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Principles of Lubrication
Published in Heinz P. Bloch, Kenneth E. Bannister, Practical Lubrication for Industrial Facilities, 2020
Heinz P. Bloch, Kenneth E. Bannister
Hydrostatic lubrication is a full film lubrication state set up when a lubricant is used to hydraulically separate a loaded surface and “float” one surface over another similar to that shown in Figure 1-10. This film regime is typically set up on precision machines and machine tools such as a plunge grinder in which the grindstone carriage is “floated” into the work piece on a controlled full film of oil to perform precision grinding on gears, etc.
Tools Required: their Care and Proper Use
Published in Les Goring, Manual of First and Second Fixing Carpentry, 2018
Figure2.25: The cutting edge of chisels should contain a grinding angle of 25°, produced on a grindstone or grinding machine, and a sharpening angle of 30°, produced on an oilstone or a diamond whetstone. The hollow-ground angle should not lessen the angle of 25° in the concave of the hollow. For extra strength, firmer and mortice chisels should be flat-ground.
Eco-friendly one-pot synthesis of some new pyrazolo[1,2-b]phthalazinediones with antiproliferative efficacy on human hepatic cancer cell lines
Published in Green Chemistry Letters and Reviews, 2018
Huda R. M. Rashdan, Sobhi M. Gomha, Marwa S. El-Gendey, Maher A. El-Hashash, Abdel Mohsen M. Soliman
Owing to the biochemical and pharmaceutical significance of 1,2,3-triazole and pyrazole rings, our growing interest in this part of the work is to incorporate between 1,2,3-triazole and pyrazole rings. Toda et al. (49) report that some of the exothermic reactions could be accomplished in excellent yield through grinding solids together (or liquid\solid) by using the mortar pestle technique which is known as grindstone chemistry. Reactions begin with grinding, with transfer of very small amounts of energy via friction (see Figure 1). Based on this simple technique, we synthesized a series of hydrazones containing 1,2,3-triazole moiety and utilizing these hydrazones in preparation of 1,2,3-triazolyl-pyrazole-carbaldhydes. Thus, condensation of acetyl triazole derivatives 1a–e (50) with phenyl hydrazine in the presence of one drop of glacial acetic acid by the grinding method at room temperature afforded the respective triazolylhydrazones 2a–e in excellent yields (Scheme 1). The chemical structure of 2a–e was established based on elemental data and also on spectral data (IR, 1HNMR, mass). For example, the 1HNMR spectrum of compound 2a displayed one signal at δ = 11.21 ppm attributed to the NH proton, in addition to the expected signals of the two methyl and aromatic protons. The mass spectral data of all products 2 exhibited in each case a molecular ion peak at the correct molecular weight for the respective compound (see Experimental).
Synthesis and cytotoxic activity of some novel benzocoumarin derivatives under solvent free conditions
Published in Green Chemistry Letters and Reviews, 2019
Anhar Abdel-Aziem, Huda Refaat Mahmoud Rashdan, Entesar Mohamed Ahmed, Sara N. Shabaan
Due to the pharmaceutical importance of coumarins, pyrazoles and pyrazolopyridazines, we are interested in this part of the work to integrate these biologically active molecules. Thus, grinding of 2-(3-(dimethylamino)acryloyl)-3H-benzo[f]chromen-3-one (1) with the appropriate of hydrazonoyl halides 2a-e in moist sodium carbonate afforded pyrazoles 4a-e, respectively. In grindstone technique, the grinding process is performed at room temperature and the reaction occurs due to heat generated by frictions between substrate and reagent. Products 4a-e were assumed to formed through 1,3-dipolar cycloaddition reaction of the nitrilimines 2′ (synthesized in situ from reaction of 2a-e with triethylamine) to the activated double bond in compound 1 affording cyclo adduct 3a-e which undergoes loss of dimethylamine molecule furnishing the final product (rout A). Another route (B), producing 7 does not operate based on spectral data. In 1H NMR spectrum of 4a as an example, the ester group was resonated as triplet and quartet signals at δ 1.28 and 4.31 ppm, respectively and methyl protons was observed at δ 2.42 ppm. The H-5 of pyrazole and H-4 of coumarin were appeared as two singlet signals at δ 8.45 and 9.21 ppm, respectively. Other signals owing to aromatic protons was observed at δ 7.27–8.39 ppm (Scheme 1). 13C NMR showed signals at 13.5 ppm due to –CH3 of ester group and at 24.2 ppm for –CH3 of p-tolyl, 63.5 ppm for –OCH2 of ester beside that signals appeared at 104.6–152.5 ppm for Ar-C. Finally, three signals related to 3 C=O at δ 159.3, 160.5, 165.2 ppm. The mass spectrum of all products 4a-e exhibited a molecular ion peak for the respective compound (see Experimental).