A new, simple, and reproducible method for determination of carboxylic acid metabolite of clopidogrel in human plasma has been developed. After liquid-liquid extraction in acidic medium with chloroform, samples were quantified on a Nova-pak C(8), 5 microm column using a mixture of 30 mM K(2)HPO(4)-THF-acetonitrile (pH = 3, 79:2:19, v/v/v) as mobile phase with UV detection at 220 nm. The flow rate was set at 0.9 mL/min. Ticlopidine was used as internal standard and the total run time of analysis was about 12 min. The method was linear over the range of 0.2-10 microg/mL of clopidogrel metabolite in plasma (r(2) > 0.999). The within-day and between-day precision values were in the range 1.0-4.8%. The limit of quantification of the method was 0.2 microg/mL. The method was successfully used to study the pharmacokinetics of clopidogrel in healthy volunteers. 相似文献
Personal safety issue is one of the major limitations in landmine detection by nuclear techniques. In this paper, the dose rate received by the operator of different hand-held landmine detection systems using the neutron backscattering method was investigated. Monte Carlo method was used to simulate a computational model of the body, instruments with different shielding configurations and soil with various moisture contents. The effective dose received by the different organs of the operator has been estimated by using two different approximation methods including average equivalent dose and dose equivalent assessment. The results obtained by these two methods were compared. The common results showed that the operator dose rate depends on the facility shielding, soil moisture level, and source-to-operator distance. Also, although the absorbed dose received by most organs generally decreases as a function of source to operator distance, for some organs such as kidneys and lungs it firstly increases when source-to-operator distance increases up to 0.7–1.2 m and after that the absorbed dose decreases. Furthermore, the results showed that the effective dose received by the operator has its maximum value when the source to operator distance is 0.60 m. 相似文献
The reaction of benzylnitrile with InMe3 in a molar ratio of 3:1 leads to 2-amino-N-[Me2In(TMEDA)]-4-amino-3,5-diphenyl-6-benzyl-pyridine 2. CsF accelerates the reaction. The treatment of Ph2CHCN with InMe3 in the presence of CsF gives the metalated ketenimine [(THF)Me2InNCCPh2]23. 3 and the corresponding Ga compound also can be obtained by the metathesis reaction of Me2MCl with LiNu═C═CPh2. The attack of the Lewis bases tBuELi2 (E = P, As) on nitriles and isonitriles also leads to oligomerizations. tBuAsLi2 reacts with two molecules of PhCN to the aromatic heterocycle [AsNC(Ph)NC(Ph)]? by forming the salt [Li(diglyme)2] [(TMEDA)Li([AsNC(Ph)NC(Ph)])2] 4, while the reaction of tBuAsLi2 with three equivalents of cHexNC leads to the dilithium compound [{Li2(diglyme)}2{tBuAs(CNcHex)3}2] 5. Six molecules cHexNC were consumed when Li2PtBu was added to the isonitrile to give [{Li(DME)}2{tBuP(CNcHex)5(CH)}] 6. 相似文献
In this study, a high performance liquid chromatography method with UV detection was developed for determination of orlistat. The chromatographic system consisted of a Nova-Pack C18 column, an isocratic mobile phase of phosphoric acid 0.1%-acetonitrile (10 : 90, v/v) and UV detection at 205 nm. Orlistat was eluted at about 6 min with no interfering peak from excipients used for preparation of dosage form. The method was linear over the range of 10-160 microg/ml orlistat (r2 > 0.9999). The within-day and between-day precision values were also in the range of 0.10-0.59%. The appropriate dissolution conditions were also determined and applied to evaluate the dissolution profile of orlistat capsules. Optimal conditions were 1000 ml of 3% SLS in water as dissolution medium and paddle at 100 rotation per minute. The proposed method was applied successfully to the determination of orlistat content in capsules and in vitro dissolution studies. 相似文献
Magnetic Fe3O4/SiO2 composite core–shell nanoparticles were synthesized, characterized, and applied for the surfactant‐assisted solid‐phase extraction of five benzodiazepines diazepam, oxazepam, clonazepam, alprazolam, and midazolam, from human hair and wastewater samples before high‐performance liquid chromatography with diode array detection. The nanocomposite was synthesized in two steps. First, Fe3O4 nanoparticles were prepared by the chemical co‐precipitation method of Fe(III) and Fe(II) as reaction substrates and NH3/H2O as precipitant. Second, the surface of Fe3O4 nanoparticles was modified with shell silica by Stober method using tetraethylorthosilicate. The Fe3O4/SiO2 composite were characterized by X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. To enhance their adsorptive tendency toward benzodiazepines, cetyltrimethylammonium bromide was added, which was adsorbed on the surface of the Fe3O4/SiO2 nanoparticles and formed mixed hemimicelles. The main parameters affecting the efficiency of the method were thoroughly investigated. Under optimum conditions, the calibration curves were linear in the range of 0.10–15 μgmL?1. The relative standard deviations ranged from 2.73 to 7.07%. The correlation coefficients varied from 0.9930 to 0.9996. 相似文献
In this research, the challenging problem of Covid-19 mitigation is looked at from an engineering point of view. At first, the behavior of coronavirus in the Iranian and Russian societies is expressed by a set of ordinary differential equations. In the proposed model, the control input signals are vaccination, social distance and facial masks, and medical treatment. The unknown parameters of the system are estimated by long short-term memory (LSTM) algorithm. In the LSTM algorithm, the problem of long-term dependency is prevented. The uncertainty and measurement noises are inherent characteristics of epidemiological models. For this reason, an extended Kalman filter (EKF) is developed to estimate the state variables of the proposed model. In continuation, a robust sliding mode controller is designed to control the spread of coronavirus under vaccination, social distance and facial masks, and medical treatment. The stability of the closed-loop system is guaranteed by the Lyapunov theorems. The official confirmed data provided by the Iranian and Russian ministries of health are employed to simulate the proposed algorithms. It is understood from simulation results that global vaccination has the potential to create herd immunity in long term. Under the proposed controller, daily Covid-19 infections and deaths become less than 500 and 10 people, respectively.
Phosphotungstic acid (H3PW12O40, PTA) supported on ZIF‐9(NH2) was synthesized for the first time and performed as an effective and environmental friendly catalyst in the one‐pot three component Biginelli condensation of different substituted benzaldehydes with ethyl acetoacetate and urea to afford the corresponding 3,4‐dihydropyrimidin‐2‐(1H)‐ones under solvent‐free conditions. ZIF‐9(NH2) and the prepared nanocatalyst PTA@ZIF‐9(NH2) were characterized by XRD, FESEM, TEM, EDX, BET, AAS, TGA, UV–Vis, and FT‐IR. After reaction, the nanocatalyst can be easily separated from the reaction mixture by centrifuge and the recovered catalyst can be reused for at least five times with a 14% reduction in yield after the fifth run. This study showed that ZIF‐9(NH2) can be utilized as a promising support for PTA and developed a highly active, stable and reusable heterogeneous catalyst under easy reaction condition in the multi‐component organic synthesis. 相似文献
Uniform SiO2 nanoparticles were successfully prepared from Equisetum arvense obtained from the north‐east of Iran. Then, surface modification of the extracted nanoparticles was performed with a methanol solution of H3PW12O40 via wet impregnation method. The prepared nanocatalyst was characterized by XRD, FESEM, ICP, UV–Vis, and FT‐IR spectroscopy. The supported heterogeneous nanocatalyst was successfully applied as a Lewis/Bronsted acid catalyst in the synthesis of a series of substituted 4H–chromenes via condensation of aromatic aldehydes, malononitrile, and 4‐hydroxycoumarin under solventless conditions with fine yields in appropriately short times. 相似文献