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71.
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
72.
A new and simple method for the synthesis of the primary allyl chlorides and bromides 9 – 16 from the secondary or tertiary allyl alcohols 3 – 8 and acyl halide was developed (Scheme 2, Table 1). Non‐commercially available secondary and tertiary allyl alcohols were synthesized from the related ketones and aldehydes via the addition of vinylmagnesium chloride. Mechanistic studies indicate that the alcohols were first acetylated by the acetyl halide and then protonated prior to substitution by the halide, Cl? or Br?, via an SN2′ reaction, to yield the primary halides (Scheme 5). 相似文献
73.
74.
Ramazan Koçak Dilan Yıldız Uğur Bozkaya Arif Daştan Özgür Altan Bozdemir 《Tetrahedron letters》2017,58(30):2981-2985
Highly fluorescent, novel dihydropyridazine-appended dibenzosuberenone type dye molecules were obtained in a single step from simple compounds using Diels-Alder chemistry. This new fluorophore structure can be used for the construction of fluorescent chemosensors, as exemplified by selective and sensitive fluoride ion sensing. The –N–H protons in these structures are acidic enough to allow for fluoride-induced deprotonation, leading to a significant color change as well as a concomitant fluorescence quenching. These fluorophores possess large Stokes shifts, high quantum yields, and long fluorescence lifetimes; therefore, this study potentially paves the way for the construction of novel dye molecules for use in fluorescent dye applications. 相似文献
75.
Daniyal M. Israfilov Ramazan Akgün 《Journal of Mathematical Analysis and Applications》2008,346(2):489-500
Let Γ be a Dini-smooth curve in the complex plane, and let G:=IntΓ. We prove some direct and inverse theorems of approximation theory by algebraic polynomials and rational functions in the weighted rearrangement invariant Smirnov spaces EX(G,ω) defined on G. 相似文献
76.
The radial part of the effective mass Klein-Gordon equation for the Hulthen potential is solved by making an approximation
to the centrifugal potential. The Nikiforov-Uvarov method is used in the calculations. Energy spectra and the corresponding
eigenfunctions are computed. Results are also given for the case of constant mass. 相似文献
77.
An efficient methodology for the synthesis of acridinedione derivatives 4a–o has been achieved by one-pot, multicomponent condensation of dimedone 1, various amines 2a–d, and substitute aromatic aldehydes 3a–k, in the presence of the easily available, inexpensive, and nontoxic catalyst vitamin B1 (VB1) as a versatile biodegradable. Synthesis of acridine-type compounds was performed in good yields in water as green solvent. Its high-yield efficiency; clean, ecofriendly, simple workup procedure; and easy purification are regarded as the main advantages of this method besides its green solvent. The synthesized compounds are characterized using spectroscopic analyses (FTIR, 1H NMR, 13C NMR, and high-resolution mass spectrometry) techniques. 相似文献
78.
PT-symmetric solutions of Schrödinger equation are obtained for the Scarf and generalized harmonic oscillator potentials with the position-dependent mass. A general point canonical transformation is applied by using a free parameter. Three different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter. 相似文献
79.
Nasrin Talebian Mohmmad Reza Nilforoushan Razieh Ramazan Ghasem 《Journal of Sol-Gel Science and Technology》2012,64(1):36-46
Nanostructure single ZnO, SnO2, In2O3 and composite ZnO/SnO2, ZnO/In2O3 and ZnO/SnO2/In2O3 films were prepared using sol?Cgel method. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV?CVis spectroscopy. The photocatalytic activities of composite films were investigated using phenol (P), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) and 4-aminophenol (4-AP) as a model organic compounds under UV light irradiation. Hybrid semiconductor thin films showed a higher photocatalytic activity than single component ZnO, SnO2 and In2O3 films. The substituted phenols degrade faster than phenol. The ease of degradation of phenols is different for each catalyst and the order of catalytic efficiency is also different for each phenol. The use of multiple components offered a higher control of their properties by varying the composition of the materials and related parameters such as morphology and interface. It was also found that the photocatalytic degradation of phenolic compounds on the composite films and single films followed pseudo-first order kinetics. 相似文献
80.
Cengiz Soykan ükran Güven Ramazan Cokun 《Journal of polymer science. Part A, Polymer chemistry》2005,43(13):2901-2911