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241.
Guillaume Toquer 《Journal of Non》2011,357(6):1552-1557
Herein, porous glass was prepared by the acid leaching of phase-separated sodium borosilicate glass. The effects of hydrochloric acid (HCl) leaching concentrations varying from 0.1 to 3 M and of leaching times varying from 2 to 48 h on pore size and shape are reported here. The porous structure evolution was investigated through small angle X-rays scattering measurements and were compared to the classical nitrogen adsorption technique. We argue that the composition of these samples is not significantly modified with the acidic concentrations of the solution or with the leaching times tested. However, as expected a priori, we clearly show strong differences in porous structure. The investigation of different HCl leaching concentrations (from 0.1 to 3 M), with a small variation between each concentration, has enabled the observation of an interesting result. That is, we clearly show a non-linear effect of acidic concentration on the porous structure of these materials. At low acid concentrations, the specific area of these materials is relatively low. Increasing the HCl concentration to approximately 0.7 M leads to a strong increase in a specific BET area and total pore volume. However, further increasing of the acid concentration of the leaching solution leads to a decrease of both the specific surface area and the total pore volume. All of these results due to the presence of colloidal silica inside the pore structure can be explained by the well-known Zhdanov's model. These nanoparticles formed at an intermediate acid concentration seem to cluster when the acidity increases. The effect of the leaching time is less significant than the HCl concentration; however, this same assumption can be explained by the experimental results. 相似文献
242.
Limin Guo Jianling Zhao Xixin Wang Rongqing Xu Yangxian Li 《Journal of Solid State Electrochemistry》2009,13(9):1321-1326
The formation and growth of a self-organized zirconia porous layer can be achieved directly by anodization of Zr in chloride
containing electrolytes. The morphology of the porous layers is affected by electrochemical conditions such as Cl− concentration. Zirconia nanotubes with diameters ranging from 250 to 300 nm and a length of 33 μm were formed under proper
conditions. The nanotubes have smooth and straight walls. The composition of the nanotubes was characterized by using an energy
dispersive spectrometer. Selected area electron diffraction investigation reveals that the as-anodized zirconia nanotubes
have an amorphous structure. Crystal phase transition and structural stability of the ZrO2 nanotubes after heat treatment were characterized. A possible growth mechanism is presented. 相似文献
243.
The aim of this work was to investigate the transformation behavior of metoclopramide HCl with monohydrate (MCP HCl H2O) using differential scanning calorimetry (DSC), thermogravimetric analysis, hot‐stage microscopy (HSM), and thermal micro‐Raman spectroscopy. The results of the present study indicate that the three‐step phase transformation of MCP HCl H2O was clearly determined via the thermal‐dependant Raman spectral changes. These three steps of phase transformation were dehydration, recrystallization, and new crystal formation, which were markedly correlated with the endothermic and exothermic results of DSC study and the observations of HSM. The results generally evidence that MCP HCl H2O crystals were first dehydrated to form an anhydrous sample, then recrystallized and transformed to a new crystal form of MCP HCl. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
244.
245.
Timm M. Reichenau Felix Steinke Dr. Michael T. Wharmby Prof. Dr. Christian Näther Dr. Tobias A. Engesser Prof. Dr. Norbert Stock 《Angewandte Chemie (International ed. in English)》2023,62(26):e202303561
A concept for obtaining isoreticular compounds with tri- instead of tetravalent metal cations using highly acidic reaction conditions was developed and successfully applied in a high throughput study using N,N′-piperazinebis(methylenephosphonic acid) (H4PMP), that resulted in the discovery of a new porous aluminium phosphonate denoted CAU-60⋅6 HCl. The high-throughput study was subsequently extended to other trivalent metal ions. Al-CAU-60⋅6 HCl demonstrates reversible desorption of HCl (18.3 wt % loading) with three distinct compositions observed with zero, four or six HCl molecules per formula unit. Structural changes were followed in detail by powder X-ray diffraction, EDX analysis as well as IR spectroscopy. Rapid desorption of HCl in water within minutes and subsequent adsorption from the gas phase and from aqueous solution are shown. Furthermore, it is possible to adsorb HBr into the guest free Al-CAU-60 framework, demonstrating the high stability of this compound. 相似文献
246.
Diltiazem (DTZ) hydrochloride, a calcium channel blocker compound, is a very well-known drug used by many clinicians to treat important diseases playing a role in increased morbidity and mortality among adults worldwide, namely hypertension, cardiac arrhythmia, and ischemic heart disease (angina pectoris). These diseases are a common public health concern, implying that the construction of a specific, accurate, and simple sensor for DTZ determination is needed. Herein, an innovative, portable, and sensitive modified carbon paste electrode (MCPE) was seamlessly developed based on the affordable green compound N-bromosuccinimide (NBS) as a sensing material and tricresyl phosphate as a solvent mediator for the voltammetric determination of DTZ. The proposed NBS-MCPE exhibited an excellent electrocatalytic activity towards the oxidation of DTZ molecules in a phosphate buffer solution of pH 5.0 in presence of 20 μM sodium dodecyl sulfate to improve the developed sensor performance. The sensor was found to respond linearly to the DTZ drug over a wide concentration ranging from 1 μM to 300 μM with a low limit of detection. LSV and EIS measurements were also used to scrutinize our sensor, in addition to using scanning electron microscopy and energy dispersive X-ray analysis techniques for its surface morphology inspection before and after soaking in the drug-containing solution. The applicability of the proposed sensor for the rapid, sensitive, and selective determination of DTZ in pharmaceutical preparation and human urine samples was assessed and the obtained results were compared with that of the reported HPLC analytical method. 相似文献