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81.
Seda Çetindere Süreyya O. Tümay Adem Kılıç Mahmut Durmuş Serkan Yeşilot 《Journal of fluorescence》2016,26(4):1173-1181
A new type of fluorescent chemosensor based on tethered hexa-borondipyrromethene cyclotriphosphazene platform (HBTC) linked via triazole groups was designed and synthesized. Its sensing behavior toward metal ions was investigated by ultraviolet-visible and fluorescence spectroscopies. Addition of a Fe2+ ion to a tetrahydrofuran solution of HBTC gave a visual color change as well as a significantly quenched fluorescence emission, while other tested 19 metal ions induced no color or spectral changes. This compound was found to be highly selective and sensitive for Fe2+ with a low limit of detection (2.03 μM) which is, to the best of our knowledge, the superior than the previously studied chemosensors for Fe2+. 相似文献
82.
Millions of employees in the World are exposed to noise at work. Block cutting machine is one of the most important noise sources in the stone processing plants. In this study, the predictability of the noise from the block cutting machines in the stone processing plants was investigated by using the physico-mechanical and mineralogical properties of rocks. The noise levels of some block cutting machines were firstly measured during the cutting of the three different rocks. Then, the core samples of the same rocks were cut by an automatic cutting machine in the laboratory and the noise levels were measured. A conversion factor was obtained by dividing the site noise levels by the laboratory noise levels. Then, nineteen different rocks were cut by the automatic cutting machine in the laboratory and the noise levels were measured. Strong correlations were found between the laboratory noise level and the rock properties. The noise level increases with increasing rock strength, abrasive mineral content, and density. However, increasing porosity decreases the noise level. It was concluded that the laboratory noise level for a new rock type to be cut can be estimated using the derived relations. Then, the laboratory noise level can be converted to the site noise level using the derived conversion factor. 相似文献
83.
84.
Oded?Berman Mahmut?ParlarEmail author David?Perry M.?J.?M.?Posner 《Methodology and Computing in Applied Probability》2005,7(2):203-224
We consider production/clearing models where random demand for a product is generated by customers (e.g., retailers) who arrive according to a compound Poisson process. The product is produced uniformly and continuously and added to the buffer to meet future demands. Allowing to operate the system without a clearing policy may result in high inventory holding costs. Thus, in order to minimize the average cost for the system we introduce two different clearing policies (continuous and sporadic review) and consider two different issuing policies (“all-or-some” and “all-or-none”) giving rise to four distinct production/clearing models. We use tools from level crossing theory and establish integral equations representing the stationary distribution of the buffer’s content level. We solve the integral equations to obtain the stationary distributions and develop the average cost objective functions involving holding, shortage and clearing costs for each model. We then compute the optimal value of the decision variables that minimize the objective functions. We present numerical examples for each of the four models and compare the behaviour of different solutions.AMS 2000 Subject Classification: 90B05 Inventory, storage, reservoirs; 90B22 Queues and service; 90B30 Production models 相似文献
85.
Süheyla Özbey F. Betül Kaynak Mahmut Toŭrul Nadir Demirel Halil Hoşgören 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(1-2):123-128
A new complex of a chiral monoaza-crown ether, [R-(-)-2-ethyl-N-benzyl-4,7,10,13-tetraoxa-8,9-benzo-1-azacyclopentadec-8-ene...NaClO4], has been prepared and studied by x-ray diffraction. The compound crystallizes in space group P21 with cell dimensions a = 8.721(1), b = 16.318(2), c = 8.905(1) Å, = 100.80(1)°. The sodium cation is heptacoordinated and located significantly out of the best plane of the macrocycle ring. The donor atoms of the macrocycle are in the half-chair arrangement. 相似文献
86.
Nano Fe3O4 particles were obtained in microvawe oven using closed system. Oxovanadium(IV) complexes of Fe3O4@SiO2@(aminomethylphosphine) type ligands were synthesized and characterized using SEM, EDX, TEM, UV‐Visible, XRD, FT‐IR and TG/DTA techniques. Catalytic properties of the synthesized pincer type oxovanadium(IV)‐aminomethylphosphine complexes supported on magnetic nano structure were investigated in the synthesis of 2‐methyl‐1, 4‐naphthoquinone (Vitamin K3, menadione, 2MNQ) from 2‐methyl naphthalene (2MN) in hydrogen peroxide, acetic acid and sulfuric acid. Magnetic‐nano particle supported oxovanadium(IV)‐aminomethylphosphine type complexes were very efficient catalysts with the 51.36‐55.20 % selectivities in conversions of 89.78‐95.01 %. Besides, the hetergeneous complexes were very active in five cycling tests on avarage evaluated in the reusability. 相似文献
87.
Artificial nanoenzymes with enzyme-like catalytic activity have gradually become an alternative to natural enzymes due to their low production cost, high stability, and good tolerance. In recent years, various enzyme mimics have emerged with the rapid development of nano-teclnology. Metal-organic frameworks(MOFs) are a novel class of porous inorganic-organic hybrid materials made from metal ions/clusters and organic ligands, and MOFs-based nanozymes show great prospect in biosensing, biocatalysis, biomedical imaging, and therapeutic applications, due to unique properties, such as high specific surface area, high porosity, tunable morphology, and excellent biocatalytic properties. In this paper, the recent progresses concerning MOFs-based nanozymes are systematically summarized, including the synthesis, design strategies and related applications, which are divided into two major categories, namely, MOFs structured nanoenzymes and MOFs composite structured nanoenzymes. Meanwhile, the applications of various classifications of MOFs research are introduced. At the end, current challenges and future perspectives of MOFs-based nanozymes are also discussed. It is highly expected that this review on this important area can provide a meaningful guidance for tumor therapy, biosensing and other aspects. 相似文献
88.
Fabienne Dumoulin Mahmut Durmuş Vefa Ahsen Tebello Nyokong 《Coordination chemistry reviews》2010,254(23-24):2792-2847
The different types of water-soluble phthalocyanines are presented and their synthesis is reviewed. 相似文献
89.
Phenyl-4,4-di(3,6-dibutoxyphthalonitrile) ( 3 ) was synthesized by the reaction of 1,4-phenylenebisboronic acid ( 1 ) and 4-bromo-3,6-dibutoxyphthalonitrile ( 2 ), using Suzuki cross-coupling reaction. The newly synthesized compound ( 3 ) was characterized by FT-IR, MALDI-MS, ESI-MS, 1 H-NMR, 13 C-NMR, and 13 C-DEPT-135-NMR. The fluorescence property of phenyl-4,4-di(3,6-dibutoxyphthalonitrile) ( 3 ) towards various metal ions was investigated by fluorescence spectroscopy, and it was observed thatthe compound ( 3 ) displayed a significantly ‘turn-off’ response to Fe 3+ , which was referred to 1:2 complex formation between ligand ( 3 ) and Fe 3+ . The compound was also studied via density functional theory calculations revealing the interaction mechanism of the molecule with Fe 3+ ions. 相似文献
90.
Durmuş M Nyokong T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(4):1170-1177
Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. 相似文献