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All types of alopecia, including androgenetic alopecia, alopecia areata, and lichen planopilaris/frontal fibrosing alopecia, affect over half of men and women. Though a common dermatological experience, many patients with visible hair loss report significant psychological and social distress and, consequently seek treatment. Current existing therapeutic regimens have proven to be efficacious, though may result in various adverse effects and require lifelong use. Laser and light-based therapies have been emerging in the current literature as a safe and alternative treatment, but their utilization for treating alopecia is poorly understood. This review evaluates the existing evidence regarding the use of lasers in the treatment of various forms of alopecia. Overall, there has been promising evidence for potential alopecia treatment efficacy: low-level light therapy for androgenetic alopecia, fractional laser for androgenetic alopecia, and excimer laser for alopecia areata.

The paper examines afterglow spectra of chlorine–xenon mixtures excited by XeCl laser pulses (308 nm). The dependence of the spectra on the composition and pressure of the mixtures is shown. The mixtures are compared with the total luminescence spectra measured under similar conditions. The time characteristics of excitation and luminescence pulses are presented. [ABSTRACT FROM AUTHOR]

Loss and absence of melanocytes due to a number of factors is responsible for vitiligo; known to be the commonest disorder of pigmentation. The aim of the current work was to compare the efficacy and safety of excimer light with topical tacrolimus ointment 0.1% versus excimer light with topical bimatoprost gel 0.01% in treatment of facial vitiligo. The study was carried out on 48 patients presented with facial vitiligo. The patients were divided randomly using sealed envelope method into two groups (24 patients each). Group 1 were treated with excimer light plus topical tacrolimus ointment 0.1% and group 2 treated with excimer light plus topical bimatoprost gel 0.01%. Clinical improvement based on the quartile grading scale at the end of treatment did not show any statistically significant difference between groups. The majority of subjects in both groups experienced good to excellent improvement. Only 20.9% of patients in group 1 and 33.3% of subjects in group 2 achieved less than 50% repigmentation (p = 0.889). Our study demonstrated that 0.01% topical bimatoprost gel in combination with excimer light is considered safe and effective as treatment of nonsegmental facial vitiligo with comparable results to 0.1% tacrolimus. [ABSTRACT FROM AUTHOR]

With the intensification of global aging,presbyopia has gradually become a global problem, and presbyopia correction surgery has emerged in recent years. The application of laser technology has brought great convenience to refractive surgery, and it also plays an increasingly important role in the correction of presbyopia. The emergence of excimer laser and femtosecond laser technology has opened a new world of surgical treatment for presbyopia, and brought new hope for surgical correction of presbyopia. In this paper, the application and new progress of excimer laser and femtosecond laser in presbyopia surgery are described.

The tuning of the luminescent properties of PtII complexes for possible use in organic light-emitting diodes (OLEDs) and sensing applications is commonly achieved by altering the electronic properties of the ligands. Our group recently demonstrated that the trifluoropropynyl ligand is strongly electron-withdrawing and possibly useful for blueshifting emission. Herein, we report the synthesis of two complexes of this trifluoropropynyl ligand, namely PtLC2CF3 and PtLFC2CF3 (L = 1,3-di(2-pyridyl)benzene; LF = 4,6-difluoro-1,3-di(2-pyridyl)benzene). The PtLC2CF3 complex crystallized in the monoclinic space group P21/n with Z = 4. The PtLFC2CF3 complex crystalized in the triclinic space group P-1 with Z = 2. Changing the tridentate ligand from L to LF resulted in a change in the packing structure, with the latter showing a metallophilic interaction (Pt-Pt distance = 3.3341(3) Å). The solution photophysics of the trifluoropropynyl complexes is compared with that of the corresponding Cl complexes, PtLCl and PtLFCl. Replacement of the chloro ligand with the trifluoropropynyl ligand blueshifted the monomer emission by less than 5 nm but blueshifted the excimer emission peaks by 15–20 nm. The complexes of the trifluoropropynyl ligand also favor the excimer emission more than the complexes of the chloro ligand. The excimer emission is quenched by dissolved oxygen significantly more than the corresponding monomer emission. The excimer emission and monomer emission are well separated, and the ratio of monomer to excimer emission is strongly dependent on oxygen concentration. [ABSTRACT FROM AUTHOR]

Organic radical luminescent materials have attracted worldwide attention because of their absolute spin‐allowed radiative transition and sensitivity to the environment, which give it multiple stimulus response properties. Nowadays, how to regulate and utilize the sensitivity of radicals has become a hot and difficult issue. Here, arylphosphonium bromide salts are introduced into the molecular backbone of naphthimide (NMI) using an intramolecular counterion strategy, and prepared a novel multifunctional stabilized radical luminescent: TPP‐o‐3OMe‐NMI‐Br. Interestingly, this molecule exhibits different assembly modes in different solvents, resulting in the generation of two crystals with different fluorescence (green: G‐C; orange–yellow: Y‐C), in which the Y‐C crystalline powder exhibits excellent stabilization properties for doublet and triplet excitons, which induce the emission of orange–yellow radical afterglow, and exhibits multi‐stimuli responsiveness to external pressure (P), temperature (T) and water (W). Moreover, interesting time‐dependent photoactivated colorful fluorescence and orange–yellow radical afterglow can be observed in TPP‐o‐3OMe‐NMI‐Br@PMMA films with different doping ratios and exhibit multi‐color tunability, multiple stimulus responses, multiple data encryption, and optical information erase/write behavior. This study not only broadens the types and applications of organic radical long afterglow materials but also provides new ideas for designing new organic "chameleon" luminescent materials in the field of smart luminescence materials. [ABSTRACT FROM AUTHOR]

Objective: Unusual or unexpected effect of treatment. Background: Pigmented purpuric dermatosis (PPD) is a rare disease that is poorly understood but thought to result from inflammation of the capillaries causing extravasation of erythrocytes into the soft tissue. There are a variety of potential causes, including medications, such as acetaminophen and aspirin, abnormal humoral immunity, and excessive exercise. Although benign, PPD can be bothersome to patients due to associated pruritus, weeping, and poor cosmetic results. Treatment of this lesion is difficult, with no standardized regimen and a tendency for relapse once treatment is discontinued. Case Report: This case reports on a 77-year-old man who presented to an outpatient dermatology clinic with bilateral lower extremity edema with associated weeping and erythema for 1 year. A biopsy was conducted and resulted as PPD. He began treatment with excimer laser therapy after conservative and topical treatment options failed, with resolution of symptoms without recurrence for approximately 1 year. Conclusions: PPD is notoriously difficult to treat, and historic treatment options include topical corticosteroids, oral supplements, and immunomodulators, all of which come with a range of adverse effects. However, new literature supports the use of phototherapy to treat PPD, with varying results. Previously implemented options include but are not limited to phototherapy with psoralen plus ultraviolet A, narrow band ultraviolet B, advanced fluorescence technology pulsed light, and fractional non-ablative 1540-nm erbium: glass laser, each with varying degrees of success. This case discusses the successful treatment of recalcitrant PPD with excimer laser therapy and maintenance of remission for approximately 1 year. [ABSTRACT FROM AUTHOR]

Background: Vitiligo is characterized by depigmented patches resulting from loss of melanocytes. Phototherapy has emerged as a prominent treatment option for vitiligo, utilizing various light modalities to induce disease stability and repigmentation. Aims and Methods: This narrative review aims to explore the clinical applications and molecular mechanisms of phototherapy in vitiligo. Results and Discussion: The review evaluates existing literature on phototherapy for vitiligo, analyzing studies on hospital‐based and home‐based phototherapy, as well as outcomes related to stabilization and repigmentation. Narrowband ultra‐violet B, that is, NBUVB remains the most commonly employed, studied and effective phototherapy modality for vitiligo. Special attention is given to assessing different types of lamps, dosimetry, published guidelines, and the utilization of targeted phototherapy modalities. Additionally, the integration of phototherapy with other treatment modalities, including its use as a depigmenting therapy in generalized/universal vitiligo, is discussed. Screening for anti‐nuclear antibodies and tailoring approaches for non‐photo‐adapters are also examined. Conclusion: In conclusion, this review provides a comprehensive overview of phototherapy for vitiligo treatment. It underscores the evolving landscape of phototherapy and offers insights into optimizing therapeutic outcomes and addressing the challenges ahead. By integrating clinical evidence with molecular understanding, phototherapy emerges as a valuable therapeutic option for managing vitiligo, with potential for further advancements in the field. [ABSTRACT FROM AUTHOR]

Introduction: Pityriasis lichenoides chronica is the chronic end of the spectrum of pityriasis lichenoides which have several forms of papulosuamous conditions. Several treatments obtained complete clearance of the condition including phototherapy and specifically narrow band ultraviolet B. The Excimer light 308 is a monochromatic light that acts within the ultraviolet B wavelength and used as a targeted phototherapy in several skin conditions. Methods: Thirty‐four patients with histopathologically diagnosed pityriasis lichenoides chronica underwent treatment with biweekly sessions of excimer light 308 nm. Treatment continued until complete clearance was obtained or to a maximum of 48 sessions (24 weeks). Results: Thirty‐one patients obtained complete clearance with no recurrence till the end of the study period, two patients had partial response and only one patient showed poor response to treatment. Conclusion: Excimer light can be a safe and effective treatment of pityriasis lichinoides chronica in different ages and genders. [ABSTRACT FROM AUTHOR]

A method for activating water by plasma of an electrodeless torch discharge in a microwave electromagnetic field in argon in an environment of water vapor, at atmospheric pressure, to obtain a pure solution of hydrogen peroxide H2O2 without impurities in distilled water is proposed. It is shown that the main mechanism for the formation of atomic hydrogen H• and hydroxyl HO• radicals in the water decomposition is photolysis under the influence of excimer vacuum ultraviolet radiation of argon plasma. Hydrated electrons can be an additional source of radicals in liquid water when the plasma torch comes into contact with the water surface. Today plasma technologies are widely used to produce activated water containing hydrogen peroxide, to solve environmental problems, to increase productivity in agriculture, and for medical use. [ABSTRACT FROM AUTHOR]

The efficient collaboration of light tunability and intelligent deformation of fluorescent materials can create an advanced spatiotemporal cascade platform that enables multi‐level and multidimensional information storage and encryption. Here, cellulose‐based dynamic double‐network hydrogels with excitation‐dependent (Ex‐De) behavior are proposed. The mechanism of multi‐channel radiative relaxation and multiple excited state transition of the photoactive component 4′‐([2,2′:6′,2″‐terpyridin]−4′‐yl)‐[1,1′‐biphenyl]−4‐carbaldehyde (TPy‐CHO) has been established, and a desirable regulation of excitation energy (wavelength, intensity) on the time scale for multi‐level encryption has been achieved. Notably, the dense hydrogen bonds and non‐covalent interactions in polymer networks not only enhance the Ex‐De behavior, but also provide excellent optical resolution and richer polychromic fluorescence. Even ideal cold white fluorescence is obtained through energy transfer between organic (TPy‐CHO) and inorganic (lanthanide ion) hybrid materials. Simultaneously, this unique network structure endows the hydrogel with temperature‐mediated self‐healing, controllable shape programming behavior and anti‐swelling ability, allowing to achieve dynamic multidimensional information encryption capability. The encoded information can reversibly emerge and disappear, allowing for instantaneous on‐demand decryption and intelligent re‐writability. As a result, a promising multi‐level and multidimensional synergistic anti‐counterfeiting mechanism is established through the cascade process of "spatial security‐ light trigger‐ fluorescence multilevel output‐temporal rewriting". [ABSTRACT FROM AUTHOR]

Purpose: Vitiligo is a disease of acquired depigmentation characterized by the destruction of melanocytes. A theoretical association between low level of 25‐hydroxyvitamin D [25(OH)D] and vitiligo has been previously suggested. The objective of this study was to determine the efficacy of intramuscular injection of cholecalciferol with excimer laser compared with the excimer laser alone for vitiligo treatment. Methods: This study included 26 patients diagnosed with non‐segmental vitiligo and low serum 25(OH)D levels (<20 ng/mL). The participants were randomly divided into two groups through randomization. The treatment using a 308‐nm excimer laser was administered to both groups, and the study group additionally received cholecalciferol injection. Results: The Vitiligo Area Scoring Index (VASI) scores showed an 83.6% improvement over the initial score in the study group, whereas the control group showed a 54.7% improvement after 6 months of treatment. After 6 months of treatment, the study group showed a significantly higher proportion of patients who achieved VASI50 and VASI75 compared with the control group. Conclusion: Intramuscular injection of cholecalciferol can be a supplemental option for the treatment of vitiligo patients with vitamin D deficiency with excimer laser therapy. [ABSTRACT FROM AUTHOR]

We reported the synthesis of a series of structurally diverse CPL‐active molecules, in which pyrene units were installed to chiral pm/po‐[2,2]PCP scaffolds either with or without a triple bond spacer for pm/po‐PCP‐P1 and pm/po‐PCP‐P2, respectively. The X‐ray crystallographic analyses revealed that these pyrene‐based [2,2]PCP derivatives exhibited diverse structures and crystal packings in the solid phases. The pyrene‐based [2,2]PCP derivatives exhibit various (chir)optical properties in organic solutions, depending on their respective structures. In a mixture of dioxane and water, pm/po‐PCP‐P1 emit green excimer fluorescence, whereas pm/po‐PCP‐P2 emit blue one. The chiroptical investigation demonstrated that Rp‐pm‐PCP‐P1 and Rp‐pm‐PCP‐P2 exhibited completely opposite CD and CPL signals even they possess the same chiral Rp‐[2,2]PCP core. The same argument also holds for other chiral pyrene‐based [2,2]PCP derivatives. The theoretical calculation revealed that these unusual phenomena were attributed to different orientation between transition electric dipole moments and the magnetic dipole moments originating from the presence or absence of a triple bond spacer. These pyrene‐based [2,2]PCP derivatives display various colours and fluorescence emissions in the solid state and PMMA films, possibly due to the different packings as observed in the crystal structure. Moreover, these compounds also can interact with perylene diimide through π‐π interactions, leading to near‐white fluorescence. [ABSTRACT FROM AUTHOR]

Due to their unique photophysical and electronic properties, pyrene and its analogues have been the subject of extensive research in recent decades. The propensity of pyrene and its derivatives to form excimers has found wide application in various fields. Nitrogen-substituted pyrene derivatives display similar photophysical properties, but for them, excimer emission has not been reported to date. Here, we use time-dependent density functional theory (TD-DFT) calculations to investigate the low-lying exciton states of dimers of pyrene and 2-azapyrene. The excimer equilibrium structures are determined and the contribution of charge transfer (CT) excitations and intermolecular interactions to the exciton states is disclosed using a diabatization procedure. The study reveals that the dimers formed by the two molecules have quite similar exciton-state patterns, in which the relevant CT contributions govern the formation of excimer states, along with the La/Lb state inversion. In contrast with pyrene, the dipole–dipole interactions in 2-azapyrene stabilize the dark eclipsed excimer structure and increase the barrier for conversion into a bright twisted excimer. It is suggested that these differences in the nitrogen-substituted derivative might influence the excimer emission properties. [ABSTRACT FROM AUTHOR]

The aggregation of perylene diimide (PDI) and its derivatives strongly depends on the molecular structure and therefore has a great impact on the excited states. By regulating the molecular stacking such as monomer, dimer, J- and/or H-aggregate, the formation of different excited states is adjustable and controllable. In this study, we have synthesized two kinds of PDI derivatives: undecane-substituted PDI (PDI-1) and diisopropylphenyl-substituted PDI (PDI-2), and the films are fabricated with spin-coating method. By employing photoluminescence, time-resolved photoluminescence, and transient absorption spectroscopy, the excited-state dynamics of two PDI amorphous films have been investigated systematically. The result reveals that both films form excimers after photoexcitation mainly due to the stronger electronic coupling among molecule aggregate in the amorphous film. It should be noted that the excited state dynamics in PDI-2 shows a singlet fission like process, which is evidenced by the appearance of triplet state absorption. This study provides the dynamics of excited state in amorphous PDI films, and paves the way for better understanding and adjusting the excited state of amorphous PDI films. [ABSTRACT FROM AUTHOR]

The tuning of the luminescent properties of PtII complexes for possible use in organic light-emitting diodes (OLEDs) and sensing applications is commonly achieved by altering the electronic properties of the ligands. Our group recently demonstrated that the trifluoropropynyl ligand is strongly electron-withdrawing and possibly useful for blueshifting emission. Herein, we report the synthesis of two complexes of this trifluoropropynyl ligand, namely PtLC2CF3 and PtLFC2CF3 (L = 1,3-di(2-pyridyl)benzene; LF = 4,6-difluoro-1,3-di(2-pyridyl)benzene). The PtLC2CF3 complex crystallized in the monoclinic space group P21/n with Z = 4. The PtLFC2CF3 complex crystalized in the triclinic space group P-1 with Z = 2. Changing the tridentate ligand from L to LF resulted in a change in the packing structure, with the latter showing a metallophilic interaction (Pt-Pt distance = 3.3341(3) Å). The solution photophysics of the trifluoropropynyl complexes is compared with that of the corresponding Cl complexes, PtLCl and PtLFCl. Replacement of the chloro ligand with the trifluoropropynyl ligand blueshifted the monomer emission by less than 5 nm but blueshifted the excimer emission peaks by 15–20 nm. The complexes of the trifluoropropynyl ligand also favor the excimer emission more than the complexes of the chloro ligand. The excimer emission is quenched by dissolved oxygen significantly more than the corresponding monomer emission. The excimer emission and monomer emission are well separated, and the ratio of monomer to excimer emission is strongly dependent on oxygen concentration.

Purpose: Compare the safety and efficacy of wavefront guided photorefractive keratotomy (PRK) 6 months after cross linking (CXL) to wavefront guided PRK alone for refractive correction in patients with bilateral asymmetric corneal topography. Methods: Prospective randomized clinical trial with 16 patients (32 eyes). CXL with subsequent PRK after 6 months in one eye, and PRK alone was performed in contralateral eyes. The follow up was 10 years. We analyzed visual outcomes, Scheimpflug topography, and corneal haze evaluation. Results: Eyes in the PRK group showed better results than in the CXL + PRK group. Mean postoperative CDVA was 0.044 logmar (SD, 0.073) in the PRK group and 0.1 logmar (SD, 0.21) in the CXL + PRK group, the mean sphere was + 0.21 (SD, 0.6) D in the PRK group and 0.87 (SD, 2.3) D in the CXL + PRK group, and mean SE was -0.35 (SD, 0.65) D in the PRK group and 0.62 (SD, 2.32) D in the CXL + PRK group. In one patient, a steepening of 2.5 D and a thinning of 17 µm occurred in PRK alone group. Two patients in the CXL + PRK group presented corneal haze. The overall complication rate was 18,75% (haze and ectasia). Conclusion: Non simultaneous CXL and PRK procedures yielded good refractive results, but worse than those obtained with PRK alone. Although one patient in the PRK group developed corneal ectasia, the CXL + PRK group had a higher loss of vision lines, indicating less safety. [ABSTRACT FROM AUTHOR]

Spectra of luminescence pulses of Cl2/Xe mixtures at a pressure of 0.8–4 Torr Cl2 and 2–10 atm Xe, excited by XeCl laser radiation are experimentally measured. Radiation of thin (0.5 cm) and thick (30 cm) active layers is observed. The spectra are wide bands with smoothed components having maxima at 412, 435, 460, 485, 512, 547, and 585 nm. These components are caused by transitions from several vibrational levels of 42Γ state of Xe2Cl*. The type of spectra depends on the active layer thickness; spectra change significantly in thick layers, i.e., collective effects appear in the form of absorption and amplification. [ABSTRACT FROM AUTHOR]

Two novel conjugate molecules were designed: pyrene and phenanthridine-amino acid units with a different linker length between the aromatic fragments. Molecular modelling combined with spectrophotometric experiments revealed that in neutral and acidic buffered water solutions conjugates predominantly exist in intramolecularly stacked conformations because of the π–π stacking interaction between pyrene and phenanthridine moieties. The investigated systems exhibited a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker exhibited a micromolar and submicromolar binding affinity for ds-polynucleotides and inactivated a mutant of dipeptidyl peptidase enzyme E451A. Confocal microscopy revealed that the conjugate with the longer linker entered the HeLa cell membranes and blue fluorescence was visualized as the dye accumulated in the cell membrane.

BackgroundPsoriasis is a chronic skin disease affecting approximately 3.2% of the population. The 308 nm light emitting diode (LED) is a novel, portable, and cost-effective light source, may have potential in the treatment of localized psoriasis patients in a home setting.ObjectiveTo compare the clinical and dermoscopic responses in localized psoriatic patients undergoing localized phototherapy with 308 nm LED light and excimer laser.MethodsTwenty-two patients with mild-to-moderate psoriasis and symmetrical skin lesions were included in this prospective, randomized, left-to-right body trial. The target lesions were randomly treated with either LED light or excimer laser twice a week for 12 weeks. The responses were evaluated by the local psoriasis severity index (LPSI) scores, and dermoscopic features of the target lesions were examined and analyzed.ResultsOut of the 22 included psoriasis patients, 10 successfully completed the 12 weeks study. Both treatment sides showed similar clinical improvement in terms of clinical response, as evidenced by a LPSI 50 rate of 70% on the LED side and 80% on the excimer side, p > 0.05. Furthermore, the dermoscopic features also exhibited comparable improvement.ConclusionThe efficacy and safety of 308 nm LED light therapy are comparable to 308 nm excimer laser therapy. Moreover, given the portability and cost-effectiveness of 308 nm LED light, it holds great promise as a home phototherapy in the treatment of psoriasis.

ABSTRACT LASIK is a refractive surgical procedure in which a corneal flap is created to expose the corneal stromal bed. Preoperative estimation of corneal flap thickness is necessary to calculate the percentage tissue altered in LASIK, an important quantitative risk factor for ectasia. The objective of this study was to assess flap thickness and calculate percentage tissue altered to check if unexpectedly thicker flaps and higher percentage tissue altered could pose as risk factors of ectasia. Four subjects (eight eyes) were submitted to mechanical LASIK in 2009 and 2010. Pre and postoperative clinical and tomographic data were reviewed. Mean preoperative estimated percentage tissue altered was 39.18±1.31%, which was borderline for increased ectasia risk when considering the limit of 40%. However, when considering the postoperatively measured flap thickness, the actual mean percentage tissue altered turned out to be 45.17 ± 4.13%, which was significantly higher than predicted preoperatively (p=0.002). Unexpectedly higher postoperative percentage tissue altered may be responsible for corneal ectasia after mechanical LASIK.

Ultralong organic room temperature phosphorescence (RTP) is attracting increasing attention due to its fascinating optical phenomena and wide applications. Among various RTP, excimer phosphorescence is of fundamental significance, but it remains a considerable challenge to achieve flexible, multicolor and large-area excimer RTP materials, which should greatly advance the understanding and development of organic light-emitting devices. Herein, we present ultralong excimer RTP films by the self-assembly and confinement of terpyridine (Tpy) derivatives in polymeric matrices. Strikingly, the self-assembly of Tpy derivatives induces the formation of excimer complexes, thus immensely minimizing singlet-triplet splitting energy (?EST) to promote the intersystem crossing process. Furthermore, the confinement by multiple hydrogen bonding interactions as well as the compact aggregation of phosphors jointly suppresses the nonradiative transitions, leading to long-lived excimer RTP (t = 543.9 ms, 19,000-fold improvements over the powder). On account of the outstanding afterglow performance and color-tunability of RTP materials, flexible and large-area films were fabricated for intelligent display, anticounterfeiting, and time-resolved information encryption. [ABSTRACT FROM AUTHOR]

Intermolecular interactions on inorganic substrates can have a critical impact on the electrochemical and photophysical properties of the materials and subsequent performance in hybrid electronics. Critical to the intentional formation or inhibition of these processes is controlling interactions between molecules on a surface. In this report, we investigated the impact of surface loading and atomic-layer-deposited Al2O3 overlayers on the intermolecular interactions of a ZrO2-bound anthracene derivative as probed by the photophysical properties of the interface. While surface loading density had no impact on the absorption spectra of the films, there was an increase in excimer features with surface loading as observed by both emission and transient absorption. The addition of ALD overlayers of Al2O3 resulted in a decrease in excimer formation, but the emission and transient absorption spectra were still dominated by excimer features. These results suggest that ALD may provide a post-surface loading means of influencing such intermolecular interactions. [ABSTRACT FROM AUTHOR]

A new water-soluble poly(propylene imine) dendrimer (PPI) modified with 4-sulfo-1,8-naphthalimid units (SNID) and its related structure monomer analog (SNIM) has been prepared by a simple synthesis. The aqueous solution of the monomer exhibited aggregation-induced emission (AIE) at 395 nm, while the dendrimer emitted at 470 nm due to an excimer formation beside the AIE at 395 nm. Fluorescence emission of the aqueous solution of either SNIM or SNID was significantly affected by traces of different miscible organic solvents, and the limits of detection were found to be less than 0.05% (v/v). Moreover, SNID exhibited the function to execute molecular size-based logic gates where it mimics XNOR and INHIBIT logic gates using water and ethanol as inputs and the AIE/excimer emissions as outputs. Hence, the concomitant execution of both XNOR and INHIBIT enables SNID to mimic digital comparators. [ABSTRACT FROM AUTHOR]

Purpose: Compare the safety and efficacy of wavefront-guided photorefractive keratotomy (PRK) 6 months after cross-linking (CXL) to wavefront-guided PRK alone for refractive correction in patients with bilateral asymmetric corneal topography. Methods: Prospective randomized clinical trial with 16 patients (32 eyes). CXL with subsequent PRK after 6 months in one eye, and PRK alone was performed in contralateral eyes. The follow-up was 10 years. We analyzed visual outcomes, Scheimpflug topography, and corneal haze evaluation. Results: Eyes in the PRK group showed better results than in the CXL + PRK group. Mean postoperative CDVA was 0.044 logmar (SD, 0.073) in the PRK group and 0.1 logmar (SD, 0.21) in the CXL + PRK group, the mean sphere was + 0.21 (SD, 0.6) D in the PRK group and 0.87 (SD, 2.3) D in the CXL + PRK group, and mean SE was −0.35 (SD, 0.65) D in the PRK group and 0.62 (SD, 2.32) D in the CXL + PRK group. In one patient, a steepening of 2.5 D and a thinning of 17 μm occurred in PRK alone group. Two patients in the CXL + PRK group presented corneal haze. The overall complication rate was 18,75% (haze and ectasia). Conclusion: Non-simultaneous CXL and PRK procedures yielded good refractive results, but worse than those obtained with PRK alone. Although one patient in the PRK group developed corneal ectasia, the CXL + PRK group had a higher loss of vision lines, indicating less safety.

The present study performed a DFT study on the conformation dependence of the properties of excited states and the excimer's formation for the tetramethyl tetraphenyl cyclotetrasiloxane. The conformations have little effect on the electronic structure of the ground state. The deformed phenyl group in the geometry of the excited state is the excimer‐forming site. The energetically matched HOMO of the excited state with the LUMO of the ground state should cause an attraction to form an excimer. Most conformations are likely to form the excimer but have different contributions to the excimer formation. The interaction of the ground state with the excited state in the excimer has been described quantitatively, which shows that the most stable intermolecular arrangement is the stacked‐eclipsed mode. The excimers display a broad excitation spectrum. The local excitation type is dominant during the excitation, and the charge transfer contributes to the excimer's stability. [ABSTRACT FROM AUTHOR]

Background/Purpose: Vitiligo is one of the most challenging dermatological diseases with little improvement promises. Various modalities of treatment both medical and surgical have been used in the treatment of vitiligo. Some proved to be effective, others with controversial results and the rest were effective less. The aim of the present study was to evaluate the additional effect of topical 5‐fluorouracil after micro‐needling to excimer light (308 nm) in treatment of non‐segmental vitiligo. Methods: Fifty patients were included in the present study, only 33 patients continued the treatment for 6 months. Two patches were selected in every patient to be treated, one patch with micro‐needling then application of 5 FU and excimer (Group A), and the other with excimer only (Group B). Results: The treatment with the combination of micro‐needling then application of 5 FU and excimer showed significant earlier response versus excimer alone. Also, the percentage of re‐pigmentation was higher in the patches treated with the combination especially in the face and trunk. The combination of 5 FU after micro‐needling and Excimer is more suitable for localized and focal vitiligo. Conclusion: Topical 5 FU after micro‐needling is a promising, rapid, and cost‐effective therapeutic strategy for treatment of non‐segmental vitiligo It had limited side effects, and the best response was reported for lesions affecting face and trunk. [ABSTRACT FROM AUTHOR]

Due to their unique photophysical and electronic properties, pyrene and its analogues have been the subject of extensive research in recent decades. The propensity of pyrene and its derivatives to form excimers has found wide application in various fields. Nitrogen-substituted pyrene derivatives display similar photophysical properties, but for them, excimer emission has not been reported to date. Here, we use time-dependent density functional theory (TD-DFT) calculations to investigate the low-lying exciton states of dimers of pyrene and 2-azapyrene. The excimer equilibrium structures are determined and the contribution of charge transfer (CT) excitations and intermolecular interactions to the exciton states is disclosed using a diabatization procedure. The study reveals that the dimers formed by the two molecules have quite similar exciton-state patterns, in which the relevant CT contributions govern the formation of excimer states, along with the La/Lb state inversion. In contrast with pyrene, the dipole–dipole interactions in 2-azapyrene stabilize the dark eclipsed excimer structure and increase the barrier for conversion into a bright twisted excimer. It is suggested that these differences in the nitrogen-substituted derivative might influence the excimer emission properties.

PurposeTo evaluate factors associated with the change in dry eye symptoms following laser vision correction.MethodsThis was a retrospective case series of 13,319 patients who underwent laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between January 2013 and February 2016 and completed a preoperative and 3-month postoperative patient-reported outcome questionnaire.ResultsIn a multivariate linear regression model, women and contact lens wearers were associated with worse preoperative dry eye symptoms. Age was not significantly associated with preoperative dry eye symptoms. The change in dry eye symptoms preoperatively to postoperatively was affected by gender, procedure type, and preoperative dry eye symptoms. Patients who underwent PRK were more likely to report an increase in dry eye after 3 months (coefficient: 3.99, 95% confidence interval (CI): 1.64 to 4.82, P < .001) and patients with worse preoperative dry eye were more likely to have improvement in symptoms after surgery (coefficient: -0.93, 95% CI: -0.97 to -0.90, P < .001). More women reported an increased level of symptoms 3 months after surgery than men (coefficient: 1.76, 95% CI: 0.68 to 2.84, P = .001).ConclusionsPreoperative dry eye symptoms, female gender, and procedure type had a significant effect on preoperative to postoperative change in dry eye symptoms after laser vision correction. Age was not associated with dry eye symptoms in this population. [J Refract Surg. 2019;35(3):161-168.].

The selective monitoring of G‐quadruplex (G4) structures in living cells is important to elucidate their functions and reveal their value as diagnostic or therapeutic targets. Here we report a fluorogenic probe (CV2) able to selectively light‐up parallel G4 DNA over antiparallel topologies. CV2 was constructed by conjugating the excimer‐forming CV dye with a peptide sequence (l‐Arg‐l‐Gly‐glutaric acid) that specifically recognizes G4s. CV2 forms self‐assembled, red excimer‐emitting nanoaggregates in aqueous media, but specific binding to G4s triggers its disassembly into rigidified monomeric dyes, leading to a dramatic fluorescence enhancement. Moreover, selective permeation of CV2 stains G4s in mitochondria over the nucleus. CV2 was employed for tracking the folding and unfolding of G4s in living cells, and for monitoring mitochondrial DNA (mtDNA) damage. These properties make CV2 appealing to investigate the possible roles of mtDNA G4s in diseases that involve mitochondrial dysfunction. [ABSTRACT FROM AUTHOR]

Excited state aromaticity is a stimulating area of research, widely used as a probe to describe and rationalize many photochemical phenomena. Herein, we review some of the recent findings of unprecedented aromatic stabilization in spin singlet excimer and through‐space aromatic character in triplet excimers of a series of linear [n]acenes, as paramount examples of polycyclic aromatic hydrocarbons (PAHs). This review also provides insights on the aromatic stabilization profile of singlet benzene excimer formation, which can be related to antiaromaticity alleviation of the molecular (localized) S1 through exciton delocalization. The theoretical investigation of excimer stabilization using magnetic, electronic, and geometric aromatic indices manifested the presence of through‐space ring current in triplet cofacial excimers. The antiaromaticity of the sandwich (D6h) spin singlet and triplet benzene excimers was also investigated by decomposing the excimer wave function as a linear combination of local exciton (LE) and charge transfer (CT) diabats and by identifying the contribution of these terms to the nucleus independent chemical shift (NICS) of the two 6‐membered rings. These results provide a detailed description of the unique (anti)aromatic properties in PAH excimers, establishing strong connection between this important chemical concept and the electronic structure intricacies of excimers. [ABSTRACT FROM AUTHOR]

The co-facially stacked dyes on semiconductor films serve as an alternative model to elucidate the photo-driven exciton dynamics occurring in a molecular assembly. In this study, we report the unique emission properties of coumarin dye adsorbed on the surface of the semiconductor film, measured by ultrafast time-resolved fluorescence. When a rigid coumarin derivative, 7-hydroxycoumarin-3-carboxylic acid (OHCCA), is anchored on the Al2O3 film, the dye manifests dual emissions from the two lowest excited states. Various anchoring modes of a carboxylic acid group on the Al2O3 surface are invoked to account for the unusual emission process. Additionally, we identified characteristic transition dipole interactions in the well-stacked dye aggregates, which leads to discernible excitonic splitting in the electronic transitions. Femtosecond time-resolved fluorescence reveals that the excimer formation in the aggregate occurs with the time constant of 550 fs. Picosecond time-resolved emission spectra confirm the subsequent structural relaxations of the nascent excimer. The enhanced transition dipole via the electronic coupling between OHCCA and metal oxide can be responsible for the dual emission and the ultrafast excimer formation. [ABSTRACT FROM AUTHOR]

Femtolasik is one of the most used techniques in refractive surgery due to good refractive results, predictability, reproducibility, and safety, achieving excellent results and a high degree of satisfaction. Although the complication rates are small, it is worth noting that there may be intercurrences. The objective of this work is to report a case of complication in the dissection of the lamella of laser in situ keratomileusis (Lasik) with Femtosecond laser, and subsequent lamella tear. Excimer Laser was applied with mitomycin 0.02% and re-approached with wavefront guided surgery, evolving with good final visual quality. [ABSTRACT FROM AUTHOR]

LASIK is a refractive surgical procedure in which a corneal flap is created to expose the corneal stromal bed. Preoperative estimation of corneal flap thickness is necessary to calculate the percentage tissue altered in LASIK, an important quantitative risk factor for ectasia. The objective of this study was to assess flap thickness and calculate percentage tissue altered to check if unexpectedly thicker flaps and higher percentage tissue altered could pose as risk factors of ectasia. Four subjects (eight eyes) were submitted to mechanical LASIK in 2009 and 2010. Pre and postoperative clinical and tomographic data were reviewed. Mean preoperative estimated percentage tissue altered was 39.18±1.31%, which was borderline for increased ectasia risk when considering the limit of 40%. However, when considering the postoperatively measured flap thickness, the actual mean percentage tissue altered turned out to be 45.17 ± 4.13%, which was significantly higher than predicted preoperatively (p=0.002). Unexpectedly higher postoperative percentage tissue altered may be responsible for corneal ectasia after mechanical LASIK. [ABSTRACT FROM AUTHOR]

Temperature-dependent luminescence of polymer compositions doped with boron difluoride β-diketonates was revealed. At room temperature, the samples are characterized by yellow-green luminescence, which turns blue on heating. The mechanism of the temperature-dependent luminescence consists in the dissociation of J-aggregates of dyes on heating. The dissociation of J-aggregates is reversible. The luminescent polymer compositions studied are promising for the development of temperature sensors. [ABSTRACT FROM AUTHOR]

The fluorescent probe is a powerful tool for biological sensing and optical imaging, which can directly display analytes at the molecular level. It provides not only direct visualization of biological structures and processes, but also the capability of drug delivery systems regarding the target therapy. Conventional fluorescent probes are mainly based on monomer emission which has two distinguishing shortcomings in practice: small Stokes shifts and short lifetimes. Compared with monomer-based emission, excimer-based fluorescent probes have large Stokes shifts and long lifetimes which benefit biological applications. Recent progress in excimer-based fluorescent sensors (organic small molecules only) for biological applications are highlighted in this review, including materials and mechanisms as well as their representative applications. The progress suggests that excimer-based fluorescent probes have advantages and potential for bioanalytical applications. [ABSTRACT FROM AUTHOR]

A method for the preparation of polydimethylsiloxanes with grafted methoxy-substituted dibenzoylmethanatoboron difluoride has been described. The structures of prepared polymers were confirmed using NMR, IR spectroscopy and gel permeation chromatography methods. Their thermal properties were investigated using thermal gravimetric analysis, differential scanning calorimetry and thermomechanical analysis. The prepared polymers had good thermal (Td5% up to 393 °C) and thermo-oxidative (Td5% = 413 °C) stability. The polymers started to transit in a viscous flow state at about 40 °C (for 3 a) and at about 20 °C (for 3 b). The viscoelastic characteristics of prepared polymers were determined in the sinusoidal oscillating vibrations mode. It was shown that the studied polymers at low frequencies at room temperature are viscoelastic fluids (G′ < G″). Increasing the frequency led to inversion (crossover) of dependences G′ and G″, which indicated the transition of polymers from viscous to elastomeric behavior characteristics, and the beginning of the formation of a physical network. Optical properties were studied using electron absorption, steady-state and time-resolved fluorescence spectroscopy. It was shown that intramolecular H-dimers exist in the ground state. The polymers studied had a bright fluorescence in the solution and in the solid state, consisting of bands of monomer and excimer emission. Thermally-activated delayed fluorescence was observed in the solution and the solid state. The prepared polymers possess intriguing properties that make them useful as optical materials, sensors or imaging agents. [ABSTRACT FROM AUTHOR]

[Display omitted] • A binuclear 0D cadmium complex with a variety of weak interactions was investigated. • This complex exhibited a reversible mechanochromic luminescence property. • A mechanism for the transformation between exciplex and excimer was proposed. In this work, the mechanochromic luminescence (MCL) property of a binuclear zero-dimensional cadmium complex with a variety of weak interactions is investigated. It exhibits a reversible transition between blue (445 nm) and yellow-green (470 nm) emission under the alternating treatments of grinding and CH 3 CN fumigation. The mechanism of MCL is proposed by combining the structural features, characterization results and theoretical calculations. During the grinding process, the ordered stacking of the structural units is disrupted and the crystalline state is transformed into an amorphous state, which is accompanied by a transition of the luminescent center from exciplex to excimer. In addition to exploring the MCL properties of a binuclear cadmium complex, this work provides feasible ideas for studying the response mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new dyad with styrylbenzoquinoline groups was designed and synthesized. • Dyad is a P-type photochrome acting via a [2 + 2] photocycloaddition reaction. • Both open (dyad) and closed (cyclobutane) isomers of photochrome fluoresce. • New photochrome can serve as a color-correlated multicolor fluorescence photoswitch. We synthesized and studied a novel bichromophoric dyad in which bridging methylene groups link two styrylbenzo[ f ]quinoline (SBQ) photochromes to a salicylic acid residue. The dyad was designed for use as a fluorescent P-type photochrome acting via a [2 + 2] photocycloaddition (PCA) reaction. Compared to previously studied dyads, a change in the attachment handle and shortening of the bridging groups resulted in simultaneous rise of the quantum yields of both fluorescence and PCA. Under light irradiation, two competitive reversible reactions occurred in the dyad. The first is photoisomerization between the trans - and cis - isomers of the SBQ moieties. The second is PCA. The latter process was predominant and resulted in the formation of the cyclobutane ring bearing two benzo[ f ]quinoline (BQ) groups. In the ground S 0 state, NMR data and DFT calculations indicated the formation of folded dyad conformers whose structure is pre-organized for PCA due to π-stacking interactions of two SBQ moieties. In the excited dyad, steady-state and time-resolved nanosecond fluorescence spectroscopy revealed the formation of an excimer, which was assumed to be a precursor of cyclobutane. Due to the fluorescence properties of SBQ and BQ, both dyad and cyclobutane fluoresce and can serve as a color-correlated multicolor fluorescence photoswitch. A simple approach is proposed for predicting the relationship between the spectral properties of the dyad and cyclobutane, which are the open and closed isomers of a new type of photochromes. The approach uses the dependence of the position of the maximum of the absorption band of an aromatic compound on the size of the π-system, as well as the fact that the sizes of the π-systems of the dyad and cyclobutane are related by a simple relation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Blue thermally activated delayed fluorescence excimers with high external quantum efficiency of 26.3% • A multi-resonance type fused indolo[3,2,1-jk]carbazole-derived compound with a planar structure for facile excimer formation. • Enhanced horizontal dipole orientation ratio and accelerated reverse intersystem crossing in the excimer. This study reports for the first time the development of an efficient blue excimer with thermally activated delayed fluorescence (TADF) properties using a multi-resonance TADF-type fused indolo[3,2,1-jk]carbazole-derived compound with a planar structure for facile excimer formation. The blue excimer was efficiently generated by doping the indolo[3,2,1- jk ]carbazole-derived emitter at a high doping concentration. The photophysical analysis demonstrated that the photoluminescence quantum yield (PLQY), rate coefficients of reverse intersystem crossing (RISC), and horizontal emitting dipole orientation values were improved by excimer formation in the solid film compared with the monomer-dominant solid film by suppressing the concentration-quenching effect. Specifically, the delayed PLQY increased because of the efficient RISC process at high doping concentrations. Consequently, an enhanced maximum external quantum efficiency of 26.3% was obtained in the excimer device (15 wt%) compared with 15.2% in the monomer prevalent device (1 wt%). Moreover, the excimer device showed a peak wavelength of 473 nm and color coordinate of (0.13, 0.19). This demonstration is the first of excimer TADF organic light-emitting diodes with a blue emission and a high external quantum efficiency of 26.3%. [ABSTRACT FROM AUTHOR]

We describe the synthesis and characterization of a photoactivated boron‐based Lewis acid catalyst based on a cage‐shaped triphenolic ligand with three pyrenylmethyl moieties. The obtained cage‐shaped borate functioned as a photoactivated Lewis acid catalyst thanks to the flexible three pyrenylmethyl moieties. The deformation of the cage‐shaped scaffold driven by intramolecular excimer formations of the pyrenes is a critical factor in realizing the photoactivation. Mannich‐type reactions and glycosylations significantly were accelerated under 370 nm light irradiations. It is noteworthy that various glycosyl fluorides, which are not easily activated in photocatalytic systems due to their high C−F bond stability, are activated by the photoimproved catalytic activity of the catalyst. [ABSTRACT FROM AUTHOR]

One of the most commonly used and effective lines of treatment in chronic skin diseases is phototherapy. A protocol of the Kasr Al-Ainy Phototherapy Unit has been proposed for the treatment of different dermatological diseases such as psoriasis, mycosis fungoides, and vitiligo based on the best current research-based guidelines and the experience of the phototherapy team. This protocol is the cornerstone of the everyday practice in Kasr Al-Ainy Phototherapy Unit and we believe dermatologists dealing with such diseases in their hospitals or clinics, can find it helpful and applicable to get better results with their patients. In part 1, the general measures of the protocol will be discussed. [ABSTRACT FROM AUTHOR]