Spectrophotometric methods for the determination of lisinopril in medicines

Two simple, rapid and green spectrophotometric methods are described for the determination of lisinopril medicines. The determination is based on the reaction of the primary amino group of the lisinopril with ninhydrin in aqueous medium (Method I) and reaction on the carboxylic group of the lisinopril with copper (II) sulfate (Method II). For both methods, optimal spectrophotometric conditions were established. The linear relationship was found between absorbance at λmax and concentration of drug in the range 40–60 µg/mL (Method I) and 0.592–2.072 mg/mL (Method II). Regression analysis of Beer’s law plot at 400 nm yielded the regression equation, y = 7.4929x – 0.0545 (Method I) and at 730 nm y = 0.0443x – 0.0832 (Method II). High values of correlations coefficient (R2 = 0.9917 (Method I) and R2 = 0.999 (Method II)) and small values of intercept validated the linearity of calibration curve and obedience to Beer’s law. The LOD and LOQ values were calculated to be 6.91 µg/mL and 23.01 µg/mL respectively (Method I) and 0.11 mg/mL and 0.36 mg/mL respectively (Method II). Intra-day and inter-day accuracy and precision were in acceptable limits. The proposed methods were applied for the quantification of lisinopril in tablets pertaining to three commercial formulations. Analytical eco-scale for greenness assessment of the proposed spectrophotometric methods showed that both methods correspond to excellent green analysis.

Numerical Investigation for Three-Dimensional Multiscale Fracture Networks Based on a Coupled Hybrid Model

The mismatching between the multi-scale feature of complex fracture networks (CFNs) in unconventional reservoirs and their current numerical approaches is a conspicuous problem to be solved. In this paper, the CFNs are divided into hydraulic macro-fractures, induced fractures, and natural micro-fractures according to their mode of origin. A hybrid model coupling various numerical approaches is proposed to match the three-dimensional multi-scale fracture networks. The macro-fractures with high-conductivity and wide-aperture are explicitly characterized by a mimetic Green element method-based hierarchical fracture model. The induced fractures and natural micro-fractures that have features of low-conductivity and small-openings are upscaled to the dual-medium grid and enhanced matrix grid through the equivalent continuum-medium method, respectively. Subsequently, some benchmark cases are implemented to confirm the high-precision and high-robustness of the proposed hybrid model that indeed accomplishes accurate modeling of fluid flow in multi-scale CFNs by comparing with commercial software tNavigator®. Furthermore, an integrated workflow of simulation modeling for multiscale CFNs combined with a field example in Sichuan from China is used to analyzing the production information of fractured horizontal wells in shale gas reservoirs. Compared with the field production data from this typical well, it can be proved that the hybrid model has strong reliability and practicability.

Synthesis, characterization and applications of chitosan based metallic nanoparticles: A review

Chitosan as a natural biopolymer has been produced to be the important host for the preparation of metallic nanoparticles (MNPs) because of its excellent characteristics like:- good stabilizing and capping ability, biocompatibility, biodegradability, eco-friendly and non-toxicity properties. Chitosan can play a very important role for synthesis of metallic nanoparticles, as chitosan is a cationic polymer. It attracts metal ions and reduces them and also Capps and stabilizes. So basically chitosan can be responsible for the controlled synthesis of metallic nanoparticle. Chitosan has a very good chelating property. This property is due to its –NH2 and –OH functional groups. Size and shape of metallic nanoparticles are much affected by chitosan concentration, molecular weight, time of reaction, degree of acetylation of chitosan, pH of the medium, method of synthesis and type of derivative of chitosan etc. Metallic nanoparticles`s properties and applications are much associated with their size and shape. Optimization of the metallic nanoparticle size and shape has been the subject of curiosity for nanotechnology scientist. Chitosan can solve this problem by applying the optimization conditions. But a very little work is reported about: - how chitosan can affect the size and shape of metallic nanoparticles and how can it reduce metal salts to prepare metallic nanoparticle, stablilized in chitosan metrics. This is very first report as a review article highlighting the effect of chitosan on synthesis of metallic nanoparticles and optimization conditions. This review will also be beneficial for scientist working on food sensing application of nanoparticles. Various synthesis methods and applications of chitosan based metallic nanoparticles have also been reported in details.

A Simplified Method for Modeling of Pressure Losses and Heat Transfer in Fixed-Bed Reactors with Low Tube-to-Particle Diameter Ratio

This manuscript presents a simplified method of modeling fixed-bed reactors based on the porous medium. The proposed method primarily allows the necessity of precisely mapping the internal structure of the bed—which usually is done using real object imaging techniques (like X-ray tomography) or numerical methods (like discrete element method (DEM))—to be avoided. As a result, problems with generating a good quality numerical mesh at the particles’ contact points using special techniques, such as by flattening spheres or the caps method, are also eliminated. The simplified method presented in the manuscript is based on the porous medium method. Preliminary research has shown that the porous medium method needs modifications. This is because of channeling, wall effects, and local backflows, which are substantial factors in reactors with small values of tube-to-particle-diameter ratio. The anisotropic thermal conductivity coefficient was introduced to properly reproduce heat transfer in the direction perpendicular to the general fluid flow. Since the commonly used fixed-bed reactor models validation method based on comparing the velocity and temperature profiles in the selected bed cross-section is not justified in the case of the porous medium method, an alternative method was proposed. The validation method used in this work is based on the mass-weighted average temperature increase and area-weighted average pressure drop between two control cross-section of the reactor. Thanks to the use of the described method, it is possible to obtain satisfactorily accurate results of the fixed-bed reactor model with no cumbersome mesh preparation and long-term calculations.

Development and Validation of Highly Sensitive Spectrophotometric Methods for Cefpirome Determination in Pharmaceutical Dosage Forms

Quantitative spectrophotometric determination of cefpirome in pure and pharmaceutical dosage has been developed. Method I produces a pink-coloured chromogen peak at λmax 510 nm by reacting diazotized cefpirome drugs with diphenylamine (DPA) in a neutral medium. Method II obtained of a coloured Schiff bases when cefpirome reacts with alcoholic p-dimethylaminobenzaldehyde (PDAB) to produce a yellow-coloured chromogen with a maximum absorption wavelength of 415 nm. In both methods I and II, Beer’s law is followed in the concentration ranges of 0.3-3.0 and 0.5-5.0 μg/mL, respectively, with molar absorptivity of 5.13 × 104 and 2.54 × 104 for each form. At three separate concentrations, intra-day and inter-day (RSD) and relative error (RE) are measured. The current methods are simple, reliable, inexpensive, speedy and highly reproducible and have been tested in broad range of pharmaceutical formulations with statistical comparisons to reference methods.

A new exponential wear model to analyze precision retention of guideway based on macro-micro multiscale method

At present, wear models and accuracy prediction of guideway are established based on elastoplastic mechanics of continuous media. These methods are limited to describe the process of accuracy degradation by using the material performance defined based on macroscopic hypothesis condition. In this paper, the multiscale method based on quasicontinuum medium(QM) principle is proposed to describe the degradation process of guideway linear precision with an exponential model. According to the wear distribution of the guideway surface with the micro-morphology evolution process, the measurement value of the guideway linear precision is modeled systematically. Then, using the quasicontinuum medium method instead of the continuum hypothesis, the exponential wear model of guideway is established. The exponential wear model uses the wear exponent to describe the wear status based on linear precision measurement rather than tremendous wear volume tests. By means of Depth From Defocus (DFD) method, the micro-topography information of the guideway surface is obtained. Therefore, the wear state of the guideway is verified under different loading conditions, and the validity of using the QM method to establish the guideway exponential wear model is verified.

Formation of the financial security of agricultural business entities

The article deals with the potential of financial security, which forms the system of financial protection of vital interests of subjects of agricultural business. It is proved that under the pressure of the external environment, leverage and financial mechanism tools that trigger the potential of financial security of agriculture can change, risk manifestation and economic depression of enterprises continue or stop. The importance of forming the aggregate value of the potential of financial security in the region is due to its component, which is capable of performing actions to mobilize the real and hidden possibilities of financial resources in a limited time period, to overcome the threats to a safe environment for the functioning of subjects of agricultural business. The priority of financial support of agriculture of Ukraine according to indicators of intensity and efficiency of use of financial resources is singled out. A differentiated approach to the clustering of the k-medium method – indicators of the use of financial resources as interdependence of the factors of the formation of the aggregate magnitude of the potential of financial security of subjects of agricultural business of Ukraine was used. With the help of inductive system analysis, a model of a stable level of potential of financial security capacity based on net profit has been developed. The model is adequate, its statistical quality, significance and reliability are sufficient for forming the forecast level of potential of financial security of subjects of agricultural business of the region. The developed methodology is based on the components of the protection of financial system of economic entities in the conditions of the restrictions of the choice of alternative sources of formation and distribution of financial resources, as well as the likelihood of their use.