Graded-index Research Articles

Modeling of High-Power Graded-Index Fiber Amplifiers

Graded-index fibers have been used in recent years to make high-power fiber lasers and amplifiers. Such fibers exhibit self-imaging, a phenomenon in which any optical beam periodically reproduces its original shape in undoped fibers (no gain). In this work, we employed analytic and numerical techniques to study how self-imaging affects the evolution of a signal beam inside a nonlinear graded-index fiber amplifier, doped with a rare-earth element and pumped optically to provide gain all along its length. We also exploited the variational technique to reduce the computing time and to provide physical insights into the amplification process. We compared the variational and fully numerical results for the two pumping schemes (clad pumping and edge pumping) commonly used for high-power fiber amplifiers and show that the variational results are reliable in most cases of practical interest. The stability of the signal beam undergoing amplification is examined numerically by launching a noisy Gaussian beam at the input end of the amplifier. Our results show that the quality of the amplified beam should improve in the case of edge pumping when a narrower pump beam provides an optical gain that varies considerably in the radial direction of the fiber. Such an improvement does not occur for the clad pumping scheme, for which the use of a relatively wide pump beam results in a nearly uniform gain all along the fiber.

Cascaded geometric parametric process in a tapered air-silica graded-like multimode microstructure fiber.

We experimentally study the spatial beam profile and the spectral broadening at the output of a multimode air-silica microstructure fiber taper, used along the direction of an increasing fiber diameter. By using a laser pump at 1064 nm emitting 60 ps Gaussian beam pulses, we observed a competition between Raman beam cleanup and Kerr beam self-cleaning: the multimode frequency conversion process permits to generate spectral sidebands with frequency detuning from the pump that are difficult to obtain in standard graded-index multimode fibers. The generated supercontinuum spans from 500 nm up to 2.5 µm.

Development and validation of stability indicating HPLC-DAD assay of adapalene, methylparaben and propylparaben in a cosmeceutical gel matrix with blueness, greenness and whiteness assessment via relative ranking: An ab initio-sub finem juxtaposed non-traditional approaches

Adapalene (ADA) is primarily used as a cosmeceutical gel in the treatment of mild-moderate acne and is also used off-label to treat keratosis pilaris as well as other skin conditions. A stability-indicating fit-for-purpose (FFP) method has been developed for co-determination of ADA, methylparaben (MPN), and propylparaben (PPN) combined in a cosmeceutical gel dosage form. This method was based on a reversed-phase RP-HPLC separation of the cited analytes. It avoided the use of tetrahydrofuran (THF), which is commonly used by both compendial and published procedures for determination of ADA, thus improving method blueness (applicability), greenness and whiteness. The method development and validation followed non-traditional eco-friendly approaches including chemical simulations and empirical modelling. The HPLC separation was performed on an RP Zorbax Eclipse XDB-C8 analytical column [150 × 4.6 mm, 5 µm (80 Å)] with gradient elution system of HPLC grade acetonitrile and 50 mM aqueous sodium dihydrogen phosphate buffer containing 5 mM ethylenediaminetetraacetic acid (EDTA) adjusted to pH 8.0 as the mobile phase at a flow rate of 2.5 mL min−1 and column oven was set at 25 °C. EDTA played an important role for reproducibility of retention time of the three analytes especially for ADA. It controlled deprotonation of the three acidic analytes under study and hence reproduce their ionization, hydrophobicity, and hence retention time. Quantitation was achieved with the photodiode array detection (DAD) at wavelengths of 256 nm for both MPN and PPN and 312 nm for ADA. Target Measurement Uncertainty (TMU) for the three analytes was determined via two approaches; misclassification rates approach employing 100,000 Monte Carlo simulations (MCS) and in-specification probability (ISP) to ascertain fitness-for-purpose of the proposed method. Microsoft Excel workbooks were developed for both TMU calculation approaches in addition to calculation of procedure capability index (Ppk) and sigma level for each analyte and attached in the Supplementary material. Moreover, linearity of the method underwent additional assessment using the previously mentioned TMU and procedure capability determination techniques. The robustness of the method was checked using Plackett-Burman experimental design (PBD) as an empirical modelling technique which was examined thoroughly to detect some interactions. The calibration graphs for each drug were rectilinear in the range of 0.34–7.08, 0.38–7.00 and 0.08–1.75 µg mL−1 for ADA, MPN, and PPN, respectively. The stress testing revealed photostability of the three components and variable degrees of degradation in the other conditions. The proposed HPLC-DAD method was successfully validated and applied for the determination of the investigated analytes in a gel matrix. In addition, method blueness and greenness were comparatively evaluated via very recent approaches of Blue Applicability Grade Index (BAGI), Green Solvents Selection Tool (GSST), Spider Diagram for Assessment of the Green Analytical Index (SDAGI), Analytical Method Greenness Score (AMGS), Carbon Footprint (CF), Modified Complementary Green Analytical Procedure Index (ComplexMoGAPI), and Analytical GREEnness Metric Approach (AGREE). Furthermore, the method whiteness was assessed via Red Green Blue Twelve (RGB 12) model following a relative ranking approach.

Determination of pesticide residues in five different corn-based products using a single and simple solid–liquid extraction without clean-up steps followed by comprehensive two-dimensional liquid chromatography coupled to tandem mass spectrometry

Pesticide residues in food products are a critical issue concerning food safety. Recent studies have increasingly focused on developing selective, rapid, innovative, and environmentally friendly analytical methods for detecting pesticides in foodstuffs. This study presents a novel analytical method utilizing comprehensive two-dimensional liquid chromatography-tandem mass spectrometry for the simultaneous determination of one hundred and thirteen multiclass pesticides in corn products. The method simplifies the process with a single-step solid–liquid extraction and benefits from two-dimensional separation to enhance resolution and minimize matrix effects. The methodology was validated according to European Commission DG-SANTE (SANTE/11312/2021) and European Committee for Standardization (EN 15662, 2018) guidelines, obtaining acceptable analytical parameters. Limits of detection ranged from 0.2 µg/L to 30.2 µg/L and limits of quantification from 0.3 to 91.6 μg/L, all bellow regulatory limits. Accuracy, ranged from 60 to 120 % and precision, estimated by relative standard deviation, was consistently below 15.1 % in all cases. The applicability of the method was demonstrated by analyzing pesticides in five representative corn products (tortilla, corn flakes, corn cake, starch, and polenta). Sixteen pesticides were detected, all within the regulatory residue limits. Three metric tools were applied to assess the analytical process. Environmental sustainability was evaluated using the AGREE metric, while analytical performance and method applicability were assessed with the Red-Green-Blue and Blue Applicability Grade Index models, respectively, yielding promising scores (0.5, ≥ 0.55, and 0.65). These findings and the comparison to previous methods indicated that this approach represents a promising, alternative and user-friendly strategy for pesticide determination, offering effective productivity and reliable analytical performance.

High Performance Thin Layer Chromatography (HPTLC) Analysis of Anti-Asthmatic Combination Therapy in Pharmaceutical Formulation: Assessment of the Method's Greenness and Blueness.

A cost-effective, selective, sensitive, and operational TLC-densitometric approach has been adapted for the concurrent assay of Hydroxyzine Hydrochloride (HYX), Ephedrine Hydrochloride (EPH), and Theophylline (THP) in their pure powder and pharmaceutical forms. In the innovative TLC-densitometric approach, HYX, EPH, and THP were efficaciously separated and quantified on a 60F254 silica gel stationary phase with chloroform-ammonium acetate buffer (9.5:0.5, v/v) adjusted to pH 6.5 using ammonia solution as a mobile liquid system and UV detection at 220 nm. The novel TLC method validation has been performed in line with the international conference for harmonization (ICH) standards and has been effectively used for the estimation of the researched medicines in their pharmaceutical formulations without intervention from excipients. Additionally, parameters affecting the chromatographic analysis have been investigated. The new TLC approach's functionality and greenness were appraised using three modern and automated tools, namely the Blue Applicability Grade Index (BAGI), the Analytical Greenness metric (AGREE), and the Green Analytical Procedure Index (GAPI) tools. In short, the greenness characteristics were not achieved as a result of using mandatory, non-ecofriendly solvents such as ammonia and chloroform. On the contrary, the applicability and usefulness of the novel TLC approach were attained via concurrent estimation for the three drugs using simple and straightforward procedures. Moreover, the novel TLC method outperforms previously published HPLC ones in terms of the short run time per sample and moderate pH value for the liquid system. According to the conclusions of comparisons with previously recorded TLC methods, our novel HPTLC method has the highest AGREE score, so it is the greenest HPTLC strategy. Moreover, its functionality and applicability are very appropriate because of the simultaneous assessment of three drugs in one TLC run. Furthermore, no tedious and complicated extraction and evaporation processes are prerequisites.

Classical and Lagrangian mechanics in ray tracing: An optimizable framework for inhomogeneous media

Ray tracing is crucial for analyzing wave behaviors in diverse applications. This study presents an approach that extends beyond traditional methods, which typically involve solving second–order differential equations to determine ray trajectories. Leveraging classical momentum–impulse relations and the system’s Lagrangian, we establish a set of intuitive first integrals that circumvent the need for direct differential solutions, paving the way for optimization techniques. Our method employs the “shooting method” a technique for approximating solutions to differential equations by iteratively applying initial conditions. We introduce a novel momentum cost function that streamlines angle determination in anisotropic environments, a significant departure from conventional practices. Numerical validations demonstrate the robustness of our approach, confirming its efficacy in handling both sharp and gradual refractive index changes with high accuracy. The results also highlight the computational intensity required in anisotropic conditions, suggesting potential areas for efficiency improvements. This groundwork not only enhances current understanding but also opens avenues for future research into more complex media.

The prognostic role of mitosis index, stage and grade of endometrial cancer in Dr. Soetomo General Academic Hospital Surabaya, Indonesia, in 2018-2020

HIGHLIGHTS 1. Mitotic index and grade are prognostic factors for endometrial cancer, but both are independent.2. Stage and mitotic index associated with cell proliferation affect the prognosis of endometrial cancer. ABSTRACT Objective: This study aimed to analyze the correlation between the mitotic index and the stage and grade of endometrial cancer. Materials and Methods: We collected pathology reports of endometrial cancer from the Pathology Laboratory at Dr. Soetomo General Hospital in Surabaya, Indonesia, covering cases diagnosed between 2018 and 2020. A total of 106 cases of endometrial cancer were included in this study. For each case, detailed records of the cancer stage, grade, and mitotic index were recorded. The mitotic index, an indicator of cell proliferation, was quantified, and its correlation with cancer stage and grade was assessed. To determine the strength and direction of these relationships, we performed a Spearman rank correlation statistical analysis for non-parametric data. Results: Our findings indicated a significant positive correlation between the mitotic index and the stage of endometrial cancer. An increase in the mitotic index, reflecting a higher proliferation rate of cancer cells, was associated with a more advanced cancer stage, suggesting that the mitotic index could potentially serve as a prognostic marker for assessing tumor progression in endometrial cancer. However, our analysis revealed no significant correlation between the mitotic index and the histological grade of endometrial cancer, implying that the grade, which typically reflects the differentiation status and morphological characteristics of the tumor cells, is independent of the proliferation rate as measured by the mitotic index. Conclusion: The mitotic index is positively correlated with the stage of endometrial cancer but does not show a correlation with the histological grade. These findings highlight the potential use of the mitotic index in staging endometrial cancer.

Raman Lasing and Transverse Mode Selection in a Multimode Graded-Index Fiber with a Thin-Film Mirror on Its End Face.

Multimode fibers are attractive for high-power lasers if transverse modes are efficiently controlled. Here, a dielectric thin-film mirror (R~20%) is micro-fabricated on the central area of the end face of a 1 km multimode 100/140 µm graded-index fiber and tested as the output mirror of a Raman laser with highly multimode (M2~34) 940 nm diode pumping. In the cavity with highly reflective input FBG, Raman lasing of the Stokes wave at 976 nm starts at the threshold pump power of ~80 W. Mode-selective properties of mirrors with various diameters were tested experimentally and compared with calculations in COMSOL, with the optimum diameter found to be around 12 µm. The measured Raman laser output beam at 976 nm has a quality factor of M2~2 near the threshold, which confirms a rather good selection of the fundamental transverse mode. The power scaling capabilities, together with a more detailed characterization of the output beam's spatial profile, spectrum, and their stability, are performed. An approximately 35 W output power with an approximately 60% slope efficiency and a narrow spectrum has been demonstrated at the expense of a slight worsening of beam quality to M2~3 without any sign of mirror degradation at the achieved intensity of >30 MW/cm2. Further power scaling of such lasers as well as the application of the proposed technique in high-power fiber lasers are discussed.

Superhydrophilic antireflection films with excellent optical and mechanical performance for perovskite solar cells

SiO2-based antireflection (AR) films can obviously improve the transmittance of the glass cover on the solar cells. Nevertheless, it’s still challenging to fabricate SiO2 films in a facile way with great antireflective properties, high hardness and good weather resistance to ensure their long-term use in outdoor environments. To solve this problem, a double-layer broadband SiO2 antireflective film with high transmittance increase and excellent mechanical properties was successfully prepared via an acid-catalyzed sol–gel method using polyethylene glycol (PEG) as pore-forming agent. The porous PEG2000-modified SiO2 films were selected as the outer layer for coating onto the pure SiO2 film to form double-layer SiO2 films with graded refractive index. When the mass ratio of PEG2000 to TEOS was 40 %, the obtained film showed the highest transmittance increase of 3.03 % in the wavelength range of 380–1100 nm and a high hardness of 3H. After applied to the perovskite solar cell, a significant enhancement of 1.19 % in photoelectric conversion efficiency (PCE) was achieved compared to the solar cell covered with bare substrate. Furthermore, the water contact angle (WCA) was also reduced to 6° while that of pure SiO2 film was 51.3°, endowing the double-layer SiO2 film superhydrophilic and anti-fogging performance. After the weather resistance test, the transmittance loss of the film was only 0.38 %. Therefore, this work demonstrated that the use of an appropriate amount of pore-forming agent PEG and the double-layer graded refractive index structure can enhance the transmittance of acid-catalyzed SiO₂ films, while maintaining high hardness and good weathering resistance for perovskite solar cells.

Greenness and practicability assessment of a new HPLC-DAD method for simultaneous determination of three drugs used for a triple-therapy regimen for helicobacter pylori and application to a pharmacokinetic study

Improving the environmental friendliness of laboratory procedures has become very strongly recommended. In this research, several metric tools evaluating the analytical methods, including eco-scale, analytical greenness calculator (AGREE), green analytical procedure index (GAPI), red–green–blue software (RGB) and blue applicability grade index (BAGI) have been used to assess the greenness, performance and practicality of a new useful HPLC-DAD method. The main cause of peptic ulcers and the problems that follow is Helicobacter pylori. Due to the bacteria’s high resistance, different medications are co-administered to overcome the resistance and manage the symptoms. Two antibiotics are mostly used to decrease bacterial resistance in addition to proton pump inhibitors. Pantoprazole, Levofloxacin, and Amoxicillin are co-administered in a triple therapy regimen for suppressing Helicobacter pylori. In this work, the first-time simultaneous estimation of the three medications in rat plasma has been designed and utilized to investigate pharmacokinetics using a new HPLC method with outstanding greenness and practicability. The method involved using a C18 analytical column with an eluent of acetonitrile: 0.03 M Na2HPO4 buffer (20:80, v/v) of 1.5 mL min−1 flow rate. Oxytetracycline was used as an internal standard and the drugs were determined at 230 nm. The validation protocol was adopted according to FDA instructions, and the results proved the ability of the new method to estimate the three medications in rat plasma.

Air-assisted solidified floating organic drop microextraction method based on green supramolecular solvent for arsenic and selenium qantification in water and food samples

A supramolecular solvent (SUPRAS) was prepared from undecanoic acid and tetrabutylammonium hydroxide and used as an extraction solvent. A fast microextraction approach based on air-assisted solidified floating organic drop (AA-SFODME) coupled to a hydride generation atomic absorption spectrometer (HG-AAS) for arsenic and selenium traces determination in water and food samples was developed. The air bubbles enhanced the extraction efficiency by reducing both the time and the required chemical amounts. The 2-((4-iodophenyl) diazenyl)-8-hydroxyquinoline (IPHQ) was used as a chelation reagent. The experimental factors that impact extraction efficiency were improved and optimized. The limits of detection (LODs) for arsenic and selenium were 0.09 and 0.07 µg L−1, respectively. Also, the preconcentration factors (PFs) and enhancement factors (EFs) were found to be 100 and 103 for both arsenic and selenium, respectively. The linearity of both two calibration curves ranged from 0.10 to 700 µg L−1, with linear regression coefficients (R2) of 0.9986 and 0.9978, respectively. Finally, the greenness score was determined using two tools: the analytical greenness calculator (AGREE) and the Blue Applicability Grade Index (BAGI). The high greenness scores from these tools can make this method even more environmentally friendly and practical.

Power over fiber using a multimode optical power with a core diameter of 50 µm

We report on the properties of the Power over Fiber (PoF) transmission link using a High-Power Laser Source operating at 976 nm and using three types of optical fiber with a core diameter of 50 µm. Two step-index profile multimode optical fibers and one fiber with a gradient index were used for optical power transmission. Optical light was converted to electricity using commercially available Photovoltaic Power Convertors (PPCs) with a maximal optical input power of 1.5 W and experimental PPCs with a maximal optical input power of 4.0 W. We experimentally proved optical power transmission up to a distance of 300 m. In the case of the commercially available working PPC and using the gradient index fiber we achieved a result of 0.534 W of electrical power and using the experimental PPC we achieved 0.645 W. In the case of the step-index optical fiber, the result was 1.3 W.

Histopathological Study of Gastric Adenocarcinoma with Special Reference to Expression of HER2/neu and Ki-67 Assessed by Immunohistochemistry

Abstract Introduction Gastric cancer has become the third leading cause of cancer deaths globally. It accounts for 5.7% of cancer around the world, with a rate of mortality around 8.2%. Evaluation of human epidermal growth factor receptor 2 (HER2)/neu overexpression for targeted therapies is presently the mainstay of treatment in gastric cancer. High Ki-67 index expression in gastric cancer is an indicator of poor prognosis. Objectives To study the prevalence of HER2/neu expression and Ki-67 index in various types, sites, grade, and stage of gastric adenocarcinoma and to determine the correlation between HER2/neu expression and Ki-67 index. Materials and Methods This is a prospective study in a tertiary care hospital, Kolkata from January 2019 to June 2020. Gastrectomy and endoscopic biopsy of gastric adenocarcinoma were studied for histopathology and immunohistochemistry (HER2/neu and Ki-67 index). Statistical analysis used: SPSS (version 21.0, IBM, Chicago, Illinois, United States) for windows software. Results Among 54 cases, most of them were intestinal type, antral, moderately differentiated, stage III cases. HER2 expression and high Ki-67 index were observed in 28.0 and 40.75% cases, respectively. Statistically significant correlation was found in both HER2 expression and high Ki-67 index with location of the tumor and pathological nodal (pN) stage. A positive correlation was found between HER2/neu score and Ki-67 index (p = 0.007) (correlation coefficient = 0.4). Conclusion A positive correlation was found between HER2/neu positivity and high Ki-67 index, both were associated with higher pathological tumor stage and pN stage. So, advanced cases may be considered for targeted therapy using trastuzumab.

Development of a nomogram to predict recurrence scores obtained using Oncotype DX in Japanese patients with breast cancer

BackgroundChemotherapy is crucial for hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer, and its survival benefits may outweigh adverse events. Oncotype DX (ODX) assesses this balance; however, it is expensive. Using nomograms to identify cases requiring ODX may be economically beneficial. We aimed to identify clinicopathological variables that correlated with the recurrence score (RS) and develop a nomogram that predicted the RS.MethodsWe included 457 patients with estrogen receptor-positive, HER2-negative breast cancer with metastases in fewer than four axillary lymph nodes who underwent surgery and ODX at our hospital between 2007 and 2023. We developed nomograms and internally validated them in 310 patients who underwent surgery between 2007 and 2021 and validated the model’s performance in 147 patients who underwent surgery between 2022 and 2023.ResultsLogistic regression analysis revealed that progesterone receptor (PgR) level, histological grade (HG), and Ki67 index independently predicted the RS. A nomogram was developed using these variables to predict the RS (area under the curve [AUC], 0.870; 95% confidence interval [CI], 0.82–0.92). The nomogram was applied to the model validation group (AUC, 0.877; 95% CI, 0.80–0.95). When the sensitivity of the nomogram was 90%, the model was able to identify 52.3% low-RS and 41.2% high-RS cases not requiring ODX.ConclusionsThis was the first nomogram model developed based on data from a cohort of Japanese women. It may help determine the indications for ODX and the use of nomogram to identify cases requiring ODX may be economically beneficial.

Study on the relevant parameters of direct economic loss assessment of reinforced concrete structure buildings considering seismic fortification and use function

The main cost and decoration cost of the building are the key parameters in the evaluation of the direct economic loss of the building. In the Earthquake Site Work Part 4 : Direct Loss Assessment of Disasters ( GB / T 18208.4-2011 ), considering factors such as economic development level, structural type, and building use, based on expert experience and engineering cost data, a grading index was developed and a corresponding correction coefficient was given to more accurately and reasonably assess the loss of the main building and the loss of decoration. In view of the rapid development of China 's economy and the acceleration of urbanization in the past ten years, the original grading indicators and coefficients need to be adjusted to adapt to the reality. This paper focuses on the reinforced concrete structure with various functions and wide distribution. By collecting a large number of corresponding building main body and decoration cost data, and combining with expert experience data, this paper analyzes the influence of seismic fortification level on the main body cost, as well as the influence of economic development level, decoration grade, use function and other factors on the decoration cost. The research results of this paper aim to provide reference for the update and refinement of several key parameters in the specification.

Ecofriendly micellar mediated spectrofluorimetric method for ultrasensitive quantification of the antiparkinsonian drug safinamide in pharmaceutical formulation and spiked human plasma

A novel, highly sensitive and eco-friendly micellar-mediated spectrofluorimetric method was developed and validated for the determination of the novel antiparkinsonian drug safinamide mesylate in the presence of its related precursor impurity, 4-hydroxybenzaldehyde. The proposed approach relies on increasing the inherent fluorescence emission at 296 nm of safinamide, by forming hydrogen bonds between the mentioned drug and sodium dodecyl sulfate in the micellar system using 0.1 N HCl as a solvent, following excitation at 226 nm. A thorough investigation was conducted into the experimental factors affecting spectrofluorimetric behavior of the studied drug. A linearity plot of safinamide over the concentration range of 10.0–1000.0 ng/mL against the relative fluorescence intensities was established. The proposed method demonstrated excellent sensitivity down to the nano-gram level with detection and quantitation limits of 1.91 and 5.79 ng/mL, respectively. The studied drug was effectively determined in Parkimedine® Tablets. Furthermore, the proposed method allows for ultrasensitive quantification of safinamide in spiked human plasma, with satisfactory percentage recovery (98.97–102.28%). Additionally, the greenness assessment using the advanced green certificate classification approach, the complementary green analytical procedure index (Complex-GAPI), and the analytical GREEness metric approach (AGREE), along with the practicality check using the Blue Applicability Grade Index in addition to the all-inclusive overall whiteness evaluation using the RGB-12 model were carried out. The outcomes demonstrated the effectiveness and whiteness of the proposed technique. Clearly, the suggested approach has the advantages of being simple, requiring no pretreatment steps, and relying solely on direct measuring procedures.

Innovative eco-friendly stability-indicating HPLC-PDA method for simultaneous determination of the emerging antiviral drugs against COVID-19 infection molnupiravir and favipiravir; degradation kinetic studies along with LC-MS based structure elucidation

The adoption of the principles of green chemistry in analytical procedures lowers the negative influence on both people and the environment, which presently has become the key goal. Additionally, the need for advanced analytical techniques for the simultaneous determination of antiviral combinations is highly recommended, one of those novel combinations that recently proved effective emerging antiviral drugs in the treatment of SARS-COV-2 is molnupiravir (MOL) and favipiravir (FAV). Therefore, the establishment of simple and precise stability-indicating HPLC-PDA method for their simultaneous determination is crucial for the probable co-formulation. The stability of MOL was studied along with FAV after forced degradation of both under different stress conditions Separation of MOL, FAV, and their corresponding degradation products was achieved by simple isocratic HPLC-PDA method using a mobile phase comprised of 25.0 mM phosphate buffer (pH 3.0 ± 0.05) − methanol (70:30, v/v) at flow rate 1.0 mL/min. A Zorbax C18 (250 × 4.6 mm, 5 μm; Agilent Technologies, USA) column was used for the separation of the components and the column oven was maintained at 30 °C, the selected wavelength for detection of both analytes and their degradation products was 230.0 nm. The method was linear over the range of 1.0 – 200.0 µg/mL for both MOL and FAV. MOL was found to be susceptible to all forced degradation conditions, namely, acid, alkali, oxidative, thermal, and photodegradation while FAV was susceptible only to acid, alkali, and oxidative degradation. The probable degradation mechanisms were assumed through the evaluation of the MS1 fragmentation pattern of the degradation products, also studying the kinetic behavior of the degradation reactions. Furthermore, the greenness profile for the proposed method was evaluated utilizing the new Complementary Green Analytical Procedure Index method (ComplexGAPI), and analytical greenness (AGREE) metrics with a score of the later one equals to 0.61 that indicated the greenness evaluation of the method. In addition, the new blue applicability grade index (BAGI) which is complementary to the green metrics showed a score of 85.0 that presents a good applicability potential of the method. The proposed method is the first sustainable, stability-indicating method developed for the simultaneous determination of this potential combination that would help in manufacturing both drugs in a fixed-dose drug combination.

Narrow bandwidth mode-locked fiber laser with the GIMF-based saturable absorber

We have demonstrated the realization of the nearly transform-limited conventional solitons (CSs) with narrow spectral bandwidth in an Er-doped linear-cavity fiber laser, which is mode-locked by the graded index multimode fiber (GIMF)-based saturable absorber (SA). To our knowledge, this is the first report of the GIMF-based SA in the narrow bandwidth soliton generation. Simultaneously, the wavelength tunability of 0.48 nm and controllable Kelly sidebands for the narrow bandwidth solitons can be realized by the polarization controller (PC). Thereby, the minimum spectral bandwidth of the CSs reaches to be 0.1 nm, accompanied by the pulse duration of 20.8 ps and pulse energy of 1.07 nJ. Our work provides a compact and low-cost alternative for the narrow bandwidth solitons and offers a promising platform in the fields such as spectroscopy, quantum optics and other fields.

High-gain far-detuned nonlinear frequency conversion in a few-mode graded-index optical fiber

We present theoretical and experimental evidence of high-gain far-detuned nonlinear frequency conversion, extending towards both the visible and the mid-infrared, in a few-mode graded-index silica fiber pumped at 1.064 μm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu \\hbox {m}$$\\end{document}, and more specifically achieving gains of hundreds of dB per meter below 0.65 μm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu \\hbox {m}$$\\end{document} and beyond 3.5 μm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu \\hbox {m}$$\\end{document}. Interestingly, our findings highlight the potential of graded-index fibers for enabling high-gain wavelength conversion into the strong-loss spectral region of silica. Such advancements require an accurate interpretation of intramodal and intermodal four-wave mixing processes.

Fracture analysis of spatially graded piezoelectric-flexoelectric materials using XIGA

Dielectric Functionally Graded Materials (FGMs) exhibit superior flexoelectric properties. Gradual changes in material properties lead to large strain gradients and excellent flexoelectric responses. Cracks behave in a complex manner inside piezoelectric-flexoelectric FGMs subjected to electromechanical loading. An extended isogeometric analysis (XIGA)-based formulation is developed for flexoelectric FGMs with crack discontinuities. Ceramic-polymer FGMs of barium titanate (BTO) and polyvinylidene fluoride (PVDF) are selected for analysis since this material combination has shown better flexoelectric response solely due to gradation. A higher-order electromechanical J-integral is used to study the behavior of cracks. The fracture behavior of different crack geometries at various grading indices and levels of flexoelectricity is investigated. A crack interaction study is conducted with varying crack parameters. The length-scale effect on the energy release rate is also shown. A significant reduction in the energy release rate is observed in FGMs due to the flexoelectric effect.