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Processing of Integrated Waveguide Devices for Optical Network Using Different Technologies
Published in Partha Pratim Sahu, Fundamentals of Optical Networks and Components, 2020
The fabrication of annealed proton exchange (APE) waveguides is a step-by-step process spanning over a considerable amount of time [1]. The fabrication process can be made in three main stages. Figure 4.11a shows the flow chart. First, standard photolithography is used for the transfer of waveguide pattern on LiNbO3 substrate. Then proton exchange method is followed for this part of the process, benzoic acid was used as the proton source. Benzoic acid is non-toxic. But above 200°C it gives fumes and penchant smells. If the proton exchange is performed, the fumes will escape and solidify at low temperature. So, proton exchange cannot be performed in an ordinary furnace. A jig is designed to perform the proton exchange in a closed chamber. The samples to be fabricated were suspended above the acid melt inside the closed chamber during warm up and cool down using a glass holder. The temperature of the melt was monitored with the help of a thermocouple inserted directly in the melt. Once the desired temperature was reached, the glass holder was moved down so that the samples were dipped in the acid melt. After a specified time of exchange, the glass holder is moved up and the whole setup is allowed to cool naturally. Then the metal is removed by using metal etchant. Finally, it is put inside a temperature-controlled furnace at a temperature of 350°C for annealing.
Chemicals from Aromatic Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
In the process, toluene is first oxidized to benzoic acid. Benzoic acid is then hydrogenated to cyclohexane carboxylic acid, which reacts with nitrosylsulfuric acid yielding caprolactam. Nitrosyl sulfuric acid comes from reacting nitrogen oxides with oleum. Caprolactam comes as an acidic solution that is neutralized with ammonia and gives ammonium sulfate as a byproduct of commercial value. Recovered caprolactam is purified through solvent extraction and fractionation.
Nanosensors for Food Contaminant Detection
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
Heera Jayan, L. Bhavani Devi, C. Anandharamakrishnan
Benzoic acid and benzoates are generally used as preservatives in drinks and other food products to prevent degradation caused by micro-organisms during storage. However, they are harmful if not used in small quantities (minimal usage limit) (Mota et al., 2003; Tfouni et al., 2002). Electrochemical sensors based on Copper germanate (CuGeO3) nanowire was proposed for the detection of benzoic acid (BA). The electrochemical peaks (anodic peak potential) of CuGeO3 nanowire modified GCE increases with the addition of BA concentration, thereby detecting BA in samples. The current electrochemical sensor detects BA in the linear range of 0.01–2 mM with LOD of 0.91 µM at a signal-to-noise ratio of three and exhibits good reproducibility and stability (Cai et al., 2013). Copper vanadate nanobelts modified GCE was used for the detection of BA based on a pair of semi-reversible electrochemical peaks whose anodic peak potential is located at 0.13 and −0.06 V. Furthermore, the intensities of electrochemical peaks have a linear relationship with the concentration of BA, and detect BA with good reproducibility and stability in the linear range of 0.001–2 mM, with detection limits of 0.61 and 1.21 μM for cvp1 and cvp2, respectively (Lin et al., 2016). A novel glutamate electrochemical biosensor was developed based on nano-porous pseudo carbon paste electrode (Nano-PPCPE) as the working electrode, coupled with L-glutamate oxidase, catalase, and bovine serum albumin, which was followed by cross-linking with glutaraldehyde. Nano-PPCPE possesses excellent selectivity and sensitivity with a linear range of detection from 5 × 10−7 M to 1 × 10−5 M, with the detection limit of 25 × 10−7 M (Deng et al., 2013).
Degradation of dimethyl phthalate through Fe(II)/peroxymonosulphate heightened by fulvic acid: efficiency and possible mechanism
Published in Environmental Technology, 2023
Yi Ding, Min Zhang, Sijie Zhou, Linbei Xie, Ao Li, Ping Wang
First of all, the assaulting of •OH to bond of DMP hydrolyzed the side chain (ester group), following by the abscission of methoxyl group (–OCH3). Then MMP was formed owing to interlinkage of •OH. Besides, SO4•− attacked –C–C– bond between benzene ring and the branched chain which leaded to the loss of methyl formate to generate methyl benzoate. The transferring of electron between the carboxyl and SO4•− set off MMP decarboxylation followed by hydroxylation of •OH. These reactions led to the appearance of phthalic acid. Methyl benzoate also was affected by •OH to shape benzoic acid, which was the product of SO4•− attacking the –C–C– bond between the benzene ring and ester group on MMP. Of course, phthalic acid and benzoic acid were oxidated by free radicals to engender salicylic acid and phenol. The above was the general oxidation process of three aromatic esters into acids and phenol. Finally, the aromatic ring would be split and yield organic acids with low molecule mass, which would be further degraded into H2O and CO2.
Synthesis and liquid crystalline behavior of hydrazide-functionalized triphenylenedicarboxyimides
Published in Liquid Crystals, 2022
Yu Du, Cai-Li Zhao, Sheng-Yuan Fan, Wen-Hao Yu, Shi-Kai Xiang, Ke-Qing Zhao, Chun Feng, Bi-Qin Wang
Each of these hydrazide-functionalised TDIs was designed to contain a hydrazide group to have the possibility of forming intermolecular hydrogen bonds. It was anticipated that the stability of the mesophase can be achieved by synergistic effects of π–π stacking, hydrogen bonding and van der Waals forces. Preparation of these hydrazides was achieved in a straightforward manner through condensation reactions between triphenylene dicarboxylic acid anhydride and hydrazide (Scheme 1). The key precursor TPC10anhydride were synthesised from the corresponding triphenylene 2,3-dicarboxylic esters as previously reported from our laboratory [38]. The hydrazide precursors were obtained by reaction of benzoic acid methyl ester with hydrazine hydrate. The final condensation reaction occurred at 130°C in toluene giving seven hydrazides in high yields. The detailed synthetic procedures and compound characterisation data for the target hydrazides are provided in the Experimental section. For comparison, analogue TDI-pC6H4Br having the similar structure as TDI-NHCO-pC6H4Br but lacking hydrogen bonding group was also prepared from triphenylene 2,3-dicarboxylic ester and 4-bromoaniline according to the literature procedure [37,39].
Morphine Dreams: Auguste Laurent and the Active Principles of Organised Matter
Published in Ambix, 2021
Laurent called this new substance “the spirit of coal tar.”31 He took inspiration from the phrase “spirit of wine,” whose incorporeal connotations had led to its banishment by Lavoisier in favour of “alcohol.” There had also been a “spirit of wood” produced by the dry distillation of wood. Dumas had isolated the substance in 1834 and renamed it methanol. Following this, Laurent had predicted that distilling coal tar would give an analogous substance. He suspected it was a derivative of benzene, bearing the same relation to it that alcohol had to sugar. Because of this, he thought the name benzene was all wrong, coming as it did from its place in the benzoic acid series, named for its origins in gum benzoin tree resin, and at that time usually derived from the essential oil of bitter almonds. Laurent wanted to emphasis its origins in coal tar. He had proposed a new name for benzene in 1836, phène, from the Greek word ϕαɩνω, meaning “I light,” which he intended as a reference to the coal tar gas illuminating street lights.32 The spirit of coal tar then became phenol, to match its predecessors, alcohol and methanol.