Action Spectrum Research Articles

Dual photoactive species in CuPd for light‐switched homo‐coupling of alkynes in anaerobic and base free condition

Various ratios of CuPd alloy are loaded on C3N4 and utilized as efficient photocatalyst for the light‐switched homo‐coupling of alkynes in anaerobic and base free condition. For the model phenylacetylene reactant, the light‐irradiation promotes the reaction rate from 36.9% to 99.9% and the selectivity of 1,3‐diynes from 0% to 68.7%. Different supports, solvents and the induction period of the prepared samples show influence on the activity. The action spectra with different light wavelengths demonstrate that both copper phenylacetylide intermediate formed during the reaction and the localized surface plasmon resonance (LSPR) effect of the copper in CuPd alloy are the photoactive species. Through the control experiments, it confirms that these dual photoactive species and the interface between Cu and Pd are essential for efficient light‐switching reaction pathway.

Infrared Photodissociation Spectroscopy of Water-Tagged Ions with a Widely Tunable Quantum Cascade Laser for Planetary Science Applications.

This work presents a benchtop method for collecting the room temperature gas phase infrared (IR) action spectra of protonated amino acids and their isomers. The adopted setup uses a minimally modified commercial electrospray ionization linear ion trap mass spectrometer (ESI-LIT-MS) coupled to a broadband continuous wave (cw) quantum cascade laser (QCL) source. This approach leverages messenger assisted action spectroscopic techniques using water-tagged molecular ions with complex formation, irradiation, and subsequent analysis, all taking place within a single linear ion trap stage. This configuration thus circumvents the use of multiple mass selection and analysis stages, cryogenic buffer cells, and complex high-power laser systems typically called upon to execute these techniques. The benchtop action spectrometer is used to collect the 935-1600 cm-1 (6.2-10.7 μm) IR action spectrum of a collection of amino acids and a dipeptide with results cross referenced against literature examples obtained with a free electron laser source. Recorded IR spectra are used for the analysis of binary mixture samples composed of constitutional isomers α-alanine and β-alanine with ratios determined to ∼4% measurement uncertainty without the aid of a front-end separation stage. This turn-key QCL-based approach is a major step in showing the viability of tag-based action spectroscopic techniques for use in future in situ planetary science sensors and general analytical applications.

Exploring the Role of Active Photosynthetic Pigments in Tomato (Solanum lycopersicum) Crop Growth Process

Photosynthesis is a necessary process for plants during which light energy is absorbed via pigments present in leaves for essential processes and needs of the particular plant. This work identified and studied the active photosynthetic pigments in tomato crop (Solanum lycopersicum) at each growth stage and grown in an open field under Sahelian conditions. Phytochemical screening, UV-visible and Fourier transform infrared spectroscopy, and thin layer chromatography analyses were done on tomatoes leaves samples. The results, first, revealed the presence of phytoconstituents such as triterpenoids and carotenoids. Then, UV spectra combined with FTIR and thin layer chromatography showed that chlorophylls (a and b), xanthophyll (lutein) and carotene (mostly β) are being synthesized at different proportions during all growth stages. Besides, the photosynthetic pigments showed more activity during the flowering stage than at the other growth stages. The various action spectra showed intense absorption within the intervals 400 – 510 nm and 560 – 710 nm which seem to be vital radiation ranges for photosynthesis. Knowing these optimum plant’s needs can help in a choice of better outdoor and indoor cultivation conditions that can ensure necessary radiations for optimum plant growth.

New piperazine and morpholine derivatives: mass spectrometry characterization and evaluation of their antimicrobial activity

Recently, pharmaceutical research has been focused on the design of new antibacterial drugs with higher selectivity towards several strains. Major issues concern the possibility to obtain compounds with fewer side effects, at the same time effectively overcoming the problem of antimicrobial resistance. Several solutions include the synthesis of new pharmacophores starting from piperazine or morpholine core units. Mass spectrometry-based techniques offer important support for the structural characterization of newly synthesized compounds to design safer and more effective drugs for various medical conditions. Here, two new piperazine derivatives and four new morpholine derivatives were synthesized and structurally characterized through a combined approach of Fourier transform-ion cyclotron resonance (FT-ICR) and Linear Trap Quadrupole (LTQ) mass spectrometry. The support of both high-resolution and low-resolution mass spectrometric data namely accurate mass measurements, isotopic distribution and MSn spectra, was crucial to confirm the success of the synthesis. These compounds were further evaluated for inhibitory activity against a total of twenty-nine Gram-positive and Gram-negative bacteria to determine the action spectrum and the antimicrobial effectiveness. Results demonstrated compounds’ antimicrobial activity against many tested bacterial species, providing an inhibitory effect linked to different chemical structure and suggesting that the new-synthesized derivatives could be considered as promising antimicrobial agents.

Phototoxicity and photoallergy – A brief review on pathogenesis, recent advances, and approach to a patient with photosensitivity

Photosensitivity can result in phototoxic or photoallergic reactions. Phototoxicity is the more frequent of the two and could be acute or chronic. Clinically, erythema and edema are the hallmarks of acute phototoxic reactions. There are two mechanisms by which phototoxic reactions can happen; photodynamic (which is oxygen dependent) and non-photodynamic (which is oxygen independent). Ultraviolet B (UVB) and less effectively UVA can cause phototoxic reactions. The main action spectrum for chronic phototoxicity falls in the UVB range, as compared to the UVA rays. Other phototoxic reactions include lichenoid or lichen planus such as reaction and photo-onycholysis. Photoallergic reactions usually are due to delayed hypersensitivity reaction that manifests with papular or eczematous eruptions. Topical medications are typically the most frequent provoking cause of photoallergic skin lesions. A thorough history with detailed clinical examination is necessary for the management of photosensitivity. Availability of newer diagnostic techniques and treatment modalities gives a promising approach to the management of photo-aggravated dermatoses.

Evaluating the Performance of UV Disinfection across the 222-365 nm Spectrum against Aerosolized Bacteria and Viruses.

Bioaerosols play a significant role in the transmission of many infectious diseases, especially in enclosed indoor environments. Ultraviolet (UV) disinfection has demonstrated a high efficacy in inactivating microorganisms suspended in the air. To develop more effective and efficient UV disinfection protocols, it is necessary to evaluate and optimize the effectiveness of UV disinfection against aerosolized bacteria and viruses across the entire UV spectrum. In this study, we evaluated the performance of UV disinfection across the UV spectrum, ranging from 222 to 365 nm, against aerosolized bacteria and viruses, including Escherichia coli, Staphylococcus epidermidis, Salmonella enterica, MS2, P22, and Phi6. Six commonly available UV sources, including gas discharge tubes and light-emitting diodes with different emission spectra, were utilized, and their performance in terms of inactivation efficacy, action spectrum, and energy efficiency was determined. Among these UV sources, the krypton chloride excilamp emitting at a peak wavelength of 222 nm was the most efficient in inactivating viral bioaerosols. A low-pressure mercury lamp emitting at 254 nm performed well on both inactivation efficacy and energy efficiency. A UV light-emitting diode emitting at 268 nm demonstrated the highest bacterial inactivation efficacy, but required approximately 10 times more energy to achieve an equivalent inactivation level compared with that of the krypton chloride excilamp and low-pressure mercury lamp. This study provides insights into UV inactivation on bioaerosols, which can guide the development of effective wavelength-targeted UV air disinfection technologies and may significantly help reduce bioaerosol transmission in public areas.

Water-Hydrocarbon Interactions in Anionic Pyrene Monohydrate.

Interactions between water and polycyclic aromatic hydrocarbons are essential in many aspects of chemistry, from interstellar and atmospheric processes to interfacial hydrophobicity and wetting phenomena. Despite their growing importance, the intermolecular potentials of the water-hydrocarbon interactions are underdeveloped compared to the water-water potentials, and there are similarly few experimental probes that are sensitive to the details of the water-hydrocarbon potential. We present a combined experimental and computational study of anionic pyrene monohydrate, one of the simplest water/hydrocarbon clusters. The action spectrum in the OH region of the mass-selected cluster ion provides a rigorous benchmark for intermolecular potentials and computational methodologies. We identify missing intermolecular interactions and shortcomings in conventional dynamics calculations by comparing experimental data to density functional theory and classical molecular dynamics calculations. Kinetic trapping is prevalent, even for one water molecule and one pyrene molecule, leading to slow equilibration in conventional molecular dynamics calculations, even on nanosecond time scales and at low temperatures (50 K). At constant energy, temperature fluctuations for the pair of molecules are substantial. Immersing the system in a bath of soft spheres and employing parallel tempering alleviates kinetic trapping and dampens temperature fluctuations, bringing the system closer to the thermodynamic limit. With such augmented sampling, a simple, flexible water model reproduces the line width and the asymmetric broadening of the symmetric OH stretching mode, which we assign to spectral diffusion. In the OH stretching region, dynamics calculations predict a more intense antisymmetric peak than experiments observe but do not predict the bimodal split symmetric peak that the experiments show. Our work suggests that electronic polarization, missing in the empirical force field, is responsible for the first discrepancy and that quantum nuclear effects, captured neither in density functional theory nor in classical dynamics, may be responsible for the second.

Guidelines for Material Design in Semitransparent Organic Solar Cells

AbstractOrganic solar cells (OSCs) are uniquely suited for semitransparent applications due to their adjustable absorption spectrum. However, most high‐performance semitransparent cells reported to date are based on materials that have shown high power conversion efficiency for opaque devices. A model is therefore presented to assess the optimum efficiency and transparency for a specific donor and acceptor bandgap. The absorption characteristics of both donor and acceptor are modeled with spectral data of typical absorber materials from the literature which are adjusted to achieve the desired bandgap value. The results show three distinct regions of high light utilization efficiency (LUE) if the photopic curve is employed as a weighting function (corresponding to window applications), and a broad maximum for the plant action spectrum as a weighting function (corresponding to greenhouse applications). When comparing these findings to reported experimental values, it is evident that the bandgaps of the materials used for the experimental studies do not correspond to the maxima identified by the simulation model. The analysis of the energy levels of molecules recorded in the literature confirms that all bandgaps and therefore all LUE maxima are chemically feasible so that the performance of semitransparent OSCs can be further improved by designing materials with optimized absorption spectra.

Use of Topical Corticosteroids in the Treatment of Noninfectious Inflammatory Dermatoses of the Scalp: A Survey of Practicing Dermatologists and Dermatology Residents Using Delphi Methodology.

Noninfectious inflammatory dermatoses of the scalp are common, and their symptomsin particular, those affecting appearance, can have a psychological effect that may be disproportionate to their clinical severity. Effective, cosmetically acceptable treatments are important to manage these conditions. Topical corticosteroids form the cornerstone of acute treatment for many of these conditions. We surveyed practicing dermatologists and dermatology residents to determine the current clinical practice in prescribing topical corticosteroids for these disorders in their various preparation formats. A Delphi method was used, consisting of 2 questionnaire rounds. The first round contained 34 questions and was completed by 612 dermatologists and dermatology residents via email. The first round of responses was analyzed, and points that had >70% agreement were used to form a second questionnaire of 21 statements. This second round was completed by 346 participants, and their responses were used to generate a final report. Participants were practicing in both public and private practices. Clobetasol propionate 0.05% topical solution was considered to be the most appropriate treatment for noninfectious inflammatory scalp dermatoses in general, with 75.1% agreement in the second round of questionnaire. The main advantages of clobetasol propionate over other topical corticosteroids were reported as potency, effectiveness, and broad action spectrum (94.8% agreement). The preferred pharmaceutical format was the solution of clobetasol propionate. Clobetasol propionate was the preferred topical treatment for the management of scalp dermatoses, usually as first-line treatment; solution was the preferred preparation.

Spectral Dependence of Light Exposure on Retinal Pigment Epithelium Disruption in Living Primate Retina.

RPE disruption with light exposures below or close to the American National Standards Institute (ANSI) photochemical maximum permissible exposure (MPE) have been observed, but these findings were limited to two wavelengths. We have extended the measurements across the visible spectrum. Retinal imaging with fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO) was used to provide an in vivo measure of RPE disruption at a cellular level. The threshold retinal radiant exposures (RREs) for RPE disruption (localized detectable change in the fluorescence image) were determined at 460, 476, 488, 530, 543, 561, 594, 632, and 671nm (uniform 0.5° square exposure) using multiples locations in 4 macaques. FAOSLO is sensitive in detecting RPE disruption. The visible light action spectrum dependence for RPE disruption with continuous wave (CW) extended field exposures was determined. It has a shallower slope than the current ANSI blue-light hazard MPE. At all wavelengths beyond 530nm, the disruption threshold is below the ANSI blue-light hazard MPE. There is reciprocity of exposure irradiance and duration for exposures at 460 and 594nm. We measured with FAOSLO the action spectrum dependence for photochemical RPE disruption across the visible light spectrum. Using this in vivo measure of phototoxicity provided by FAOSLO, we find that thresholds are lower than previously measured. The wavelength dependence in our data is considerably shallower than the spectral dependence of the traditional ANSI blue-light hazard, emphasizing the need for more caution with increasing wavelength than expected.

Solar urticaria: clinical characteristics, treatment effectiveness, long-term prognosis, and QOL status in 29 patients.

Solar urticaria (SU), a relatively rare skin inflammatory and photosensitivity disease, is often resistant to standard urticaria treatment. Quality of life (QOL) among SU patients has not been extensively explored. This study was performed to clarify the clinical features and effectiveness of therapies (e.g., hardening therapy) for SU and to determine QOL among SU patients. The authors examined the characteristics, treatments, and QOL statuses of 29 Japanese SU patients using medical records and a questionnaire approach. Among 29 patients, H1 antihistamine therapy (H1) was effective in 22 (75.8%) patients. H2 antihistamine therapy (H2) was effective in three of seven (42.9%) patients. Ultraviolet radiation A (UVA) hardening therapy was effective in eight of nine (88.9%) patients. Visible light (VL) hardening therapy was ineffective in three of three patients. In one patient who underwent both UVA and VL hardening therapy, only UVA hardening therapy was effective. In the questionnaire, 18 patients (90%) reported some improvement compared with disease onset (four had complete remission, six had completed treatment although mild symptoms persisted, and eight were receiving treatment with moderate symptoms), whereas two patients reported exacerbation. Patients in complete remission had a mean disease duration of 4 years, whereas patients not in remission had a mean disease duration of 8.8 years. The mean Dermatology Life Quality Index (DLQI) score for the current status was 7.4. There was a correlation between DLQI and symptom/treatment status. However, neither DLQI and action spectra nor DLQI and treatments exhibited significant differences. The questionnaire revealed current QOL status and long-term prognosis in SU patients. Compared with disease onset, most patients showed improvement when assessed for this study. Both H1 and H2 should be attempted for all SU patients. UVA hardening therapy may be an option for SU patients with an action spectrum that includes UVA.

Heat action spectrum of Rhodamine B through two-photon absorption in near-infrared region studied by optical-probing photoacoustic spectroscopy

The heat action spectrum of Rhodamine B by two-photon absorption has been measured by a new system of optical-probing photoacoustic spectroscopy (OPPAS) coupled with a nanosecond near-infrared OPO laser. The highly resolved spectrum was obtained in the wide spectral range from 680 nm to 900 nm. The two-photon absorption cross-section of Rhodamine B was successfully determined by comparing the signal intensity of Rhodamine B with that of the reference. The OPPAS system was able to measure a well-resolved two-photon absorption spectrum of both fluorescent and non-fluorescent molecules in the wider spectral range from visible to near-infrared region.

Mild and Efficient Extraction of Fluorescent Chlorophyll a from Spinach Leaves for Application as the Sustainable Emitter in Light‐Emitting Electrochemical Cells

AbstractNatural pigments are sustainable compounds that can be employed as emitters, sensors and sensitisers in optoelectronics. The most abundant pigment, chlorophyll, offers advantages of easily available and plentiful feedstock, biodegradability and non‐toxicity. However, strenuous extraction and separation limit its application on larger scale. In this work, a practically mild and scalable extraction and separation method for rapid isolation of chlorophyll a from spinach is presented. Three different stationary phases for column chromatography were evaluated, and a new solvent system was developed for the elution of chlorophyll a on a neutral alumina chromatography column. The purified product was obtained with a yield of 0.98 mg ⋅ g−1 with respect to the dry leaves. A first light‐emitting electrochemical cell (LEC) based on chlorophyll a as the emitter is reported, using the extracted chlorophyll a as the guest compound dispersed in a blend‐host matrix in a concentration of 2.5 or 5 mass %. The higher‐chlorophyll‐concentration LEC exhibits emission solely from the chlorophyll emitter, with the main emission peak located at 675 nm. The lower‐chlorophyll‐concentration LEC features two distinct emission bands, one in the red region that is originating from the chlorophyll guest and one in the blue region (main peak at 430 nm) that stems from the blend host. This combined red:blue emission can be attractive for, e. g., greenhouse applications, since it matches the action spectrum of plant photosynthesis.

Extraction Method for Determining Dinotefuran Insecticide in Soil Samples

Dinotefuran is a third-generation neonicotinoid insecticide that has a broad action spectrum in agriculture pests. Dinotefuran was authorized in Brazil in 2019, being classified as a very dangerous product for the environment. Therefore, this study aimed to optimize and validate the solid-liquid extraction with low temperature purification to determine dinotefuran in soil samples using high-performance liquid chromatography coupled diode array detection. The results showed that the best extracting phase was acetonitrile:water (8:2 v/v), followed by the clean-up with 50 mg of primary-secondary amine. The method under these conditions has a linear range of 15.0 to 140 µg kg-1 and reached limits of detection and quantification of 10.0 and 15.0 µg kg-1, respectively. The validation revealed that the method was selective, precise, accurate, and presented a matrix effect of 15%. Although dinotefuran was not detected in real soil samples, the proposed method proved to be an efficient alternative for monitoring dinotefuran in soil samples.

In Silico Activity Prediction and Docking Studies of the Binding Mechanisms of Levofloxacin Structure Derivatives to Active Receptor Sites of Bacterial Type IIA Topoisomerases

The need for new antimicrobial agents (AntAg) is driven by the persistent antibiotic resistance in microorganisms, as well as the increasing frequency of pandemics. Due to the deficiency of AntAg, research aimed at developing speedy approaches to find new drug candidates is relevant. This study aims to conduct an in silico study of the biological activity spectrum as well as the molecular binding mechanisms of four structurally different forms of levofloxacin (Lvf) with bacterial topoisomerases targets of type IIA (DNA gyrase and topoisomerase IV) to enable the development of drugs with an improved characterization of the safety profile. To achieve this goal, a number of software products were used, such as ChemicPen v. 2.6, PyMol 2.5, Avogadro 1.2.0, PASS, AutoDockTools 1.5.7 with the new generation software Autodock Vina. These software products are the first to be made available for visualization of clusters with determination of ligand-receptor pair binding affinity, as well as clustering coordinates and proposed mechanisms of action. One of the real structures of Lvf, a decarboxylated derivative, was obtained with tribochemical (TrbCh) exposure. The action spectrum of molecular ligands is described based on a Bayesian probability activity prediction model (PASS software Version 2.0). Predicted and real (PMS and RMS) molecular structures of Lvf, with decreasing levels of structural complexity, were translated into descriptors via Wiener (W), Balaban (Vs), Detour (Ip), and Electropy € indices. The 2D «structure-activity» diagrams were used to differentiate closely related structures of levofloxacin. PMS and RMS were visualized as 3D models of the ligand-receptor complexes. The contact regions of RMS and PMS with key amino acid residues—SER-79, DT-15, DG-1, DA-1—were demonstrated. The intra- and inter-molecular binding sites, data on free energy (affinity values, kcal/mol), the binding constant Kb (M−1), and the number of clusters are presented. The research results obtained from the presented in silico approach to explore the spectrum of action find quantitative “structure-activity” correlations, and predict molecular mechanisms may be of applied interest for directed drug discovery.

Exploring the fluorescence action spectrum of photosynthesis

The mathematical study of the fluorescence action spectrum of photosynthesis was performed. The calculation of typical spectra for photosynthesis was done for the red and blue frequencies. The transition of the action spectrum of photosynthesis from wavelengths to the frequency scale was completed. A numerical method based on the use of the inverse Fourier transform approach was used to obtain a relaxation curve for the impulse (time) characteristic of fluorescence. It turned out that the radius vector of the module of impulse response in polar coordinates makes one half-turn or half of the period of light oscillations in time. It was established that the optical medium of a plant during the relaxation time has a negative space charge of electrons, inverse properties and properties of the coherent radiation. The condition of neutrality of the material environment is not met. It was found that the ratio of the variable chlorophyll fluorescence for red and blue light has almost the same value. An analysis of the dependence of the quality factor of the chlorophyll spectrum on frequency shows that the fluorescence energy loss in blue light significantly exceeds the energy loss in red light. The proposed method can be used for express analysis of the intensity of photosynthesis. It was also concluded that plants can emit ultra-wideband signals. The relaxation time of chlorophyll fluorescence is shorter than the relaxation time of electronic polarization in atoms (molecules). As a result, a population inversion is created in the optical medium of chlorophyll - there are more atoms in the upper energy level than in the lower level. Due to this, stimulated emission and amplification of light of the radiative recombination occur. In this case, the emission of fluorescence light becomes coherent. All these properties of plants are considered for the first time and have not been described either in domestic or in foreign articles.

Genotoxicity and the stability of N-nitrosomorpholine activity following UVA irradiation

This study investigated N-nitrosomorpholine (NMOR) genotoxicity following UVA irradiation without metabolic activation. Following UVA irradiation, the photo treated NMOR (irradiated NMOR) was directly mutagenic, without UVA or metabolic activation, in the Ames test. The activity was relatively stable, and approximately 79% of the activity remained after 10 days of storage at 37 °C, 4 °C, or −20 °C. Micronuclei (MN) formation was observed in HaCaT cells after treatment with irradiated NMOR without metabolic activation. The action spectrum of MN formation in response to NMOR irradiation followed the NMOR absorption curve. In vivo, MN formation was observed in the peripheral blood reticulocytes of mice injected with irradiated NMOR under the inhibition of cytochrome P450-mediated metabolism of NMOR. Volatile NMOR may attach to environmental materials and be irradiated with environmental UVA light. Photoactivated NMOR-attached air pollutants could float in the air and fall onto the human body, leading to genotoxicity induced by the irradiated NMOR.

Rhombohedral boron monosulfide as a metal-free photocatalyst

Most of previous photocatalysts contain metal species, thus exploring a metal-free photocatalyst is still challenging. A metal-free photocatalyst has an advantage for the development of economical and non-toxic artificial photosynthesis system and/or environmental purification applications. In this study, rhombohedral boron monosulfide (r-BS) was synthesized by a high-pressure solid-state reaction, and its photocatalytic properties were investigated. r-BS absorbed visible light, and its photocurrent action spectrum also exhibited visible light responsivity. The r-BS evolved hydrogen (H2) from water under ultraviolet (UV) as well as under visible light irradiation, and its internal quantum efficiency reached 1.8% under UV light irradiation. In addition to the H2 evolution reaction, the r-BS photocatalyst drove carbon dioxide (CO2) reduction and dye oxidation reactions under UV irradiation. Although bare r-BS was not so stable under strong light irradiation in water, cocatalyst modification improved its stability. These results indicate that r-BS is a new class of non-metal photocatalyst applicable for H2 production, CO2 reduction, and environmental purification reactions.

Assessing the safety of new germicidal far-UVC technologies.

The COVID-19 pandemic underscored the crucial importance of enhanced indoor air quality control measures to mitigate the spread of respiratory pathogens. Far-UVC is a type of germicidal ultraviolet technology, with wavelengths between 200 and 235 nm, that has emerged as a highly promising approach for indoor air disinfection. Due to its enhanced safety compared to conventional 254 nm upper-room germicidal systems, far-UVC allows for whole-room direct exposure of occupied spaces, potentially offering greater efficacy, since the total room air is constantly treated. While current evidence supports using far-UVC systems within existing guidelines, understanding the upper safety limit is critical to maximizing its effectiveness, particularly for the acute phase of a pandemic or epidemic when greater protection may be needed. This review article summarizes the substantial present knowledge on far-UVC safety regarding skin and eye exposure and highlights research priorities to discern the maximum exposure levels that avoid adverse effects. We advocate for comprehensive safety studies that explore potential mechanisms of harm, generate action spectra for crucial biological effects and conduct high-dose, long-term exposure trials. Such rigorous scientific investigation will be key to determining safe and effective levels for far-UVC deployment in indoor environments, contributing significantly to future pandemic preparedness and response.

The action spectra of visible light and the skin redoxome

The action spectra of visible light and the skin redoxome