The utilisation of ultrasonics has been shown to enable efficient and environmentally friendly textile wet processing. This study conducted a comparative investigation of silk degumming by using a conventional heating bath and ultrasonic irradiation at a range of ultrasonic frequencies. Citric acid, sodium carbonate and papain were used as degumming agents. Sericin degumming rate, fibre whiteness, fibre surface morphology, fibre structure characteristics and fibre tensile properties were measured and analysed. Results showed that ultrasonics at a lower frequency produced a greater degumming rate than at a higher frequency. Ultrasonics is a more effective way than the conventional heating bath of improving degumming efficiency, especially at a lowered temperature of 60°C. When sodium carbonate was applied at 90°C, a conventional heating bath was found to be more effective than ultrasonics. Papain was found to be more effective in sericin removal than citric acid and sodium carbonate, with a degumming rate of 22% achieved at 60°C under ultrasonic irradiation at 40 kHz. The use of papain can, however, cause a possible overreaction to silk under certain severe conditions, resulting in a loss of fibre whiteness. Negligible changes in fibre structure characteristics were measured by Fourier Transform-infrared spectroscopy and X-ray diffraction after ultrasonic degumming with papain. Slightly reduced fibre strength and increased fibre extensibility were observed in ultrasonically degummed silk samples compared with un-degummed and conventionally degummed silk samples.
In our previous studies, we occasionally found that high-dose glucocorticoids (GC) induced decrease in [Ca(2+)](i) in hypothalamus neurons. In previous articles, modulation of Ca(2+) channels by GC has been shown to contribute to the elementary regulation of several neuronal functions. However, little is known about the regulation of the Ca efflux pathways that counterbalance the Ca(2+) influx in neurons caused by high-dose GC. In this study, we demonstrate that a high-dose of GC (10 M dexamethasone) caused a 20% decrease in [Ca(2+)](i) within 2 s in cultured hypothalamic neurons; furthermore, we show that an antagonist of the GC receptor blocks this action. To ascertain the temporal sequence of relevant calcium transport mechanisms we selectively blocked the main calcium transporters, including sodium/calcium exchanger (NCX), plasma membrane calcium pumps (PMCA), and P-type Ca(2+)-ATPases of the sarcoplasmic reticulum (SERCA). The GC-induced [Ca(2+)](i) decrease disappeared completely when PMCA was blocked, but not when NCX and SERCA were blocked. These results suggest that high-dose GC (10(-6) M) rapidly decreases [Ca(2+)](i) by activating PMCA but not NCX or SERCA.
The alkaline–surfactant–polymer
(ASP) enhanced oil
recovery (EOR) is a promising tertiary oil recovery technique for
maximizing oil production. However, strong alkaline (e.g., NaOH) or
high concentration of an alkali may cause new problems, such as formation
erosion, alkali deposition, and high production costs. In this study,
a new EOR method was proposed by combining a traditional weak alkaline
(Na2CO3) ASP flooding and nanotechnology. We
investigated the synergistic effects of weak alkaline ASP chemicals
and SiO2 nanoparticles on the EOR through comprehensive
experiments. The efficacy of the mixtures was examined using a framework
including interfacial tension and wettability characterizations, flow
visualization experiments of emulsion, and oil recovery tests under
reservoir temperature conditions. Moreover, the effects of weak alkaline
ASP chemicals and SiO2 nanoparticles on interfacial properties
and the EOR were carefully investigated by a comprehensive analysis.
The experimental results show that the ASP + SiO2 nanoparticles
mixture has a greater ability to reduce the interfacial tension (IFT)
between oil and water as well as their contact angle, compared with
a hydrolyzed polyacrylamide (HPAM)/ASP-only solution. The ASP + SiO2 nanoparticles mixture is better than the HPAM/ASP-only solution
in profile control and displacement efficiency after water flooding.
The SiO2 NPs/ASP mixture increases the oil recovery by
6.67% of original oil in place (OOIP), compared to the ASP-only solution.
In visualization flooding experiments, the ASP + SiO2 nanoparticles
mixture forms strong viscoelastic, thermodynamic, and kinetic stability
of the droplets, thereby resulting in a larger sweep efficiency and
better displacement efficiency by the stable blocking effects and
strong scratch effect. It indicates that this new method can enhance
oil recovery, have potential to reduce chemical agent cost, and avoid
probable formation erosion and alkali deposition.
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