Nonlinear Absorption Processes Research Articles

Physiologically based in vitro – in vivo correlation of modified release oral formulations with non-linear intestinal absorption: A case study using mirabegron

Establishing an in vitro – in vivo correlation (IVIVC) for oral modified release (MR) formulations would make it possible to substitute an in vitro dissolution test for human bioequivalence (BE) studies when changing the formulation or manufacturing methods. However, the number of IVIVC applications and approvals are reportedly low. One of the main reasons for failure to obtain IVIVCs using conventional methodologies may be the lack of consideration of the dissolution and absorption mechanisms of drugs in the physiological environment. In particular, it is difficult to obtain IVIVC using conventional methodologies for drugs with non-linear absorption processes. Therefore, the aim of the present study was to develop a physiologically based biopharmaceutics model (PBBM) that enables Level A IVIVCs for mirabegron MR formulations with non-linear absorption characteristics.Using human pharmacokinetic (PK) data for immediate-release formulations of mirabegron, the luminal drug concentration-dependent membrane permeation coefficient was calculated through curve fitting. The membrane permeation coefficient data were then applied to the human PK data of the MR formulations to estimate the in vivo dissolution rate by curve fitting. It was assumed that in vivo dissolution could be described using a zero-order rate equation. Furthermore, a Levy plot was generated using the estimated in vivo dissolution rate and the in vitro dissolution rate obtained from the literature. Finally, the dissolution rate of the MR formulations from the Levy plot was applied to the PBBM to predict the oral PK of the mirabegron MR formulations.This PB-IVIVC approach successfully generated linear Levy plots with slopes of almost 1.0 for MR formulations with different dose strengths and dissolution rates. The Cmax values of the MR formulations were accurately predicted using this approach, whereas the prediction errors for AUC exceeded the Level A IVIVC criteria. This can be attributed to the incomplete description of colonic absorption in the current PBBM.

Enhancement of third-order optical nonlinearity of VSe2 by hybridizing with CoSe2 as flower-like nanoparticles.

Through one-pot hydrothermal synthesis, we synthesized VSe2-CoSe2 nanostructures with a distinctive flower-like morphology. The structural characterizations were conducted using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR). By modulating the proportion of the CoSe2 phase, we transformed these hybrid nanostructures into nanoparticles, thereby influencing their nonlinear optical properties. The third-order nonlinear optical parameters (n 2 and β) were rigorously examined via the precise Z-scan technique under various laser power conditions. The nanostructures demonstrated a self-focusing refractive response and exhibited pronounced two-photon absorption during the nonlinear absorption process. The magnitudes of n 2 and β were determined to be in the order of 10-8 (cm2 W-1) and 10-4 (cm W-1), respectively. The exceptional figure of merit (FOM) of these composite flower-like structures underscores their superior nonlinear optical characteristics, establishing them as promising candidates for photonic applications, particularly in optical switching devices.

Electron Bernstein wave aided Hermite cosh-Gaussian laser beam absorption in collisional plasma

In this paper, we theoretically study the electron Bernstein wave aided Hermite-Cosh-Gaussian laser beam absorption in collisional plasma with a static magnetic field. This laser beam may have the potential to couple the pre-existing electron Bernstein wave with the coupled wave frequency and wave number where and are the electron Bernstein wave and laser beam frequencies, respectively, and and are the electron Bernstein wave and laser beam wave numbers, respectively. The plasma electron oscillatory velocities associated with the coupled wave mode produce the linear and nonlinear current density. An expression for the nonlinear absorption coefficient of an electron Bernstein wave aided Hermite cosh-Gaussian laser beam is analytically derived and more concisely discussed via different relative graphs. The graphical results promise that the absorption coefficient is strongly dependent on Hermite mode index m, beam decentered parameter d associated with the cosh term, laser beam width, laser beam frequency, electron Bernstein wave frequency, electron cyclotron frequency, electron thermal velocity and collisional frequency. Nonlinear coupling, collision phenomena and laser beam decentered parameter (very sensitive parameter) play an important role in absorption processes. The association of a very small electron Bernstein wave frequency with the laser beam causes too much of an increase in the absorption coefficient compared to only the laser beam. This efficient nonlinear absorption process may be applicable to plasma electron heating and the harmonic generation process.

Metal−Organic Framework-Based Ultrafast Logic Gates for High-Security Optical Encryption

Optical logic gates call for materials with giant optical nonlinearity to break the current performance bottleneck. Metal–organic frameworks (MOFs) provide an intriguing route to achieve superior optical nonlinearity benefitting from structural diversity and design flexibility. However, the potential of MOFs for optoelectronics has been largely overlooked and their applications in optical logic have not been exploited. Here, through temporally manipulating the nonlinear optical absorption process in porphyrin-based MOFs, we have successfully developed AND and XOR logic gates with an ultrafast speed approaching 1 THz and an on–off ratio above 90%. On this basis, all-optical information encryption is further demonstrated using transmittance as primary codes, which shows vast prospects in avoiding the disclosure of security information. To the best of our knowledge, this is the first exploration of MOFs for applications in ultrafast optical logic devices and information encryption.

Crossover from Reverse Saturable to Saturable Absorptions in Two-Dimensional Tungsten Disulfide

The Tungsten disulfide atomic layer has enormous scientific merits that play a key role in the nonlinear absorption process. Four distinct excitonic peaks in the absorption spectra are crucial for identifying the polarity of nonlinear absorption by virtue of the resonant or non-resonant excitation process. The excitation source of 532 nm is enough for the one-photon optical transition at both low-energy excitonic peaks and two-photon transition at both higher-energy excitonic peaks. The Tungsten disulfide atomic layer exhibited the reverse saturable (or positive nonlinear) absorption through the two-step excitation process which could be possible due to the optical transition at the higher energy excitonic peaks. In addition, the polarity of the nonlinear absorption coefficient and its interchange have been analytically studied with the aid of a magnitude of excited-state absorption cross-section and Ground-state absorption cross-section. Besides, the various possible factors affecting the Z-scan results are discussed.

Hot-carrier tunable abnormal nonlinear absorption conversion in quasi-2D perovskite

Controlling the high-power laser transmittance is built on the diverse manipulation of multiple nonlinear absorption (NLA) processes in the nonlinear optical (NLO) materials. According to standard saturable absorption (SA) and reverse saturable absorption (RSA) model adapted for traditional semiconductor materials, the coexistence of SA and RSA will result in SA induced transparency at low laser intensity, yet switch to RSA with pump fluence increasing. Here, we observed, in contrast, an unusual RSA to SA conversion in quasi-two-dimensional (2D) perovskite film with a low threshold around 2.6 GW cm−2. With ultrafast transient absorption (TA) spectra measurement, such abnormal NLA is attributed to the competition between excitonic absorption enhancement and non-thermalized carrier induced bleaching. TA singularity from non-thermalized “Fermi Sea” is observed in quasi-2D perovskite film, indicating an ultrafast carrier thermalization within 100 fs. Moreover, the comparative study between the 2D and 3D perovskites uncovers the crucial role of hot-carrier effect to tune the NLA response. The ultrafast carrier cooling of quasi-2D perovskite is pointed out as an important factor to realize such abnormal NLA conversion process. These results provide fresh insights into the NLA mechanisms in low-dimensional perovskites, which may pave a promising way to diversify the NLO material applications.

Optical nonlinearity of Cu1.81S nanodisks decorated with silver nanoparticles

The nonlinear absorption (NLA) and ultrafast dynamics process of Cu1.81S nanodisks (NDs) and Ag-Cu1.81S nanocomposites are investigated by using femtosecond Z-scan measurements and femtosecond time-resolved transient absorption spectrum, respectively. After decoration with Ag particles, Ag-Cu1.81S nanocomposites exhibit stronger saturable absorption and smaller saturable intensity at 600 and 800 nm. The carrier relaxation time is measured using femtosecond time-resolved techniques, and the results showed that the prolongation of the carrier relaxation time of the composite material can lead to a stronger saturation absorption effect.

Knowledge domain and hotspots analysis concerning applications of two-photon polymerization in biomedical field: A bibliometric and visualized study.

Objective: Two-photon polymerization (TPP) utilizes an optical nonlinear absorption process to initiate the polymerization of photopolymerizable materials. To date, it is the only technique capable of fabricating complex 3D microstructures with finely adjusted geometry on the cell and sub-cell scales. TPP shows a very promising potential in biomedical applications related to high-resolution features, including drug delivery, tissue engineering, microfluidic devices, and so forth. Therefore, it is of high significance to grasp the global scientific achievements in this field. An analysis of publications concerning the applications of TPP in the biomedical field was performed, and the knowledge domain, research hotspots, frontiers, and research directions in this topic were identified according to the research results. Methods: The publications concerning TPP applications in biomedical field were retrieved from WoSCC between 2003 and 2022, Bibliometrics and visual analysis employing CiteSpace software and R-language package Bibliometrix were performed in this study. Results: A total of 415 publications regarding the TPP applications in the biomedical field were retrieved from WoSCC, including 377 articles, and 38 review articles. The studies pertaining to the biomedical applications of TPP began back in 2003 and showed an upward trend constantly. Especially in the recent 5 years, studies of TPP in biomedical field have increased rapidly, with the number of publications from 2017 to 2021 accounting for 52.29% of the total. In terms of output, China was the leading country and Chinese Acad Sci, Tech Inst Phys and Chem was the leading institution. The United States showed the closest cooperation with other countries. ACS applied materials and interfaces was the most prolific journal (n = 13), followed by Biofabrication (n = 11) and Optics express (n = 10). The journals having the top cited papers were Biomaterials, Advanced materials, and Applied physic letters. The most productive author was Aleksandr Ovsianikov (27 articles). Meanwhile, researchers who had close cooperation with other researchers were also prolific authors. “cell behavior”, " (tissue engineering) scaffolds”, “biomaterials,” and “hydrogel” were the main co-occurrence keywords and “additional manufacturing”, “3D printing,” and “microstructures” were the recent burst keywords. The Keyword clusters, “stem cells,” and “mucosal delivery”, appeared recently. A paper reporting unprecedented high-resolution bull models fabricated by TPP was the most locally cited reference (cited 60 times). “Magnetic actuation” and “additive manufacturing” were recently co-cited reference clusters and an article concerning ultracompact compound lens systems manufactured by TPP was the latest burst reference. Conclusion: The applications of TPP in biomedical field is an interdisciplinary research topic and the development of this field requires the active collaboration of researchers and experts from all relevant disciplines. Bringing up a better utilization of TPP as an additive manufacturing technology to better serve the biomedical development has always been the research focus in this field. Research on stem cells behaviors and mucosal delivery based on microstructures fabricated using TPP were becoming new hotspots. And it can be predicted that using TPP as a sourcing technique to fabricate biomedical-related structures and devices is a new research direction. In addition, the research of functional polymers, such as magnetic-driven polymers, was the frontier topic of TPP biomedical applications.

Regulable nonlinear absorption and ultrafast dynamics process of monolayer Nb2CTx

Regulable nonlinear absorption and ultrafast dynamics process of monolayer Nb2CTx

Измерение коэффициента двухфотонного поглощения ультракоротких лазерных импульсов с длиной волны 1030 nm на центрах окраски природного алмаза

An experimental study of nonlinear absorption process of ultrashort laser pulses in bulk of natural diamond has been carried out. The results of experimental studies on measuring nonlinear transmission of 1 mm thick plane-parallel plate made of diamond irradiated with focused by micro lens (NA=0.55 with focal length f'=5 mm) 0.3 and 10 ps laser pulses with 1030 nm wavelength are presented. It is shown that in this sample the main attenuation mechanism of ultrashort laser pulses with 1030 nm wavelength at intensities not exceeding 10 TW/cm2 is two-photon absorption at color centers, the absorption coefficient β2 =4.1 ± 0.3 cm/TW is determined.

Measurement of two-photon absorption coefficient of 1030 nm ultrashort laser pulses on natural diamond color centers

An experimental study of nonlinear absorption process of ultrashort laser pulses in bulk of natural diamond has been carried out. The results of experimental studies on measuring nonlinear transmission of 1 mm thick plane-parallel plate made of diamond irradiated with focused by micro lens (NA=0.55 with focal length f'=5 mm) 0.3 and 10 ps laser pulses with 1030 nm wavelength are presented. It is shown that in this sample the main attenuation mechanism of ultrashort laser pulses with 1030 nm wavelength at intensities not exceeding 10 TW/cm2 is two-photon absorption at color centers, the absorption coefficient β2 =4.1 ± 0.3 cm/TW is determined. Keywords: femtosecond laser pulses, nonlinear absorption, natural diamond, multiphoton absorption, color centers.

Cooperative Spontaneous Four-wave Mixing in Single-channel and Dualchannel Sequences of Side-coupled Ring Resonators

Cooperative photon pair generation by Spontaneous Four-Wave Mixing (SFWM) process in singlechannel and dual-channel side-coupled ring resonator sequences is investigated. Our analysis shows that superlinear growth of generation rate with respect to the number of rings is possible even in presence of loss. Experimental evidence of super-SFWM is provided by comparing individual and collective generation rates obtained from a dual-channel ring resonator sequence. The results are in good agreement with theory and suggest that high photon pair generation rates can be achieved from integrated silicon ring resonator sequences without initiating nonlinear absorption processes.

Prospects for More Efficient Multi-Photon Absorption Photosensitizers Exhibiting Both Reactive Oxygen Species Generation and Luminescence.

The use of two-photon absorption (TPA) for such applications as microscopy, imaging, and photodynamic therapy (PDT) offers several advantages over the usual one-photon excitation. This creates a need for photosensitizers that exhibit both strong two-photon absorption and the highly efficient generation of reactive oxygen species (ROS), as well as, ideally, bright luminescence. This review focuses on different strategies utilized to improve the TPA properties of various multi-photon absorbing species that have the required photophysical properties. Along with well-known families of photosensitizers, including porphyrins, we also describe other promising organic and organometallic structures and more complex systems involving organic and inorganic nanoparticles. We concentrate on the published studies that provide two-photon absorption cross-section values and the singlet oxygen (or other ROS) and luminescence quantum yields, which are crucial for potential use within PDT and diagnostics. We hope that this review will aid in the design and modification of novel TPA photosensitizers, which can help in exploiting the features of nonlinear absorption processes.

Silver Nanoparticles under Nanosecond Pulsed Laser Excitation as an Intensity Sensitive Saturable Absorption to Reverse Saturable Absorption Switching Material

Optical nonlinearity involved switching draws an important consideration in nonlinear optical studies. Based on that, we explored nonlinear absorption processes in silver nanoparticles synthesized by liquid phase laser ablation technique employing a second harmonic wavelength (532 nm) of Q switched Nd:YAG laser pulses with 7 ns pulse width and 10 Hz repetition rates. The typical surface plasmon resonance induced absorption (~418 nm) confirmed the formation of Ag NPs. The Z-scan technique was used to study the nonlinear optical processes, employing the same laser system used for ablation. Our study reveals that there is an occurrence of a saturable to reverse saturable absorption switching activity in the Ag nanoparticles, which is strongly on-axis input intensity dependent as well. The closed aperture Z-scan analysis revealed the self-defocusing nature of the sample.

Nonlinear response of sodium and potassium doped ZnO along with improvement in bandgap structure: A combined physicochemical study

In this study, zinc oxide nanoparticles have been synthesized in the presence of alkali hydroxides (NaOH and KOH) using the Sol-Gel method. The XRD, DLS, Z-scan, and UV–Vis spectroscopy were used to investigate nanoparticles' structural and optical properties. XRD diffraction patterns show enhancement in structural constants by adding sodium and especially potassium atoms. Correspondingly, the bandgap energy reduces because of decreasing the lattice energy. Also, the nonlinear absorption coefficient is measured using the z-scan technique, and it is found that reverse saturable absorption (RSA) is the prominent nonlinear optical phenomenon in this samples upon increasing the power of the incident laser beam and the magnitude of nonlinear absorption coefficient enhance by introducing Na and K atoms into the ZnO (named as NZO and KZO, respectively) crystal lattice. In accordance with the enhancement of nonlinear absorption processes, NZO and KZO are bestowed with optical bistability characteristics, which is beneficial for manufacturing optical switchers.

Third‐Order Nonlinear Optical Response‐Driven Upconversion Phosphors

AbstractA series of silicate materials with noncentrosymmetric structures, namely, Na3ScSi3O9 (NSSO), NSSO:Ce3+, NSSO:Eu2+, and NSSO:Tb3+, have been successfully synthesized by a microwave‐assisted solid‐state reaction. The materials reveal interesting second‐ and third‐harmonic generation and two‐photon absorption (2PA) properties attributable to the unusual connectivity and unique coordination environments around the cations, as evidenced by detailed structural analysis and maximum entropy method calculations. Upon irradiation with 980 nm laser light, the activator‐doped NSSO materials show an unusual upconversion emission property without using Yb3+ sensitizer ions, because of nonlinear absorption processes, as evidenced from 2PA spectroscopy results. The materials also show good chemical stability compared to NaYF4:Er3+, Yb3+. The findings of this work can stimulate the creation of a new scientific field devoted to upconversion luminescence in solid‐state materials.

3D printing of silica glass through a multiphoton polymerization process.

We introduce a laser-based process relying on multiphoton-induced polymerization to produce complex three-dimensional (3D) glass parts. A focused, intense laser beam is used to polymerize a transparent resin, loaded with additives and silica nanoparticles, at the wavelength of the laser beam through nonlinear absorption processes. The object is created directly in the volume, overcoming the limitation of the layer-by-layer process. The process enables the production of silica parts with consecutive debinding and sintering processes. With bulk silica density and a resolution that depends on the laser spot size, 3D objects of centimetric dimensions are obtained.

γ-Hydroxybutyric Acid: Pharmacokinetics, Pharmacodynamics, and Toxicology.

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid present endogenously in the brain and used therapeutically for the treatment of narcolepsy, as sodium oxybate, and for alcohol abuse/withdrawal. GHB is better known however as a drug of abuse and is commonly referred to as the "date-rape drug"; current use in popular culture includes recreational "chemsex," due to its properties of euphoria, loss of inhibition, amnesia, and drowsiness. Due to the steep concentration-effect curve for GHB, overdoses occur commonly and symptoms include sedation, respiratory depression, coma, and death. GHB binds to both GHB and GABAB receptors in the brain, with pharmacological/toxicological effects mainly due to GABAB agonist effects. The pharmacokinetics of GHB are complex and include nonlinear absorption, metabolism, tissue uptake, and renal elimination processes. GHB is a substrate for monocarboxylate transporters, including both sodium-dependent transporters (SMCT1, 2; SLC5A8; SLC5A12) and proton-dependent transporters (MCT1-4; SLC16A1, 7, 8, and 3), which represent significant determinants of absorption, renal reabsorption, and brain and tissue uptake. This review will provide current information of the pharmacology, therapeutic effects, and pharmacokinetics/pharmacodynamics of GHB, as well as therapeutic strategies for the treatment of overdoses. Graphical abstract.

Vision with pulsed infrared light is mediated by nonlinear optical processes.

When the eye is exposed to pulsed infrared (IR) light, it is perceived as visible of the corresponding half wavelength. Previous studies have reported evidence that this is due to a non-linear two-photon absorption process. We have carried out a study which provides additional support to this nonlinear hypothesis. To this end, we have measured the spectral sensitivity at 2 different pulse repetition rates and have developed a theoretical model to account for the experimental observations. This model predicts a ratio between the minimum powers needed to detect the visual stimulus at the 2 pulse repetition rates employed of 0.45 if the stimulus were detected through a nonlinear effect and 1 if it were caused by a linear effect as in normal vision. The value experimentally found was 0.52 ± 0.07, which supports the hypothesis of a nonlinear origin of the two-photon vision phenomena.

Enhanced nonlinear optical absorption of WS2 by Ag nanoparticles

The nonlinear absorption and ultrafast dynamics process of WS2 and WS2-Ag nanocomposite were investigated by using nanosecond Z-scan measurements and femtosecond time-resolved transient absorption spectrum, respectively. Z-scan measurements showed that WS2 exhibit saturation absorption (SA) at low excitation intensities, with the increase of incident intensity, a switch from SA to reverse saturation absorption (RSA) occurs, but WS2-Ag nanocomposite exhibit SA at the same intensity. Transient absorption spectrum provided information show that the response time did not change much. The investigation shows that WS2 and WS2-Ag nanocomposite can be used for mode-locker and optical switcher.