Ratio Spectra Research Articles

Quantitative study ternary mixture of paracetamol, ibuprofen and caffeine in solid pharmaceutical dosage forms by ratio ultraviolet spectroscopy

This paper aims to apply ratio ultraviolet spectroscopy to determine the concentration of substances in a ternary mixture containing paracetamol (PA), ibuprofen (IBU), and caffeine (CA) without chemical treatment, the solvent used in the analysis is a mixture of ethanol with water friendly to environment and safety for users. The ratio ultraviolet spectroscopy method is based on the difference between the peak amplitude of the proportional spectrum at two wavelengths to build regression equations and analytical parameters. The two wavelengths selected in the ratio spectrum for PA, IBU, CA are 246 and 275 nm, 218 and 245 nm, 244 and 278 nm, respectively. The linear range for PA and IBU is 4-40 μg/ml, and for CA, it is 0.8-8 μg/ml; limit of detection (LOD) and limit of quantification (LOQ) of PA, IBU, CA were 0.78, 1.18, 0.38 μg/ml and 2.37, 3.59, 1.17 μg/ml, respectively. The ratio ultraviolet spectroscopy method has successfully determined the concentrations of three substances in a mixture of laboratory and commercial drugs.

Numerical Simulation of Carbon Oxygen Ratio Logging Response in Natural Gas Hydrate Reservoirs

In the process of oil and gas field development, in order to identify the gas hydrate reservoir more accurately, we try to use the carbon oxygen ratio spectrum logging technology to study the log response law of this reservoir, and compare it with the reservoir response law to better guide the oil field production. Firstly, the theoretical response law of carbon and oxygen concentration ratio of natural gas hydrate reservoir and oil layer is deduced according to the petrophysical model, and then the response law of carbon and oxygen concentration ratio of two types of reservoirs simulated by Monte Carlo numerical simulation is studied, and the similarity law and difference between the two types of reservoirs are summarized. The results show that the carbon oxygen ratio has a regular change relationship with the porosity and saturation of the reservoir. The carbon oxygen ratio can be used to preliminarily distinguish and qualitatively identify the two types of reservoirs.

Clinical Feasibility of Deep Learning-Based Image Reconstruction on Coronary Computed Tomography Angiography.

This study evaluated the feasibility of deep-learning-based image reconstruction (DLIR) on coronary computed tomography angiography (CCTA). By using a 20 cm water phantom, the noise reduction ratio and noise power spectrum were evaluated according to the different reconstruction methods. Then 46 patients who underwent CCTA were retrospectively enrolled. CCTA was performed using the 16 cm coverage axial volume scan technique. All CT images were reconstructed using filtered back projection (FBP); three model-based iterative reconstructions (MBIR) of 40%, 60%, and 80%; and three DLIR algorithms: low (L), medium (M), and high (H). Quantitative and qualitative image qualities of CCTA were compared according to the reconstruction methods. In the phantom study, the noise reduction ratios of MBIR-40%, MBIR-60%, MBIR-80%, DLIR-L, DLIR-M, and DLIR-H were 26.7 ± 0.2%, 39.5 ± 0.5%, 51.7 ± 0.4%, 33.1 ± 0.8%, 43.2 ± 0.8%, and 53.5 ± 0.1%, respectively. The pattern of the noise power spectrum of the DLIR images was more similar to FBP images than MBIR images. In a CCTA study, CCTA yielded a significantly lower noise index with DLIR-H reconstruction than with the other reconstruction methods. DLIR-H showed a higher SNR and CNR than MBIR (p < 0.05). The qualitative image quality of CCTA with DLIR-H was significantly higher than that of MBIR-80% or FBP. The DLIR algorithm was feasible and yielded a better image quality than the FBP or MBIR algorithms on CCTA.

Ratio derivative-zero crossing and successive derivative of ratio spectra for simultaneous determination of urea, creatinine, and uric acid in human urine samples

ABSTRACT. Two simple precise and accurate spectrophotometric techniques are developed for simultaneous determination of ternary mixture of urea, creatinine, and uric acid in humane urine sample. The first technique is a ratio derivative zero - crossing where measured urea at 216.61 nm, creatinine at 260.56 nm, and uric acid at 283 nm. The second technique is a successive derivative of ratio spectra where urea, creatinine, and uric acid measured at 203 nm, 261 nm, and 283 nm, 287 nm, respectively. These procedures do not need separation. The proposed methods showed excellent linear range over the concentration ranges of 1.0–15.0 μg/mL, 1.0–16.0 μg/mL, and 2.0–15.0 μg/mL for urea, creatinine, and uric acid, respectively. The recoveries ranged from 97.10% to 101.9% for urea, 97.22% to102.70 % for creatinine, and 97.45% to102.55 % for uric acid with relative standard deviations less than 1.56% for urea, 3.87% for creatinine, and 3.71% for uric acid. The analytical eco-scale and green analytical procedure index tools were used to evaluate how the proposed procedures will affect the environment. The simultaneous quantification of urea, creatinine, and uric acid in human urine samples can be accomplished with remarkable effectiveness by using the suggested approaches.&#x0D; &#x0D; KEY WORDS: Urea, Creatinine, Uric acid, Derivative spectrophotometry&#x0D; Bull. Chem. Soc. Ethiop. 2023, 37(4), 817-829. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v37i4.2

Symplectic period mode decomposition method and its application in fault diagnosis of rolling bearing

The rolling bearing fault signals are accompanied with the specific periodic impulse components in case of fault. Due to the background noise, the periodic impulse component is extremely weak and difficult to be extracted. The periodic segment matrix (PSM) has excellent singular value aggregation property and can accurately separate the periodic impulse components from the signal. Based on this, a symplectic period mode decomposition (SPMD) method is proposed. Firstly, the singular value squared difference ratio (SVSDR) spectrum is defined, and the embedded dimension of PSM is determined. Then, the symplectic geometry component matrix is obtained by symplectic geometry similarity transformation, and the first symplectic geometry period component (SPC) is obtained by periodic impact intensity (PII). Finally, the spectral L2/L1 norm (SNL2/L1) index is used as the termination condition, and the iterative decomposition is terminated when the SNL2/L1 of the residual signal decreases. The emulation and experimental signals results indicate that the SPMD method can extract periodic impulse components accurately and is an effective rolling bearing fault diagnosis method.

Precise qualitative analysis of foreign protein adulteration in milk powder by fully exploring the spectral information in laser-induced breakdown spectroscopy

To improve the qualitative accuracy of foreign protein adulteration in milk powder, a novel method named multidimensional spectral information laser-induced breakdown spectroscopy (MSI-LIBS) was proposed, which fully mined the effective information in the spectra by integrating the absolute intensity, the first derivative spectra, and the ratio spectra. Compared with traditional LIBS, the performance of the models based on MSI-LIBS was significantly improved. The accuracy of the cross-validation set of support vector machine, k-nearest neighbor, and random subspace method-linear discriminant analysis models increased from 80.98%, 75.61%, and 79.25% to 85.17%, 79.32%, and 81.18%, respectively. The accuracy of the prediction set increased from 81.50%, 76.03%, and 79.07% to 85.82%, 79.74%, and 81.28%, respectively. Furthermore, the visualization results of t-distributed stochastic neighbor embedding also showed that there was a more obvious boundary between the spectra of different samples based on MSI-LIBS. Therefore, these results fully prove the effectiveness of MSI-LIBS in improving the performance of LIBS classification.

Spectrophotometric platform windows' exploitation for the green determination of Alcaftadine in presence of its oxidative degradation product

This study presents the determination of Alcaftadine (ALF) in its oxidative degradation product presence by applying comprehensive study comparative of four different green stability indicating spectrophotometric approaches through successful exploitation of different spectrophotometric platform windows. Window I; based on absorption spectrum zero order data manipulation using the newly developed extended absorbance difference (EAD). Window II; based on derivative spectra by second order derivative (D2) data manipulation. Window III; based on ratio spectra applying constant multiplication (CM) and absorptivity centering via factorized ratio difference spectrum (ACT-FSRΔP) methods data manipulation. Finally, window IV; based on derivative of ratio spectrum by virtue of first derivative of ratio spectral (DD1) method data manipulation. Calibration curves construction were over linearity range; 1.0–14.0 µg/mL for ALF. The proposed methods accuracy, precision, and linearity range were determined and validated as per ICH guidelines. Moreover, they were able to analyze ALF in raw form, dosage form and in existence of its oxidative degradation product. Statistical comparisons were done between the proposed methods and the reported one showing no significant difference concerning accuracy and precision. Furthermore, greenness profile assessment was accomplished by means of four metric tools; namely: analytical greenness (AGREE), green analytical procedure index (GAPI), analytical eco-scale, and national environmental method index (NEMI).

Simultaneous Determination of Montelukast Sodium and Loratadine by Eco-Friendly Densitometry and Spectrophotometric Methods.

Recently, the aim of analytical community is to reduce the usage of hazardous chemicals; so eco-friendly, rapid, selective and cost-effective methods were developed for simultaneous determination of montelukast sodium (MKT) and loratadine (LRT). The first method was based on chromatographic separation performed on precoated silica gel 60 GF254 plates with ethyl acetate-ethanol 9: 1 (v/v) as the mobile phase. The developed plates were scanned and quantified at 260nm. The method gives linear correlation over concentration ranges of 0.3-3.6μg/spot and 0.2-4.0μg/spot for MKT and LRT, respectively. It was also successfully applied to analysis of both drugs in their pharmaceutical preparation and human plasma. The other methods are UV-spectrophotometric methods based on smart spectra manipulating to zero order spectrum of each drug. These methods are named response correlation (RC), a-centering and ratio derivative methods. RC and a-centering methods were dependent on the presence of an isosbestic point between the overlapped spectra of both drugs. While ratio derivative method based on manipulation of the ratio spectra of both drugs. The two drugs obey Beer-Lambert law over the concentration ranges of 3.0-30.0μg/mL in the three spectrophotometric methods. Moreover, the greenness of the developed methods is assessed using suitable analytical Eco-Scale and Green Analytical Procedure Index.

Spider diagram and sustainability evaluation of UV-methods strategy for quantification of aspirin and sildenafil citrate in the presence of salicylic acid in their bulk and formulation

The cutting-edge combination of aspirin (ASA) and sildenafil citrate (SIC) has been presented as a suggested dosage form for the treatment of thin endometrium and erectile dysfunction, particularly in patients with cardiovascular diseases. However, ASA is highly sensitive to degradation into its major deterioration product, known as salicylic acid (SA). Consequently, it is eminently essential to evolve approaches for the synchronous quantification of ASA and SIC in the presence of SA.The main objective of this work is to develop three approaches for the synchronous quantification of ASA and SIC in the presence of SA in their commixtures and suggested formulations without any prior separation.Three green UV-methods were employed for the synchronous quantification, namely: Dual Wavelength in Ratio Spectra (DW-RS), Advanced Amplitude Centering (AAC), and Double Divisor of Ratio Difference Derivative (DDRD-D1). In DW-RS and AAC two-wavelength manipulation was used for resolution, while in DDRD-D1 only an appropriate wavelength for the synchronous quantification of the triplex commixture was used. All approaches can be able to resolve the highly interfering spectrum of the three components presented in the triplex commixture.Good linearity was inspected in the range of 20.0–100.0, 5.0–50.0, and 4.0–60.0 μg/mL for the ASA, SIC, and SA, respectively.All developed approaches have been advocated in accordance with ICH guidelines.All results from these approaches are presented and statistically reconciled with the proclaimed HPLC method, with no considerable differences.Furthermore, the approaches' eco-friendliness was predestined by Analytical Greenness (AGREE), and the complex GAPI.Moreover, the sustainability of the used solvent was evaluated by Green Solvents Selecting Tool (GSST); in addition, the greenness of the solvent was evaluated by Greenness Index tool with a spider diagram.The suggested UV-methods may be employed for routine quality control studies of the suggested formulations ASA & SIC since they were considered sustainable, economical, and effective.

Deep Multimodal Networks for M-type Star Classification with Paired Spectrum and Photometric Image

Traditional stellar classification methods include spectral and photometric classification separately. Although satisfactory results can be achieved, the accuracy could be improved. In this paper, we pioneer a novel approach to deeply fuse the spectra and photometric images of the sources in an advanced multimodal network to enhance the model’s discriminatory ability. We use Transformer as the fusion module and apply a spectrum–image contrastive loss function to enhance the consistency of the spectrum and photometric image of the same source in two different feature spaces. We perform M-type stellar subtype classification on two data sets with high and low signal-to-noise ratio (S/N) spectra and corresponding photometric images, and the F1-score achieves 95.65% and 90.84%, respectively. In our experiments, we prove that our model effectively utilizes the information from photometric images and is more accurate than advanced spectrum and photometric image classifiers. Our contributions can be summarized as follows: (1) We propose an innovative idea for stellar classification that allows the model to simultaneously consider information from spectra and photometric images. (2) We discover the challenge of fusing low-S/N spectra and photometric images in the Transformer and provide a solution. (3) The effectiveness of Transformer for spectral classification is discussed for the first time and will inspire more Transformer-based spectral classification models.

Smart eco-friendly mathematically manipulated UV spectroscopic methods to resolve severely overlapped spectra of a binary mixture of dapagliflozin with sitagliptin and vildagliptin

The binary formulations consisting of dapagliflozin with sitagliptin and vildagliptin are prescribed for the management of diabetes. The current study presents novel eco-friendly ultraviolet spectrophotometric methods for concurrent quantification of dapagliflozin with sitagliptin or vildagliptin in their binary formulations. The ratio spectra of series of sitagliptin, vildagliptin, and dapagliflozin were generated using dapagliflozin 7.5 µg/mL, sitagliptin 10 µg/mL, and vildagliptin 10 µg/mL as divisor than the ratio difference and ratio first derivative techniques were established. Also, the parent spectra of analytes were extracted from the mixture spectrum by successive mathematical filtration for quantification of individual analytes from the binary mixture without prior separation. The procedure showed good correlation in the series of 5–100 µg/mL for sitagliptin, 7.5–75 µg/mL for vildagliptin, and 1–15 µg/mL for dapagliflozin with an excellent correlation coefficient and good levels of detection and quantification. For the quantification of dapagliflozin levels in combination with different analytes, a single calibration curve was constructed. To create repeatable methods, the wavelength selection for measuring the peak amplitude and analyte concentration of divisor spectra was carefully optimized. The explored methods showed a low relative error percentage of 0.44–1.52, 0.20–0.94, and 0.02–1.22 and relative standard deviation percentages of 0.47–1.44, 1.16–1.41, and 0.94–1.81 for SGT, VGT, and DAP respectively, which confirmed the trueness and precision of the established processes. The validity of the ultraviolet methods was confirmed by quantifying the laboratory mixtures with varying dapagliflozin, sitagliptin, and vildagliptin ratios in addition to the standard addition technique. Additionally, the method's greenness evaluated by hexagonal and AGREE models and whiteness by the red–greenblue model demonstrated greater environmental sustainability in terms of safety and waste generated. Thus, utilizing environmentally friendly UV spectrophotometric techniques, a binary formulation including dapagliflozin + sitagliptin and dapagliflozin + vildagliptin can be evaluated for routine quality control.

Multi-spectroscopic assay methods for concurrent determination of recent anti-gout combination, a comparative study

Recently, Chemometric calibration methods in spectrophotometric analysis are achieving significant attention in the quality control of resolving drug mixtures and pharmaceutical formulations containing two or more drugs with overlapping spectra. The simple univariate methods have been used over the last few decades and has proven to be highly efficient and easy to apply. In this study, a comparative study was performed between some univariate and multivariate methods to determine if chemometric methods can substitute univariate methods in pharmaceutical analysis. In this study, three chemometric techniques were compared to seven univariate techniques to resolve a mixture of mefenamic acid and febuxostat in their raw materials, dosage forms and spiked human plasma. Mefenamic acid and febuxostat were used together for treatment of gout. The applied chemometric methods are partial least squares (PLS), artificial neural network (ANN) and genetic algorithm partial least squares (GA-PLS), while the used univariate methods include first derivative, second derivative, ratio spectra, derivative ratio spectra, ratio subtraction, Q-Absorbance ratio and mean centering spectrophotometric methods. The ten proposed methods were found to be green, sensitive, and rapid. They are simple and did not require any pre-separation steps. The results of both univariate and multivariate approaches were statistically compared with the reported spectrophotometric methods using student’s t test and ratio variance F-test. They were also compared with each other, using one-way analysis of variance (ANOVA). These methods were assessed and validated according to ICH guidelines. The studied drugs were analyzed in their pharmaceutical dosage forms and spiked human plasma with good recoveries using the developed methods, which qualify them for routine quality control of the studied drugs.

New Eco-friendly UV-spectroscopic Methods for Simultaneous Assessment of Dapagliflozin, Saxagliptin and Metformin in Ternary Mixture

Abstract: Background and Aim: Qternmet XR® consisting of dapagliflozin (10 mg), saxagliptin (5 mg), and metformin hydrochloride (1000 mg), is a fixed-dose combination (tablets) that improves glycemic control in individuals with diabetes mellitus (type 2). The projected work presents four spectrophotometric methods that are eco-friendly, quick, effortless, accurate and reproducible for the concurrent assessment of the ternary mixture. Materials and Methods: The 1st approach works on the notion of unravelling pre-existing equations (simultaneous) by measuring absorbance at 223, 212 and 232.6 nm for dapagliflozin, saxagliptin and metformin hydrochloride, sequentially. The second method namely ratio difference spectroscopy works by evaluating the variation in amplitude at two dissimilar wavelengths in the ratio spectra. Whereas the derivative ratio spectrum zero-crossing approach (third approach) relied on the utilization of the derivative ratio signals at zero-crossing locations. The fourth approach is the double divisor-ratio spectra derivative approach in which the first derivative of ratio spectrum was acquired and the concentrations of all 3 drugs in their combination were quantified. Results and Discussion: All the three drugs exhibited excellent linear correlation in the concentration series of 2-10 μg/mL for simultaneous equation method and 0.5-10 μg/mL for all the other methods with an exceptional correlation coefficient value. Furthermore, the projected approaches were authenticated in line with ICH strategies and which displayed suitable precision, accuracy and sensitivity. Conclusion: The developed spectrophotometric approaches when compared to other analytical procedures are regarded to be more cost-effective because they do not require expensive solvents or sophisticated instruments. Therefore, the projected methods could be effectively employed for the concurrent assessment of dapagliflozin, saxagliptin and metformin hydrochloride in ternary mixture. Keywords: Dapagliflozin, Saxagliptin, Metformin, Simultaneous Equation Method, Ratio Difference Spectroscopic approach, Derivative Ratio Spectrum-Zero crossing approach, Double Divisor Ratio Spectra Derivative approach, Ternary mixture.

What drives major channel widening in mountain rivers during floods? The role of debris floods during a high-magnitude event

Our capability to accurately predict at the local scale the morphological changes in a mountain river affected by a severe flood is currently limited. Given the importance of including geomorphological hazards in flood risk evaluation, some improvements in this direction are required. In fact, on the basis of the controlling factors typically considered in the literature, that are the unit stream power (ωpk) and the confinement index (CI), a relatively broad spectrum of width ratios (WR = ratio between channel width after a flood and channel width before a flood) occurring in response to major floods is commonly observed in streams. We extended previous research focused on parameters that influence the morphological response of a channel to a severe flood by investigating the role played by the type of sediment transport process that occurs in a mountain river. In particular, we explored whether a relationship exists between debris flood (i.e. a condition characterised by extremely high bedload) and intense channel widening. The case study was the Cordevole River (the Dolomites, Italy) and four of its tributaries, which were affected by the severe flooding induced by the Vaia storm in October 2018. WR was determined at the sub-reach scale, and ωpk was calculated with consideration for the flood peak discharge ascertained via hydrological modeling. Despite the significant relationships found among WR, ωpk and CI, 21 sub-reaches (out of 144) of the studied stream network widened intensely reaching a WR higher than approximately 4, often to a substantially larger extent than predicted by statistical models. Such sub-reaches were certainly or probably affected by debris floods, leading us to infer that debris floods can induce widening processes that are more intense than those occurring in response to water flows. Having said that, debris floods do not automatically imply very intense widening. In addition to hydraulic and morphological constraints, the sediment transport processes possibly taking place at a sub-reach of a mountain river should be regarded as another driver of channel modifications during high-magnitude hydrological events.

Green-assisted spectrophotometric techniques utilizing mathematical and ratio spectra manipulations to resolve severely overlapped spectra of a cardiovascular pharmaceutical mixture

Cardiovascular diseases, in particular hypertension and hypercholesterolemia, are two of the main causes of death worldwide. These conditions are silent killer syndromes that need a variety of pharmacological treatments to be effectively controlled. This study introduces novel, environmentally friendly spectrophotometric techniques for the simultaneous determination of telmisartan (TMS) and rosuvastatin calcium (RVS) in their pharmaceutical dosage forms. For the simultaneous determination of the binary mixture, the suggested methods included the dual wavelength method (DWM) which utilizes mainly the absorbance difference at 233 nm and 253 for TMS determination and, the absorbance difference at 274 nm and 310 for RVS determination as the selected wavelengths for each drug is directly proportional to the drug of interest independent on the other interfering component. The Fourier-self deconvolutions method (FSDM) depends on compressing their bandwidth to resolve the overlap. Ratio difference spectrophotometric method (RDSM) that utilizes TMS 35 μg.mL−1 and RVS 20 μg.mL−1, respectively as divisors to produce the ratio spectra for each drug. Further manipulation of the produced ratio spectra was applied for the determination of the two drugs. Mean centering method (MCM) where a suitable wavelength range was chosen to exclusively use the informative portions and prevent experimental spectrum noises. The investigated methods showed good levels of detection and quantification together with excellent linearity. The suggested methods' greenness was evaluated using two different greenness evaluation tools, which showed that the methods were green in terms of several factors, including the safety of the chemicals, instruments, and waste. The validity of the methodologieswas investigated by resolving prepared laboratory mixtureswith varying TMS and RVS ratios. The standard addition method also assured the newly added methods. Finally, statistical analysis using the reported method did not reveal any appreciable differences in terms of accuracy and precision. The developed methods can be employed in quality control laboratories to ascertain the binary mixture due to their high precision and affordability.

Three developed spectrophotometric methods for determination of a mixture of ofloxacin and ornidazole; application of greenness assessment tools

This work is dedicated to the greenness estimation of three proposed spectrophotometric techniques [e.g., ratio difference (RD), mean centering of ratio spectra (MCR) and continuous wavelet transform of ratio spectra (CWT)] for the determination of a binary combination named Ofloxacin (OFL) and Ornidazole (ORN). Applying the green analytical chemistry methods to assess the proposed methods has widely attained the analytical community care. The greenness assessment was performed via three evaluation approaches; the “Analytical Eco-Scale”, the “National Environmental Method Index” (NEMI) and “Green Analytical Procedure Index” (GAPI). Following the examination of the zero spectrum of OFL and ORN, it is observed that OFL and ORN spectra are overlapped, so they can be detected by the methods mentioned previously. The ratio difference method was carried out at wavelengths of 294.6 nm and 265.6 nm for OFL, 292 nm and 315 nm for ORN. The linear range was (2–15 µg/mL) for OFL and (3–30 µg/mL) for ORN. The MCR method based on the use of mean centered ratio spectra in dual steps and calculating the second ratio spectra mean centered values at 294.6 nm for OFL and 315 nm for ORN. The continuous wavelet transformation which carried out using MATLAB at wavelengths of 265 nm for OFL and 306 for ORN. These techniques were intended for the binary mixture analysis in bulk powder and pharmaceutical formulations with high recoveries. The developed methods were validated according to ICH guidelines. All techniques were statistically compared to either an official method for OFL or a reported method for ORN and the results indicate that there were not any significant differences.

Multicomponent spectrophotometric determination of a ternary mixture of widely-prescribed cardiovascular drugs by four different methods

Four accurate, green, uncomplicated, and fast spectrophotometric procedures were established for the purpose of resolving as well as quantifying a ternary combination prescribed for cardiovascular patients, such as aspirin, atorvastatin, and ramipril. Method (A) is based on the first derivative zero-crossing spectrophotometry for the determination of aspirin and atorvastatin at 247.4 nm and 302.6 nm, respectively. Ramipril was determined using the second derivative at 211 nm. Method (B) depends on the ratio spectra first derivative (RDS) where the absorption spectrum of the ternary combination was divided by the spectrum of one of the analytes. When treated similarly, the concentrations of the other two analytes were measured using their corresponding calibration graphs. For the determination of ASP and RAM, ATR was used as a divisor with a concentration of 26 µg/mL, and the RDS values at 272.0 and 225.8 nm, respectively, were plotted against the ASP and RAM concentrations. Using 40 µg/mL ASP as a divisor, ATR was analyzed, and the RDS values at 295 nm were plotted versus the ATR concentration. Method (C) is based on the double divisor-ratio spectra derivative technique. In this technique, the derivative of the ratio spectrum is computed by dividing the absorption spectra of the studied combination by the standard spectrum of abinary combination of two of the three analytes being studied. The concentrations of the three analytes in the mixture were assayed by determining the absorbance either at the positive or the negative amplitude. For the determination of ASP, ATR, and RAM, the wavelengths used were 244, 295, and 220 nm, respectively. Method (D) was a hybrid double divisor-ratio spectra technique based on convolving the double divisor-ratio spectra with trigonometric Fourier functions. The magnitudes of the Fourier function coefficients at either maximum or minimum points were correlated to the concentration of each drug in the mixture. The specificity of the suggested methods was tested by analyzing synthetic laboratory-prepared combinations and laboratory-made tablets. Furthermore, the accuracy and precision were ensured by statistically comparing the obtained results with those obtained from comparison method using Bartlett's Test for Equality of Variances and ANOVA test.

Seeking more robust early warning signals for climate tipping points: the ratio of spectra method (ROSA)

Potential tipping points in the Earth System present challenges for society and ecosystems, especially as the global warming thresholds at which these may be triggered remain uncertain. Fortunately, a theory of ‘critical slowing down’ has been developed which could warn of approaching tipping points. Applications of this theory often implicitly assume stationary white-noise forcing, itself requiring a clean separation between forced trends and variability, which is especially difficult under contemporary climate change. This paper proposes a modified method to derive early warning signal in a system, such as the climate, which is forced by time correlated processes. The method looks at the ratio of spectra (ROSA) of a system state variable relative to a forcing variable. We demonstrate the ROSA method on an idealised forced dynamical system, before applying it to a particular challenging example from the Earth System: dieback of the Amazon rainforest. We show that ROSA identifies more examples of abrupt transitions in the Amazon than conventional early warning signals in state-of-the-art CMIP6 Earth System Models.

Manipulation and Processing of Spectral Signals for the Assay of the Newly Authorized Mixture of Bupivacaine/Meloxicam Using Fully Green Solvents and a Comparative Green Evaluation Supporting the Greenness and Sustainability of the Developed Smart Spectrophotometric Methods.

The bupivacaine (BVC)/meloxicam (MLX) combination is the first extended-release dual-acting local anesthetic (DALA) that provides 72 h of postoperative pain relief. It reduces opioid use after surgery and manages pain better than BVC alone over 72 h, and overcomes surgical site inflammation with a new synergistic mode of action that combines BVC with a low dosage of MLX. In today's pharmaceutical research, we take great care to only use non-toxic solvents that pose no threat to either humans or the environment. This work determines BVC and MLX simultaneously, utilizing water and 0.1 M HCl in water as solvents. Moreover, the eco-friendliness of the specified solvents and the whole method development steps was evaluated based on how user-friendly they were using four standard methodologies. The developed spectrophotometric methods depended on either zero-order, derivative, or ratio spectra that only required simple mathematical handling. The current techniques include dual wavelength (DW), Fourier self-deconvolution (FSD), first derivative (D1), ratio difference (RD), and first ratio derivative (DD1). Linearity was confirmed over a concentration range of 50-700 μg/mL for BVC and 1-10 μg/mL for MLX. For BVC and MLX, the LOQs were 26.85-41.33 μg/mL and 0.21-0.95 μg/mL, while the LODs were 8.86-13.64 μg/mL and 0.06-0.31 μg/mL, respectively. For the full validation of the proposed methods, ICH (international conference on harmonization) criteria were followed. Current methods have the advantage of sticking to the basis of zero-order, derivative, or ratio spectra and needing just the barest minimum of data processing: no complex software, lengthy stages, or transformations are needed. No spectrophotometric methods have been published for the simultaneous analysis of BVC and MLX. As a result, the newly developed spectrophotometric approaches have great relevance and originality in the field of pharmaceutical analysis.

Innovative Spectrum Handoff Process Using a Machine Learning-Based Metaheuristic Algorithm.

A cognitive radio network (CRN) is an intelligent network that can detect unoccupied spectrum space without interfering with the primary user (PU). Spectrum scarcity arises due to the stable channel allocation, which the CRN handles. Spectrum handoff management is a critical problem that must be addressed in the CRN to ensure indefinite connection and profitable use of unallocated spectrum space for secondary users (SUs). Spectrum handoff (SHO) has some disadvantages, i.e., communication delay and power consumption. To overcome these drawbacks, a reduction in handoff should be a priority. This study proposes the use of dynamic spectrum access (DSA) to check for available channels for SU during handoff using a metaheuristic algorithm depending on machine learning. The simulation results show that the proposed "support vector machine-based red deer algorithm" (SVM-RDA) is resilient and has low complexity. The suggested algorithm's experimental setup offers several handoffs, unsuccessful handoffs, handoff delay, throughput, signal-to-noise ratio (SNR), SU bandwidth, and total spectrum bandwidth. This study provides an improved system performance during SHO. The inferred technique anticipates handoff delay and minimizes the handoff numbers. The results show that the recommended method is better at making predictions with fewer handoffs compared to the other three.