Comparison of safety and effectiveness of micropulse transscleral cyclophotocoagulation and "slow cook" diode laser transscleral cyclophotocoagulation in patients with refractory open-angle glaucoma

ABSTRACT Purpose: This study aimed to compare the safety and effectiveness of intraocular pressure reduction between micropulse transscleral cyclophotocoagulation and "slow cook" transscleral cyclophotocoagulation in patients with refractory primary open-angle glaucoma. Methods: We included patients with primary open angle glaucoma with at least 12 months of follow-up. We collected and analyzed data on the preoperative characteristics and postoperative outcomes. The primary outcomes were a reduction of ≥20% of the baseline value (criterion A) and/or intraocular pressure between 6 and 21 mmHg (criterion B). Results: We included 128 eyes with primary open-angle glaucoma. The preoperative mean intraocular pressure was 25.53 ± 6.40 and 35.02 ± 12.57 mmHg in the micropulse- and "slow cook" transscleral cyclophotocoagulation groups, respectively (p<0.001). The mean intraocular pressure was reduced significantly to 14.33 ± 3.40 and 15.37 ± 5.85 mmHg in the micropulse- and "slow cook" transscleral cyclophotocoagulation groups at the last follow-up, respectively (p=0.110). The mean intraocular pressure reduction at 12 months was 11.20 ± 11.46 and 19.65 ± 13.22 mmHg in the micropulse- and "slow cook" transscleral cyclophotocoagulation groups, respectively (p<0.001). The median preoperative logMAR visual acuity was 0.52 ± 0.69 and 1.75 ± 1.04 in the micropulse- and "slow cook" transscleral cyclophotocoagulation groups, respectively (p<0.001). The mean visual acuity variation was −0.10 ± 0.35 and −0.074 ± 0.16 in the micropulse- and "slow cook" transscleral cyclophotocoagulation, respectively (p=0.510). Preoperatively, the mean eye drops were 3.44 ± 1.38 and 2.89 ± 0.68 drugs in the micropulse- and "slow cook" transscleral cyclophotocoagulation groups, respectively (p=0.017), but those were 2.06 ± 1.42 and 1.02 ± 1.46 at the end of the study in the "slow cook" and micropulse transscleral cyclophotocoagulation groups, respectively (p<0.001). The success of criterion A was not significant between both groups. Compared with 11 eyes (17.74%) in the "slow cook" transscleral cyclophotocoagulation group, 19 eyes (28.78%) in the micropulse transscleral cyclophotocoagulation group showed complete success (p=0.171). For criterion B, 28 (42.42%) and 2 eyes (3.22%) showed complete success after micropulse- and "slow cook" transscleral cyclophotocoagulation, respectively (p<0.001). Conclusion: Both techniques reduced intraocular pressure effectively.

Methods in molecular photocrystallography.

Over the last three decades, the technology that makes it possible to follow chemical processes in the solid state in real time has grown enormously. These studies have important implications for the design of new functional materials for applications in optoelectronics and sensors. Light-matter interactions are of particular importance, and photocrystallography has proved to be an important tool for studying these interactions. In this technique, the three-dimensional structures of light-activated molecules, in their excited states, are determined using single-crystal X-ray crystallography. With advances in the design of high-power lasers, pulsed LEDs and time-gated X-ray detectors, the increased availability of synchrotron facilities, and most recently, the development of XFELs, it is now possible to determine the structures of molecules with lifetimes ranging from minutes down to picoseconds, within a single crystal, using the photocrystallographic technique. This review discusses the procedures for conducting successful photocrystallographic studies and outlines the different methodologies that have been developed to study structures with specific lifetime ranges. The complexity of the methods required increases considerably as the lifetime of the excited state shortens. The discussion is supported by examples of successful photocrystallographic studies across a range of timescales and emphasises the importance of the use of complementary analytical techniques in order to understand the solid-state processes fully.

Generalized Optical Binding for Multiple Assemblies of Nanoparticles under Multiple Laser Beams.

Optical forces enable noncontact manipulation of micro- and nanoscale objects, offering diverse applications. When a laser beam irradiates multiple nanoparticles in a solvent, it induces the formation of an ordered array with a finite distance between particles due to optical binding, which results from the optical force exerted by scattered light. This scattered light extends beyond the irradiation area, facilitating interactions between spatially separated nanoparticle assemblies under multiple laser beams. However, the extension of optical binding in this context remains underexplored. In this study, we propose a concept of generalized optical binding between particle assemblies using two focal laser beams. Under carefully designed conditions, the scattered light between assemblies leads the particles to stable positions and impedes rotational dynamics driven by the circular polarization of the lasers. We demonstrate the fusion and reordering of two hexagonal assemblies, offering a blueprint for creating on-demand particle arrays through laser beam manipulation.

Standard operating protocol for utilizing energy-based devices in aesthetic practice.

BACKGROUND: Lasers and other energy-based devices are increasingly becoming popular in aesthetic practice. Many centers employ doctors or technicians to perform these procedures where treating doctor and operating doctor may be different. Hence the need for standard operative protocols, to be followed while performing these procedures to avoid mistakes, complications and to get optimum results. In the current review article, group of doctors who have worked with these energy-based devices over many years worked together and suggested the protocols to be followed for the most commonly used energy-based procedures. AIM: To provide Standard operating protocols for the operator and staff to ensure, efficacy, safety, for the patient and for the devices. METHODS: The following protocols have been drafted based on the best practices followed by the authors in their clinics and reflect their consensus opinion. The objective is to provide operating protocols in a standard format, which can be of use by practicing dermatologists and their staff. The protocols include both general guidelines for the laser room and specific protocols for different machines. The draft follows the following schema: General instructions for all the energy-based devices. Specific protocols for different devices: Laser hair removal, fractional lasers, Q-switched lasers, fractional microneedling radiofrequency and cryolipolysis. CONCLUSIONS: The protocols proposed help to maintain the uniformity and avoid complications. However, these instructions are generalized and not machine or lesion specific. There may be variations in the protocols depending on the treatment lesion and treating doctor as well as machine.

Effectiveness of KTP lasers in tooth bleaching, by comparing tooth color change after bleaching with KTP, Nd:YAG, Er:YAG, and diode laser system: A systematic review.

This systematic review evaluated the role of Potassium-titanyl-phosphate (KTP) lasers in dental bleaching by comparing tooth color change and rise in intrapulpal temperature after bleaching with KTP, Neodymium-doped yttrium aluminum garnet (Nd:YAG), Er:YAG, and diode laser system. Following were the inclusion criteria: in vitro studies in English available in full text. Articles published between 2000 and 2021 were selected. The search for was conducted on PubMed, Cochrane library/CENTRAL, Wiley online library, ProQuest, Science Direct, and Hand searching/specialized registers. Keywords were used: "Lasers" [Mesh] and "Tooth bleaching" [Mesh] using Boolean operators. A total of four articles fulfilled the inclusion criteria. The quality assessment of studies included was undertaken independently as part of data extraction process. KTP lasers demonstrated more effectiveness in attaining color change in stained teeth and showed the lowest rise in intrapulpal temperature. Based on the data obtained in the present review, the choice of bleaching treatment is directly related to the type of discoloration, activation of the bleaching agent, and esthetic requirement. Although all bleaching procedures were effective in color change, the KTP laser showed better results when compared to other laser activation. The bleaching treatment protocol is directly related to the type of discoloration, activation of the bleaching agent, and esthetic requirement. It has been demonstrated that a faster change in color can be obtained when bleaching is performed in combination with a light source, i.e., power bleaching aiming for a more in-depth change of color.

Effectiveness of the Association of Fibrin Scaffolds, Nanohydroxyapatite, and Photobiomodulation with Simultaneous Low-Level Red and Infrared Lasers in Bone Repair.

Biomaterials and biopharmaceuticals for correcting large bone defects are a potential area of translational science. A new bioproduct, purified from snake venom and fibrinogen from buffalo blood, aroused interest in the repair of venous ulcers. Expanding potential uses, it has also been used to form biocomplexes in combination with bone grafts, associated with physical therapies or used alone. The aim of this preclinical study was to evaluate low-level laser photobiomodulation (PBM) in critical defects in the calvaria of rats filled with nanohydroxyapatite (NH) associated with the heterologous fibrin biopolymer (HFB). Sixty animals were used, divided into six groups (n = 10 each): G1 (NH); G2 (HFB); G3 (NH + HFB); G4 (NH + PBM); G5 (HFB + PBM); G6 (NH + HFB + PBM). PBM simultaneously used red (R) and infrared (IR) light emission, applied intraoperatively and twice a week, until the end of the experiment at 42 days. Microtomography, bone formation can be seen initially at the margins of the defect, more evident in G5. Microscopically, bone formation demonstrated immature and disorganized trabeculation at 14 days, with remnants of grafting materials. At 42 days, the percentage of new bone formed was higher in all groups, especially in G5 (HFB, 45.4 ± 3.82), with collagen fibers at a higher degree of maturation and yellowish-green color in the birefringence analysis with Picrosirius-red. Therefore, it is concluded that the HFB + PBM combination showed greater effectiveness in the repair process and presents potential for future clinical studies.

Effects of Dislocation Filtering Layers on Optical Properties of Third Telecom Window Emitting InAs/InGaAlAs Quantum Dots Grown on Silicon Substrates.

Integrating light emitters based on III-V materials with silicon-based electronics is crucial for further increase in data transfer rates in communication systems since the indirect bandgap of silicon prevents its direct use as a light source. We investigate here InAs/InGaAlAs quantum dot (QD) structures grown directly on 5° off-cut Si substrate and emitting light at 1.5 µm, compatible with established telecom platform. Using different dislocation defect filtering layers, exploiting strained superlattices, and supplementary QD layers, we mitigate the effects of lattice constant and thermal expansion mismatches between III-V materials and Si during growth. Complementary optical spectroscopy techniques, i.e. photoreflectance and temperature-, time- and polarization-resolved photoluminescence, allow us to determine the optical quality and application potential of the obtained structures by comparing them to a reference sample-state-of-the-art QDs grown on InP. Experimental findings are supported by calculations of excitonic states and optical transitions by combining multiband k•p and configuration-interaction methods. We show that our design of structures prevents the generation of a considerable density of defects, as intended. The emission of Si-based structures appears to be much broader than for the reference dots, due to the creation of different QD populations which might be a disadvantage in particular laser applications, however, could be favorable for others, e.g., in broadly tunable devices, sensors, or optical amplifiers. Eventually, we identify the overall most promising combination of defect filtering layers and discuss its advantages and limitations and prospects for further improvements.

Real-World Experience Using a Multi-Modality System using Intense Pulsed Light, Radiofrequency Microneedling, High-Intensity Focused Ultrasound, or Thermal Radiofrequency, 808, HIFU for Skin Rejuvenation Treatment.

BACKGROUND: Medical aesthetic procedures for facial rejuvenation with laser and energy-based devices (EBDs) are rapidly increasing. The following cases highlight real-life experience using a multi-modality system with various handpieces that combine intense pulsed light (IPL), laser hair removal (808 diode), high-intensity focused ultrasound (HIFU), radiofrequency microneedling (RFM), and thermal radiofrequency (RF) for antiaging and rejuvenation treatment. Laser and RFM treatments may improve skin conditions by inducing cutaneous changes that remodel the skin matrix. METHODS: Six physicians who treat patients for skin rejuvenation reported on clinical cases from their practice using a multi-modality system with various handpieces. RESULTS: During the meeting, the advisors discussed 15 cases and agreed to select seven patients with different ages and skin phototypes receiving various treatments for photodamage of the face, neck, and décolleté. The advisors discussed why they selected the case, previous treatment, type of treatment, results, and clinical pearls. CONCLUSION: Sharing best practices in medical aesthetics using combination treatments on a single multi-modality energy-based device such as laser and MRF for facial, neck, and chest skin may support healthcare providers treating patients for skin rejuvenation to improve clinical outcomes.

The impact of photobiomodulation on angiogenic differentiation of two different dental derived stem cells using two irradiation protocols: an in vitro investigation.

The present study aimed to compare the effect of photobiomodulation with different energy densities on the angiogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and stem cells from human exfoliated deciduous teeth (SHED). Photobiomodulation therapy with a 660 nm diode laser (2.4 J/cm2 and 3.9 J/cm2) on two consecutive days post-culture was applied to two types of stem cells (hPDLSCs and SHED). The Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) test was undertaken to investigate Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin I (ANG-I) genes on days 1, 3, 5, 7, and 10 after the first session of laser application. The 4',6-diamidino-2-phenylindole (DAPI) staining and Methyl Thiazolyl Tetrazolium (MTT) test were conducted on days 1, 3, and 5 after the first session of laser application, to assess the cell viability. The Two-way ANOVA with Tukey post hoc test was used to analyze the outcomes of the MTT and RT-qPCR tests. The results of the MTT and DAPI convergently illustrated that the groups receiving photobiomodulation with 2.4 J/cm2 had higher cell viability compared to 3.9 J/cm2. All experimental groups showed an upregulation of VEGF-A and ANG-I gene expression from day 1 to 5, followed by a downregulation from day 5 to 10. The groups with cultured hPDLSCs and SHED receiving photobiomodulation using 2.4 J/cm2 had the most amounts of VEGF-A and ANG-I gene expression on day 5, respectively. In conclusion, the 660 nm mediated photobiomodulation therapy of cultured SHED and hPDLSCs with 2.4 J/cm2 energy density may be associated with higher angiogenic differentiation (the expression of VEGF-A and ANG-I) as well as higher cell viability compared to the photobiomodulation therapy with 3.9 J/cm2.

Carbon dioxide laser excision as a novel treatment for large xanthelasma palpebrarum: long-term efficacy and safety.

AIMS: This study evaluates the long-term efficacy and safety of carbon dioxide (CO2) laser excision as a novel treatment for large xanthelasma palpebrarum. METHODS: The study included 295 patients diagnosed with xanthelasma palpebrarum, categorised as 246 patients with grade I, 16 with grade II, 22 patients with grade III and 11 with grade IV lesions. All underwent CO2 laser excision and were followed up for a 12-month period. Treatment efficacy was assessed through clearance and recurrence rates, evaluated using digital photography and complications were recorded. RESULTS: The participant group consisted of 66 males and 229 females, with an average age of 41.7±11.6 years. Clearance rates exceeded 99% for grades I-III and were around 95% for grade IV lesions. The recurrence rate was 6.8%, with higher recurrence rates observed in lesions over 2 mm in height compared with those under 2 mm (p<0.001). The main complications over the 12-month follow-up were scarring (4.4%), hyperpigmentation (8.1%) and hypopigmentation (8.5%), with no severe complications reported. CONCLUSION: CO2 laser excision emerges as a precise, minimally invasive and effective modality for treating xanthelasma palpebrarum, marking a significant advancement in treatment modalities. Further research is required to reinforce these results and refine treatment protocols.

Tailoring polarization in WSe2 quantum emitters through deterministic strain engineering.

Quantum emitters in transition metal dichalcogenides (TMDs) have recently emerged as a promising platform for generating single photons for optical quantum information processing. In this work, we present an approach for deterministically controlling the polarization of fabricated quantum emitters in a tungsten diselenide (WSe2) monolayer. We employ novel nanopillar geometries with long and sharp tips to induce a controlled directional strain in the monolayer, and we report on fabricated WSe2 emitters producing single photons with a high degree of polarization (99 ± 4%) and high purity (g (2)(0) = 0.030 ± 0.025). Our work paves the way for the deterministic integration of TMD-based quantum emitters for future photonic quantum technologies.

Effect of Er:YAG Laser Application and Sandblasting on Shear Bond Strength of Veneering Ceramic to Zirconia Core.

Objectives: Porcelain chipping and delamination are among the shortcomings of all-ceramic restorations. This study aimed to assess the effect of laser irradiation and sandblasting on shear bond strength (SBS) of zirconia to veneering porcelain. Materials and Methods: In this in vitro, experimental study, 60 zirconia blocks were randomly divided into three groups (n=20) for surface treatment with Er:YAG laser, sandblasting, and no surface treatment (control). Each group was randomly divided into two subgroups (n=10) for porcelain application by the layering or the pressing technique. The surface roughness, SBS, and failure mode were determined and analyzed using two-way ANOVA, Tukey's HSD test, Chi-square test, and Pearson's correlation test (alpha=0.05). Results: The mean SBS was 8.16±3.66 MPa, 9.32±2.7 MPa, and 11.85±3.06 MPa in the control, laser, and sandblasting groups, respectively. The SBS was significantly different among the three groups (P=0.002). The failure mode of the three groups was not significantly different (P>0.05). The sandblasted group showed significantly higher surface roughness than the control and laser groups (P<0.001). Conclusion: Sandblasting yielded higher SBS particularly when the porcelain was applied by the layering technique. Although laser irradiation increased the SBS, the difference with the control group was not statistically significant.

The role of excimer light in dermatology: a review.

Excimer light is a subtype of NB-UVB that emits a 308 nm wavelength, and can provide targeted phototherapy treatment. The absorption of 308 nm light by skin cells leads to therapeutic response in various common and ultraviolet-responsive skin diseases, such as psoriasis and vitiligo, and photo-resistant skin diseases such as prurigo nodularis, localized scleroderma, genital lichen sclerosis, and granuloma annulare, cutaneous T-cell lymphomas, among others. Excimer light has few adverse reactions and overall is well tolerated by patients, furthermore, it can be performed in places that are difficult to access. This article aims to explain the therapeutic bases and applications of excimer light in current dermatology.

Safety and efficacy of lasers compared to cold knife in direct visual internal urethrotomy: a systematic review and Meta-analysis.

Cold knife urethrotome was introduced in 1971 and it had an 80% success rate. New advancements in this field have shed light on the use of various lasers such as carbon dioxide, Nd: YAG, KTP, Argon, Ho: YAG, and excimer lasers. It has been observed that cold knife urethrotomy has a higher recurrence rate than laser urethrotomy, but the superiority of either treatment modality has not been established yet. Data were thoroughly searched through PubMed, Scopus, and clinicaltrials.gov. We also used clinicaltrials.gov for ongoing and published research. The data was analyzed via R studio version 2023.12.1 (oceanstorm). For dichotomous variables, Odds Ratio (OR) were used to pool data and standardized mean difference was used for continuous variables with 95% confidence intervals (CIs). A total of 14 studies including 1114 participants were included in this meta-analysis. The results of the combined analysis revealed significant relation with a mean difference of 0.99 (95% CI: 0.37; 1.62), and favored laser group. The overall results have shown the laser to have a significant favorable profile demonstrating a recurrence, Odds Ratio of 0.42 (95% CI:0.27;0.65). Patients with laser therapy had a lower risk of complication rate (OR 0.49, 95% Cl: 0.35; 0.67). All the findings obtained by the analysis in this study favour lasers significantly over the cold knife technique especially when mean Qmax, with recurrence and complications taken into account.

Electrocautery-Assisted Management of Aberrant Frena Causing Midline Diastema: A Case Report.

Various oral complications such as gingival recession, restricted lip movement and tooth malalignment are the result of an abnormal frenum. Management of these types of frenum is either frenectomy or frenotomy. Methods for performing frenectomies include the conventional scalpel technique, Z-plasty, Miller's technique, V-Y plasty, lasers, and electrocautery. This case report details the successful management of an abnormal frenum attachment using electrocautery to ease and reduce discomfort to the 19-year-old female patient, causing aesthetic concerns. For its precision, minimal bleeding and post-operative discomfort, electrocautery was chosen. This procedure was performed under local anaesthesia. There were favourable post-operative outcomes as the patient experienced minimal pain and rapid recovery from the surgical site. Significant improvement in gingival health was seen in the follow-up examination. This case demonstrates the efficacy of using electrocautery in managing abnormal frenum attachment while highlighting its benefits over traditional surgical methods for ease and reduced discomfort.

Micronano Lasers Based on Aggregation-Induced Emission Molecules: Diverse Resonant Cavities Investigation.

Aggregation-induced emission (AIE) molecules have great potential to enhance the performance of micronano lasers due to their excellent aggregated luminescence properties, so it is valuable to expand their applications in micronano lasers. In this work, a typical AIE active fluorescent dye motif 9,10-bis(2,2-diphenylvinyl) anthracene (BDPVA) was selected as the gain medium. First, drop-casting was used to fabricate BDPVA single-crystal nanowires, which can be used as Fabry-Perot (FP)-type resonators with a lasing threshold of 49.4 µJ/cm2. Furthermore, we innovatively doped BDPVA molecules as gain mediums into external polymer Whispering-Gallery-Mode (WGM)-type resonators via the emulsion self-assembly method. Fabricated BDPVA-doped polystyrene (PS) microspheres exhibit a much lower lasing threshold of 9.04 µJ/cm2. These results prove that the BDPVA molecules, in addition to realizing the reported AIE single-crystal lasers, can also be used as a guest-doped gain medium in the resonant cavity for obtaining better fluorescence gain. In addition, multimode tunability of two types of lasers has been successfully achieved by tuning the structure of the resonant cavity. This work further expands the application potential of AIE materials and will provide a useful reference for the rational design and fabrication of photonic micronano laser components using AIE materials.

Outcomes of ureteroscopy and laser fragmentation using a 60 W MOSES laser: a 3-year prospective study from a University Teaching Hospital.

Introduction: Modulated optics enhancement system (MOSES) holmium lasers use "pulse modulation" to increase the efficacy of laser lithotripsy. As the clinical evidence on the efficacy of 60 W holmium laser with MOSES technology is scarce, we analyzed the outcomes of patients treated with this laser at our institution. Methods: A total of 96 consecutive patients with urinary stones (72 renal stones and 24 ureteral stones) were treated with the 60 W MOSES laser from 2019 until 2022 and were included in our analysis. Patient data and outcomes were prospectively collected, and analysis was performed regarding patient demographics, stone parameters, as well as stone-free rate, operating time, length of stay, and perioperative and postoperative complications. Results: With a median age of 55 (IQR: 35-69.25) years, the male:female ratio was 53:43. The median stone size was 12 mm (IQR: 7-19), with a mean number of urinary stones of 1.82 (SD ± 1.4). While 36 (35%) patients were pre-stented, a ureteral access sheath was inserted in 36 (37.5%) patients. The median operative time was 44 min (IQR: 22.5-59.5), and 63 (65.5%) patients received postoperative stenting. Perioperative complications (all Clavien ⩽ II complications) were observed in 5 (5.2%) patients (four urinary tract infections and one acute urinary retention), and after the first procedure, 90 (93.8%) patients were stone-free. The median length of hospital stay was 1 day (IQR: 1-1). Conclusion: This study demonstrated that the 60 W MOSES laser was safe and efficient for the treatment of urinary stones with high stone-free rates and a small risk of minor complications. More studies with larger cohorts are necessary in the future to confirm our results.

Indications and Outcomes of Laser Retinopexy in Eyes With High-Risk Lattice Degeneration.

Purpose: To examine the characteristics of eyes with high-risk lattice degeneration treated with laser retinopexy and determine the indications, safety, and outcomes of the treatment. Methods: This interventional single-surgeon consecutive retrospective study was conducted at Wills Eye Hospital between 2014 and 2021. The series included eyes with lattice degeneration with high-risk lesions. Documented characteristics and outcomes of these eyes and fellow eyes were documented. Results: The study comprised 167 eyes of 143 patients (53.3% women; mean age [±SD], 50 ± 17 years). Complications after laser treatment included new posterior vitreous detachment (PVD) (n = 21), epiretinal membrane (ERM) (n = 13), retinal detachment (RD) (n = 5), and additional laser required (n = 22). Eyes that developed ERMs were more likely to develop PVDs (odds ratio, 5.39; 95% CI, 1.57-18.47). Patents who developed ERMs were older (mean, 60 ± 7 years vs 49 ± 17 years; P = .016), as were those developing PVDs (mean, 59 ± 8 years vs 48 ± 17; P = .005). No eye with a new ERM required surgery (n = 13). Four eyes with a new RD required laser retinopexy alone; 1 eye was treated surgically. No eye had an RD at the most recent evaluation. Conclusions: Despite high-risk lesions in areas of lattice degeneration, few eyes developed RDs after prophylactic laser retinopexy. Older patients may have a higher risk for ERM or PVD after laser treatment. Eyes with post-laser PVD were more likely to develop an ERM.

Design, Construction, and Test of Compact, Distributed-Charge, X-Band Accelerator Systems that Enable Image-Guided, VHEE FLASH Radiotherapy.

The design and optimization of laser-Compton x-ray systems based on compact distributed charge accelerator structures can enable micron-scale imaging of disease and the concomitant production of beams of Very High Energy Electrons (VHEEs) capable of producing FLASH-relevant dose rates. The physics of laser-Compton x-ray scattering ensures that the scattered x-rays follow exactly the trajectory of the incident electrons, thus providing a route to image-guided, VHEE FLASH radiotherapy. The keys to a compact architecture capable of producing both laser-Compton x-rays and VHEEs are the use of X-band RF accelerator structures which have been demonstrated to operate with over 100 MeV/m acceleration gradients. The operation of these structures in a distributed charge mode in which each radiofrequency (RF) cycle of the drive RF pulse is filled with a low-charge, high-brightness electron bunch is enabled by the illumination of a high-brightness photogun with a train of UV laser pulses synchronized to the frequency of the underlying accelerator system. The UV pulse trains are created by a patented pulse synthesis approach which utilizes the RF clock of the accelerator to phase and amplitude modulate a narrow band continuous wave (CW) seed laser. In this way it is possible to produce up to 10 µA of average beam current from the accelerator. Such high current from a compact accelerator enables production of sufficient x-rays via laser-Compton scattering for clinical imaging and does so from a machine of "clinical" footprint. At the same time, the production of 1000 or greater individual micro-bunches per RF pulse enables > 10 nC of charge to be produced in a macrobunch of < 100 ns. The design, construction, and test of the 100-MeV class prototype system in Irvine, CA is also presented.

Exploring Carbon Dots: Green Nanomaterials for Unconventional Lasing.

In recent years, the progress toward lighting miniaturization is focused on luminescent nanomaterials. Among them, fluorescent carbon dots (CDs) are receiving increasing attention thanks to their astonishing optical properties complemented by their intrinsic biocompatibility and low toxicity. The CDs can be easily dispersed in water, organic solvents or incorporated in polymeric matrices, preserving their emission properties. However, the relationship between their structural and optical properties is still not fully elucidated, motivating a consistent research effort for the comprehension of their features. Nevertheless, CDs demonstrate to be efficient gain materials for lasing, thanks to their high quantum yield (QY), emission tunability in the visible and near infrared (NIR) range, short lifetimes, and high absorption cross section, even if the synthetic reproducibility, the low reaction yield and the spectral width of the emission may limit their effective exploitation. This review summarizes the latest advancements in the investigation of the characteristic properties of CDs that make laser action possible, illustrating optical geometries for lasing and random lasing, both in solution and solid state, and the few currently demonstrated breakthroughs. While the journey toward their effective application is still long, the potential of CD-based laser sources is promising in various technological fields and futuristic perspectives will be discussed.