indirect determination
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2022 ◽  
Vol 905 ◽  
pp. 169-173
Author(s):  
Hui Ping Xi ◽  
Xiu Wei Fang ◽  
Bao Hua Wu

In Britton Robinson (B-R) buffer solution with pH = 7.00 and sodium dodecyl sulfate (SDS) medium, an effective energy transfer between acridine orange (AO) and Rhodamine B (RB) can occur, which can enhance the fluorescence of RB. The addition of Gemifloxacin (GMFX) can quench the fluorescence of RB. So a new method for the indirect determination of Gemifloxacin was established by AO-RB fluorescence resonance energy transfer. This method was applied to the determination of Gemifloxacin tablets. The results were consistent with those of high performance liquid chromatography (HPLC) . Experiments show that this method is simple, rapid, accurate and sensitive.


Author(s):  
María Elvira Garrido ◽  
Ferry B. Petnga ◽  
Víctor Martínez-Ibáñez ◽  
José B. Serón ◽  
Carlos Hidalgo-Signes ◽  
...  

AbstractThe effect of exposure to high temperature on rock strength is a topic of interest in many engineering fields. In general, rock strength is known to decrease as temperature increases. The most common test used to evaluate the rock strength is the uniaxial compressive strength test (UCS). It can only be carried out in laboratory and presents some limitations in terms of the number, type and preparation of the samples. Such constrains are more evident in case of rocks from historical monuments affected by a fire, where the availability of samples is limited. There are alternatives for an indirect determination of UCS, such as the point load test (PLT), or non-destructive tests such as the Schmidt’s hammer, that can also be performed in situ. The aims of this research are: (i) measuring the effect of high temperatures and cooling methods on the strength and hardness of a limestone named Pedra de Borriol widely used in several historic buildings on the E of Spain, and (ii) studying the possibility of indirectly obtaining UCS by means of PLT and Leeb hardness tests (LHT), using Equotip type D. Limestone samples were heated to 105 (standard conditions), 200, 300, 400, 500, 600, 700, 800 and 900 ºC and cooled slowly (in air) and quickly (immersed in water). After that, UCS, PLT and LHT tests were performed to evaluate the changes as temperature increases. Results show decreases over 90% in UCS, of between 50 and 70% in PLT index and smaller than 60% in LHT index. Insignificant differences between cooling methods were observed, although slowly cooled samples provide slightly higher values than quickly cooled ones. The results indicate that LHT can be used to indirectly estimate UCS, providing an acceptable prediction. Research on correlating strength parameters in rocks after thermally treated is still scarce. This research novelty provides correlations to predict UCS in historic buildings if affected by a fire, from PLT and non-destructive methods such as LHT whose determination is quicker and easier.


2021 ◽  
Vol 92 (10) ◽  
pp. 568-571
Author(s):  
A. A. Pugachev ◽  
S. V. Morozov ◽  
A. N. Marikin ◽  
V. A. Kruchek

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1273
Author(s):  
Ricardo D. dos Reis ◽  
Luana Caron ◽  
Sanjay Singh ◽  
Claudia Felser ◽  
Michael Nicklas

Magnetic shape-memory materials are potential magnetic refrigerants, due the caloric properties of their magnetic-field-induced martensitic transformation. The first-order nature of the martensitic transition may be the origin of hysteresis effects that can hinder practical applications. Moreover, the presence of latent heat in these transitions requires direct methods to measure the entropy and to correctly analyze the magnetocaloric effect. Here, we investigated the magnetocaloric effect in the Heusler material Ni1.7Pt0.3MnGa by combining an indirect approach to determine the entropy change from isofield magnetization curves and direct heat-flow measurements using a Peltier calorimeter. Our results demonstrate that the magnetic entropy change ΔS in the vicinity of the first-order martensitic phase transition depends on the measuring method and is directly connected with the temperature and field history of the experimental processes.


2021 ◽  
Vol 15 (1) ◽  
pp. 64-72
Author(s):  
Włodzimierz Opoka ◽  
Marek Szlósarczyk ◽  
Adam Chojnacki ◽  
Agata Kryczyk-Poprawa ◽  
Przemysław Talik ◽  
...  

This article presents the potentiometric method of determination of chlorides using the original BO-05 electrochemical microanalyzer. The quantification of chlorides is one of the frequently performed methods, both in the indirect determination of active pharmaceutical ingredients (API) and impurities in pharmaceutical raw materials, pharmacopoeial substances or pharmaceutical formulations as well. Successfully validated method was used to the analysis of chlorides in the preparations containing verapamil hydrochloride in form of tablets Staveran® and Verapamil®. The mean content of the studied API calculated to one tablet was close to the declared and equal to 123.6±1.5 mg and 122.6±1.1 mg, respectively. The presence of excipients have no significant impact on the final results. Thus shown that the electrochemical microanalyzer BO-05 is suitable for scientific, didactic and analytical applications.


2021 ◽  
Vol 11 (4) ◽  
pp. 4033-4057
Author(s):  
Mohaned R. Mohamed ◽  
Bushra B. Qassim

A new simple, sensistive and green environmental method of Flow-injection/merging zones technique was developed for indirect determination of α-cypermethrin pesticide in pure form, industrial and biological samples. This method based on oxidation reaction of pesticide (α-cypermethrin) with a calculated increase of N-bromosuccinamide (NBS) in acidic medium then react with Tartrazine dye (TART) and estimation of the excess of the oxidizing agent by measuring the residual absorption of TART (yellow color) at λmax = 430nm, this method is a green chemistry, low cost and less consumption of poisonous chemical reagents. The limit of detection and limit of quantification for this method are 0.05 μg.ml-1 and 0.17 μg.ml-1 respectively, RSD% = 0.69% and the recovery is about = 102.15%. Chemical and physical parameters was optimized that effect on the pesticide reaction. The calibration curve was linear within concentration range (0.5 – 30) μg.mL-1 with sampling through put is about 65 sample.hour-1; the results of determination were compared with those given by trusted method (HPLC). No significant differences between both methods regarding in terms of accuracy and precision at 95% dependability level.


2021 ◽  
Vol 263 (3) ◽  
pp. 3708-3713
Author(s):  
Juan Carlos Rodríguez Vercher ◽  
Romina del Rey ◽  
Jesús Alba

Airflow resistance is a non-acoustic parameter of great relevance in the acoustic characterization of porous materials. It is used in several sound absorbing material prediction models and it is also a control parameter for acoustic conditioning and insulation in different building solutions. The ISO 9053 standard defines several methods to obtain it, using both direct measurements and indirect techniques. However, both procedures may involve problems related to the placement of the textile samples in the tube or to the stability of the samples during testing. In this work, the use of reference materials to stabilize the measurement of thin materials is proposed. Airflow resistance results obtained for different materials in an impedance tube are presented. The tests have been carried out by following the Ingard & Dear method, as an indirect technique accepted by the standard. Several material compositions with a wide range of airflow resistance values have been analyzed with different reference materials.


2021 ◽  
Vol 104 (1) ◽  
Author(s):  
G. G. Kiss ◽  
M. La Cognata ◽  
R. Yarmukhamedov ◽  
K. I. Tursunmakhatov ◽  
I. Wiedenhöver ◽  
...  

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