View large Download slide View large Download slide Close modal In recent years, mental disorders have become serious health problems. Monitoring the usage of psychotropic drugs can reflect the prevalence of mental disorders in the population, and wastewater analysis is an effective method for monitoring the use of psychoactive pharmaceuticals. In our study, we collected 58 samples from 12 wastewater treatment plants (WWTPs) in a southern city in China. We then analyzed the concentrations and loads of 18 frequently used psychoactive drugs and corresponding metabolites. The most abundant compounds in wastewater were diazepam, sulpiride, clozapine, venlafaxine, and quetiapine, with a detection frequency close to 100%. Sulpiride had the highest average load, followed by venlafaxine, clozapine, quetiapine, and diazepam. The higher load of diazepam in suburban WWTPs than in urban WWTPs reflects the large numbers of older people living in suburban areas in most of China. The lower loads of most target compounds in suburban WWTPs than in urban WWTPs indicate a greater likelihood of mental disorders in urban people than in suburban people. A correlation analysis of the target compounds revealed a correlation between the occurrence of venlafaxine, sulpiride, and clozapine. Overall, wastewater analysis is expected to be a significant tool for monitoring the consumption of psychoactive pharmaceuticals. Timing and regional distribution of 18 psychoactive drugs and metabolites in a Chinese city. The loads of most target compounds were lower in suburban WWTPs than in urban WWTPs. Schools showed high loads of diazepam, indicating that diazepam may be abused among students. Correlation was observed between venlafaxine, sulpiride, and clozapine loads.
Xiaojun Li,Yue Cheng,Jianfeng Zhang,Yarui Hou,Xiaojuan Xu,Qingye Liu
A novel strategy to fabricate bilayer hydrogel actuators based on the asymmetric distribution of crystalline regions across the bilayer structures was proposed. By employing PVA polymer chains into an alkali solvent-derived chitosan hydrogel matrix, chitosan/PVA hybrid bilayer hydrogels with both excellent responsive bending and mechanical properties were obtained as pH-controlled manipulators. In the design, the chitosan/PVA hydrogels upon treatment with freeze-thawing cycles were taken as the first monolayer, where excessive crystalline regions appeared. The original chitosan/PVA hydrogel as the second monolayer was then integrated into one bilayer device through the chemical-crosslinking of epichlorohydrin at the interface. The results showed that the resultant chitosan/PVA bilayer hydrogel actuator with a weight ratio of 3 : 1 displayed better sensitivity upon exposure to stimuli. The actuation behaviors are strongly dependent on experimental parameters such as the pH, PVA content and the chemical-crosslinking density. It is proposed that the driving force originates from the asymmetric distribution of crystalline regions, thus resulting in differential swelling ratios between the monolayers. In addition, programmable 3D shape transformations were achieved by using the bilayer hydrogel with designed 2D geometric patterns, and the tailored gripper-like hydrogel actuator can successfully capture and transport the cargo. Moreover, this actuation behavior can be erased and re-written on demand under certain conditions. Taking advantage of this universal strategy, more attractive actuators derived from synthetic or natural polymers in combination with PVA are highly expected, which can be used as smart soft robots in various fields such as manipulators, grippers, and cantilever sensors.
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