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Lipases as Biocatalyst for Production of Biolubricants
Published in Brajendra K. Sharma, Girma Biresaw, Environmentally Friendly and Biobased Lubricants, 2016
Jasneet Grewal, Sunil K. Khare
In an interesting comparison, Akerman et al. [1] synthesized esters from TMP and carboxylic acids (C5 to C18) by (i) heterogeneous catalysts (silica sulfuric acid and Amberlyst-15) and (ii) biocatalyst Novozym 435. Silica sulfuric acid was found to be a better catalyst as compared to Amberlyst-15 for short-chain carboxylic acids. Novozym 435 exhibited increased activity with increase in length of the fatty acid chain. Thus, in the synthesis of C18-ester, enzyme was as good as silica sulfuric acid and gave better quality product. The biolubricant had good cold-flow properties for low-temperature applications. Pour point (−75°C to −42°C) and VI (80–208) increased with increasing alkyl chain length.
Swelling triggered release of cisplatin from gelatin coated gold nanoparticles
Published in Inorganic and Nano-Metal Chemistry, 2022
Nishi Verma, Alka Tiwari, Jaya Bajpai, Anil Kumar Bajpai
In addition, boehmite is the one type of nanofibre martial first synthesized by John Bugosh in 1961. Various methods like sol–gel, hydrothermal, precipitation, and sprays have been used to synthesize this nanofibre. Boehmite materials having 20–50 nm sizes are creating huge attention because of their outstanding advantages like large surface area, narrow pore size distributions within the mesoporous range, as well as suitable surface acidic–basic properties.[12] Recently, nano silica functionalized sulfonic acid as heterogeneous solid acid catalyst has been used for performing various reactions. Amidoalkyl naphthols can be synthesized by using nano silica sulfuric acid as an efficient heterogeneous catalyst under thermal solvent-free conditions and it is the most promising tool for biological and pharmaceutical activities.[13]Electrospinning,[14] as a peer technology of electrospraying,[15] can fabricate polymeric nanofibers with variable structural features in a single-step process. These new types of polymer-based nanofibers can be loaded with different kinds of active ingredients, including those for treating corona virus disease 2019 (COVID-19). Core-shell nanofibers generated from coaxial and modified triaxial processes can provide many strategies for constructing new functional nanomaterials, including those for providing drug sustained release profiles.[16]
An amino acid@isopolyoxometalate nanoparticles catalyst containing aspartic acid and octamolybdate for the synthesis of functionalized spirochromenes
Published in Inorganic and Nano-Metal Chemistry, 2021
Majid Momahed Heravi, Tayebeh Momeni, Masoud Mirzaei, Vahideh Zadsirjan, Morteza Tahmasebi
As summarized in Table 4, the AFO catalyst was compared with was compared by previously reported catalyst, such as CoFe2O4@SiO2@SO3H,[76] SiO2@g-C3N4,[77] NiO@g-C3N4,[78] L-Proline,[66] triphenylphosphine,[79] β-cyclodextrin,[43] (SB-DBU)Cl,[35] Silica sulfuric acid magnetic,[45] Mn(bpyo)2/MCM-41,[74] nanoMgO,[80] triphenylphosphine.[79] As can be seen in Table 4, the catalytic performance of AFO was compared with different catalysts that have been formerly applied as catalysts in our model reaction including the reaction of isatin 1a (1 mmol), malononotrile 2a (1 mmol), and dimedone 3a (1 mmol) in H2O/EtOH under reflux condition. As exhibited in Table 4, some catalysts provide better results but our catalyst also demonstrated good results.
Polybrominated diphenyl ethers (PBDEs) levels in blood samples from children living in the metropolitan area of Guadalajara, Jalisco, Mexico
Published in International Journal of Environmental Health Research, 2018
Sandra T. Orta-García, Ángeles C. Ochoa-Martínez, José A. Varela-Silva, Iván N. Pérez-Maldonado
Blood PBDEs levels were quantified following the technique that has been previously described by our research group (Perez-Maldonado et al. 2009; Ochoa-Martinez et al. 2016; Perez-Maldonado et al. 2017; Orta-Garcia et al. 2014). Briefly, serum samples (2 mL) were mixed with hydrochloric acid (6 M, 1 mL) and 2-propanol (6 mL). The sample was then extracted using 6 mL of n-hexane/methyl-tert-butyl ether (1:1 by volume). The water phase (previous extraction stage) was re-extracted with an additional volume of solvent mixture. Then, the two organic phases obtained were washed using potassium chloride in water (1 %). Then, the solvent used in the extraction phases was evaporated and through a gravimetrical method, the lipid content of each analyzed sample was determined. Subsequently, lipids were removed using a column packed (silica/silica: sulfuric acid) and PBDEs collected for quantitative chromatographic analyses. Lastly, the analytical quantification of the target PBDEs (BDE47, BDE99, BDE100, BDE153, and, BDE154) was completed through an instrumental method [gas chromatography (GC-HP6890)/mass spectrometer (MS-HP5973)]. The LOD (method detection limit) was approximately 0.10 ng/mL for all BDE congeners measured. The reference standard SRM 1958 (organic contaminants in fortified human serum) of the National Institute of Standards and Technology was used as an external quality control, the recovery was approximately 95 ( 5 % for all compounds tested. BDE congeners concentrations on lipid-weight basis were estimated according to previously described method (Bergonzi et al. 2009). For statistical analysis, when the blood level of individual BDE congeners was below LOD, LOD/2 was used.