Extracts from plant materials have great potential as alternatives to inorganic corrosion inhibitors, which typically have harmful consequences. Experimental and theoretical methodologies studied the effectiveness of agricultural waste, namely, date palm seed extract as a green anti-corrosive agent in 0.5 M hydrochloric acid. Experimental results showed that immersion time and temperature are closely related to the effectivity of date palm seed as a corrosion inhibitor. The inhibition efficiency reduced from 95% to 91% at 1400 ppm when the immersion time was increased from 72 h to 168 h. The experimental results also indicated that the inhibition efficiency decreased as the temperature increased. The presence of a protective layer of organic matter was corroborated by scanning electron microscopy. The adsorption studies indicated that date palm seed obeyed Langmuir adsorption isotherm on the carbon steel surface, and Gibbs free energy values were in the range of −33.45 to −38.41 kJ·mol−1. These results suggested that the date palm seed molecules interacted with the carbon steel surface through mixture adsorption. Theoretical calculations using density functional theory showed that the capability to donate and accept electrons between the alloy surface and the date palm seed inhibitor molecules is critical for adsorption effectiveness. The HOMO and LUMO result indicated that the carboxyl (COOH) group and C=C bond were the most active sites for the electron donation-acceptance type of interaction and most auxiliary to the adsorption process over the Fe surface. 相似文献
A two-dimensional equation of generalized thermoelasticity with one relaxation time in an isotropic elastic medium with the
elastic modulus dependent on temperature and with an internal heat source is established using a Laplace transform in time
and a Fourier transform in the space variable. The problem for the transforms is solved in the space of states. The problem
of heating of the upper and the lower surface of a plate of great thickness by an exponential time law is considered. Expressions
for displacements, temperature, and stresses are obtained in the transform domain. The inverse transform is obtained using
a numerical method. Results of solving the problem are presented in graphical form. Comparisons are made with the results
predicted by the coupled theory and with the case of temperature independence of the elastic modulus. 相似文献
Nanoassemblies (NAs) with sizes ranging from 60 to 160nm were spontaneously formed in water after mixing a host polymer (polymerized cyclodextrin (pβ-CD)) and a guest polymer (dextran grafted with lauroyl side chains (MD)). The combination of microscopy, dynamic light scattering (DLS), nuclear magnetic resonance ((1)H NMR), isothermal titration calorimetry (ITC) and molecular modelling was used to investigate the parameters which govern the association between MD and pβ-CD. Remarkably, when pβ-CD was progressively added to a solution of MD, NAs with a well-defined diameter were spontaneously formed and their diameter was constant whatever the composition of the system. According to NMR data, almost all the alkyl chains of MD were included into CDs' cavities of the polymer when the molar ratio lauroyl chain (C(12))/CD was ?1. The hydrophobic interaction between C(12) and the hydrophobic cavities of CDs appears as the main driving force for NAs' formation, with a minor contribution arising from van der Waals' interactions. The inclusion of C(12) into β-CD cavities is almost a completely enthalpy-driven process, whereas the MD-C(12)/pβ-CD interaction was found to be an entropy-driven process. Major conclusions which can be drawn from these studies are that the interactions between the two polymers are restricted neither by the MD substitution yield, nor by the micellization of MD. The simultaneous effects of several CD linked together in pβ-CD and of many alkyl chains grafted on dextran were necessary to generate these stable NAs. 相似文献
In this study, both zeolites NaA and NaY were synthesized from rice husk ash (RHA) by a simple conventional hydrothermal route.
Rice husk (RH) was used as a silicate source to produce various zeolites. The hydrothermal route was conducted via a seeding
technique involving the preparation of two separate gels, i.e. colloidal seed and feedstock gel. The zeolite was first produced
using commercially available chemicals and followed by the replacement of the commercial silicate sources with RHA derived
silicate. The RHA silicate was obtained by combusting the RH at different temperatures and durations i.e. 450 °C for both
2 and 6 hours, as well as 750 °C for 6 hours. Zeolite NaY (faujasite) was successfully synthesized with commercial chemical
seed and RHA derived feedstock gel. On the other hand, using RHA silicate in both colloidal seed and feedstock gel would give
only zeolite NaA. Elemental, structural and morphological analyses of RHA and zeolites were carried out with X-ray fluorescence
(XRF) spectrometer, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). 相似文献
A new, simple and accurate spectrofluorimetric method for the determination of metoclopramide hydrochloride was developed.
The metoclopramide hydrochloride can remarkably enhance the luminescence intensity of the Tb3+ ion doped in PMMA matrix at λex = 360 nm in methanol at pH 6.9. The intensity of the emission band at 545 nm of Tb3+ ion doped in PMMA matrix is increased due to the energy transfer from metoclopramide hydrochloride to Tb3+ in the excited stated. The effect of different parameters, e.g., pH, temperature, Tb3+ concentration, foreign ions that control the fluorescence intensity of the produced ion associate was critically investigated.
The calibration curve of the emission intensity at 545 nm shows linear response of metoclopramide over a concentration range
of 5 × 10−5–5.0 × 10−8 M with detection limit of 8.7 × 10−10 M. The method was used successfully for the determination of metoclopramide in pharmaceutical preparations and human serum.
The average recovery of 99.48% with standard deviation of 0.32% and 96.98% with standard deviation of 0.4%, of pharmaceutical
preparations and human serum respectively, were obtained which compared will with the results obtained from standard LC method
of average recovery 99.04% and standard deviation of 0.6% and average recovery of 98.19% with standard deviation of 0.6% of
pharmaceutical preparations and human serum, respectively. 相似文献
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献
ABSTRACTWe investigated the alignment director of a frustrated cholesteric liquid crystal (CLC) confined in a planar cell. Three cells with different confinement ratio (c?=?d/p) (where p is the pitch and d is the cell thickness) are prepared. Under an electric field, the CLC planar texture is transformed into a cholesteric fingerprint (CF). The results showed that CF contrast depends on c. When c?≈?2, CLC stripes are formed by a periodic CF, with a period equal to the CLC pitch. The CF is developed and slowly extended to the whole cell surface along the rubbing direction and the contrast of the grating stripes keeps unchangeable. Yet, the CLC finger borders have a different light intensity. However, when c?≈?1, the CF contrast increases with time. When c?1, an isolated CF is obtained whose borders contrast change by varying the angle θ between the polarizer and the CFs. 相似文献
In this article, we propose a new kind of quantum states based on acting the number operator M times \( {\hat{n}}^M \) on the coherent state. We term this state the Mth coherent state, based on the value of the power M. We find that it is strongly similar to the coherent state as the analysis of the photonic statistical distributions and the overlap with the coherent state illustrate. Also, we find that it asymptotically reaches the minimum uncertainty and has a localized behavior in the Husimi function. However, in contrast to coherent state, the Mth coherent state has strong nonclassical features such as antibunching and squeezing for a relatively long range. Other parameters and measurements are discussed and studied. Finally, we highlight the similarity between the higher orders of the near coherent states and the Mth coherent states in order to potentially generate our proposed state.
The DNA binding studies of the triterpenoid derivative, cholesterol, N,N-Bis(3β-acetoxy-5α-cholest-6-yl-idene)hydrazine (L) with CT DNA were carried out by employing different optical methods viz, UV–vis and fluorescence spectroscopy. The ligand binds to DNA through hydrophobic interaction with Kb value found to be 4.7×103 M?1. These observations have been validated also by fluorescence spectroscopy. (L) exhibits a remarkable DNA cleavage activity with pBR322 DNA in the presence of different activators and the DNA is probably cleaved by an other than oxidative mechanism, possibly by a discernable hydrolytic pathway. In the presence of major and minor groove binding agents, (L) prefers major groove binding of the DNA. 相似文献