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51.
Seddighi Chahrborj S Sadat Kiai SM Abu Bakar MR Ziaeian I Gheisari Y 《Journal of mass spectrometry : JMS》2012,47(4):484-489
The homotopy analysis method (HAM) is applied to study the behavior of a hyperbolic rods of quadrupole mass filter and a sinusoidal potential form V(ac) cos(Ωt). Numerical computation method of a 20th-order HAM is employed to compare the physical properties of the confined ions with fifth-order Runge-Kutta method. Also, comparison is made for the first stability region, the ion trajectories in real time, the polar plots, and the ion trajectory in x?-?y plan. The results show that the two methods are fairly similar; therefore, the HAM method has potential application to solve linear and nonlinear equations of the charge particle confinement in quadrupole field. 相似文献
52.
Alper Tolga ?olak G?nül Pamuk Okan Zafer Ye?ilel Filiz Y?lmaz Orhan Büyükgüng?r 《Journal of chemical crystallography》2012,42(1):76-82
Abstract
The [Co(H2O)6][Co(pydc)2(en)]2·14H2O (1) compound (H2pydc = Pyridine-2,3-dicarboxylic acid and en = ethylenediamine) was synthesized and characterized by elemental analysis, magnetic and spectroscopic measurements (UV–Vis and IR spectra) and single crystal X-ray diffraction technique. There are two coordination spheres with different charges inside this aqueous compound of ionic character. The cationic part is composed of Co(II) encircled by six aqua ligand. Whereas the anionic part contains two anions complex unit each with −1 charge and have Co(III) ions in the centre. As a result different coordination spheres have cobalt ions with different states. The crystallographic analysis revealed that 1 consists of both discrete one-cationic and two-anionic entities, [Co(H2O)6]2+ and [Co(pydc)2(en)]2− and fourteen crystal water molecules. Two water molecules within the water cluster act as hydrogen-bonding acceptors, whereas one water molecule acts as a hydrogen-bonding donor to form a discrete water trimer. These water molecules have stabilized the crystal structure by strong hydrogen bonding interactions. 相似文献53.
Filiz Taneri Tamer Güneri Zoltán Zoltán Michael Kata 《Journal of inclusion phenomena and macrocyclic chemistry》2003,47(1-2):15-23
The effects of hydroxypropyl-β-cyclodextrin and methyl-β-cyclodextrin on the solubility of ketoconazole were studied. Products were prepared by physical mixing, kneading and spray-drying methods in four molecular ratios. Kneaded products in a ratio of drug: cyclodextrin (1:2) and spray-dried products showed the highest dissolution rate. Phase solubility diagrams of ketoconazole with these cyclodextrins at 25,°C in water and simulated intestinal medium were constructed. A solubility diagram of AL type was obtained with hydroxypropyl-β-cyclodextrin, and AP type with methyl-β-cyclodextrin. The complexes were characterized by thermal methods (DSC, TG, DTG and DTA). Multicomponent systems were prepared with tartaric acid. The effects of water-soluble polymers, e.g., polyvinylpyrrolidone, on the aqueous solubility of ketoconazole were investigated. The particle size of ketoconazole (70 ~ μm) is reduced to 12 μm by the preparation of spray-dried products. As the solubilty in water increased, the partition coefficient, surface tension and wetting angle values decreased. Ketoconazole needed more energy for dissolution compared to the products. In order to examine complex formation thermal methods were used. 相似文献
54.
This study reports the preparation of poly(sodium-4-styrene sulfonate) (PSS) treated bentonite and clinoptilolite to prevent the agglomeration and sedimentation of these inorganic fillers during the preparation of hydrogel. For this purpose PSS treated fillers were prepared by using various techniques (dip and dry, hydrothermal, one-step ball milling and ultrasonication methods). The most suitable technique for preparing these PSS treated inorganic fillers (abbreviated as BP-dip and CP-dip) was the dip and dry method. BP-dip and CP-dip based polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composite hydrogels were prepared using the freeze/thawing method after the addition of one of BP-dip and CP-dip inorganic fillers in various amounts. The swelling properties, stability behaviors and Rhodamine B (RhB) adsorption of the composite hydrogels were studied. It was found that the swelling degrees of CP-dip and BP-dip based composite hydrogels with 25 mg of filler were higher than that of all other samples. The kinetic mechanism of RhB adsorption process and the related characteristic kinetic parameters were investigated by Pseudo kinetic models. The adsorption kinetics results for RhB adsorption were found best fitted with pseudo-second-order kinetics model. The maximum RhB adsorption capacity was determined to be for PVA/PVP-CP-dip25, which was 3.3 times higher than that of the unfilled PVA/PVP hydrogel. 相似文献
55.
Joseph Bagi Suleiman Mahaneem Mohamed Ainul Bahiyah Abu Bakar Victor Udo Nna Zaida Zakaria Zaidatul Akmal Othman Abdulqudus Bola Aroyehun 《Molecules (Basel, Switzerland)》2021,26(16)
The aim of the study was to determine the chemical profile, antioxidant properties and antimicrobial activities of Heterotrigona itama bee bread from Malaysia. The pH, presence of phytochemicals, antioxidant properties, total phenolic content (TPC) and total flavonoid content (TFC), as well as antimicrobial activities, were assessed. Results revealed a decrease in the pH of bee bread water extract (BBW) relative to bee bread ethanolic extract (BBE) and bee bread hot water extract (BBH). Further, alkaloids, flavonoids, phenols, tannins, saponins, terpenoids, resins, glycosides and xanthoproteins were detected in BBW, BBH and BBE. Also, significant decreases in TPC, TFC, DPPH activity and FRAP were detected in BBW relative to BBH and BBE. We detected phenolic acids such as gallic acid, caffeic acid, trans-ferulic acid, trans 3-hydroxycinnamic acid and 2-hydroxycinnamic acid, and flavonoids such as quercetin, kaempferol, apigenin and mangiferin in BBE using high-performance liquid chromatography analysis. The strongest antimicrobial activity was observed in Klebsilla pneumonia (MIC50 1.914 µg/mL), followed by E. coli (MIC50 1.923 µg/mL), Shigella (MIC50 1.813 µg/mL) and Salmonella typhi (MIC50 1.617 µg/mL). Bee bread samples possess antioxidant and antimicrobial properties. Bee bread contains phenolic acids and flavonoids, and could be beneficial in the management and treatment of metabolic diseases. 相似文献
56.
Cansu Bayraktar Bahire Filiz Senkal 《International journal of environmental analytical chemistry》2018,98(10):889-906
In this study, a carbon paste electrode modified with a novel 1-(3-aminopropyl) imidazole functionalised crosslinked chlorosulfonated poly(styrene)-divinyl benzene polymer was used for selective and sensitive determination of the trace amounts of Pb2+, Cu2+ and Hg2+ ions by square wave anodic stripping voltammetry. The effect of some parameters such as paste composition, pH, preconcentration time, reduction potential and time, type of supporting electrolyte and potential scan rate on the determination of metal ions were investigated to find the optimal conditions. The effective open-circuit accumulation of the studied metal ions was succeeded only by the modification of the carbon paste electrode with functional polymer. For 6 min open-circuit preconcentration, the detection limit of Pb2+, Cu2+ and Hg2+ was found to be 5, 9 and 14 µgL?1, respectively at 100 mVs?1. The results confirmed that the lower concentration levels of these trace metal ions can be determined with the increase of preconcentration time and/or potential scan rate. Good detection limits and large dynamic concentration ranges were also obtained for their binary and ternary mixtures. The optimised method was successively applied to determine the concentration of Pb2+, Cu2+ ions in the tap water sample and Cu2+ ion in the waste water sample in the presence of possible interfering species (RSD<1%, recoveries 96–110% for 4 min preconcentration). 相似文献
57.
Islam Shumaila Bidin Noriah Saeed M. Alam Riaz Saira Bakar M. Aizat A. Naseem Shahzad Abbas Khaldoon Naji Sanagi Mohd Marsin 《Journal of Sol-Gel Science and Technology》2017,81(2):623-631
Journal of Sol-Gel Science and Technology - Using in-situ sol–gel processing, Sn-doped MgO2 nanofilm has been fabricated by spin-coating technique. Cracked and uneven distribution of... 相似文献
58.
In this study, two novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine derivatives, 3-[2-(4-methoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 1) and 3-[2-(3,4,5-trimethoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 2), having analgesic–anti-inflammatory activity were synthesized and characterized by IR, 1H-NMR, and mass spectroscopic techniques besides elementary analysis. Additionally, the structures and molecular packings
of the mentioned compounds have been investigated by X-ray single crystal diffraction. The six-membered thiadiazine ring adopts
the screw boat conformation in both the compounds. In the crystal packings of the compounds 1 and 2, C–H···N and C–H···O interactions link the molecules into a two-dimensional network and generate infinite chains. Furthermore,
C–H···π intermolecular interactions provide further stability to the molecular packing in both the molecules. The conformers
have been predicted by the potential energy surface scan employing the AM1 method. Geometry optimizations and electrostatic
properties have been obtained using AM1 and ab initio quantum methods. 相似文献
59.
W. L. Tan M. Abu Bakar N. H. H. Abu Bakar 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1111-1122
The thermal and kinetic studies of epoxidized natural rubber (ENR) and its polymer electrolytes, LiX/ENR PEs, (where X = ClO 4 ? , CF3SO 3 ? , COOCF 3 ? , I?, and BF 4 ? ) were carried out using thermogravimetric analysis at different heating rates. The thermal behaviors for LiX/ENR PEs are closely related to the morphology and interactions between the LiX and ENR chains. The LiCF3SO3, LiCOOCF3, and LiI form pseudo-crosslinking within the ENR; their thermal behavior resembled purified ENR. The LiClO4 tends to form aggregates within the ENR. This phenomenon has promoted a much earlier decomposition of epoxide in the ENR. The occurrence of ring-opening and complexation or cross-linking reactions in and between the ENR chains in the LiBF4/ENR has produced a thermally stable macrostructure. The activation energy for the thermal degradation (E d) of purified ENR was 239.8 and 239.9 kJ mol?1 using Kissinger and FWO methods, respectively. According to the Coats–Redfern method, the degradation mechanism of purified ENR follows the F1 type model, while the Criado method revealed that the degradation starts with F1 followed by D3 type models. The E d for LiX/ENR (X = COOCF 3 ? , CF3SO 3 ? , I?, and BF 4 ? ) PE’s obtained via the Kissinger method are 258.5, 257.0, 251.0, and 198.9 kJ mol?1, respectively, and the corresponding E d values obtained by FWO are 236.0, 223.6, 349.7, and 206.6 kJ mol?1, respectively. The degradation of ENR in these PEs followed the D3 type model. However, for LiClO4/ENR, the presence of two distinct degradations of ENR gave two E d values. These are 174.5 and 234.7 kJ mol?1 using Kissinger and 117.8 and 293.6 kJ mol?1 using FWO method. The degradation mechanism of ENR in the LiClO4/ENR PE was similar to purified ENR that is F1 followed by D3 type models. 相似文献
60.