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排序方式: 共有222条查询结果,搜索用时 31 毫秒
101.
Azri Farah Asilah Eissa Shimaa Zourob Mohammed Chinnappan Raja Sukor Rashidah Yusof Nor Azah Raston Nurul Hanun Ahmad Alhoshani Ali Jinap Selamat 《Mikrochimica acta》2020,187(5):1-9
An in situ preparation of metal-organic framework (HKUST-1) on the surface of an organic polymer is reported. The hybrid material was evaluated as sorbent for solid-phase extraction (SPE) of oxygenated and nitrated polycyclic aromatic hydrocarbons (PAHs). The growth of HKUST-1 on MAA-based polymer was accomplished using a layer-by-layer assembly strategy. The HKUST-1-polymer was characterized using powder X-ray diffraction and scanning electron microscopy to demonstrate the incorporation of MOF crystals onto the polymer surface. The MOF (nano)crystals were characterized using high-resolution transmission electron microscopy and high-angle annular-dark-field scanning transmission electron microscopy. The water-stable MOF-polymer was evaluated as SPE sorbent, and several variables that can influence the extraction recoveries of PAH derivatives were investigated. Under the selected conditions, the detection limits varied between 4 and 21 ng·L−1, and the precision (relative standard deviation) was below 12%. The recovery values for spiked solutions ranged from 95 to 104%, and the enrichment factor achieved was close to 1000-fold using a high sample volume (100 mL) and very low desorption volume (100 μL). The SPE enrichment combined with HPLC and DAD detector was successfully applied to the extraction and determination of polycyclic hydrocarbons in environmental water samples. 相似文献
102.
Buong Woei Chieng Nor Azowa Ibrahim Wan Md Zin Wan Yunus Mohd Zobir Hussein Yuet Ying Loo 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1551-1559
Plasticized PLA-based nanocomposites were prepared by melt blending of the matrix with 5 mass% of epoxidized palm oils (EPO) and different amount of graphene nanoplatelets (xGnP). Plasticized PLA (p-PLA) reinforced with 0.3 mass% xGnP resulted in an increase of up to 26.5 and 60.6 % in the tensile strength and elongation at break of the nanocomposites, respectively. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were performed to study the thermal behavior of the prepared nanocomposites. p-PLA reinforced with xGnP shows that increasing the xGnP content triggers a substantial increase in thermal stability. Crystallinity of the nanocomposites as well as cold crystallization and melting temperature did not show any significant changes upon addition of xGnP. However, there is a significant decrease of glass transition temperature up to 0.3 mass% of xGnP incorporation. 相似文献
103.
Spatial and Directional Control over Self‐Assembly Using Catalytic Micropatterned Surfaces
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Dr. Alexandre G. L. Olive Nor Hakimin Abdullah Dr. Iwona Ziemecka Dr. Eduardo Mendes Dr. Rienk Eelkema Prof. Dr. Jan H. van Esch 《Angewandte Chemie (International ed. in English)》2014,53(16):4132-4136
Catalyst‐assisted self‐assembly is widespread in nature to achieve spatial control over structure formation. Reported herein is the formation of hydrogel micropatterns on catalytic surfaces. Gelator precursors react on catalytic sites to form building blocks which can self‐assemble into nanofibers. The resulting structures preferentially grow where the catalyst is present. Not only is a first level of organization, allowing the construction of hydrogel micropatterns, achieved but a second level of organization is observed among fibers. Indeed, fibers grow with their main axis perpendicular to the substrate. This feature is directly linked to a unique mechanism of fiber formation for a synthetic system. Building blocks are added to fibers in a confined space at the solid–liquid interface. 相似文献
104.
Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non-radiative Decay Pathway
Riki Iwai Dr. Satoshi Suzuki Dr. Shunsuke Sasaki Amir Sharidan Sairi Prof. Dr. Kazunobu Igawa Prof. Dr. Tomoyoshi Suenobu Prof. Dr. Keiji Morokuma Prof. Dr. Gen-ichi Konishi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10653-10660
To broaden the application of aggregation-induced emission (AIE) luminogens (AIEgens), the design of novel small-molecular dyes that exhibit high fluorescence quantum yield (Φfl) in the solid state is required. Considering that the mechanism of AIE can be rationalized based on steric avoidance of non-radiative decay pathways, a series of bridged stilbenes was designed, and their non-radiative decay pathways were investigated theoretically. Bridged stilbenes with short alkyl chains exhibited a strong fluorescence emission in solution and in the solid state, while bridged stilbenes with long alkyl chains exhibited AIE. Based on this theoretical prediction, we developed the bridged stilbenes BPST[7] and DPB[7], which demonstrate excellent AIE behavior. 相似文献
105.
Othman Nor Azillah Fatimah Selambakkannu Sarala Yamanobe Takeshi Hoshina Hiroyuki Seko Noriaki Abdullah Tuan Amran Tuan 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):429-440
Journal of Radioanalytical and Nuclear Chemistry - Radiation grafting of two tertiary amine methacrylates; 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 2-(diethylamino)ethyl methacrylate... 相似文献
106.
El Hassane Anouar Salwa Raweh Imene Bayach Muhammad Taha Mohd Syukri Baharudin Florent Di Meo Mizaton Hazizul Hasan Aishah Adam Nor Hadiani Ismail Jean-Frédéric F. Weber Patrick Trouillas 《Journal of computer-aided molecular design》2013,27(11):951-964
Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure–antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH. 相似文献
107.
Emad A. Jaffar Al-Mulla Nor Azowa Bt Ibrahim Isam Hussain T. Al-Karkhi Kamyar Shameli Mohammed Zidan Mansor Bin Ahmad Wan Md. Zin Wan Yunus 《Research on Chemical Intermediates》2013,39(5):2133-2139
Fatty methylydrazides (FMHs) have been successfully synthesized from palm oil. Glycerol was produced as a by-product. The synthesis was carried out by reflux palm oil with methylhydrazine in hexane. FMHs have been characterized using elemental analysis, Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance technique. The results showed that a 6:1 molar ratio of palm oil to methylhydrazine, a round 78 % maximum conversion of palm oil into FMHs and a 10 h reaction time are the optimum reaction conditions. 相似文献
108.
Two new heteroyohimbine-type oxindole alkaloids, rauniticine-allo-oxindole B and rauniticinic-allo acid B, have been successfully isolated from the stems extract of Malaysian Uncaria longiflora var. pteropoda. The structures of the two new alkaloids were determined by spectroscopic analysis. 相似文献
109.
In this research, silver nanoparticles (AgNPs) were synthesized in chitosan (Cts), Cts/gelatin and gelatin suspensions using a chemical reducing agent. Cts and gelatin were used as natural stabilizers and solid support, whereas AgNO(3) was used as the silver precursor. Sodium borohydride (NaBH(4)) was used as the reducing agent. The properties of AgNPs in Cts, Cts/gelatin and gelatin bionanocomposites (BNCs) were studied in terms of their surface plasmon resonance, crystalline structure, average diameter size, particle distributions, surface topography and functional groups. All the samples were characterized by UV-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy. 相似文献
110.
Fahlquist H Noréus D Callear S David WI Hauback BC 《Journal of the American Chemical Society》2011,133(37):14574-14577
The first examples of a new class of gallium hydride clusters with direct Ga-Ga bonds and common hydrocarbon structures are reported. Neutron powder diffraction was used to find a Ga[GaH(3)](4)(5-) cluster ion with a neopentane structure in a novel cubic structure type of Rb(8)Ga(5)H(15). Another cluster ion with a polyethylene structure, [GaH(2)](n)(n-), was found in a second novel (RbGaH(2))(n) hydride. These hydrocarbon-like clusters in gallium hydride materials have significant implications for the discovery of hydrides for hydrogen storage as well as for interesting electronic properties. 相似文献