Amplitude Subtraction Research Articles

Validation of spectrophotometric methods for the simultaneous determination of fluconazole and riparin B in the development of lipid nanoparticles modified by β-cyclodextrin: Application for in vitro characterization and ex vivo studies of nail retention

Fluconazole (FLC) has been used in the clinic for almost thirty years as a treatment for fungal infections, but its widespread use has led to the emergence of resistant strains. In this context, synthetic analogues of riparins, phytocompounds isolated from Aniba riparia (Nees) Mez (Lauraceae), such as Riparin B (RIP), stand out as an important agent for modulating antimicrobial resistance, potentially useful for treating superficial mycoses resistant to conventional antifungals. Onychomycosis is one of the main fungal infections affecting the nails. Its local treatment is desirable but has limited efficacy due to poor drug permeation. The use of nanoparticles and permeation promoters can increase permeability and improve treatment. Therefore, nanostructured lipid carriers coated with β-cyclodextrin (MNLC) were developed for the topical application of FLC and RIP on nails. To support the formulation, four spectrophotometric methods (amplitude factor, amplitude subtraction, modified amplitude subtraction, and fourth-order derivative), based on derivative spectroscopy and simple mathematical manipulations, were validated, in accordance with the International Conference on Harmonization (ICH), for simultaneous determination of FLC and RIP in the MNLC and in in vitro characterization studies of the formulation. In addition, the methods were applied to quantify drug retention in porcine hooves using an optimized extraction process. All the methods developed were found to be linear (r > 0.999), precise (RSD < 5 %), and accurate (92.33 to 108.86 %) without being affected by the components of the formulation or the biological matrix. The methods developed made it possible to determine the encapsulation efficiency and sustained release profile of the drugs. In addition, successive extractions revealed the amount of FLC and RIP retained in the superficial and deeper regions of porcine hooves. Thus, the results indicated that FLC and RIP can be determined simultaneously, quickly, simply, and economically, using any of the proposed methods, in complex MNLC samples and the biological matrix of porcine hooves.

Simultaneous Determination of Binary Mixture of Estradiol and Progesterone Using Different Spectrophotometric Methods

Four rapid, accurate and very simple derivative spectrophotometric techniques were developed for the quantitative determination of binary mixtures of estradiol (E2) and progesterone (PRG) formulated as a capsule. Method I is the first derivative zero-crossing technique, derivative amplitudes were detected at the zero-crossing wavelength of 239.27 and 292.51 nm for the quantification of estradiol and 249.19 nm for Progesterone. Method II is ratio subtraction, progesterone was determined at λmax 240 nm after subtraction of interference exerted by estradiol. Method III is modified amplitude subtraction, which was established using derivative spectroscopy and mathematical manipulations. Method IIII is the absorbance ratio technique, absorbance of both medicines was measured at two wavelengths λ1= 260, -absorptive point and λ2=240max of progesterone. The Q equations were used to calculate the final concentrations. The calibration curve is linear from 5.0–140 and 2.0–32.0 µg/ml for estradiol and progesterone respectively. The proposed techniques' selectivity was tested using synthetic combinations created in the lab and assessed using the standard addition method. Using one-way ANOVA, the outputs of the proposed ways were compared, and the result showed no significant differences between the proposed techniques.

Galilean-invariant effective field theory for the X(3872) at next-to-leading order

XEFT is a low-energy effective field theory for charm mesons and pions that provides a systematically improvable description of the $X(3872)$ resonance. To simplify calculations beyond leading order, we introduce a new formulation of XEFT with a dynamical field for a pair of charm mesons in the resonant channel. We simplify the renormalization of XEFT by introducing a new renormalization scheme that involves the subtraction of amplitudes at the complex $D^{*0} \bar D^0$ threshold. The new formulation and the new renormalization scheme are illustrated by calculating the complex pole energy of $X$ and the $D^{*0} \bar D^0$ scattering amplitude to next-to-leading order using Galilean-invariant XEFT.

Paired wavelength relevance as spectrophotometric strategy for evaluation the potency of medicine affecting human health.

Paired wavelength relevance as spectrophotometric strategy was carried for simultaneous analysis of unresolved bands of doxycycline hydrochloride (DOX) and tylosin tartrate (TYT) as an example of veterinary binary mixture. These methods based on the relation between two points on the scanned or manipulated spectra (derivative, ratio). The methods using the absorbance difference between two wavelengths namely, dual wavelength (DW), induced dual wavelength (IDW), absorption correction (AC) and advanced absorbance subtraction (AAS) or amplitude difference namely, ratio difference (RD), amplitude subtraction namely, amplitude correction (PC) and advanced amplitude modulation (AAM) as well as amplitude addition namely, derivative ratio (DD1). Calibration graphs are direct relation in the range of (5-40) μg/mL for doxycycline hydrochloride and (5-45) μg/mL for tylosin tartrate. The suggested methods was successfully applied for evaluate the potency of their veterinary medicine that has direct affecting human health. The method has been validated according to the guideline of international conference on Harmonization and parameters like linearity, range, accuracy and precision have been studied. The outcomes were matched statistically with those of the authorized systems; Student's t-test, F-test, and One-way ANOVA, presenting acceptable values and no momentous change with accuracy. The procedures can be considered useful for the quantitative analysis.

Dynamic balancing of a two-plane rotor without phase angle measurement using the amplitude subtraction method

Two-plane balancing is required on a rotor where the length is greater than the diameter. Balancing such a rotor is tricky, since the effects of unbalanced forces on both of the planes need to be considered when determining the corrective action. This paper presents a method of dynamic balancing for a two-plane rotor without the need to measure the phase angle. The rotor is balanced by measuring vibration amplitudes at the support bearing of the rotor shaft. A new rotor balancing method of amplitude subtraction is used to calculate the balancing weights and their positions on the rotor. The advantages of this method over the phase angle measurement method are also discussed in the paper.

Amplitude anisotropy of shear-wave splitting and fluid detection in thin-layer reservoir

Thin interbeds are typical reservoirs in eastern China. Thin layers and fractures bring huge challenge to fluid identification in anisotropic reservoir. This study focuses on thin-fractured reservoirs and amplitude attributes of shear-wave splitting, and consequently predicted fluid type in fractured reservoir based on the response of fast and slow S-waves to fluids. 3D HTI viscoelastic equation was employed to analyze amplitudes of split S-waves through fluid-filled and fractured media, including oil- and water-saturated synthetic models. Similar to velocity anisotropy, amplitude anisotropy was proposed to avoid the calculation of S-wave quality factor. Amplitude ratio and substation derived from amplitude anisotropy were used to identify fluid type. Example from the Luojia area of Shengli oilfield was used to demonstrate the effectiveness of the inversion method. Results show that amplitude ratio and amplitude subtraction are useful to distinguish fluids, while the former works better than the latter.

Dynamic balancing of two-plane rotor without phase angle measurement using amplitude subtraction method

Two-plane balancing is required for a rotor whose length is greater than its diameter. Balancing such a rotor is tricky, since the effects of unbalanced forces on both the planes need to be considered in determining the corrective action. This article presents a method of dynamic balancing of a two-plane rotor without the need to measure the phase angle. The rotor is balanced by measuring vibration amplitudes at the support bearing of the rotor shaft. A new rotor balancing method of amplitude subtraction is used to calculate the balancing weights and their positions on the rotor. The advantages of this method over the phase angle measurement method are also discussed in the article.

Developing spectral numerical factor technique for the determination of amlodipine besylate and the latest generation of statins in their new pharmaceutical combination.

Spectral numerical factor techniques have been developed for quantification of a new pharmaceutical combination. Five simple, fast and accurate spectrophotometric methods using spectral factor manipulation have been tested and validated so as to determine quantitatively a new fixed-dose combination tablet containing both amlodipine besylate (ADB) and rosuvastatin calcium (ROS). Namely, these methods are induced dual wavelength, absorbance correction, absorbance subtraction, amplitude correction and advanced amplitude subtraction. Their corresponding spectral factors are equality, absorption, absorbance, amplitude and unity factor, respectively. Calibration curves of ADB and ROS were set up for all the previously mentioned methods under the optimum conditions in a concentration range of 3.0-21.0 μg/mL with correlation coefficients ≥0.9990. Selectivity was calculated by analyzing laboratory-prepared synthetic blends of the cited drugs. A comparative study between these methods and the reported ones has been carried out statistically forming a judgment that the difference between both results is totally insignificant. Actually, the suggested spectral factor technique is so effective for use in routine laboratory essay owing to its simplicity, rapidity and precision. Generally, the proposed factor procedures have the ability to run smoothly without any interference from additives that may deteriorate analysis efficiency of a pharmaceutical combination.

DERIVATIVE UV SPECTROSCOPIC APPROACHES IN MULTICOMPONENT ANALYSIS–A REVIEW

The spectrophotometric multi-component analysis involves spectrum recording and mathematical equations. However, spectral interference poses a major limitation when mixture samples are encountered. To overcome this derivative spectrophotometry (DS) has been introduced for the resolution of overlapping peaks.&#x0D; In this review modified methods like derivative quotient spectra, double divisor ratio spectra derivative method, double divisor means centering of ratio spectra method, derivative subtraction coupled with the constant multiplication method (DS-CM), amplitude subtraction (AS), modified amplitude subtraction (MAS), amplitude factor method (P-Factor), amplitude modulation method (AM), amplitude summation method (A-Sum), simultaneous derivative ratio spectrophotometry (S1DD), derivative compensation ratio via regression equation, differential dual wavelength (D1 DWL), differential derivative ratio (D1DR), successive derivative subtraction method (SDS) and derivative transformation (DT) of derivative spectrophotometry theories and applications are reviewed.&#x0D; These methods were applied to solve different complex pharmaceuticals mixtures. These developed methods were simple and cost-effective.

A new rotor balancing method using amplitude subtraction and its performance analysis with phase angle measurement-based rotor balancing method

In order to balance a rotor, the standard rotor balancing methods involve measurement of vibration amplitude and vibration phase angle. But accurate phase angle measurement is generally difficult because vibration phase is sensitive to speed variations and it is difficult to maintain a constant speed in operating condition. Also, phase angle measurement requires very high end instrumentation for accurate phase angle measurement. Number of trial runs during balancing process also plays an important criterion in deciding the effectiveness of that method. A Method is considered to be more effective if it balances a rotor in less number of trial runs. This paper presents a novel rotor balancing method called amplitude subtraction method in which vibration amplitudes are measured only. Performance of this method is analysed by a comparative study with phase angle based rotor balancing method (trim balancing method). Trim balancing and amplitude subtraction method are compared on the basis of its accuracy and number of trial runs during balancing process. The results of experimentation demonstrate successful implementation of proposed method.

Validated Spectrophotometric Methods for Determination of Weakly UV absorbed Perindopril Arginine in Bulk and Combined Dosage Form

Five simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antihypertensive drugs; perindopril arginine (PER) and amlodipine besylate (AML) in their combined dosage form. AML can be determined directly by measuring its absorbance at λmax357 nm. On the other hand PER was determined by five different methods. The first two methods, ratio derivative (RD) and Derivative subtraction coupled with the constant multiplication method (DS-CM), were performed using the ratio spectra. While the other three methods, amplitude factor (P-Factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS), were developed based on derivative spectroscopy followed by mathematical manipulation. No preliminary separation steps were required for the proposed spectrophotometric methods. Linearity, accuracy and precision of the method was found to be acceptable over the concentration ranges of 20-80 μg/mL for PER and 5-40 μg/mL for AML. The proposed spectrophotometric methods were statistically compared to that of reference methods using one-way analysis of variance (ANOVA). The results showed that there was no significant difference between them.

Superpositions of asymmetrical Bessel beams.

We considered nonparaxial asymmetrical Bessel modes of the first and second types, which differ from a conventional symmetrical Bessel mode by a real-valued shift along one Cartesian coordinate and an imaginary shift along another (both shifts are equal in modulus). The first- and second-type Bessel modes differ only in signs of the shift and, therefore, have different orbital angular momentum (OAM) (integer or fractional). Addition and subtraction of complex amplitudes of two identical asymmetrical Bessel modes of the first and second type lead to light beams with the same integer OAM equal to the topological charge n of the original mode, but with different transverse intensity distributions, which depend on the shift magnitude. This proposed method allows controlling of the OAM of the beam with simultaneous changing of its shape, i.e., for matching with the object being trapped.

A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

Real-time edge detection by cyclic-path polarization interferometer

In a triangular path cyclic interferometer employing a polarizing beam splitter (PBS), the two counterpropagating beams are orthogonally polarized. A sample placed almost equidistant from the PBS is imaged by a lens placed in the path of the emerging beams so that two defocused images of the sample are recorded on a CCD. Using a linear polarizer in the path of the orthogonally polarized imaging beams, it is possible to achieve amplitude subtraction between the two images, resulting in an edge-enhanced image of the sample. The proposed real-time edge-enhancement technique is experimentally demonstrated.

Validated Stability Indicating Spectrophotometric Methods for the Determination of Lidocaine Hydrochloride, Calcium Dobesilate, and Dexamethasone Acetate in their Dosage Forms

Simple, specific, accurate and precise spectrophotometric methods were developed for determination of lidocaine hydrochloride, and calcium dobesilate in their binary mixture, or combined with dexamethasone acetate as a ternary mixture; in the presence of hydroquinone, the degradation product of calcium dobesilate without prior separation. In binary mixture lidocaine hydrochloride was determined using novel mathematical methods namely amplitude subtraction and amplitude factor, in addition to ratio subtraction coupled with first derivative. While dexamathasone acetate was assayed by first derivative method. Lidocaine and dexamethasone in ternary mixture could be determined by a novel resolution technique namely successive spectrophotometric resolution; including successive ratio subtraction coupled with either first derivative, or extended ratio subtraction for dexamethasone and ratio subtraction coupled with first derivative for lidocaine hydrochloride; and finally the calcium dobesilate could be determined by first derivative, derivative ratio and the novel modified amplitude subtraction methods. The calibration curves are linear over the concentration range of 2-20 µg mL-1 for both lidocaine hydrochloride and dexamethasone acetate, 2-19 µg mL-1 or 6-50 µg mL-1 for calcium dobesilate. The proposed methods could be successfully applied to commercial pharmaceutical preparations of the cited drugs. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the reference reported methods using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

Acoustic radiation pressure, torques, and scatterings: Insight for today from Gideon Maidanik's thesis research

Renewed interest in the identification of structural contributions to the scattering by complicated objects and the radiation forces and torques on simple objects in complicated acoustic beams makes it timely to review aspects of Maidanik's thesis research [J. Acoust. Soc. Am. 29, 738-742 (1957); 29, 936-940 (1957); 30, 620-623 (1958)]. Maidanik and Westervelt recognized the importance of King's earlier study of the low-frequency radiation forces on rigid movable spheres and extended that work to ka of 10. Hickling and Wang (1966) examined the properties of the scattering by such spheres and more recently Marston [J. Acoust. Soc. Am. 125, 3539-3547 (2009)] found that such a sphere approximates the low ka backscattering by an aluminum sphere in water. It was also found that negative radiation forces were possible for movable rigid spheres in a helicoidal Bessel beam. Recently, subtraction of complex amplitudes for movable semi-rigid targets has been used to isolate elastic contributions in finite-element based computations for finite cylinders [D. B. Thiessen et al., J. Acoust. Soc. Am. 129, 2686 (2011)]. Maidanik's analysis of radiation torques has recently been reconciled with other approaches [L. K. Zhang and P. L. Marston, J. Acoust. Soc. Am. 129, 1679-1680 (2011)]. [Work supported by ONR and NASA.]

Speech enhancement using constrained spectral amplitude subtraction based on noncausal a priori SNR

Two gain forms of spectral amplitude subtraction are derived theoretically without neglecting the correlation of speech and noise spectrum during the period of a frame. In the implementation, the constrained gain is expressed as a function of noncausal a priori SNR (Signal-to-Noise Ratio). Noise and noncausal a priori SNR are estimated from the multitaper spectrum of the noisy signal with algorithms modified to be suitable for the multitaper spectrum. Objective evaluations show that in case of white Gaussian noise the proposed method outperforms some methods based on LSA (Log Spectral Amplitude) in terms of MBSD (Modified Bark Spectral Distortion), segmental SNR and overall SNR, and informal listening tests show that speech reconstructed in this way has little speech distortion and musical noise is nearly inaudible even at low SNR.

The discovery and development of HMG-CoA reductase inhibitors

Spectral numerical factor techniques have been developed for quantification of a new pharmaceutical combination. Five simple, fast and accurate spectrophotometric methods using spectral factor manipulation have been tested and validated so as to determine quantitatively a new fixed-dose combination tablet containing both amlodipine besylate (ADB) and rosuvastatin calcium (ROS). Namely, these methods are induced dual wavelength, absorbance correction, absorbance subtraction, amplitude correction and advanced amplitude subtraction. Their corresponding spectral factors are equality, absorption, absorbance, amplitude and unity factor, respectively. Calibration curves of ADB and ROS were set up for all the previously mentioned methods under the optimum conditions in a concentration range of 3.0–21.0 μg/mL with correlation coefficients ≥0.9990. Selectivity was calculated by analyzing laboratory-prepared synthetic blends of the cited drugs. A comparative study between these methods and the reported ones has been carried out statistically forming a judgment that the difference between both results is totally insignificant. Actually, the suggested spectral factor technique is so effective for use in routine laboratory essay owing to its simplicity, rapidity and precision. Generally, the proposed factor procedures have the ability to run smoothly without any interference from additives that may deteriorate analysis efficiency of a pharmaceutical combination.

Real-time optical image subtraction using dynamic holographic interference in photorefractive media

A method of optical image subtraction is proposed. It provides parallel and real-time amplitude subtraction of two images by using holographic interference in photorefractive media. This new method provides an automatic phase shift of 180 deg between the two images and may be viewed as a real-time implementation of Gabor’s image-subtraction technique. Some experimental results are presented and discussed.

A new method for simultaneous complex addition and subtraction

General results are given for the influence of coherence and misalignments on the complex amplitude addition and subtraction method using a holographic beam splitter. A new method for simultaneous complex addition and subtraction is also investigated.