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Materials (Basel, Switzerland) Jun 2024The availability of new-generation femtosecond lasers capable of delivering pulses with energies in the hundreds of mJ, or even in the joules range, has called for a...
The availability of new-generation femtosecond lasers capable of delivering pulses with energies in the hundreds of mJ, or even in the joules range, has called for a revision of the effect of scaling spot size on the material distribution within the plasma plume. Employing a state-of-the-art Szatmári-type hybrid dye-excimer laser system emitting 248 nm pulses with a maximum energy of 20 mJ and duration of 600 fs, copper films were grown in the classical pulsed laser deposition geometry. The exceptionally clean temporal profile of the laser pulses yielded a femtosecond component of 4.18 ± 0.19 mJ, accompanied by a 0.22 ± 0.01 mJ ASE pedestal on the target surface. While varying the spot sizes, the plasma plume consistently exhibited an extremely forward-peaked distribution. Deposition rates, defined as peak thickness per number of pulses, ranged from 0.030 to 0.114 nm/pulse, with a gradual narrowing of the thickness distribution as the spot area increased from 0.085 to 1.01 mm while keeping the pulse energy constant. The material distribution on the silicon substrates was characterized using the (Θ) = cosΘ + (1 - )cosΘ formalism, revealing exponents characterizing the forward-peaked component of the thickness profile of the film material along the axes, ranging from = 15 up to exceptionally high values exceeding 50, as the spot area increased. Consequently, spot size control and outstanding beam quality ensured that majority of the ablated material was confined to the central region of the plume, indicating the potential of PLD (pulsed laser deposition) for highly efficient localized deposition of exotic materials.
PubMed: 38893975
DOI: 10.3390/ma17112712 -
Optics Express Jun 2024In most liquid dye lasers, dye cell windows are the optical components most susceptible to laser damage even at very low fluences. Although various mechanisms and...
In most liquid dye lasers, dye cell windows are the optical components most susceptible to laser damage even at very low fluences. Although various mechanisms and mitigation techniques have been explored, damage still occurs at some point, and some behaviors of the process cannot be effectively explained. In this work, we investigated three special behaviors of dye cell window damage which cannot be explained by ordinary laser-induced damage mechanisms. We proposed that damage to dye cell windows can be caused by a contamination process similar to laser-induced contamination (LIC) on space optics, and used the LIC mechanism to analyze the cause of those damage behaviors. Additional experiments and calculations were conducted, providing more evidence in support of the analysis. In addition, it was found that dye molecules, which are necessary for dye lasers, are the primary contaminants in the LIC process. This explains the inevitable damage to dye cell windows.
PubMed: 38859497
DOI: 10.1364/OE.523296 -
Optics Express May 2024Besides the scattering structures, the energy transfer (ET) process in the gain medium plays a significant role in the competition between coherent (comprising strongly...
Besides the scattering structures, the energy transfer (ET) process in the gain medium plays a significant role in the competition between coherent (comprising strongly coherent components) and incoherent (consisting of weakly coherent or "hidden" coherent components) modes of random lasers. In this study, bichromatic emission random lasers were successfully created using polydimethylsiloxane (PDMS) replicas with grooved structures that imitate the inner surface of abalone shells as scattering substrates. The influence mechanism of the ET process from the monomer to dimer in the Rhodamine 640 dye on the competition of random laser modes was thoroughly investigated from both spectral and temporal dimensions. It was confirmed that the ET process can reduce the gain of monomers while amplifying the gain of dimers. By considering the dominant high-efficiency ET processes, an energy transfer factor associated with the pump energy density was determined. Notably, for the first time, it was validated that the statistical distribution characteristics of the time sequence variations in the coherent random laser generated by dimers closely resemble a normal distribution. This finding demonstrates the feasibility of producing high-quality random number sequences.
PubMed: 38859088
DOI: 10.1364/OE.525288 -
Indian Journal of Dermatology 2024Psoriasis is a chronic inflammatory skin condition affecting millions of individuals worldwide. Over the years, various treatment modalities have been explored to...
Psoriasis is a chronic inflammatory skin condition affecting millions of individuals worldwide. Over the years, various treatment modalities have been explored to alleviate the symptoms and improve the quality of life for patients with psoriasis. Among these treatment options, lasers and lights have emerged as promising non-invasive approaches with significant efficacy. This review aims to provide an overview of the current understanding and clinical applications of lasers and lights in the management of psoriasis. We have discussed the mechanisms of action behind different laser and light therapies and their impact on psoriatic plaques. Additionally, we discuss the various types of lasers and lights utilized, including excimer lasers, pulsed dye lasers, and narrowband ultraviolet B (NB-UVB) phototherapy, highlighting their unique properties and clinical outcomes. Moreover, we have addressed important considerations related to patient selection, treatment protocols, and potential side effects associated with lasers and lights. We emphasize the need for proper evaluation, monitoring, and customization of treatment plans to ensure optimal outcomes and minimize adverse events.
PubMed: 38841222
DOI: 10.4103/ijd.ijd_423_23 -
Journal of Biomedical Optics Jun 2024Preparation of a recipient cytoplast by oocyte enucleation is an essential task for animal cloning and assisted reproductive technologies in humans. The femtosecond...
SIGNIFICANCE
Preparation of a recipient cytoplast by oocyte enucleation is an essential task for animal cloning and assisted reproductive technologies in humans. The femtosecond laser is a precise and low-invasive tool for oocyte enucleation, and it should be an appropriate alternative to traditional enucleation by a microneedle aspiration. However, until recently, the laser enucleation was performed only with applying a fluorescent dye.
AIM
This work is aimed to (1) achieve femtosecond laser oocyte enucleation without applying a fluorescent dye and (2) to study the effect of laser destruction of chromosomes on the structure and dynamics of the spindle.
APPROACH
We applied polarized light microscopy for spindle visualization and performed stain-free mouse and human oocyte enucleation with a 1033 nm femtosecond laser. Also, we studied transformation of a spindle after metaphase plate elimination by a confocal microscopy.
RESULTS
We demonstrated a fundamental possibility of inactivating the metaphase plate in mouse and human oocytes by 1033 nm femtosecond laser radiation without applying a fluorescent dye. Irradiation of the spindle area, visualized by polarized light microscopy, resulted in partly or complete metaphase plate destruction but avoided the microtubules impairment. After the metaphase plate elimination, the spindle reorganized, however, it was not a complete depolymerization.
CONCLUSIONS
This method of recipient cytoplast preparation is expected to be useful for animal cloning and assisted reproductive technologies.
Topics: Animals; Mice; Oocytes; Humans; Female; Lasers; Spindle Apparatus; Microscopy, Confocal; Metaphase; Microscopy, Polarization
PubMed: 38812963
DOI: 10.1117/1.JBO.29.6.065002 -
Archives of Dermatological Research May 2024Melanoma, accounting for a significant proportion of skin cancer-related deaths, has variable survival outcomes based on the stage at diagnosis and treatment efficacy.... (Review)
Review
Melanoma, accounting for a significant proportion of skin cancer-related deaths, has variable survival outcomes based on the stage at diagnosis and treatment efficacy. Traditional treatments, while effective, pose risks of scarring and systemic side effects. Laser therapy offers an emerging non-surgical alternative, with CO2 lasers particularly showing promise in palliative care.A comprehensive search was conducted using PubMed, focusing on laser therapy for melanoma treatment. The search included studies on both stand-alone and adjunct laser therapies, with inclusion criteria requiring peer-reviewed articles detailing treatment outcomes for primary, recurrent, or metastatic melanoma.The literature shows that laser therapy for melanoma falls into four major types when categorized by laser medium: solid-state, diode, pulse-dye, and gas (CO2). Data on solid-state lasers for melanoma are limited and their use remains controversial. However, one study with high-energy pulsed neodymium lasers reported a 5-year survival of 82.9% with minimal adverse effects for primary melanoma. CO2 laser therapy has been effective for palliative treatment, with one study showing 54.8% of patients with recurrent melanoma surviving 5.4 years post-ablation. For metastatic melanoma, numerous studies have shown that CO2 laser therapy can provide symptomatic relief and disease control. Combination therapies using lasers and immune-based therapies have demonstrated enhanced outcomes and immune activation, highlighting the potential of laser therapies in melanoma management.While traditional treatments remain the standard for primary melanoma, laser therapies, particularly CO2 laser ablation, show substantial promise in palliative care for metastatic melanoma. Careful patient selection and assessment are crucial for achieving positive outcomes.
Topics: Humans; Melanoma; Skin Neoplasms; Palliative Care; Treatment Outcome; Lasers, Gas; Laser Therapy; Combined Modality Therapy; Lasers, Solid-State; Neoplasm Recurrence, Local
PubMed: 38795247
DOI: 10.1007/s00403-024-03107-9 -
Lasers in Medical Science May 2024Pulsed dye lasers are used effectively in the treatment of psoriasis with long remission time and limited side effects. It is, however, not completely understood which...
Pulsed dye lasers are used effectively in the treatment of psoriasis with long remission time and limited side effects. It is, however, not completely understood which biological processes underlie its favorable outcome. Pulsed dye laser treatment at 585-595 nm targets hemoglobin in the blood, inducing local hyperthermia in surrounding blood vessels and adjacent tissues. While the impact of destructive temperatures on blood vessels has been well studied, the effects of lower temperatures on the function of several cell types within the blood vessel wall and its periphery are not known. The aim of our study is to assess the functionality of isolated blood vessels after exposure to moderate hyperthermia (45 to 60°C) by evaluating the function of endothelial cells, smooth muscle cells, and vascular nerves. We measured blood vessel functionality of rat mesenteric arteries (n=19) by measuring vascular contraction and relaxation before and after heating vessels in a wire myograph. To this end, we elicited vascular contraction by addition of either high potassium solution or the thromboxane analogue U46619 to stimulate smooth muscle cells, and electrical field stimulation (EFS) to stimulate nerves. For measurement of endothelium-dependent relaxation, we used methacholine. Each vessel was exposed to one temperature in the range of 45-60°C for 30 seconds and a relative change in functional response after hyperthermia was determined by comparison with the response per stimulus before heating. Non-linear regression was used to fit our dataset to obtain the temperature needed to reduce blood vessel function by 50% (Half maximal effective temperature, ET50). Our findings demonstrate a substantial decrease in relative functional response for all three cell types following exposure to 55°C-60°C. There was no significant difference between the ET50 values of the different cell types, which was between 55.9°C and 56.9°C (P>0.05). Our data show that blood vessel functionality decreases significantly when exposed to temperatures between 55°C-60°C for 30 seconds. The results show functionality of endothelial cells, smooth muscle cells, and vascular nerves is similarly impaired. These results help to understand the biological effects of hyperthermia and may aid in tailoring laser and light strategies for selective photothermolysis that contribute to disease modification of psoriasis after pulsed dye laser treatment.
Topics: Animals; Rats; Male; Lasers, Dye; Myocytes, Smooth Muscle; Vasodilation; Temperature; Muscle, Smooth, Vascular; Endothelial Cells; Vasoconstriction; Endothelium, Vascular; Rats, Wistar
PubMed: 38703271
DOI: 10.1007/s10103-024-04070-7 -
Biomaterial Investigations in Dentistry 2024To evaluate the penetration of a dye in root dentin after activation with different laser wavelengths.
OBJECTIVE
To evaluate the penetration of a dye in root dentin after activation with different laser wavelengths.
MATERIALS
Palatal roots of 38 human molars were enlarged and disinfected. Irrigation activation was performed with an Er:YAG laser: @50 mJ, 15 Hz (Er:YAG); a 9.3 µm CO laser: @40% power (CO); diode lasers 455 nm/970 nm: @0.8 W, 15 Hz (D455, D970) and 808/980 nm: @1 W (D808, D980) and compared to positive control: etching with 35% HPO (POS); negative control: water (NEG) and conventional needle irrigation: NaOCl and ethylenediaminetetraacetic acid (EDTA) (CONV). Methylene blue solution was introduced in the canal and laser-activated or left untouched for 100 s before the roots were dried and cut into horizontal slices. Dye penetration was automatically calculated by color recognition of two samples per root third ( = 8 per group in each coronal, middle and apical root thirds). The presence and absence of a smear layer was checked in two additional samples of the negative and positive control under scanning electron microscopy (SEM).
RESULTS
Full-depth infiltration was not achieved in any group. Dye penetration in CONV was significantly less than in Er:YAG, CO POS, D455, D970, D808 and similar to NEG and D980 when results of different root thirds were pooled.
CONCLUSION
Laser activation using certain parameters enhanced dye penetration compared to conventional needle irrigation with NaOCl and EDTA (CONV).
PubMed: 38645926
DOI: 10.2340/biid.v11.40311 -
RSC Advances Apr 2024As a rising star among metal oxide nanomaterials, titanium dioxide (TiO) has been widely investigated and employed in optical applications because of its excellent...
As a rising star among metal oxide nanomaterials, titanium dioxide (TiO) has been widely investigated and employed in optical applications because of its excellent optical properties. In this work, we demonstrate the efficient and broadband nonlinear photonic properties of methylene blue (MB)-loaded reduced TiO (TiO-MB) and explore the performance of a TiO-MB-microfiber photonic device in broadband ultrafast photonics. Within an erbium-doped fiber laser (EDFL) system, utilizing the TiO-MB-microfiber photonic device as a saturable absorber (SA), steady mode-locked pulses together with chaotic pulses were successfully achieved at the wavelength of 1.55 μm. Furthermore, by incorporating the TiO-MB SA into a thulium-doped fiber laser (TDFL) system, an ultrashort single pulse and multiple pulses were obtained at 2.0 μm. These results indicate that TiO-MB is an excellent nanomaterial for use in mode-locked lasers, being an alternative candidate for ultrafast fiber lasers exploiting the chemical and physical properties of oxide nanomaterials.
PubMed: 38605890
DOI: 10.1039/d3ra08925h -
Transfusion Medicine and Hemotherapy :... Apr 2024Before being implemented in daily clinical routine, new production strategies for platelet concentrates (PCs) must be validated for their efficacy. Besides in vitro...
INTRODUCTION
Before being implemented in daily clinical routine, new production strategies for platelet concentrates (PCs) must be validated for their efficacy. Besides in vitro testing, the establishment of new methods requires the labeling of platelets for in vivo studies of platelets' survival and recovery. Indocyanine green (ICG) is a Food and Drug Administration-approved near-infrared (NIR) fluorescent dye for diagnostic use in vivo, suitable for non-radioactive direct cell labeling of platelets.
METHODS
Platelets from PCs in storage solutions with different plasma concentrations were labeled with ICG up to concentrations of 200 μm. Whole blood (WB) was used as an ex vivo matrix to monitor the labeling stability of ICG-labeled platelets. The impact of labeling processes was assessed by the quantification of CD62P expression and PAC-1 binding as platelet function markers. Platelet aggregation was analyzed by light transmission aggregometry. ICG-labeling efficiency and stability of platelets were determined by flow cytometry.
RESULTS
Platelets from PCs could be successfully labeled with 10 μm ICG after 1 and 4 days of storage. The best labeling efficiency of 99.8% ± 0.1% (immediately after labeling) and 81% ± 6.2% (after 24 h incubation with WB) was achieved by plasma replacement by 100% platelet additive solution for the labeling process. Since the washing process slightly impaired platelet function, ICG labeling itself did not affect platelets. Immediately after the ICG-labeling process, plasma was re-added, resulting in a recovered platelet function.
CONCLUSION
We developed a Good Manufacturing Practice compatible protocol for ICG fluorescent platelet labeling suitable for survival and recovery studies in vivo as a non-radioactive labeling alternative.
PubMed: 38584698
DOI: 10.1159/000533623