Records Added in December 2021
Records added in December 2021
Change year: 2018 | 2019 | 2020 | 2021 | 2022
Change month: January | February | March | April | May | June | July | August | September | October | November | December
A Fructan Sucrase Secreted Extracellular and Purified in One-Step by Gram-Positive Enhancer Matrix Particles
Jingyue Wang, Huazhi Xiao, Fangkun Zhao, Bo Zhao, Min Xu, Zhijiang Zhou, Ye Han
December 6, 2021 (v1)
Subject: Biosystems
Keywords: Bacillus subtilis, Escherichia coli, fructan sucrase, secretory expression
Fructan sucrase is a kind of biological enzyme that catalyzes the synthesis of fructan, and fructan is a polysaccharide product with important industrial application value. In this study, the Fructan sucrase gene of Bacillus subtilis was cloned to plasmid PET-28A-ACMA-Z, and three clones were obtained after the transformation of Escherichia coli BL21, namely BS-FF, BSO, and BS. The clones BS-FF and BSO secreted the recombinant enzymes outside the cells, while the clone BS expressed them inside the cells. The induction experiment results showed that the optimum IPTG concentration in the medium was 0.5 mM and 1.0 mM for clones BS-FF and BSO, respectively, while the incubation conditions were at 28 °C for 8 h. The recombinant fructan sucrase was purified one step using a material called GEM particles. The results indicated that 95.25% of fructan sucrase expressed by the clone BS-FF could be secreted into the extracellular area, and even 98.78% by the clone BSO. With the above purification... [more]
The Effect of Carbonyl and Hydroxyl Compounds on Swelling Factor, Interfacial Tension, and Viscosity in CO2 Injection: A Case Study on Aromatic Oils
Asep Kurnia Permadi, Egi Adrian Pratama, Andri Luthfi Lukman Hakim, Doddy Abdassah
December 6, 2021 (v1)
Subject: Materials
Keywords: Carbon Dioxide, IFT, MMP, swelling factor, VIPS, viscosity
A factor influencing the effectiveness of CO2 injection is miscibility. Besides the miscible injection, CO2 may also contribute to oil recovery improvement by immiscible injection through modifying several properties such as oil swelling, viscosity reduction, and the lowering of interfacial tension (IFT). Moreover, CO2 immiscible injection performance is also expected to be improved by adding some solvent. However, there are a lack of studies identifying the roles of solvent in assisting CO2 injection through observing those properties simultaneously. This paper explains the effects of CO2−carbonyl and CO2−hydroxyl compounds mixture injection on those properties, and also the minimum miscibility pressure (MMP) experimentally by using VIPS (refers to viscosity, interfacial tension, pressure−volume, and swelling) apparatus, which has a capability of measuring those properties simultaneously within a closed system. Higher swelling factor, lower viscosity, IFT and MMP are observed from a C... [more]
Optimal Cleaning Cycle Scheduling under Uncertain Conditions: A Flexibility Analysis on Heat Exchanger Fouling
Alessandro Di Pretoro, Francesco D’Iglio, Flavio Manenti
December 6, 2021 (v1)
Keywords: flexibility, fouling, heat exchanger, maintenance, Scheduling
Fouling is a substantial economic, energy, and safety issue for all the process industry applications, heat transfer units in particular. Although this phenomenon can be mitigated, it cannot be avoided and proper cleaning cycle scheduling is the best way to deal with it. After thorough literature research about the most reliable fouling model description, cleaning procedures have been optimized by minimizing the Time Average Losses (TAL) under nominal operating conditions according to the well-established procedure. For this purpose, different cleaning actions, namely chemical and mechanical, have been accounted for. However, this procedure is strictly related to nominal operating conditions therefore perturbations, when present, could considerably compromise the process profitability due to unexpected shutdown or extraordinary maintenance operations. After a preliminary sensitivity analysis, the uncertain variables and the corresponding disturbance likelihood were estimated. Hence, cl... [more]
A Process for the Synthesis and Use of Highly Aromatic Organosilanes as Additives for Poly(Vinyl Chloride) Films
Safaa H. Mohamed, Ayad S. Hameed, Gamal A. El-Hiti, Dina S. Ahmed, Mohammed Kadhom, Mohammed A. Baashen, Muna Bufaroosha, Ahmed A. Ahmed, Emad Yousif
December 6, 2021 (v1)
Keywords: dehydrochlorination, organosilanes, photostability, Schiff’s bases, ultraviolet irradiation absorbers, weight and molecular weight loss
Three organosilanes were synthesized in good yields from the condensation of 4,4′,4″-((phenylsilanetriyl)tris(oxy))tribenzaldehyde and 4-substituted anilines under acidic conditions. The structure of the organosilanes was confirmed using a variety of techniques. Organosilanes were mixed with poly(vinyl chloride) (PVC) and homogenous films were produced. The effect of long-term irradiation on the films containing organosilanes was tested using various methods. Monitoring the infrared spectra of PVC films before, during and after irradiation processes showed the formation of side products comprising polyene, carbonyl and hydroxyl groups. The intensities of absorption bands due to these functional groups were much lower in the presence of organosilanes as compared to the blank film. Also, the decrease in the weight and molecular weight of PVC films after irradiation was lower in the presence of organosilanes. Additionally, there was a minimal surface change of irradiated PVC in the presen... [more]
Change year: 2018 | 2019 | 2020 | 2021 | 2022
Change month: January | February | March | April | May | June | July | August | September | October | November | December