Imparting pH and temperature dual-responsiveness in a micellar solution of cationic surfactants by introducing a hydrotrope.

Over the recent years, intelligent, multi-responsive micelles have received considerable attention due to their promising application in a variety of fields, including biomedical technology, drug delivery, separation, and catalysis. However, the design of such systems with controlled self-assembly is challenging both experimentally and theoretically and is still in the nascent stage. In this study, a novel dual-stimuli triggered wormlike micellar solution is prepared by mixing cationic surfactants 3-hexadecyloxy-2-hydroxypropyltrimethylammonium bromide (R16HTAB) and sodium hydrogen phthalate (SHP). The viscoelasticity, aggregate morphology, and pH- and thermo-responsive behavior of the micellar solution are examined by rheological measurements, cryogenic-transmission electron microscopy (cryo-TEM), nuclear magnetic resonance (1H NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The dual-sensitive fluid can be switched between a water-like state and a gel-like state by adjusting the pH and temperature. The variations in the flowing behavior are ascribed to the microstructural transition between wormlike micelles, short cylindrical micelles, and spherical micelles. Furthermore, based on the experimental results, dual-responsive behavior of the mixed solution is attributed to the different binding modes between SHP and the surfactant with the variation in the pH and temperature. We hope that the proposed system provides a new route for developing multi-stimuli-responsive materials that are capable of adapting to local environmental variations.

A pH, thermal and light triple-stimuli responsive micellar solution formed by a cationic surfactant and trans-o-hydroxycinnamic acid.

Controlling the viscoelastic characteristics of wormlike micelles is of great significance to both basic theory and practical applications. In this article, a novel multi-stimuli responsive wormlike micellar solution was prepared by mixing cationic surfactant 3-hexadecyloxy-2-hydroxypropyltrimethylammonium bromide (R16HTAB) with trans-o-hydroxycinnamic acid (OHCA). Rheological studies, nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and cryogenic-transmission electron microscopy (cryo-TEM) were utilized to investigate the wormlike micellar system's multi-responsive activity. The results showed that the self-assembled structure and viscoelasticity of the mixed system could be regulated by pH, temperature, and light irradiation. With the increasing trans-OHCA concentration, η0 of the mixed solution increases first and then decreases and the turning point is presented at 30 mM trans-OHCA, indicating the transformation of spherical micelles to wormlike micelles, and then to short micelles. The microstructure of the mixed systems could be reversibly altered by adjusting the pH between 6.41 and 3.90, which was ascertained by cryogenic-transmission electron microscopy (cryo-TEM). The relationship of temperature and η0 obeys the Arrhenius law, attributed to the decreasing micellar contour length. η0 of a 40 mM R16HTAB/15 mM OHCA solution sharply increases after UV irradiation, mainly because the cis-isomer could insert into the micelle more easily, and the transition mechanism was studied by UV-vis and 1H NMR. The multi-responsive self-assembled system may open a new vista for building multi-functional aggregates to adapt to various environmental changes.

[Modified sandwich urethral reconstruction in laparoscopic radical prostatectomy improves early recovery of urinary continence].

OBJECTIVE: To explore the safety of modified sandwich urethral reconstruction (MSUR) in laparoscopic radical prostatectomy (LRP) and its effect on the early recovery of urinary continence. METHODS: We retrospectively analyzed the clinical data on 20 patients treated by LRP with MSUR (the MSUR group) and another 21 cases of LRP without MSUR (the conventional control group) from January 2018 to September 2019. We compared the two groups of patients in the general data, anastomosis time, operation time and urinary continence recovery. RESULTS: There were no statistically significant differences between the two groups of patients in the age, body mass index, Gleason scores, prostate volume and baseline PSA level (P > 0.05) or in operation time, intraoperative blood loss, drainage tube indwelling time, postoperative feeding time and postoperative hospital stay (P > 0.05). Anastomotic stenosis occurred in 1 case in the MSUR group postoperatively, which was cured after regular urethral dilation, and anastomotic fistula developed in 1 case in the control group, which was healed after 5 days of prolonged catheterization. The recovery rate of urinary continence at 12 weeks after catheter removal was significantly higher in the MSUR than in the control group (80.0% vs 47.6%, P < 0.05). CONCLUSIONS: Modified sandwich urethral reconstruction in LRP is a safe, effective and feasible surgical strategy, which can significantly improve postoperative urinary continence recovery of the patient.

A Novel Impedance Micro-Sensor for Metal Debris Monitoring of Hydraulic Oil.

Hydraulic oil is the key medium for the normal operation of hydraulic machinery, which carries various wear debris. The information reflected by the wear debris can be used to predict the early failure of equipment and achieve predictive maintenance. In order to realize the real-time condition monitoring of hydraulic oil, an impedance debris sensor that can detect inductance and resistance parameters is designed and studied in this paper. The material and size of wear debris can be discriminated based on inductance-resistance detection method. Silicon steel strips and two rectangular channels are designed in the sensor. The silicon steel strips are used to enhance the magnetic field strength, and the double rectangular detection channels can make full use of the magnetic field distribution region, thereby improving the detection sensitivity and throughput of the sensor. The comparison experiment shows that the coils in series are more suitable for the monitoring of wear debris. By comparing and analyzing the direction and the presence or absence of the signal pulses, the debris sensor can detect and distinguish 46 µm iron particles and 110 µm copper particles. This impedance detection method provides a new technical support for the high-precision distinguishing measurement of metal debris. The sensor can not only be used for oil detection in the laboratory, but also can be made into portable oil detection device for machinery health monitoring.