Detection of volatile
organic compounds (VOCs) at room temperature
(RT) currently remains a challenge for metal oxide semiconductor (MOS)
gas sensors. Herein, for the first time, we report on the utilization
of porous SnO2 thin films for RT detection of VOCs by defect
engineering of oxygen vacancies. The oxygen vacancies in the three-dimensional-ordered
SnO2 thin films, prepared by a colloidal template method,
can be readily manipulated by thermal annealing at different temperatures.
It is found that oxygen vacancies play an important role in the RT
sensing performances, which successfully enables the sensor to respond
to triethylamine (TEA) with an ultrahigh response, for example, 150.5–10
ppm TEA in a highly selective manner. In addition, the sensor based
on oxygen vacancy-rich SnO2 thin films delivers a fast
response and recovery speed (53 and 120 s), which can be further shortened
to 10 and 36 s by elevating the working temperature to 120 °C.
Notably, a low detection limit of 110 ppb has been obtained at RT.
The overall performances surpass most previous reports on TEA detection
at RT. The outstanding sensing properties can be attributed to the
porous structure with abundant oxygen vacancies, which can improve
the adsorption of molecules. The oxygen vacancy engineering strategy
and the on-chip fabrication of porous MOS thin film sensing layers
deliver great potential for creating high-performance RT sensors.
Van der Waals p-n junctions of 2D materials present great potential for electronic devices due to the fascinating properties at the junction interface. In this work, an efficient gas sensor based on planar 2D van der Waals junctions is reported by stacking n-type and p-type atomically thin MoS 2 films, which are synthesized by chemical vapor deposition (CVD) and soft-chemistry route, respectively. The electrical conductivity of the van der Waals p-n junctions is found to be strongly affected by the exposure to NO 2 at room temperature (RT). The MoS 2 p-n junction sensor exhibits an outstanding sensitivity and selectivity to NO 2 at RT, which are unavailable in sensors based on individual n-type or p-type MoS 2 . The sensitivity of 20 ppm NO 2 is improved by 60 times compared to a p-type MoS 2 sensor, and an extremely low limit of detection of 8 ppb is obtained under ultraviolet irradiation. Complete and very fast sensor recovery is achieved within 30 s. These results are superior to most of the previous reports related to NO 2 detection. This work establishes an entirely new sensing platform and proves the feasibility of using such materials for the high-performance detection of gaseous molecules at RT.
Highly dynamic mitotic spindle microtubules are superb therapeutic targets for a group of chemically diverse and clinically successful anticancer drugs. Microtubule-targeted drugs disrupt microtubule dynamics in distinct ways, and they are primarily classified into two groups: microtubule destabilizing agents (MDAs), such as vinblastine, colchicine, and combretastatin-A4, and microtubule stabilizing agents (MSAs), such as paclitaxel and epothilones. Systematic discovery and development of new MSAs have been aided by extensive research on paclitaxel, yielding a large number of promising anticancer compounds. This review focuses on the natural sources, structural features, mechanisms of action, structure-activity relationship (SAR) and chemical synthesis of MSAs. These MSAs mainly include paclitaxel, taccalonolides, epothilones, FR182877 (cyclostreptin), dictyostatin, discodermolide, eleutherobin and sarcodictyins, zampanolide, dactylolide, laulimalides, peloruside and ceratamines from natural sources, as well as small molecular microtubule stabilizers obtained via chemical synthesis. Then we discuss the application prospect and development of these anticancer compounds.
The detection of harmful volatile organic compounds is of great significance to environmental quality and human health. However, it still remains a challenge to achieve high detection sensitivity at a relatively low temperature. Herein, an ultrasensitive catalytic sensor for the detection of triethylamine (TEA) based on ZnO/ PtO/Pt nanoarray thin films was realized. Sensor measurements reveal that the PtO/Pt sensitizer dramatically reduces the working temperature from 195 °C of a pristine ZnO sensor to 125 °C of ZnO/PtO/Pt sensors. The ZnO/PtO/Pt sensors exhibit an extremely high response of 3513 to 50 ppm TEA, which is three orders of magnitude higher than that of pristine ZnO. Meanwhile, an ultralow limit of detection of 8.3 ppb is achieved. The outstanding performances are superior to those in most previous reports on TEA detection. Mechanistic investigations reveal that the outstanding performances are ascribed to the strong electronic interaction between PtO and ZnO and the catalytic spillover effect of Pt.
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