

Pound-Drever-Hall locking scheme free from Trojan operating points

The Pound-Drever-Hall (PDH) technique is a popular method for stabilizing the frequency of a laser to a stable optical resonator or, vice versa, the length of a resonator to the frequency of a stable laser. We propose a refinement of the technique yielding an "infinite" dynamic (capture) range so that a resonator is correctly locked to the seed frequency, even after large perturbations. The stable but off-resonant lock points (also called Trojan operating points), present in conventional PDH error signals, are removed by phase modulating the seed laser at a frequency corresponding to half the free spectral range of the resonator. We verify the robustness of our scheme experimentally by realizing an injection-seeded Yb:YAG thin-disk laser. We also give an analytical formulation of the PDH error signal for arbitrary modulation frequencies and discuss the parameter range for which our PDH locking scheme guarantees correct locking. Our scheme is simple as it does not require additional electronics apart from the standard PDH setup and is particularly suited to realize injection-seeded lasers and injection-seeded optical parametric oscillators.

Experimental analysis on CPA-free thin-disk multipass amplifiers operated in a helium-rich atmosphere

We present an experimental investigation on the benefits of helium as an atmospheric gas in CPA-free thin-disk multipass amplifiers (TDMPAs) for the amplification to average powers exceeding 1 kW and pulse peak powers reaching 5 GW. Both the performance of the amplifier and the properties of the amplified sub-400 fs laser pulses centred at a wavelength of 1030 nm are compared for different helium concentrations in air, outlining and quantifying the benefits of a helium-rich atmosphere. The amplification of 100 µJ pulses in an atmosphere with 60% helium instead of air led to a maximum increase in efficiency from 24% to 29%. This translated into an increase of average output power and pulse energy of 34 W (i.e +19%) and 0.34 mJ (i.e. +19%) respectively. At the same time an improvement of the beam quality from M² = 1.18 to M² = 1.14 was achieved. For the amplification of 10 µJ pulses to over 1 kW of average power an atmosphere with 33% helium led to an improved beam pointing stability by a factor of 2. Moreover, the beam propagation factor M² improved by 0.1, and the power stability improved by approximately 10%.

Mechanical dyssynchrony, a novel marker to predict long-term survival in patients with cardiac resynchronization

Background

Cardiac resynchronization therapy (CRT) is an established therapy in patients with symptomatic heart failure with reduced left ventricular ejection fraction (LVEF &lt;35%) (HFrEF) that have conduction disturbances as measured by prolonged QRS duration of &gt;130 ms. Mechanical dyssynchrony (MD) in echocardiography has not proven benefit to determine CRT indication, but is hypothesized to be of predictive value. Both MD aspects of “apical rocking” (AR) but also “septal flash” (SF) have been shown to be a predictive value in short- and medium-term follow-up in CRT, but no trial has tested long-term effects yet.

Purpose

This study investigated the impact of AR and SF on long-term survival in CRT recipients.

Methods and results

425 HFrEF patients (mean age: 63.0±10.6 years, 72.3% male, 60.7% non-ischemic etiology) with ESC guideline-derived CRT indication have been implanted and additionally investigated for MD markers at baseline as well as after a 11.5±8.0 months follow-up including long-term survival. Herein AR and/or SF were identified in 307 (72,2%) participants at baseline. During follow-up both AR and/or SF disappeared in 256 (83.4%) patients through CRT use. The overall mean survival was 95.9±52.9 months. Univariable analysis showed beneficial survival for women over men (109.1±52.4 vs. 90.9±52.4 months; p&lt;0.001). Moreover, younger (&lt;60 years) patients profit more than older patients (110.6±53.7 vs. 88.6±51.1 months; p&lt;0.001). Interestingly, patients with MD markers at baseline generally had an improved overall survival (106.2±52.0 vs. 68.9±45.4 months; p&lt;0.001), and in addition to that we found the best survival in patients with disappeared over persisting mechanical dyssynchrony echocardiography parameters in CRT (111.6±51.2 vs. 79.7±47.6 months p&lt;0.001). Multivariate analysis shows age and presence of MD at baseline to be powerful predictors for long-term survival in CRT HFrEF patients (Figures 1 and 2).

Conclusion

Novel echocardiography MD parameters before CRT implantation predict long-term survival. Moreover, long-term survival even further improves when AR and/or SF disappear through CRT in HFrEF. Our results encourage a prospective, randomized, controlled, multicenter trial to study clinical implementation of MD in CRT patients.

Funding Acknowledgement

Type of funding sources: None.

Outcome of Reduction of Subcondylar Fracture in Retromandibular Transparotid Approach

Among all mandibular fracture 25.0 to 40.0% fractures are regarded as condylar and subcondylar fracture. Commonly, reduction of subcondylar fracture is done under general anaesthesia. Different approaches were found for the surgical treatment of condylar fractures besides intraoral approaches such as the pre-auricular, submandibular, rhytidectomy, retromandibular. This is a prospective observational study which was performed to find out the outcome of retromandibular approach for subcondylar fracture treatment of mandible i.e. to find out correction of occlusion and establishment of jaw function, infection, hematoma, salivary fistula, facial nerve damage, haematoma etc complication. Surgical treatment of subcondylar fractures of 15 patients was done in Dhaka Dental College and Hospital and different private centres in Dhaka and Mymensingh, Bangladesh from January 2019 to December 2021 in retromandibular transparortid approach. The patients were evaluated for hematoma, infection, Frey's syndrome, salivary fistula, facial nerve damage, occlusion, fracture site stability, chronic pain in the fracture site and temporomandibular joint movements in the post operative period. Facial nerve injury was not observed. Postoperative swelling of parotid region developed in first two patients. Single patient developed paresis in zygomatic branch of facial nerve causing left upper eyelid muscle weak and after two weeks of physiotherapy it became normal. Salivary fistula developed in three patients which resolved spontaneously. Outcome of this approach like good anatomy and function was found in all cases. Good articular function was obtained in all the cases. By this retromandibular approach condylar fracture reduction; fixation and healing were managed comfortably. However, direct vision of facial nerve fibres has limited the risk of facial nerve injury.

Theoretical investigation on the elimination of the period chirp by deliberate substrate deformations

We present a theoretical investigation on the approach of deliberately bending the substrate during the exposure within laser interference lithography to compensate for the period chirp. It is shown that the yet undiscovered function of the surface geometry, necessary to achieve the zero-chirp case (i.e. having a perfectly constant period over the whole substrate) is determined by a first-order differential equation. As the direct analytical solution of this differential equation is difficult, a numerical approach is developed, based on the optimization of pre-defined functions towards the unknown analytical solution of the differential equation by means of a Nelder-Mead simplex algorithm. By applying this method to a concrete example, we show that an off-center placement of the substrate with respect to the point sources is advantageous both in terms of achievable period and substrate curvature and that a fourth-order polynomial can greatly satisfy the differential equation leading to a root-mean-square deviation of only 1.4 pm with respect to the targeted period of 610 nm.

High-power quasi-CW diode-pumped 750-nm AlGaAs VECSEL emitting a peak power of 29.6 W and an average power of 8.5 W

A peak output power of 29.6 W and an average output power of 8.5 W at a wavelength of 750 nm were demonstrated in quasi-CW multi-mode operation using an AlGaAs-based vertical external-cavity surface-emitting laser (VECSEL) diode-pumped at a wavelength of 675 nm. The comparatively low bandgap of the barrier material that was tuned to the pump-photon energy allowed a good compromise between low heat generation due to the quantum defect and strong absorptance of the pump radiation. The limitations for the average output power came mainly from insufficient heat flow from the intra-cavity heat spreader to the heat sink. These results show the potential for power scaling of diode-pumped VECSELs and the importance of effective heat removal.

Comprehensive theoretical analysis of the period chirp in laser interference lithography

We present a theoretical investigation on laser interference lithography used for the exposure of linear gratings. The focus is on the geometry of the arising interference lines on the substrate, in particular on their period and orientation, depending on the illumination geometry as determined by the setup. The common approach with point sources emitting spherical wavefronts is considered for the illumination. Three different cases are discussed, namely the interference between two point sources with either two convex, two concave or mixed, i.e., convex and concave wavefronts. General equations focusing mainly on the calculation of the period and the orientation of the grating lines are derived for each of the three exposure cases considering arbitrarily positioned point sources and arbitrarily shaped substrates. Additionally, the interference of symmetrically positioned point sources illuminating plane substrates is investigated, as these boundary conditions significantly simplify the derived equations.

Integration of fuzzy-weighted zero-inconsistency and fuzzy decision by opinion score methods under a q-rung orthopair environment: A distribution case study of COVID-19 vaccine doses

Owing to the limitations of Pythagorean fuzzy and intuitionistic fuzzy sets, scientists have developed a distinct and successive fuzzy set called the q-rung orthopair fuzzy set (q-ROFS), which eliminates restrictions encountered by decision-makers in multicriteria decision making (MCDM) methods and facilitates the representation of complex uncertain information in real-world circumstances. Given its advantages and flexibility, this study has extended two considerable MCDM methods the fuzzy-weighted zero-inconsistency (FWZIC) method and fuzzy decision by opinion score method (FDOSM) under the fuzzy environment of q-ROFS. The extensions were called q-rung orthopair fuzzy-weighted zero-inconsistency (q-ROFWZIC) method and q-rung orthopair fuzzy decision by opinion score method (q-ROFDOSM). The methodology formulated had two phases. The first phase 'development' presented the sequential steps of each method thoroughly.The q-ROFWZIC method was formulated and used in determining the weights of evaluation criteria and then integrated into the q-ROFDOSM for the prioritisation of alternatives on the basis of the weighted criteria. In the second phase, a case study regarding the MCDM problem of coronavirus disease 2019 (COVID-19) vaccine distribution was performed. The purpose was to provide fair allocation of COVID-19 vaccine doses. A decision matrix based on an intersection of 'recipients list' and 'COVID-19 distribution criteria' was adopted. The proposed methods were evaluated according to systematic ranking assessment and sensitivity analysis, which revealed that the ranking was subject to a systematic ranking that is supported by high correlation results over different scenarios with variations in the weights of criteria.

Nonlinear absorption in lithium triborate frequency converters for high-power ultrafast lasers

We report on an analysis of the nonlinear absorption in lithium triborate (LBO) used for second and third harmonic generation of ultrashort laser pulses at average powers in the order of kW and with sub-picosecond pulse duration. Thermographic imaging of the LBO crystals together with a simple analytical model revealed the presence of nonlinear absorption in both harmonic generation processes. Subsequent processing with a numerical model considering the nonlinear mixing, the absorption, and the heat conduction was used to estimate the absorption coefficients. Average powers exceeding 100 W in the ultraviolet and 400 W in the visible spectral range were obtained while maintaining a good beam quality by avoiding excessive nonlinear absorption.

Effect of Application of Platelet-Rich Plasma on Bone Regeneration after Removal of Jaw Cysts

Platelets are involved in regeneration at sites of bony defect, apart from their function in coagulation. An autologous preparation platelet-rich plasma gel applied to sites of bony defects after surgical treatment of jaw cyst. This case-control study was conducted in Bangabandhu Sheikh Mujib Medical University (BSMMU) in the department of Oral and Maxillofacial Surgery from September 2017 to August 2018. Total 30 patients were chosen having jaw cyst. They were divided into 2 groups; Group A and Group B, where Group A got the platelet rich plasma, after removal of the cystic lesion; and Group B got the normal usual treatment. Platelet rich plasma gel was prepared using a standardized technique and applied to the surgical site of the Group A. The differences of radiographic changes between the two groups at 6th, 12th, 18th and 24th weeks after surgery were analyzed. Study showed significant changes in early bone regeneration in group A at 12th and 18th weeks post operatively. Platelet rich plasma induces early bone regeneration and it has proven successful outcome.

Ceramic Yb:Lu2O3 thin-disk laser oscillator delivering an average power exceeding 1 kW in continuous-wave operation

We report on continuous-wave (cw) laser experiments with a high-quality and large-size Yb:Lu₂O₃ polycrystalline transparent ceramic in a thin-disk laser oscillator. An output power of up to 1190 W was achieved in multimode operation with an optical efficiency of 60.3%. In fundamental-mode operation, a cw output power of 409 W was extracted with an optical efficiency of 35.6% and a beam propagation factor of M² = 1.11.

Multi-perspectives systematic review on the applications of sentiment analysis for vaccine hesitancy

A substantial impediment to widespread Coronavirus disease (COVID-19) vaccination is vaccine hesitancy. Many researchers across scientific disciplines have presented countless studies in favor of COVID-19 vaccination, but misinformation on social media could hinder vaccination efforts and increase vaccine hesitancy. Nevertheless, studying people's perceptions on social media to understand their sentiment presents a powerful medium for researchers to identify the causes of vaccine hesitancy and therefore develop appropriate public health messages and interventions. To the best of the authors' knowledge, previous studies have presented vaccine hesitancy in specific cases or within one scientific discipline (i.e., social, medical, and technological). No previous study has presented findings via sentiment analysis for multiple scientific disciplines as follows: (1) social, (2) medical, public health, and (3) technology sciences. Therefore, this research aimed to review and analyze articles related to different vaccine hesitancy cases in the last 11 years and understand the application of sentiment analysis on the most important literature findings. Articles were systematically searched in Web of Science, Scopus, PubMed, IEEEXplore, ScienceDirect, and Ovid from January 1, 2010, to July 2021. A total of 30 articles were selected on the basis of inclusion and exclusion criteria. These articles were formed into a taxonomy of literature, along with challenges, motivations, and recommendations for social, medical, and public health and technology sciences. Significant patterns were identified, and opportunities were promoted towards the understanding of this phenomenon.

Telehealth utilization during the Covid-19 pandemic: A systematic review

During the coronavirus disease (COVID-19) pandemic, different technologies, including telehealth, are maximised to mitigate the risks and consequences of the disease. Telehealth has been widely utilised because of its usability and safety in providing healthcare services during the COVID-19 pandemic. However, a systematic literature review which provides extensive evidence on the impact of COVID-19 through telehealth and which covers multiple directions in a large-scale research remains lacking. This study aims to review telehealth literature comprehensively since the pandemic started. It also aims to map the research landscape into a coherent taxonomy and characterise this emerging field in terms of motivations, open challenges and recommendations. Articles related to telehealth during the COVID-19 pandemic were systematically searched in the WOS, IEEE, Science Direct, Springer and Scopus databases. The final set included (n = 86) articles discussing telehealth applications with respect to (i) control (n = 25), (ii) technology (n = 14) and (iii) medical procedure (n = 47). Since the beginning of the pandemic, telehealth has been presented in diverse cases. However, it still warrants further attention. Regardless of category, the articles focused on the challenges which hinder the maximisation of telehealth in such times and how to address them. With the rapid increase in the utilization of telehealth in different specialised hospitals and clinics, a potential framework which reflects the authors' implications of the future application and opportunities of telehealth has been established. This article improves our understanding and reveals the full potential of telehealth during these difficult times and beyond.

A novel BiVO3/SnO2 step S-scheme nano-heterojunction for an enhanced visible light photocatalytic degradation of amaranth dye and hydrogen production

The destruction of toxic pollutants and production of hydrogen gas on the surface of semiconductors under light irradiation is the main significance of photocatalysis. Heterojunctions with matching in band gap energy are urgently required for enhancing the redox power of the charge carriers. A step S-scheme BiVO₃/SnO₂ nano-heterojunction was carefully synthesized for a successful photodegradation of amaranth dye and photocatalytic hydrogen evolution. Tetragonal SnO₂ nanoparticles of 80 m² g^-1 surface area and distinct mesoporous structure were fabricated by a sol-gel route in the presence of Tween-80 as the pore structure directing agent. BiVO₃ nanoparticles were deposited homogeneously on the SnO₂ surface in an ultrasonic bath of power intensity 300 W. The photocatalytic efficiency in the destruction of amaranth dye soar with increasing BiVO₃ contents of up to 10 wt%. The hydrogen evolution rate reached 8.2 mmol g^-1 h^-1, which is eight times stronger than that of pristine SnO₂. The sonicated nanocomposites were investigated by XRD, BET, FESEM, HRTEM, EDS, DRS and PL techniques. The step S-scheme heterojunction with superior oxidative and reductive power is the primary key for the exceptional photocatalytic process. The PL of terephthalic acid and the scavenger trapping experiments reveal the charge migration through the step S-scheme mechanism rather than the type (II) heterojunction mechanism.

Azimuthally polarized picosecond vector beam with 1.7 kW of average output power

We report on a thin-disk multipass amplifier delivering azimuthally polarized, 7.8 ps short, laser pulses at an average power and with pulse energies of up to 1.7 kW and 5.8 mJ, respectively. High polarization purity was achieved by compensating for the arbitrary linear phase shifts that are introduced by tilted optical elements.

The controlled synthesis and DFT investigation of novel (0D)-(3D) ZnS/SiO2 heterostructures for photocatalytic applications

A ZnS/SiO2 photocatalyst was synthesized using a low-cost sol-gel wet chemical procedure. The as-synthesized ZnS/SiO2 nanocomposites with different molar ratios exhibited superior performance in the photodegradation of two organic dyes under UV irradiation, with complete degradation of both dyes after 2 hours of exposure to UV irradiation. The photocatalyst structure, microstructure, and surface area were studied using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), and nitrogen adsorption (S BET) studies. The results demonstrate that the ZnS/SiO2 photocatalyst with 15% ZnS content has a bandgap energy similar to that of ZnS alone with a higher surface area of approximately 150 m2 g-1, which effectively increases the number of active sites and improves the photocatalytic activity of the prepared material. The measured bandgap energies were compared with the theoretical values obtained using the density functional theory (DFT) method, and the values were found to be very similar, with a low error percentage. In the case of a high ZnS content (greater than 15%), active site blocking occurred, and the removal rate dropped below 50%. The obtained results indicate that the photocatalytic data are in good agreement with the experimental characterization results for the prepared materials, including the BET and XRD results, confirming a close association between the photocatalytic activity and the surface area of the fabricated photocatalyst.

Efficient and high-throughput ablation of platinum using high-repetition rate radially and azimuthally polarized sub-picosecond laser pulses

A highly productive ablation process of 100 nm thick platinum films with a processed area rate of up to 378 cm²/min is presented using radially and azimuthally polarized laser beams. This was achieved by developing a laser amplifier generating 757 fs long laser pulses at a maximum average power of 390 W and a repetition rate of 10.6 MHz with adjustable polarization states, i.e., linear, radial, and azimuthal polarization on the work piece. The pulse train emitted from the laser was synchronized to a custom-designed polygon scanner and directed into an application machine.

Diversity of Vibrio parahaemolyticus in marine fishes of Bangladesh

AIMS

To determine the occurrence, diversity, antibiotic resistance and biofilm formation of Vibrio parahaemolyticus isolated from marine fishes in Bangladesh.

METHODS AND RESULTS

A total of 80 marine fishes were obtained from the local markets and examined for the presence of V. parahaemolyticus. All the isolated V. parahaemolyticus were characterized for the presence of virulence markers, thermostable direct hemolysin (TDH) or thermostable direct hemolysin related hemolysin (TRH). Isolates were serotyped and further characterized by enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) typing to analyse the genetic diversity. Moreover, biofilm formation and antibiotic resistance patterns were also determined. About 63·75% (51/80) of the tested marine fishes were contaminated with V. parahaemolyticus. From the contaminated fishes, 71 representatives V. parahaemolyticus were isolated and none of them harboured tdh and trh virulence genes. Nine different O-groups and seven different K-types were found by serological analysis and the dominant serotype was O5:KUT. In ERIC-PCR analysis, eight clusters (A-H) were found and the most common pattern was A (46·5%). All of the isolates were resistant to ampicillin and 78·9% of isolates were resistant to streptomycin. The highest biofilm formation was found at 37°C compared to 25°C and 4°C.

CONCLUSION

Diverse V. parahaemolyticus are present in marine fishes in the local market of Bangladesh with antibiotic-resistant properties and biofilm formation capacity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The widespread prevalence of diverse V. parahaemolyticus in marine fishes is an issue of serious concern, and it entails careful monitoring to ascertain the safety of seafood consumers.

Publisher Correction: Measuring the α-particle charge radius with muonic helium-4 ions

A Correction to this paper has been published: https://doi.org/10.1038/s41586-021-03360-2.

SESAM mode-locked Yb:YAB thin-disk oscillator delivering an average power of 19 W

We report on a semiconductor saturable absorber mirror mode-locked thin-disk oscillator based on Yb:YAB delivering pulses with a duration of 462 fs at an average output power of 19.2 W and a pulse energy of 0.38 µJ.

High-quality high-throughput silicon laser milling using a 1 kW sub-picosecond laser

We report on high-quality high-throughput laser milling of silicon with a sub-ps laser delivering more than 1 kW of average laser power on the workpiece. In order to avoid heat accumulation effects, the processing strategy for high-quality laser milling was adapted to the available average power by using five-pulse bursts, a large beam diameter of 372 µm to limit the peak fluence per pulse to approximately 0.7J/cm², and a high feed rate of 24 m/s. As a result, smooth surfaces with a low roughness of S_a≤0.6µm were achieved up to the investigated milling depth of 313 µm while maintaining a high material removal rate of 230mm³/min.

Measuring the α-particle charge radius with muonic helium-4 ions

The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering¹, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle^2-5, in line with recent determinations of the proton charge radius^6-9, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties.

Ultrafast green thin-disk laser exceeding 1.4 kW of average power

We present an ultrafast laser with a near-diffraction-limited beam quality delivering more than 1.4 kW of average power in the visible spectral range. The laser is based on second harmonic generation in a lithium triborate crystal of a Yb:YAG thin-disk multipass amplifier emitting more than 2 kW of average power in the infrared.

Analysis of material concentration in step-index fibers with alumina cores produced by means of the powder-in-tube technique

Step-index fibers (SIFs) with alumina cores were fabricated employing the powder-in-tube technique. The fabricated SIFs have alumina concentrations of up to 32 mol%, which is the highest value reported so far for fibers with core diameters smaller than 25 μm. The mixing mechanisms between alumina and silica during fiber drawing were revealed by energy dispersive X-ray analysis of the neck-down area of the preform. The results of the measurements and simulations indicate that besides diffusion, fluid dynamics between softened silica and alumina powder also play an important role in the resulting alumina and silica concentrations in the fiber. The influence of different drawing parameters on the alumina and silica concentrations of the fibers is also presented.

The effect of gestational age on women's preference for quality goods

Background

It is a well-established fact that hormonal changes significantly influence the consumer behaviors and their purchase intentions. However, attention to the conspicuous buying due to the mood swings, as a result of hormonal changes, during the pregnancy have been largely ignored in the literature.

Aims

The current research aims to examine the prospective association of conspicuous purchase intentions with hormonal changes and mood swings during the pregnancy.

Methods

An experimental procedure was used to assess the data collected from pregnant women (n = 116) and the hypotheses were analyzed using recall probability and recall position measures.

Results

The hormonal changes during the pregnancy were analyzed in three stages known as pregnancy trimesters suggested by the relevant literature (Trimester-1 = 39, Trimister-2 = 36 and Trimester-3 = 41). The respondents were exposed to visual attention of specifically designed images with a unique combination of the status and functional products. The ROC values for Trimester 2 is higher in all 4 graphs (0.923, 0.960, 0.892, and 0.923) respectively than Trimester 1 and 3.

Conclusion

Findings revealed that the women purchase preferences shift as pregnancy move from one trimester to another. Women pay more attention to status products during the 2^nd trimester as compared to 1^st and 3^rd trimesters of pregnancy.

GGE biplot analysis of Line by tester for seed yield and its attributes in sunflower

Nine genetically diverse sunflower promising lines in their economic trait were crossed using line by tester mating design in 2018 spring season, to estimate per se performance, combining ability, heterosis, gene action and heritability for earliness, yield and its attributes traits. The parents involved four sunflower CMS lines namely L1 (A3), L2 (A5), L3 (A9) and L4 (A13) (called hereafter “Lines” (as female parents) and five sunflower genotypes T1 (RF9), T2 (RF10), T3 (RF11), T4 (RF14) and T5 (RF1) as male parents (called hereafter “Tester”). In 2018 and 2019 summer season, the nine parents along with their 20 F1s seeds were evaluated at Shandaweel Agricultural Research Station, ARC, Sohag Governorate, Egypt using a randomized complete blocks design with three replications. Mean squares due to parents (P), crosses (C), CMS lines (L), RF testers (T), P vs C and L x T were significant for all studied traits. A larger magnitude of non-additive gene action than additive was revealed by greater ratios (GCA/ SCA) than unity for all studied traits (except for days to 50% flowering). A5 and A13 of CMS lines and RF11 and RF14 of RF lines proved to be the best general combiners for seed weight plant-1 and one or more of its attributes traits. Moreover, the best cross combinations A13 x RF11, A13 x RF1 and A5 x RF9 performed better than other developed hybrids in view of seed weight plant-1 and one or more of its attributes, hence these F1 hybrids could further be used on commercial exploitation.

Pretreatment of sugarcane bagasse using hydrodynamic cavitation technology: Semi-continuous and continuous process

Development of new technologies for pretreatment of lignocellulosic biomass is a current research challenge. In this way, hydrodynamic cavitation (HC) was used to assist alkaline hydrogen peroxide pretreatment of sugarcane bagasse (SCB) in sequential batches (SB-HC), semi-continuous (SC-HC) and continuous (C-HC) processes. Pretreatment resulted in compositional modifications in the material, mainly regarding the cellulose and lignin contents. The released sugars after enzymatic hydrolysis resulted, on average, in 42 g and 32-35 g of glucose per 100 g of SCB for samples treated in B-HC (10 min of process) and SC-HC process (7.5 min residence time), respectively. In C-HC process, with an average residence time of 7.5 min and 3.75 min, 38-46 g and 32-38 g of glucose per 100 g of SCB were obtained respectively in enzymatic hydrolysis step. HC technology was shown as a promising alternative for pretreatment of lignocellulosic biomass in all evaluated configurations aiming to produce high value bioproducts.

Trimming method for a high-yield manufacturing of high-efficiency diffraction gratings

The tolerances in manufacturing of fully dielectric diffraction gratings based on the leaky-mode resonance in the -1st diffraction order can be challenging, especially if the grating design exhibits high diffraction efficiency (DE) only within a comparatively narrow spectral bandwidth. To gain improved control on the spectral bandwidth exhibiting high DE, we implemented a two-step etching approach within the fabrication process of the grating. First, a dry and anisotropic etching step was used for pre-shaping the grating, followed by iterative isotropic wet-etching steps using an alkaline solution (KOH) at a temperature of 90°C to adjust the maximum efficiency around the desired wavelength with high precision. This straightforward method gave us very good control on tailoring the DE as a function of the wavelength and led to the demonstration of DEs as high as 99.7±0.2% in the -1st diffraction order at a wavelength of 1030 nm and of >99% in the wavelength range between 1020 and 1070 nm. The gratings were used as cavity end mirrors of an Yb:YAG thin-disk laser, generating an output power of 145 W in fundamental mode operation (M²<1.1).

Radially polarized passively mode-locked thin-disk laser oscillator emitting sub-picosecond pulses with an average output power exceeding the 100 W level

We report on a high-power passively mode-locked radially polarized Yb:YAG thin-disk oscillator providing 125 W of average output power. To the best of our knowledge, this is the highest average power ever reported from a mode-locked radially polarized oscillator without subsequent amplification stages. Mode-locking was achieved by implementing a SESAM as the cavity end mirror and the radial polarization of the LG*₀₁ mode was obtained by means of a circular Grating Waveguide Output Coupler. The repetition rate was 78 MHz. A pulse duration of 0.97 ps and a spectral bandwidth of 1.4 nm (FWHM) were measured at the maximum output power. This corresponds to a pulse energy of 1.6 µJ and a pulse peak power of 1.45 MW. A high degree of radial polarization of 97.3 ± 1% and an M²-value of 2.16 which is close to the theoretical value for the LG*₀₁ doughnut mode were measured.

Passive compensation of the misalignment instability caused by air convection in thin-disk lasers

Wavefront distortions caused by the convection of heated ambient air in front of the laser crystal induce severe pump-power-dependent misalignment in thin-disk laser (TDL) resonators. This effect is particularly pronounced in fundamental mode operation and limits the output power when no realignment of the resonator is possible during operation. In this Letter, we present a new approach to passively compensate for this misalignment instability by exploiting the spectral dispersion of a highly efficient grating-waveguide mirror used as a cavity end-mirror in a Littrow configuration. By this, it was possible to almost triple the output power of a fundamental mode Yb:LuAG TDL pumped at 969 nm.

Fiber-integrated spectroscopy device for hot alkali vapor

We introduce an all-glass, vacuum tight, fiber-integrated and alkali compatible spectroscopy device consisting of two conventional optical fibers spliced to each end of a capillary. This is mainly realized through a decentered splicing method allowing refilling of the capillary and controlling the vapor density inside. We analyze the light guidance of the setup through simulations and measurements of the transmission efficiency at different wavelengths and show that filling it with highly reactive alkali metals is possible, and that the vapor density can be controlled reliably.

An efficient adsorption of indigo carmine dye from aqueous solution on mesoporous Mg/Fe layered double hydroxide nanoparticles prepared by controlled sol-gel route

A new approach for removal of indigo carmine blue (IC) dye which is extensively used in jeans manufacture was successfully performed on novel mesoporous [LDH] nanoparticles prepared by sol-gel route using CTAB as shape and pore directing agent. The physicochemical features were monitored by X-ray diffraction (XRD), Fourier transformer infra-red (FTIR), N₂ adsorption-desorption isotherm, Field emission electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The influence of reaction parameters affecting dye adsorption including contact time, initial dye concentration, pH and temperature were investigated. Textural analysis and HRTEM images indicate the existence of mesoporous spherical nanoparticles of size = 26 nm connected to each other's and embedded large numbers of mesopores of average pore radius = 43.5 Å. A successful adsorption of IC on LDH nanoparticles of surface area = 85.6 m²/g at various pH with maximum adsorption capacity = 62.8 mg/g at pH = 9.5. Langmuir model is more favorable to describe the adsorption of IC rather than Freundlich model which reflecting the preferential formation of monolayer on the surface of LDH. Both film diffusion and the intraparticle diffusion affect the dye adsorption. The values of enthalpy change (ΔH) for and (ΔS) are + 28.18 and + 0.118 kJ/mol, respectively indicating that the removal process is endothermic. The results indicated that LDH nanoparticles conserved a good activity even after five consecutive cycles of reuse. Our results suggest that mesoporous LDH nanoparticles are considered a potential novel adsorbent for remediation of wastewater containing IC.

Thin-disk laser operation of Ti:sapphire

We report on the first demonstration, to the best of our knowledge, of a Ti:sapphire thin-disk laser oscillator, and discuss the thermal behavior and the thermally induced lens for different sizes of the pump spot. In multimode cw operation a maximum output power of 7 W was achieved with an optical efficiency of 11%. The emission spectrum exhibits a spectral width of about 10 nm FWHM centered at a wavelength of 790 nm.

Deformable mirrors for intra-cavity use in high-power thin-disk lasers

We present deformable mirrors for the intra-cavity use in high-power thin-disk laser resonators. The refractive power of these mirrors is continuously adaptable from -0.7 m^-1 to 0.3 m^-1, corresponding to radii of curvature ranging between 2.86 m (convex) and 6.67 m (concave). The optimized shape of the mirror membrane enables a very low peak-to-valley deviation from a paraboloid deformation over a large area. With the optical performance of our mirrors being equal to that of standard HR mirrors, we were able to demonstrate the tuning of the beam quality of a thin-disk laser in a range of M² = 3 to M² = 1 during laser operation at output powers as high as 1.1 kW.

Metabolic adaptation via regulated enzyme degradation in the pathogenic yeast Candida albicans

The virulence of Candida albicans is dependent upon fitness attributes as well as virulence factors. These attributes include robust stress responses and metabolic flexibility. The assimilation of carbon sources is important for growth and essential for the establishment of infections by C. albicans. Previous studies showed that the C. albicans ICL1 genes, which encode the glyoxylate cycle enzymes isocitratelyase are required for growth on non-fermentable carbon sources such as lactate and oleic acid and were repressed by 2% glucose. In contrast to S. cerevsiae, the enzyme CaIcl1 was not destabilised by glucose, resulting with its metabolite remaining at high levels. Further glucose addition has caused CaIcl1 to lose its signal and mechanisms that trigger destabilization in response to glucose. Another purpose of this study was to test the stability of the Icl1 enzyme in response to the dietary sugars, fructose, and galactose. In the present study, the ICL1 mRNAs expression was quantified using Quantitative Real Time PCR, whereby the stability of protein was measured and quantified using Western blot and phosphoimager, and the replacing and cloning of ICL1 ORF by gene recombination and ubiquitin binding was conducted via co-immuno-precipitation. Following an analogous experimental approach, the analysis was repeated using S. cerevisiaeas a control. Both galactose and fructose were found to trigger the degradation of the ICL1 transcript in C. albicans. The Icl1 enzyme was stable following galactose addition but was degraded in response to fructose. C. albicans Icl1 (CaIcl1) was also subjected to fructose-accelerated degradation when expressed in S. cerevisiae, indicating that, although it lacks a ubiquitination site, CaIcl1 is sensitive to fructose-accelerated protein degradation. The addition of an ubiquitination site to CaIcl1 resulted in this enzyme becoming sensitive to galactose-accelerated degradation and increases its rate of degradation in the presence of fructose. It can be concluded that ubiquitin-independent pathways of fructose-accelerated enzyme degradation exist in C. albicans.

Novel thin-disk oscillator concept for the generation of radially polarized femtosecond laser pulses

We report on the first demonstration of a radially polarized passively mode-locked thin-disk oscillator. Radial polarization was achieved by the use of a novel circular grating waveguide output coupler. We showed mode-locked operation up to a maximum average output power of 13.3 W with an optical efficiency of 21.8%. The degree of radial polarization of the emitted beam was measured to be 97±1%. The laser system generated pulses with a duration of 907 fs and an energy of 316 nJ corresponding to a peak power of 0.35 MW. To the best of our knowledge, these values exceed the performance of previously reported radially polarized mode-locked oscillator systems.

2.5 W continuous wave output at 665 nm from a multipass and quantum-well-pumped AlGaInP vertical-external-cavity surface-emitting laser

An output power of 2.5 W at a wavelength of 665 nm was obtained from a quantum-well (QW) and multipass-pumped AlGaInP-based vertical-external-cavity surface-emitting laser operated at a heat sink temperature of 10°C. Intracavity frequency doubling resulted in an output power of 820 mW at a wavelength of 333 nm. To the best of our knowledge, these are the highest continuous wave output powers from this type of laser both at the fundamental wavelength and in frequency-doubled operation. In fundamental wavelength operation, further power scaling by increasing the pump-spot size increased the output power to 3.3 W. However, at this power level, the laser was highly unstable. When the laser was operated at 50% pump duty cycle, a reproducible and stable peak output power of 3.6 W was obtained. These results demonstrate the potential of optical QW pumping combined with multipass pumping for the operation of AlGaInP-based semiconductor disk lasers.

Highly efficient 400 W near-fundamental-mode green thin-disk laser

We report on the efficient generation of continuous-wave, high-brightness green laser radiation. Green lasers are particularly interesting for reliable and reproducible deep-penetration welding of copper or for pumping Ti:Sa oscillators. By intracavity second-harmonic generation in a thin-disk laser resonator designed for fundamental-mode operation, an output power of up to 403 W is demonstrated at a wavelength of 515 nm with almost diffraction-limited beam quality. The unprecedented optical efficiency of 40.7% of green output power with respect to the pump power of the thin-disk laser is enabled by the intracavity use of a highly efficient grating waveguide mirror, which combines the functions of wavelength stabilization and spectral narrowing, as well as polarization selection in a single element.