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In single vibronic level (SVL) fluorescence experiments, the electronically excited initial state is also excited in one or several vibrational modes. Because computing such spectra by evaluating all contributing Franck–Condon factors becomes impractical (and unnecessary) in large systems, here we propose a time-dependent approach based on Hagedorn wavepacket dynamics. We use Hagedorn functions—products of a Gaussian and carefully generated polynomials—to represent SVL initial states because in systems whose potential is at most quadratic, Hagedorn functions are exact solutions to the time-dependent Schrödinger equation and can be propagated with the same equations of motion as a simple Gaussian wavepacket. Having developed an efficient recursive algorithm to compute the overlaps between two Hagedorn wavepackets, we can now evaluate emission spectra from arbitrary vibronic levels using a single trajectory. We validate the method in two-dimensional global harmonic models by comparing it with quantum split-operator calculations. In addition, we study the effects of displacement, distortion (squeezing), and Duschinsky rotation on SVL fluorescence spectra. Finally, we demonstrate the applicability of the Hagedorn approach to high-dimensional systems on a displaced, distorted, and Duschinsky-rotated harmonic model with 100 degrees of freedom. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of excited-state vibrational energy relaxation in photosynthetic pigments is crucial for elucidating the mechanisms underlying energy transfer processes in light-harvesting complexes. Utilizing advanced femtosecond broadband transient fluorescence (TF) spectroscopy, we explored the excited-state vibrational dynamics of Chlorophyll-a (Chl-a) both in solution and within the light-harvesting complex II (LHCII). We discovered a vibrational cooling (VC) process occurring over ∼6 ps in Chl-a in ethanol solution following Soret band excitation, marked by a notable ultrafast TF blueshift and spectral narrowing. This VC process, crucial for regulating the vibronic lifetimes, was further elucidated through the direct observation of the population dynamics of higher vibrational states within the Qy electronic state. Notably, Chl-a within LHCII demonstrated significantly faster VC dynamics, unfolding within a few hundred femtoseconds and aligning with the ultrafast energy transfer processes observed within the complex. Our findings shed light on the complex interaction between electronic and vibrational states in photosynthetic pigments, underscoring the pivotal role of vibrational dynamics in enabling efficient energy transfer within light-harvesting complexes. [ABSTRACT FROM AUTHOR]

Proflavine, a fluorescent cationic dye with strong absorption in the visible, has been proposed as a potential contributor to diffuse interstellar bands (DIBs). To investigate this hypothesis, it is essential to examine the spectra of cold and isolated ions for comparison. Here, we report absorption spectra of proflavine ions, trapped in a liquid-nitrogen-cooled ion trap filled with helium-buffer gas, as well as fluorescence spectra to provide further information on the intrinsic photophysics. We find absorption- and fluorescence-band maxima at 434.2 ± 0.1 and 434.7 ± 0.3 nm, corresponding to a Stokes shift of maximum 48 cm−1, which indicates minor differences between ground-state and excited-state geometries. Based on time-dependent density functional theory, we assign the emitting state to S2 as its geometry closely resembles that of S0, whereas the S1 geometry differs from that of S0. As a result, simulated spectra involving S1 exhibit long Franck-Condon progressions, absent in the experimental spectra. The latter displays well-resolved vibrational features, assigned to transitions involving in-plane vibrational modes where the vibrational quantum number changes by one. Dominant transitions are associated with vibrations localized on the NH2 moieties. Experiments repeated at room temperature yield broader spectra with maxima at 435.5 ± 1 nm (absorption) and 438.0 ± 1 nm (fluorescence). We again conclude that prevalent fluorescence arises from S2, i.e., anti-Kasha behavior, in agreement with previous work. Excited-state lifetimes are 5 ± 1 ns, independent of temperature. Importantly, we exclude the possibility that a narrow DIB at 436.4 nm originates from cold proflavine cations as the band is redshifted compared to our absorption spectra. [ABSTRACT FROM AUTHOR]

Polymer-based ternary nanocomposites with tunable optical properties are the key components for optoelectronics applications. Here, we demonstrate the linear and nonlinear optical properties of polypyrrole (PPy) and its ternary composites with different concentrations of the MoS2–ZnO core–shell (ZnO@MoS2) heterostructure. The interesting observation of multiple excitons and their transportation through the interface of PPy and ZnO@MoS2 by using photoluminescence and fluorescence lifetime spectroscopy was studied. Furthermore, the third-order nonlinear optical properties of all samples were also measured by employing the z-scan technique at an excitation wavelength of 532 nm. The reverse saturable absorption of pure PPy was switched to saturable absorption after the addition of ZnO@MoS2 at the uniform linear transmittance. These ternary composites with good nonlinear responses provide an option for the development of high-performance nonlinear optical devices and open a new path for the future development of ternary systems in the optical fields. [ABSTRACT FROM AUTHOR]

We combine on-the-fly trajectory surface hopping simulations and the doorway–window representation of nonlinear optical response functions to create an efficient protocol for the evaluation of time- and frequency-resolved fluorescence (TFRF) spectra and anisotropies of the realistic polyatomic systems. This approach gives the effective description of the proper (e.g., experimental) pulse envelopes, laser field polarizations, and the proper orientational averaging of TFRF signals directly from the well-established on-the-fly nonadiabatic dynamic simulations without extra computational cost. To discuss the implementation details of the developed protocol, we chose cis-azobenzene as a prototype to simulate the time evolution of the TFRF spectra governed by its nonadiabatic dynamics. The results show that the TFRF is determined by the interplay of several key factors, i.e., decays of excited-state populations, evolution of the transition dipole moments along with the dynamic propagation, and scaling factor of the TFRF signals associated with the cube of emission frequency. This work not only provides an efficient and effective approach to simulate the TFRF and anisotropies of realistic polyatomic systems but also discusses the important relationship between the TFRF signals and the underlining nonadiabatic dynamics. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ co-doped Na2O–CaF2–ZnO–Al2O3–SiO2 glasses with different Zn/Si ratios were prepared using the melt-quenching technique. The thermal stability was investigated by differential scanning calorimetry. Additionally, the absorption spectra were also analyzed to gather more information about their properties. The down-conversion luminescence corresponding to the strongest fluorescence at a wavelength of 547 nm was obtained under the 378 nm excitation, and a 4S3/2 level fluorescence lifetime was studied. By utilizing a laser pump with a wavelength of 980 nm, the process of both up-conversion and down-conversion luminescence was accomplished. In particular, the glasses substantially enhance fluorescence properties when the Zn/Si ratio is about 0.16. The changes in the Zn/Si ratio lead to modifications in the glass network structure, changing the coordination field environment around the fluorescence center and ultimately impacting the luminescence properties of the rare-earth ions. These effects are evidenced through the findings obtained from Fourier transform infrared spectroscopy and fluorescence spectroscopy analysis of the glass material. [ABSTRACT FROM AUTHOR]

Rotationally resolved Fourier-transform spectra of laser-induced fluorescence A 1 Σ u + ∼ b 3 Π u → X 1 Σ g + of K2 molecules were recorded and analyzed, yielding 4053 term values of the spin–orbit (SO) coupled A ∼ b complex of the 39K2 isotopologue with ∼0.01 cm−1 accuracy. Their compilation with 1739 term values from previously published sources allowed them to cover the energy range [9955, 17 436] cm−1 from the bottom of the lower-lying b3Πu state up to the vicinity of the atomic asymptote 4 s 2 S 1 2 + 4 p 2 P 1 2 , with a rotational quantum number J ∈ [0, 149]. The experimental data were processed by a direct 6 × 6 coupled-channel (CC) deperturbation treatment, which accounted explicitly for both SO and electronic-rotational interactions between all six e-symmetry states: A 1 Σ u + ( 0 u + ), b3Πu( 0 u + , 1 u , 2 u ), c3Σu(1u), and B1Πu(1u). The initial parameters of the global deperturbation model have been estimated in the framework of ab initio electronic structure calculations applying multi-reference configuration-interaction and coupled-clusters methods. The interatomic potentials analytically defined for A and b states, as well as SO-splitting of the triplet b state and A ∼ b SO-coupling functions, have been particularly refined to fit the 5792 term values of the 39K2 isotopologue, whereas the rest parameters were fixed on their ab initio values. The resulting mass-invariant parameters of the 6 × 6 CC model reproduced the overall rovibronic term energies of the A ∼ b complex of 39K2 with accuracy, which is well within the experimental errors. The quality of the deperturbation analysis was independently confirmed by comparison with the present obtained 705 and 14 term values of respective 39K41K and 41K2 isotopologues, as well as by agreement between measured and predicted relative intensity distributions in long A ∼ b → X(vX) band progressions. This deperturbation analysis provided the refined dissociation energy Tdis = 17 474.569(5) cm−1 and the long-range coefficient C 3 Σ = 5.501(4) × 105 cm−1 Å3 relevant to the non-relativistic atomic limit 4s + 4p. The derived Tdis yielded the accurate well depth De = 4450.910(5) cm−1 for the ground X 1 Σ g + state, whereas the new C 3 Σ value yielded the improved estimates for atomic K(4 p 2 P 1 2 ; 3 2 ) radiative lifetimes, τ 1 2 = 26.67(3) and τ 3 2 = 26.32(3) ns. [ABSTRACT FROM AUTHOR]

We developed a spectroscopic method for directly obtaining the spectra of electromagnetic (EM) enhancement of plasmonic hotspots (HSs). The method was applied to one-dimensional (1D) HSs generated between silver nanowire (NW) dimers. The EM enhancement spectra were derived by dividing the spectra of surface-enhanced fluorescence (SEF) from single NW dimers with SEF obtained from large nanoparticle aggregates, where aggregate-by-aggregate variations in the SEF spectra were averaged out. Some NW dimers were found to exhibit EM enhancement spectra that deviated from the plasmon resonance Rayleigh scattering spectra, indicating that their EM enhancement was not generated by superradiant plasmons. These experimental results were examined by numerical calculation based on the EM mechanism by varying the morphology of NW dimers. The calculations reproduced the spectral deviations as the NW diameter dependence of EM enhancement. Phase analysis of the enhanced EM near-fields along the 1D HSs revealed that the dipole–quadrupole coupled plasmon, which is a subradiant mode, mainly generates EM enhancement for dimers with NW diameters larger than ∼80 nm, which was consistent with scanning electron microscopic measurements. [ABSTRACT FROM AUTHOR]

GaCH2, a free radical thought to play a role in the chemical vapor deposition of gallium-containing thin films and semiconductors, has been spectroscopically detected for the first time. The radical was produced in a pulsed discharge jet using a precursor mixture of trimethylgallium vapor in high pressure argon and studied by laser-induced fluorescence and wavelength resolved emission techniques. Partially rotationally resolved spectra of the hydrogenated and deuterated species were obtained, and they exhibit the nuclear statistical weight variations and subband structure expected for a 2A2–2B1 electronic transition. The measured spectroscopic quantities have been compared to our own ab initio calculations of the ground and excited state properties. The electronic spectrum of gallium methylene is similar to the corresponding spectrum of the aluminum methylene radical, which we reported in 2022. [ABSTRACT FROM AUTHOR]

The manipulation of the ultrafast quantum dynamics of a molecular system can be achieved through the application of tailored light fields. This has been done in many ways in the past. In our present investigation, we show that it is possible to exert specific control over the nonadiabatic dynamics of a generic model system describing ultrafast charge-transfer within a condensed dissipative environment by using frequency-chirped pulses. By adjusting the external photoexcitation conditions, such as the chirp parameter, we show that the final population of the excitonic and charge-transfer states can be significantly altered, thereby influencing the elementary steps controlling the transfer process. In addition, we introduce an excitation scheme based on double-pump time-resolved fluorescence spectroscopy using chirped-pulse excitations. Here, our findings reveal that chirped excitations enhance the vibrational system dynamics as evidenced by the simulated spectra, where a substantial signal intensity dependence on the chirp is observed. Our simulations show that chirped pulses are a promising tool for steering the dynamics of the charge-transfer process toward a desired target outcome. [ABSTRACT FROM AUTHOR]

Drier and hotter conditions linked with anthropogenic climate change can increase wildfire frequency and severity, influencing terrestrial and aquatic carbon cycles at broad spatial and temporal scales. The impacts of wildfire are complex and dependent on several factors that may increase terrestrial deposition and the influx of dissolved organic matter (DOM) from plants into nearby aquatic systems, resulting in the darkening of water color. We tested the effects of plant biomass quantity and its interaction with fire (burned vs. unburned plant biomass) on dissolved organic carbon (DOC) concentration and degradation (biological vs. photochemical) and DOM composition in 400 L freshwater ponds using a gradient experimental design. DOC concentration increased nonlinearly with plant biomass loading in both treatments, with overall higher concentrations (>56 mg/L) in the unburned treatment shortly after plant addition. We also observed nonlinear trends in fluorescence and UV-visible absorbance spectroscopic indices as a function of fire treatment and plant biomass, such as greater humification and specific UV absorbance at 254 nm (a proxy for aromatic DOM) over time. DOM humification occurred gradually over time with less humification in the burned treatment compared to the unburned treatment. Both burned and unburned biomass released noncolored, low molecular weight carbon compounds that were rapidly consumed by microbes. DOC decomposition exhibited a unimodal relationship with plant biomass, with microbes contributing more to DOC loss than photodegradation at intermediate biomass levels (100-300 g). Our findings demonstrate that the quantity of plant biomass leads to nonlinear responses in the dynamics and composition of DOM in experimental ponds that are altered by fire, indicating how disturbances interactively affect DOM processing and its role in aquatic environments.

We propose a novel UV/Vis femtosecond spectroscopic technique, two-dimensional fluorescence-excitation (2D-FLEX) spectroscopy, which combines spectral resolution during the excitation process with exclusive monitoring of the excited-state system dynamics at high time and frequency resolution. We discuss the experimental feasibility and realizability of 2D-FLEX, develop the necessary theoretical framework, and demonstrate the high information content of this technique by simulating the 2D-FLEX spectra of a model four-level system and the Fenna–Matthews–Olson antenna complex. We show that the evolution of 2D-FLEX spectra with population time directly monitors energy transfer dynamics and can thus yield direct qualitative insight into the investigated system. This makes 2D-FLEX a highly efficient instrument for real-time monitoring of photophysical processes in polyatomic molecules and molecular aggregates. [ABSTRACT FROM AUTHOR]

Most biological processes in living cells rely on interactions between proteins. Live-cell compatible approaches that can quantify to what extent a given protein participates in homo- and hetero-oligomeric complexes of different size and subunit composition are therefore critical to advance our understanding of how cellular physiology is governed by these molecular interactions. Biomolecular complex formation changes the diffusion coefficient of constituent proteins, and these changes can be measured using fluorescence microscopy-based approaches, such as single-molecule tracking, fluorescence correlation spectroscopy, and fluorescence recovery after photobleaching. In this review, we focus on the use of single-molecule tracking to identify, resolve, and quantify the presence of freely-diffusing proteins and protein complexes in living cells. We compare and contrast different data analysis methods that are currently employed in the field and discuss experimental designs that can aid the interpretation of the obtained results. Comparisons of diffusion rates for different proteins and protein complexes in intracellular aqueous environments reported in the recent literature reveal a clear and systematic deviation from the Stokes–Einstein diffusion theory. While a complete and quantitative theoretical explanation of why such deviations manifest is missing, the available data suggest the possibility of weighing freely-diffusing proteins and protein complexes in living cells by measuring their diffusion coefficients. Mapping individual diffusive states to protein complexes of defined molecular weight, subunit stoichiometry, and structure promises to provide key new insights into how protein–protein interactions regulate protein conformational, translational, and rotational dynamics, and ultimately protein function. [ABSTRACT FROM AUTHOR]

We develop the theory for the Stark fluorescence (SF) of molecular aggregates by taking into account the mixing of the excited states [including the states with charge-transfer (CT) characters]. We use the sum-over-state approach and modified rotating wave approximation to describe interactions of the static and optical fields with the permanent and transition dipoles of the excited states. The SF spectral profiles are calculated using the standard and modified Redfield theories for the emission lineshapes. The resulting expression allows an interpretation of the SF response based on the calculation of only one-exciton states (i.e., the calculation of two-exciton states is not needed). The shape and amplitude of the SF spectrum can exhibit dramatic changes in the presence of the CT states, especially when the CT state is mixed with the red-most emitting exciton levels. In this case, the SF responses are much more sensitive to the exciton-CT mixing as compared with the usual Stark absorption. The limitation of the proposed theory is related to the simplified nature of the Redfield picture, which neglects the dynamic localization within the mixed exciton-CT configuration. [ABSTRACT FROM AUTHOR]

Hydrophilic semiconductor quantum dots (QDs) with emission in the second near-infrared window (NIR-II) have been widely studied in bioimaging applications. In such cases, QDs are usually dispersed in water. As is known, water has strong absorbance in the NIR-II region. However, investigations on the interaction between NIR-II emitters and water molecules are ignored in previous studies. Herein, we synthesized a series of mercaptoundecanoic acid-coated silver sulfide (Ag2S/MUA) QDs with various emissions that partially or completely overlapped with the absorbance of water at 1200 nm. By constructing a hydrophobic interface of cetyltrimethylammonium bromide (CTAB) with MUA on the Ag2S QDs surface via forming an ionic bond, significant enhancement of Ag2S QDs photoluminescence (PL) intensity was observed, as well as a prolonged lifetime. These findings suggest that there is an energy transfer between Ag2S QDs and water in addition to the classical resonance absorption. Transient absorption and fluorescence spectra results revealed that the increased PL intensities and lifetime of Ag2S QDs originated from the suppressed energy transfer from Ag2S QDs to the water due to the CTAB bridged hydrophobic interfaces. This discovery is important for a deeper understanding of the photophysical mechanisms of QDs and their applications. [ABSTRACT FROM AUTHOR]

Three bis-benzimidazolyl bidentate ligands with phenolyl ether linkers, 1,n-bis[2-(1H-1,3-benzimidazol-1-ylmethyl)phenoxy]alkane (L1: n = 1, L2: n = 3, L3: n = 4), and their six metal complexes were synthesized by the reactions of the respective ligands with metal salts. The six metal complexes included two cobalt(II) complexes ([Co(L1)(NO3)2] (1) and [Co(L3)(LA)]n (6) (LA = maleate)), two copper(II) complexes ([Cu(L1)(SO4)]2 (4) and [Cu(L3)(SO4)]2 (5)), one zinc(II) complex ([Zn(L1)(NO3)2] (2)) and one nickel(II) complex ([Ni(L2)(NO3)2] (3)). Complexes 1 and 2 had one 16-membered macrometallocycle, and complex 3 had one 18-membered macrometallocycle. In complexes 4 and 5, two SO42- joined two macrometallocycles together (16-membered macrometallocycle for 4 and 19-membered macrometallocycle for 5). In complexes 1-5, each macrometallocycle was constructed from one ligand and one metal ion. In complex 6, 19-membered macrometallocycles were connected together by maleate groups (LA) to form a 1D polymeric chain, where each 19-membered macrometallocycle was constructed from one L3 and one Co(II) ion. In crystal packings of complexes 1-6, H-bonds, π--π interactions and C--H•••π contacts participated in the formation of 2D supramolecular layers and 3D supramolecular architectures. The conformations of complexes 1-6 were also analyzed. Additionally, the recognition performance of complex 1 as a chemosensor for HSO4- was studied through fluorescence spectra, UV/vis spectra, 1H NMR titrations, HRMS spectra and IR spectra. The large binding constant (1.81 x 104 M-1) showed that there was a strong acting force between 1 and HSO4-, and the low detection limit (1.40 x 10-7 mol L-1) indicated that the detection of 1 for HSO4- was sensitive. The experimental results showed that complex 1 can effectively differentiate HSO4- from other anions. [ABSTRACT FROM AUTHOR]

Hydrazine hydrate and hydrogen peroxide are both important raw materials for industrial production and have a wide range of applications in several fields. Owing to their damage to the human body and cellular functions by excessive exposure or ingestion, it is essential to develop an efficient and rapid assay for the detection of hydrazine hydrate and hydrogen peroxide. Fluorescence switches have been applied in many fields including for metal ion detection. However, the assembly of Prussian blue (PB) and carbon quantum dots (CDs) has never been reported for the fabrication of a fluorescence switch for the detection of hydrazine and hydrogen peroxide. In this work, a fluorescent switch PB@CD/SiO2 based on PB and CDs was constructed, which could be used as a detection platform for hydrazine hydrate and hydrogen peroxide. The surface of PB was coated with a silica layer, which contained CDs to fabricate PB@CD/SiO2 nanoparticles. The composite demonstrated reversible switching between fluorescence quenching and recovering states through the mutual conversion of PB and Prussian white (PW). The prepared composite was utilized for the detection of N2H4 and H2O2 by fluorescence spectroscopy and UV-vis absorption spectroscopy. It is worth-mentioning that the detection limit for N2H4 is calculated to be 0.15 μM (fluorescence) and the detection limit for H2O2 can reach 0.93 μM (UV). Moreover, both detection methods showed low detection limits, wide detection ranges and a short response time for N2H4 and H2O2. The proposed fluorescence switch system exhibits good performance towards the dual-spectral determination of hydrazine and hydrogen peroxide by fluorescence spectroscopy and UV-vis spectroscopy, which may be beneficial for further application in practical fields. [ABSTRACT FROM AUTHOR]

Three bis-benzimidazolyl bidentate ligands with phenolyl ether linkers, 1,n-bis[2-(1H-1,3-benzimidazol-1-ylmethyl)phenoxy]alkane (L1: n = 1, L2: n = 3, L3: n = 4), and their six metal complexes were synthesized by the reactions of the respective ligands with metal salts. The six metal complexes included two cobalt(II) complexes ([Co(L1)(NO3)2] (1) and [Co(L3)(LA)]n (6) (LA = maleate)), two copper(II) complexes ([Cu(L1)(SO4)]2 (4) and [Cu(L3)(SO4)]2 (5)), one zinc(II) complex ([Zn(L1)(NO3)2] (2)) and one nickel(II) complex ([Ni(L2)(NO3)2] (3)). Complexes 1 and 2 had one 16-membered macrometallocycle, and complex 3 had one 18-membered macrometallocycle. In complexes 4 and 5, two SO42- joined two macrometallocycles together (16-membered macrometallocycle for 4 and 19-membered macrometallocycle for 5). In complexes 1-5, each macrometallocycle was constructed from one ligand and one metal ion. In complex 6, 19-membered macrometallocycles were connected together by maleate groups (LA) to form a 1D polymeric chain, where each 19-membered macrometallocycle was constructed from one L3 and one Co(II) ion. In crystal packings of complexes 1-6, H-bonds, π--π interactions and C--H•••π contacts participated in the formation of 2D supramolecular layers and 3D supramolecular architectures. The conformations of complexes 1-6 were also analyzed. Additionally, the recognition performance of complex 1 as a chemosensor for HSO4- was studied through fluorescence spectra, UV/vis spectra, 1H NMR titrations, HRMS spectra and IR spectra. The large binding constant (1.81 x 104 M-1) showed that there was a strong acting force between 1 and HSO4-, and the low detection limit (1.40 x 10-7 mol L-1) indicated that the detection of 1 for HSO4- was sensitive. The experimental results showed that complex 1 can effectively differentiate HSO4- from other anions. [ABSTRACT FROM AUTHOR]

Hydrazine hydrate and hydrogen peroxide are both important raw materials for industrial production and have a wide range of applications in several fields. Owing to their damage to the human body and cellular functions by excessive exposure or ingestion, it is essential to develop an efficient and rapid assay for the detection of hydrazine hydrate and hydrogen peroxide. Fluorescence switches have been applied in many fields including for metal ion detection. However, the assembly of Prussian blue (PB) and carbon quantum dots (CDs) has never been reported for the fabrication of a fluorescence switch for the detection of hydrazine and hydrogen peroxide. In this work, a fluorescent switch PB@CD/SiO2 based on PB and CDs was constructed, which could be used as a detection platform for hydrazine hydrate and hydrogen peroxide. The surface of PB was coated with a silica layer, which contained CDs to fabricate PB@CD/SiO2 nanoparticles. The composite demonstrated reversible switching between fluorescence quenching and recovering states through the mutual conversion of PB and Prussian white (PW). The prepared composite was utilized for the detection of N2H4 and H2O2 by fluorescence spectroscopy and UV-vis absorption spectroscopy. It is worth-mentioning that the detection limit for N2H4 is calculated to be 0.15 μM (fluorescence) and the detection limit for H2O2 can reach 0.93 μM (UV). Moreover, both detection methods showed low detection limits, wide detection ranges and a short response time for N2H4 and H2O2. The proposed fluorescence switch system exhibits good performance towards the dual-spectral determination of hydrazine and hydrogen peroxide by fluorescence spectroscopy and UV-vis spectroscopy, which may be beneficial for further application in practical fields. [ABSTRACT FROM AUTHOR]

This study explores strontium (Sr) and caesium (Cs) dynamics in Moroccan agricultural soils, focusing on contaminant impacts and soil properties. Soil samples from El Koudia, Merchouch, and El Guich exhibit different textures: clayey (Merchouch), sandy clay loam (El Koudia), and sandy (El Guich). Chemical analysis shows consistent pH, with %CaCO3 at 1%, 4%, and 6%, and organic matter content at 4.5%, 1.1%, and 3.3% in Merchouch, El Guich, and El Koudia, respectively. Cation exchange capacity (CEC) and levels of Ca, K, Na, Mn, and Fe were measured. X-ray diffraction (XRD) identified quartz as the main mineral, with site-specific variations. X-ray fluorescence spectrometry (XRF) indicated consistent Cr, Ni, Cu, Zn, As, and Pb levels, and Rb varied significantly. Sr concentrations were 0.17 ppm in El Koudia and Merchouch, and 0.32 ppm in El Guich. Cs was undetected. This research highlights complex soil properties, elemental composition, and contaminant distribution in agricultural soils. [ABSTRACT FROM AUTHOR]

Background: Drug combination therapy is preferred over monotherapy in clinical research to improve therapeutic effects. Developing a new nanodelivery system for cancer drugs can reduce side effects and provide several advantages, including matched pharmacokinetics and potential synergistic activity. This study aimed to examine and determine the efficiency of the gemini surfactants (GSs) as a pH-sensitive polymeric carrier and cell-penetrating agent in cancer cells to achieve dual drug delivery and synergistic effects of curcumin (Cur) combined with tamoxifen citrate (TMX) in the treatment of MCF-7 and MDA-MB-231 human BC cell lines. Methods: The synthesized NPs were self-assembled using a modified nanoprecipitation method. The functional groups and crystalline form of the nanoformulation were examined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dynamic light scattering (DLS) used to assess zeta potential and particle size, and the morphological analysis determined by transmission electron microscopy (TEM). The anticancer effect was evaluated through an in vitro cytotoxicity MTT assay, flow cytometry analysis, and apoptosis analysis performed for mechanism investigation. Results: The tailored NPs were developed with a size of 252.3 ± 24.6 nm and zeta potential of 18.2 ± 4.4 mV capable of crossing the membrane of cancer cells. The drug loading and release efficacy assessment showed that the loading of TMX and Cur were 93.84% ± 1.95% and 90.18% ± 0.56%, respectively. In addition, the drug release was more controlled and slower than the free state. Polymeric nanocarriers improved controlled drug release 72.19 ± 2.72% of Tmx and 55.50 ± 2.86% of Cur were released from the Tmx-Cur-Gs NPs after 72 h at pH = 5.5. This confirms the positive effect of polymeric nanocarriers on the controlled drug release mechanism. moreover, the toxicity test showed that combination-drug delivery was much more greater than single-drug delivery in MCF-7 and MDA-MB-231 cell lines. Cellular imaging showed excellent internalization of TMX-Cur-GS NPs in both MCF-7 and MDA-MB-231 cells and synergistic anticancer effects, with combination indices of 0.561 and 0.353, respectively. Conclusion: The combined drug delivery system had a greater toxic effect on cell lines than single-drug delivery. The synergistic effect of TMX and Cur with decreasing inhibitory concentrations could be a more promising system for BC-targeted therapy using GS NPs. [ABSTRACT FROM AUTHOR]

This paper used different concentrations of xylose as a cross‐linker to initiate the Maillard reaction with the soy protein isolate matrix. The mechanical performance and moisture resistance of the soy protein isolate film were enhanced. Measuring the specific wavelength absorbance, free amino group concentration, and fluorescence spectrum of the cross‐linked result revealed the alteration of the soy protein isolate. Simultaneously, composite films made by crosslinking soy protein isolate with xylose were thoroughly investigated. Mechanical properties, contact angle measurement, water vapour transmission rate, optical properties, and thermal performance were used to determine the film's fundamental properties, and the interaction relationship between soy protein isolate, xylose, and glycerol was studied using infrared spectroscopy. The study found that the modified SPI film outperformed the unmodified film, particularly when the xylose content was 20%. The tensile strength reached 6.26 MPa, and the water vapour permeability was reduced to 5.45 × 10−8 g·mm/m2·s·Pa. It also exhibited excellent UV resistance and good thermal stability. [ABSTRACT FROM AUTHOR]

Organelles have unique structures and molecular compositions for their functions and have been classified accordingly. However, many organelles are heterogeneous and in the process of maturation and differentiation. Because traditional methods have a limited number of parameters and spatial resolution, they struggle to capture the heterogeneous landscapes of organelles. Here, we present a method for multiparametric particle-based analysis of organelles. After disrupting cells, fluorescence microscopy images of organelle particles labeled with 6 to 8 different organelle markers were obtained, and their multidimensional data were represented in two-dimensional uniform manifold approximation and projection (UMAP) spaces. This method enabled visualization of landscapes of 7 major organelles as well as the transitional states of endocytic organelles directed to the recycling and degradation pathways. Furthermore, endoplasmic reticulum–mitochondria contact sites were detected in these maps. Our proposed method successfully detects a wide array of organelles simultaneously, enabling the analysis of heterogeneous organelle landscapes. Organelles have unique structures and molecular composition, but can form heterogeneous populations and change substantially during maturation and differentiation, and traditional methods have failed to reflect these variations. In this study, the authors introduce a multi-parametric, fluorescence spectroscopy method that allows simultaneous visualization of a wide array of organelles in different maturation states. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3) has attracted much attention due to its promising applications in optical and electronic devices, while it is difficult to fabricate high‐quality Ga2O3 transparent ceramics because of the non‐cubic crystal structure. In this work, fully densified undoped and rare earth (RE = Tb, Dy. Er)‐doped Ga2O3 transparent ceramics were successfully fabricated by using spark plasma sintering (SPS) and co‐precipitated ceramic powders. Both the powders and ceramics showed pure monoclinic β‐ Ga2O3 crystal structure and unique orientation. After sintering by SPS for 30 min, all the ceramics reached a relative density higher than 99.21%. The total transmittance of RE‐doped Ga2O3 transparent ceramics ranges from 60% to 69% originating from the oriented and dense microstructures. The photoluminescence spectra and fluorescence lifetime of RE‐doped Ga2O3 transparent ceramics confirm characteristics of energy transfers corresponding to Tb3+, Dy3+, or Er3+ ions in the visible and NIR spectral region. This study demonstrates that oriented RE‐doped Ga2O3 transparent ceramics have great potential to be used in various optical applications. [ABSTRACT FROM AUTHOR]

Two phenothiazine derivatives, PTCNB and PTCNTBB, were designed and synthesized to confirm whether triaryl-substituted phenothiazine has mechanofluorochromic (MFC) properties and investigate the impact of tert-butyl (t-butyl) as a steric hindrance group on the molecular response to force stimuli. It was observed that the introduction of the t-butyl moiety did not significantly alter the molecular photophysical properties in the solution state due to its minimal effect on molecular π-conjugation. However, the presence of t-butyl strongly influenced their photoluminescence behavior and force-stimulus response in the solid state. PTCNB without t-butyl exhibited orange fluorescence in its pristine solid, which transformed into red fluorescence upon grinding, accompanied by a spectral shift of 23 nm. Conversely, PTCNTBB with t-butyl displayed green fluorescence in the as-synthesized solid and subsequently emitted orange fluorescence under force stimuli, demonstrating a more pronounced color variation. The corresponding spectral shift value was measured to be 58 nm. Remarkably, both ground solids regained their original fluorescence colors after vapor fuming, indicating a reversible MFC process. XRD patterns suggested that the application of force stimuli disrupted the intermolecular ordered packing while the fuming process restored ordered stacking, leading to the recovery of fluorescence emission. Absorption spectral changes implied that the presence of t-butyl induced loose packing and weak π--π interactions in PTCNTBB's initial solid, resulting in a short-wavelength fluorescence. Under force stimuli, the intermolecular interaction between PTCNTBB molecules was significantly enhanced, leading to an obvious redshift in the fluorescence spectra. In contrast, due to the absence of bulky steric groups, intermolecular packing between PTCNB molecules was relatively dense in its pristine solid and then applying pressure did not cause significant changes in a π-packing arrangement; hence only a small spectral shift occurred. [ABSTRACT FROM AUTHOR]

Age-related neurodegenerative disorders like Alzheimer's disease (AD) and Parkinson's disease (PD) are characterized by deposits of protein aggregates, or amyloid, in various regions of the brain. Historically, aggregation of a single protein was observed to be correlated with these different pathologies: tau in AD and α-synuclein (αS) in PD. However, there is increasing evidence that the pathologies of these two diseases overlap, and the individual proteins may even promote each other's aggregation. Both tau and αS are intrinsically disordered proteins (IDPs), lacking stable secondary and tertiary structure under physiological conditions. In this study we used a combination of biochemical and biophysical techniques to interrogate the interaction of tau with both soluble and fibrillar αS. Fluorescence correlation spectroscopy (FCS) was used to assess the interactions of specific domains of fluorescently labeled tau with full length and C-terminally truncated αS in both monomer and fibrillar forms. We found that full-length tau as well as individual tau domains interact with monomer αS weakly, but this interaction is much more pronounced with αS aggregates. αS aggregates also mildly slow the rate of tau aggregation, although not the final degree of aggregation. Our findings suggest that co-occurrence of tau and αS in disease are more likely to occur through monomer-fiber binding interactions, rather than monomer-monomer or co-aggregation. [ABSTRACT FROM AUTHOR]

Accurate measurement of metal concentrations in soil and water is vital for healthy crop production and decision making for environmental surveys. While there are a multitude of laboratory‐based soil analysis methods, such as inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), flame emission spectrometry, and atomic absorption spectroscopy, most are time and resource intensive. Additionally, there is a lack of information for rapid analysis of elements for aqueous soil extractions. The goal of this research is to establish elemental correlations between portable X‐ray fluorescence (pXRF) measurements of Mehlich III soil extractions and traditional elemental measurements via ICP‐OES. We hypothesize that certain metals can be accurately measured in aqueous soil extraction solutions by pXRF to the same degree as they are measured by ICP‐OES. To test this hypothesis, Mehlich III and 2% nitric acid solutions with known elemental concentrations were analyzed via ICP‐OES and pXRF. Soil samples extracted using Mehlich III were compared between ICP‐OES and pXRF to verify correlations. High correlations were found for As, Ca, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, V, and Zn in both the Mehlich III and 2% nitric acid solutions at concentrations between 5 and 85 mg L−1. P, S, and Si did not show high correlations at concentrations <100 mg L−1. These results indicate that between 5 and 85 mg L−1, pXRF analysis of aqueous solutions and soil extractions is a reliable technique; however, at low concentrations (i.e., <5 mg L−1 for metals and <100 mg L−1 for P and S), pXRF is not well suited. [ABSTRACT FROM AUTHOR]

Fluorescence lifetime imaging microscopy (FLIM) is a well-established technique with numerous imaging applications. Yet, one of the limitations of FLIM is that it only provides information about the emitting state. Here, we present an extension of FLIM by interferometric measurement of fluorescence excitation spectra. Interferometric Excitation Fluorescence Lifetime Imaging Microscopy (ixFLIM) reports on the correlation of the excitation spectra and emission lifetime, providing the correlation between the ground-state absorption and excited-state emission. As such, it extends the applicability of FLIM and removes some of its limitations. We introduce ixFLIM on progressively more complex systems, directly compare it to standard FLIM, and apply it to quantitative resonance energy transfer imaging from a single measurement. The authors introduce an extension of the popular fluorescence lifetime imaging microscopy (FLIM) named ixFLIM. By correlating the excitation spectrum with emission lifetime, ixFLIM can distinguish the fluorescent species in each pixel of the microscope image. [ABSTRACT FROM AUTHOR]

A new amphiphilic boron-dipyrromethene (BODIPY) dye bearing a hydrophobic 2,3,4-tris(n-dodecyloxy) phenyl group at the meso-position and two hydrophilic cationic moieties at the boron was synthesized. This dye exhibited kinetically controlled and thermodynamically controlled aggregation pathways in aqueous solution, leading to the formation of two types of J-aggregates, i.e., the metastable Agg. I and thermodynamically more stable Agg. II. Further kinetic analysis of the spontaneous transformation from Agg. I to Agg. II indicated that Agg. I was an off-pathway aggregate species. Moreover, both Agg. I and Agg. II displayed J-aggregate characteristics with enhanced fluorescence quantum yields and shortened fluorescence lifetime with respect to that of the monomeric dye. In particular, Agg. II exhibited a narrowed and intense J-band, reflecting the strong excitonic coherence in the aggregate. Morphological studies revealed that Agg. I consisted of spherical nanoparticles, while Agg. II had a multilamellar vesicular structure. In addition, in the fluorescence spectra of Agg. I and Agg. II, an unexpected broad band at longer wavelength than that of the J-aggregate emission was observed, which could be ascribed to the possible formation of excimers in these J-aggregates in aqueous solution. [ABSTRACT FROM AUTHOR]

Summary This study investigated the impact of varying ethanol concentrations on the functionality and structure of conjugates of gallic acid (GA) and whey protein isolate (WPI). The solubility, total phenolic content, and sulfhydryl group content of the conjugates significantly decreased with increasing ethanol concentration. The structure of the conjugates was altered as indicated by changes in their infrared and fluorescence spectra. By measuring the emulsification and foaming properties, we found that ethanol improved the functional properties of the conjugates. The study examined the influence of ethanol on the conjugates of polyphenolic compounds with whey protein, broadening the scope of research on protein modification. Furthermore, it provided a scientific basis for the future development of novel functional foods. [ABSTRACT FROM AUTHOR]

AbstractPolyphenolic compounds have received much attention due to their major function as antioxidants. Sinapic acid (SA) is an orally bioavailable phytochemical with excellent free radical scavenging property transported in the blood by human serum albumin (HSA) which is the chief carrier protein found abundantly in human plasma. SA contains a single phenolic group. This study investigates the binding and interaction mechanism between SA and HSA by multiple spectroscopic and calorimetric techniques, such as UV/visible absorption spectroscopy, intrinsic fluorescence studies, Fourier transform infrared (FTIR) spectroscopy and isothermal titration calorimetry (ITC). UV/visible absorption spectroscopy showed hyperchromicity in the absorption spectra, suggestive of structural change due to complex formation between HSA and SA. Intrinsic fluorescence measurements, performed at three different temperatures, showed quenching of the fluorescence spectra and the mechanism of quenching was static in nature which occurred due to ground state complex formation. The FTIR results demonstrated a 16% decrease in α-helical content of the secondary structure of HSA in the presence of SA. Hydrogen bonds and hydrophobic forces were the main forces of interaction, according to the thermodynamic characteristics found through ITC. Moreover, the data obtained through ITC indicated strong binding affinity between HSA and SA and supported the exothermic and spontaneous nature of the interaction. [ABSTRACT FROM AUTHOR]

Femtosecond fluorescence upconversion experiments were combined with CASPT2 and time dependent DFT calculations to characterize the excited state dynamics of the mutagenic etheno adduct 1,N2‐etheno‐2'‐deoxyguanosine (ϵdG). This endogenously formed lesion is attracting great interest because of its ubiquity in human tissues and its highly mutagenic properties. The ϵdG fluorescence is strongly modified with respect to that of the canonical nucleoside dG, notably by an about 6‐fold increase in fluorescence lifetime and quantum yield at neutral pH. In addition, femtosecond fluorescence upconversion experiments reveal the presence of two emission bands with maxima at 335 nm for the shorter‐lived and 425 nm for the longer‐lived. Quantum mechanical calculations rationalize these findings and provide absorption and fluorescence spectral shapes similar to the experimental ones. Two different bright minima are located on the potential energy surface of the lowest energy singlet excited state. One planar minimum, slightly more stable, is associated with the emission at 335 nm, whereas the other one, with a bent etheno ring, is associated with the red‐shifted emission. [ABSTRACT FROM AUTHOR]

ABSTRACT Fluorescence spectroscopy has been applied for analysis of complex samples, such as food and beverages. Parallel factor analysis (PARAFAC) is a well‐known decomposition method for fluorescence excitation–emission matrices (EEMs). When the complexity of the system increases, it becomes considerably more difficult to determine the optimal number of PARAFAC components, especially when the fluorophores of the system are unknown. The two commonly applied diagnostics, core consistency and split‐half analysis, appear to underestimate the model complexity due to covarying components and local minima, respectively. As a more robust alternative, we propose a resampling approach with multiple initializations and submodel comparisons for estimating the optimal number of PARAFAC components in complex data. [ABSTRACT FROM AUTHOR]

Purpose: Astaxanthin (AX), commonly used for dermal applications, exhibits anti-inflammatory and antioxidant activities; however, it has poor water solubility. In this study, we investigated the physicochemical properties of AX-containing particulates formulated using the amphiphilic graft copolymer Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer: Sol) and polyethylene glycol-2000 (PEG 2000); in addition, the stability and skin applications of AX particulates were investigated. Methods: AX, Sol, and PEG were mixed by weight to prepare AX particles using the hydration method. The prepared particles were subjected to stability evaluations including particle size distribution, zeta potential estimation, and fluorescence spectroscopy as well as physical evaluations including 1H-1H NOESY NMR spectral measurement, powder X-ray diffraction, and differential scanning calorimetry. Functional evaluations included singlet oxygen scavenging, skin permeation test, and fluorescence microscopy. Results: Relatively stable particles of Sol/AX and Sol/PEG 2000/AX, approximately 100 nm and 125 nm in size, respectively, were formed at a mixed weight ratio (9/1) of 0.1 M Ascorbic Acid solution (0.1 M ASC) and a mixed weight ratio (8/1/1) of 0.1 M ASC, respectively, at 25 °C after storage for 14 days under light-shielded condition. Stability evaluations revealed a decrease in fluorescence intensity and color fading for Sol/AX = 9/1 and Sol/PEG 2000/AX = 8/1/1 (dispersion medium: distilled water); however, no change in fluorescence intensity of AX was observed immediately after preparation in Sol/AX = 9/1 and Sol/PEG 2000/AX = 8/1/1 (dispersion medium: 0.1 M ASC). The fluorescence intensity of AX did not fluctuate significantly immediately after adjustment, and the particles remained stable, showing a bright orange color with time. NMR spectra of Sol/AX = 9/1 and Sol/PEG 2000/AX (dispersion medium: 0.1 M ASC) showed the interactions between the CH3 group e from Sol (1.8 ~ 2.0 ppm) and the CH groups H-15,11 from AX (6.7 ~ 6.8 ppm), 8',12' (6.4 ~ 6.5 ppm), H-10,14 (6.4 ~ 6.5 ppm), and 7,7' (6.2 ~ 6.3 ppm), indicating the disappearance of cross peaks. Furthermore, new cross peaks were identified for the CH3 group e of Sol (1.8 ~ 2.0 ppm), the 7-membered ring z of Sol (1.5 ~ 1.8 ppm), the 5-membered ring S of ASC (3.5 ~ 3.6 ppm), the CH group T (3.8 ~ 3.9 ppm), and the CH group U (4.7 ppm). Fluorescence microscopy observations of microparticles formulated with Sol/PEG 2000/AX showed a slight improvement in skin penetration. Conclusion: New AX particulates were formed using Sol/PEG 2000/AX = 8/1/1, suggesting that Sol/PEG 2000/AX maintained the stability and improved the skin penetration of AX. [ABSTRACT FROM AUTHOR]

Metal ion-DNA interactions play a crucial role in modulating the structure and function of genetic material in the natural environment. In this study, we report on the favorable electrochemical activity of holmium(III) (Ho3+) on a glassy carbon electrode (GCE) and its interaction with double-stranded DNA. The interaction between DNA and Ho3+ was investigated for the first time using cyclic voltammetry and differential pulse voltammetry. The electrochemical behavior of Ho3+ ions on a GCE exhibited a reversible electron transfer process, indicative of its redox activity. A linear correlation between the peak current and the square root of the scan rate was observed, suggesting a diffusion-controlled kinetic regime for the electrochemical process. Additionally, fluorescence and absorption spectroscopy were employed to confirm the binding of Ho3+ to DNA. Our findings demonstrate that, at pH 7.2, specific DNA bases and phosphate groups can interact with Ho3+ ions. Moreover, electrochemical measurements suggest that Ho3+ ions bind to DNA via a groove binding mode, with a calculated binding ratio of 1:1 between Ho3+ and DNA. Notably, under optimal conditions, an increase in the amount of DNA leads to a significant reduction in the current intensity of Ho3+ ions. [ABSTRACT FROM AUTHOR]

Glutinous rice mortar is a traditional lime-based building material which was first used in China during the Southern Song Dynasty (1127-1279 CE) according to ancient Chinese documents. The Tieguai Tomb, dating back to the late Northern Song Dynasty (960-1127 CE) in Nanling, Southern China, was built by using mortar for its tomb chamber, making it the earliest mortar tomb found in China to date. In this study, X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), thin-section petrography, Fourier transform infrared spectroscopy (FTIR), and starch grain analyses were conducted to comprehensively investigate the manufacturing techniques of the mortar from the Tieguai tomb. The results show that the mortar is a type of organic–inorganic mixed material made of glutinous rice pulp, lime, clay, and fine sand. This finding indicates that glutinous rice mortar had already been used as a building material as early as the late Northern Song Dynasty, which is the earliest use record for this material in China. This study also provides direct scientific evidence for exploring the origin of glutinous rice mortar and is of great importance for reconstructing the history of Chinese traditional building materials and architectural techniques. [ABSTRACT FROM AUTHOR]

ABSTRACT The SARS‐CoV‐2 main protease (Mpro) is an essential enzyme that promotes viral transcription and replication. Mpro conserved nature in different variants and its nonoverlapping nature with human proteases make it an attractive target for therapeutic intervention against SARS‐CoV‐2. In this work, the interaction mechanism between Mpro and diindolylmethane derivatives was investigated by molecular docking, enzymatic inhibition assay, UV–vis, fluorescence spectroscopy, and circular dichroism spectroscopy. Results of IC50 values show that 1p (9.87 μM) was the strongest inhibitor for Mpro in this work, which significantly inhibited the activity of Mpro. The binding constant (4.07 × 105 Lmol−1), the quenching constant (5.41 × 105 Lmol−1), and thermodynamic parameters indicated that the quenching mode of 1p was static quenching, and the main driving forces between 1p and Mpro are hydrogen bond and van der Waals force. The influence of molecular structure on the binding is investigated. Chlorine atoms and methoxy groups are favorable for the diindolylmethane derivative inhibitors of Mpro. This work confirms the changes in the microenvironment of Mpro by 1p, and provides clues for the design of potential inhibitors. [ABSTRACT FROM AUTHOR]

Identifying the types of materials such as plastics, microplastics, and oil pollutants is essential for understanding their effects on marine life. We propose a new methodology for the real-time detection and identification of microplastics in aquatic environments. Our experiments are based on a compact Laser Induced Fluorescence (LIF) device, with machine learning techniques applied to classify the materials. A 405 nm CW laser excitation source effectively induces fluorescence spectra in the visible spectrum from material samples that are either floating or submerged in water. We examine known plastic pollutants in seawater, including polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET), as well as maritime fuels, lubricating oils, and other organic substances that are abundant in the marine environment. Our two-step identification process first employs machine learning algorithms to distinguish microplastics from other organic materials with a high degree of accuracy (97.6%). Subsequently, the type of plastic is determined with an accuracy of 88.3% in a second application of machine learning techniques. [ABSTRACT FROM AUTHOR]

Using a solid-state technique under low temperature conditions, Er3+/Yb3+ co-doped Bi2Mo2O9 phosphors with different concentrations were prepared, exhibiting excellent green up-conversion luminescence property. A thorough investigation was conducted on the phase structure, optical transition, up-conversion luminescence, and down-shifting luminescence properties of the prepared samples. Bi2Mo2O9: Er3+/Yb3+ phosphors excited at 381, 980, and 1550 nm showed strong green fluorescence together with very faint red emission. The mechanism of up-conversion luminescence and its capacity for temperature sensing were examined under the excitation of various wavelengths. Under 980 nm excitation, the maximal relative and absolute sensitivities were determined to be 1.107%K− 1 and 0.756%K− 1 at 303 K and 513 K, respectively. Furthermore, the Judd-Ofelt intensity parameters of Er3+ in Bi2Mo2O9: Er3+/Yb3+ phosphors were calculated using the diffuse reflectance spectra and fluorescence lifetime of Er3+. In addition, material was combined with polyacrylic acid to make an anti-counterfeiting pattern. The results indicate that Bi2Mo2O9: Er3+/Yb3+ phosphor is an excellent green phosphor with optical temperature measurement function, and it also has certain applications in the field of anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The red-emitting material SrBaMoO4:0.16Eu3+ was synthesized by using a high-temperature solid-state method. X-ray diffraction (XRD) and fluorescence spectroscopy were employed to analyze the crystal structure and luminescent properties. The results revealed that the sintering temperature had an influence on the crystal structure of the samples, with an optimal sintering temperature of 800℃. SrBaMoO4:0.16Eu3+ synthesized at 800℃ for 6.5 h exhibited a pure crystalline phase of SrBaMoO4. The luminescent intensity of the SrBaMoO4:0.16Eu3+ sample under excitation at 394 nm was tested at different temperatures. When the temperature reached 100℃, the luminescent intensity was 72.11% of the initial intensity, and the temperature reached 175℃, it dropped to 35.27% of the initial intensity. The sample demonstrated efficient excitation by blue light (464 nm), resulting the emission peak at 615 nm corresponding to the 5D0-7F2 transition of Eu3+. The luminescent intensity of the sample was found to increase with increasing Ba2+ concentration, reaching its maximum intensity when the Ba2+ doping concentration x was 0.27, followed by a gradual decreaseat excessive doping concentration, indicating concentration quenching. The CIE coordinates were calculated for the sample under excitation at 464 nm, revealing exhibited the best red emission at the Ba2+ doping concentration of x = 0.27. Additionally, first-principles calculations were used to determine the band structure and density of states of the sample. [ABSTRACT FROM AUTHOR]

A novel Ni (II) coordination polymer [Ni(pdc)(bib)(H2 O)]n (Ni-CP) was synthesised by solvothermal method with 3,5-pyridyl dicarboxylic acid (3,5-H2 pdc), 1, 4-bis (1-imidazolyl) benzene (bib) and Ni(NO3)2, and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric, IR spectroscopic and fluorescence spectroscopy analysis. The results show that Ni-CP crystallized as a monoclinic system with C2/c space group. The asymmetric unit of Ni-CP was comprised of one Ni(II), two half bib ligands, one completely deprotonated 3,5-pdc2 - ligands and one coordinated water molecule. The environment around central Ni(II) can be described as irregular hexacoordination octahedral geometry of NiO3 N3. The bib and 3,5-pdc2 - ligands were bridged by the bidentate coordination mode in the μ2-η1∶η1 fashion and the tridentate coordination mode in the μ3-η1∶η1∶η1 fashion to form a three-dimensional network framework. From a topological point of view, the two-dimensional frame structure can be simplified to a 3-connected topology with a Schläfli symbol (4·82). We consider the 3,5-pdc2 - ligands and Ni(II) as nodes and the bib ligands as connectors, forming a threedimensional structure can be simplified to a 3,5-connected double nodes with topological symbols (4·6·8)(4·62 ·87). The porosity of Ni-CP is 17. 4%. Ni-CP could selectively detect Fe3 +, CrO2 - 4 and Cr2 O2 - 7 with detection limits of 4. 275 ×10 -5, 2. 681 ×10 -5, 2. 681 ×10 -5 mol/L, respectively, and have a high quenching rate. [ABSTRACT FROM AUTHOR]

A series of Eu3 + singly- and Dy3 + / Eu3 + co-doped CaLaGa3 O7 single matrix phosphors were successfully prepared by high-temperature solid-phase method. The phase and luminescence properties of the samples were characterized by X-ray diffraction (XRD) and photoluminescence spectra. The XRD patterns show that all the prepared samples have a tetragonal structure consistent with the matrix crystal, indicating the successful synthesis of that Eu3 + singly- and Dy3 + / Eu3 + co-doped CaLaGa3 O7 phosphors. Under excitation of 393 nm, Eu3 + ∶CaLaGa3 O7 exhibits characteristic red emission of Eu3 + (5 D0→7 F2), and the luminescence purity is as high as 100%. After introducing Dy3 +, Dy3 + / Eu3 + co-doped CaLaGa3 O7 phosphors could be excited not only by 393 nm light but also by 348 nm. Regardless of the excitation wavelength, the emission spectra of Dy3 + / Eu3 + ∶CaLaGa3 O7 include both the characteristic red emission of Eu3 + and the yellow emission of Dy3 + (4 F9/2 →6 H13/2). By analyzing the emission spectra and fluorescence lifetime, it is confirmed that there exists effective energy transfer process between Dy3 + and Eu3 + in the co-doped phosphors. Further, the corresponding chromaticity coordinates and CCT values were calculated. The results show that the overall chromaticity coordinates shift from the yellow-green region to the yellow-orange region when the excitation wavelength is changed from 348 nm to 393 nm. Therefore, the Dy3 + / Eu3 + ∶CaLaGa3 O7 is a tunable luminescent material with good application prospects in displays and solid-state lighting. [ABSTRACT FROM AUTHOR]

The adsorption and fluorescence spectra of the grown Nd∶GdYAG were measured. The spectral parameters, such as oscillator strength, line strength, intensity parameter Ωt, transition probability between 4 F3/2→4 IJ levels, radiation lifetime, and fluorescence branching ratio, were calculated with Judd-Ofelt theory. The calculated Ωt are Ω2 = (0.813 ±0.200) ×10-20 cm2, Ω4 = (3. 381 ±0. 187) × 10 -20 cm2, Ω6 = (5. 135 ± 0. 278) × 10 -20 cm2, respectively. Compared with Nd-doped YAG, LuAG, YVO4, and other crystals, Nd∶GdYAG crystal has a larger Ω2, showing that the addition of Gd3 + increases the disorder of the host. The absorption cross-section and refractive index in the range of 300 ~1 200 nm were calculated and fitted. The absorption cross-section at 808 nm is 5. 0 ×10 -20 cm2. The refractive index at 1 064 nm is 1. 80. The measured fluorescence lifetime of 4 F3/2 level is 228 μs, which is close to the calculated radiation lifetime of 240 μs. The emission cross-section at 1 064 nm is 1. 23 × 10 -19 cm2, which is close to that of Nd∶ YAG crystal. Addition, at room temperature, the thermal conductivity of Nd∶GdYAG crystal is 5. 992 W/(m·K), which is slightly smaller than that of Nd∶YAG and Nd∶GGG, but larger than that of Nd∶YVO4 crystal. The results show that Nd∶GdYAG is a promising new laser crystal material. [ABSTRACT FROM AUTHOR]

How plasmonic nanostructures modulate the behavior of exciplexes and excimers within materials remains unclear. Thus, advanced knowledge is essential to bridge this gap for the development of optoelectronic devices that leverage the interplay between plasmonic and conjugated polymer hybrid materials. Herein, this work aims to explore the role of gold nanoparticles (AuNPs) in modulating exciplex and excimer states within the conjugated polymer poly(2,5-di(3,7-dimethyloctyloxy) cyanoterephthalylidene) (PDDCP), known for its photoluminescent and semi-conductive properties, aiming to create innovative composite materials with tailored optical features. The spectral analysis was conducted to investigate the effects of AuNPs on the PDDCP, varying AuNP volume percentages to measure changes in the absorption profile, molar extinction coefficient (ε), absorption cross-section (σa), and optical bandgap ( E g ). Fluorescence spectra of the mixture at different volume ratios were also examined to assess exciplex formation, while amplified spontaneous emission (ASE) profiles were analyzed to study the behavior and photochemical stability of the polymer–NP hybrid material. Increasing AuNP volume induced both blue and red shifts in the absorption profile of the PDDCP. Higher AuNPs concentrations correlated with decreased ε and σa, inversely impacting E g . The emission spectra obtained at varied AuNP volume ratios indicated significantly enhanced exciplex and excimer formations. The ASE profiles remained consistent but showed reduced intensity with increasing AuNPs concentrations, indicating their influence on hybrid material behavior and stability. The findings suggest that AuNPs affect PDDCP's optical characteristics, altering the absorption profile, bandgap, and fluorescence spectra. Furthermore, the observed reduction in ASE intensity highlights their influence on the behavior and photochemical stability of the hybrid material. These results contribute to a better understanding of the versatile applications of plasmonic-conjugated hybrid polymers. [ABSTRACT FROM AUTHOR]

The peculiarities of the decoration of gravure imprints on cardboard using fluorescent inks are considered. The influence of the number of fluorescent impurities added to gravure printing ink on the optical indicators of printed image quality, particularly optical density, and gloss, is investigated. Increasing the number of fluorescent impurities added to the ink from 10 to 30% helps to increase the gloss on imprints from 2 to 15 units. Conducted thermogravimetric studies show the resistance of fluorescent imprints to the influence of temperatures during drying in the printing process. The topography of the surface of the substrates and its influence on the quality of imprints is studied. Conducted electron microscopic studies of imprints obtained with inks with different amounts of fluorescent impurities show their uniform distribution on the surface of the substrate. Studies of the fluorescence spectra of the ink and the imprints formed by it confirm the phenomenon of an increase in the intensity of the glow of printed images. The studies confirm the well-known influence of substrate roughness on the smoothness of gravure imprints. It is established that the absence of significant macro irregularities on the surface of Koppargloss FBB cardboard is due to the presence of two coating layers. Analysis of the surface profiles of FBB cardboard shows that its roughness parameter (Ra = 0.424 μm) is three times smaller compared to Incada Silk C GC1 cardboard (the roughness parameter Ra = 1.28 μm), with a single-layer coating. Such a pattern is also preserved on the imprints, which is reflected in their quality accordingly. Studies show that for imprints on GC1 cardboard, the average ΔE value is 2.23, for imprints on FBB cardboard, the average ΔE value is 3.71, which is due to the presence of double coating. The factors that can influence the process of fluorescence of printed images are outlined. The technological characteristics of inks for gravure printing on packaging are described. [ABSTRACT FROM AUTHOR]

Since the colorimetric method has the characteristics of being simple and low cost, the fluorescence spectrum has the characteristics of a strong signal, and Surface-enhanced Raman scattering (SERS) detection has the characteristics of high sensitivity and strong specificity, people usually use these three methods for detection, but the detection of a single sample takes more time. If multiple samples can be tested at the same time, the detection efficiency and sensitivity can be improved, and the selectivity and reliability will be greatly improved. Multiplex sensing also provides a new direction for researchers. To fully understand the research of multiplex sensing based on the plasmonic optics of noble metal nanostructures, this review summarizes all the results previously reported in this field. It also discusses the principles of various detection methods and the biochemical application of multiple detections and finally summarizes the challenges and prospects. [ABSTRACT FROM AUTHOR]

Summary: To address the adverse effects of current hypoglycaemic drugs and the limited effect of individual extracts, this research investigated the inhibitory effect of combined green tea extract (GTE) and coffee (CE) on α‐amylase (α‐AMY) and α‐glucosidase (α‐GLU) and their inhibitory mechanisms. The inhibitory effects of single extracts and the complexes on α‐AMY and α‐GLU activities were compared by the principle of equivalence line. The results showed that the complexes had a good synergistic inhibition effect on both α‐AMY and α‐GLU at GTE: CE = 4:1 (w/w). Fluorescence spectroscopy and circular dichroism spectroscopy indicated that the complexes of GTE: CE = 4:1 (w/w) altered the secondary and tertiary structures of α‐AMY and α‐GLU more than the individual extracts, resulting in a synergistic inhibitory effect. The orthogonal experiments showed that tea polyphenols (TP) and coffee polyphenols (CP) were the main components responsible for the synergistic inhibitory effect of the two extracts. [ABSTRACT FROM AUTHOR]