The development of low temperature gas sensor with ultra-high response has important application value for actual monitoring of harmful gases. Herein, we utilized poplar branch (PB) as bio-template ...to synthesize SnO2 sensing material through immersing PB into SnCl4.6 H2O solution, followed by calcining the immersed precursor in air. The material calcined at 600 ℃ (named as SnO2-600) exhibits the hierarchical microtube structure inherited from PB, which is cross-linked by small-sized nanoparticles. Meanwhile, uniform mesoporous structure and abundant oxygen vacancies are also present on the inner and outer surface of SnO2-600 microtubes. The synergistic effect of these microstructure characteristics can not only greatly enhance surface chemical reaction of sensing materials, but also effectively improve surface diffusion, adsorption and desorption behavior of target gas. At 50 ℃, SnO2-600 sensor presents high response value (S = Rg/Ra) of 3411 and rapid recovery time of 17 s to 10 ppm NO2. In addition, the sensor also has low detection limit, good selectivity, satisfactory reproducibility, humidity resistance and long-term stability. Therefore, the present mesoporous SnO2-600 microtubes are available as candidate for detecting NO2 gas at low temperature.
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•Mesoporous SnO2-600 microtubes were simply and repeatably prepared from cheap poplar branch as bio-template.•At lower 50 ℃, SnO2-600 sensor presents ultra-high response and rapid recovery time of 17 s to 10 ppm NO2 gas.•The synergism of unique microstructure and oxygen vacancies are highly responsible for excellent sensing performance.•The bio-template method provides a new perspective for the preparation of other oxides with excellent sensing properties.
In this work, biomorphic ZnO materials were prepared by simple and controllable zinc salt immersion plus air calcination method using waste willow catkins as biomass template, which present high ...sensing ability to trace NO2 at low energy consumption. The ZnO hollow nanotube calcined at 500 ℃ was assembled by cross-linkage of small-size nanoparticles with uniform mesoporous distribution and rich oxygen vacancies. The synergistic effect of these microstructure characteristics can not only dramatically promote the rapid gas diffusion on sensing layer, but also greatly increase active sites for surface adsorption and chemical reaction, thus enhancing gas-sensing performance. At low operating temperature of 92 °C, its fabricated sensor exhibits high response of 100.4–10 ppm NO2, which is separately 2.3, 5.6 and 12.1 times larger than those of ZnO hollow nanotube calcined at 600 ℃, thin nanorods (ZnO-TRs) and columnar nanorods (ZnO-CRs). And it is also higher than that of most reported 1-D nanostructured ZnO-based sensors. Meanwhile, this sensor also exhibits high selectivity and satisfactory response-recovery characteristics, as well as excellent humidity resistance and long-term stability. In addition, the enhanced sensing mechanism was also explored in great detail.
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•Porous ZnO nanotube rich in oxygen vacancies were simply prepared using waste willow catkins as bio-template.•The satisfactory response of ZnO nanotube sensor to NO2 and real gases indicates its potential application prospect.•The porous ZnO nanotube rich in oxygen vacancies is responsible for its well over-all sensing performance to NO2.•The simple and eco-friendly bio-template method provides a new way for preparing other metal oxides with surface defects.
Herein, Cr2O3 nanomaterials with high sensing towards trace H2S at low energy consumption were controllably synthesized by simple chromium nitrate solution immersion and air calcination using waste ...willow catkins as bio-template. Amongst, Cr-400 hierarchical structure obtained from the calcination of 400 °C exhibits monotube morphology assembled by well-crystalline nanoparticles, and it has uniform mesoporous distribution and large specific surface area. This structure features help to the fast accessibility of gas molecules and provide an effective platform for surface adsorption and chemical reaction, which dramatically enhances the detection ability of Cr2O3-based sensor to trace H2S gas for the first time. At low operating temperature of 133 °C, Cr-400 sensor exhibits high response value (S = 24.4) to 50 ppm H2S gas and low actual detection limit (100 ppb). Simultaneously, it also has good comprehensive gas-sensing performance involving reversible response-recovery, high selectivity, satisfactory stability and moisture resistance. In addition, we also discussed the enhanced gas-sensing mechanism in details.
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•Mesoporous Cr2O3 monotubes were simply and controllably prepared using waste willow catkin as bio-template.•Synergism of microstructure features and surface vulcanization-desulfurization reaction endow Cr2O3 with high sensing to H2S.•Low-cost bio-template method provides a new inspiration for preparing other metal oxides with enhanced sensing performance.
In the paper, poly(methyl methacrylate)(PMMA)/SBA-15 composite materials were prepared by four different methods, that is, in-situ batch emulsion polymerization in the presence of mesoporous SBA-15, ...PMMA emulsion mixed with SBA-15 powder or dispersion in water, PMMA powder mixed with SBA-15 powder, and the properties of the composite materials were determined and compared. The composites were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanics analysis (DMA) and scanning electron microscope (SEM). The results showed that the glass transition temperatures (Tg), the storage modulus and tensile strength of the PMMA/SBA-15 composites were all improved obviously, while the thermal decomposition temperature did not influenced apparently. The composite made by in-situ batch polymerization exhibited the most improvement in the mechanical properties and Tg while the composite prepared by mixing PMMA emulsion and SBA-15 dispersion gave rise to the least improvement in the mechanical properties and Tg. These results were contributed to introducing different amount of voids into polymer matrix which were demonstrated by dielectric constant measurement and SEM morphology observation.
Osteopontin (OPN) involves in tumor formation, and strongly correlated with the tumor progression. It was overexpressed in human esophageal squamous cell carcinoma (ESCC). To study the molecular ...mechanisms of OPN in ESCC, we examined its roles in inhibiting proliferation and invasion of ECA-109 (esophageal squamous cell carcinoma) cells. The expression of OPN gene was knockdown by RNA interference (RNAi) in the Eca-109 cell. The transcription level of OPN was to detect by reverse transcription-quantitative PCR (RT-qPCR). Western blot assay was performed to detect the expression of OPN, Caspase-3,Caspase-8, Caspase-9, ERK1/2, phospho-ERK1/2 and MMP2 after RNAi. The cell proliferation and apoptosis were detected by MTT and Hoechst33342 assay. Transwell inserts was used for detecting ECA-109 cell's migration ability. The results shown that the level of OPN mRNA and protein was significantly reduced after RNAi. Proliferation and migration of cell line (ECA-109) was significantly inhibited in vitro. The protein phosphorylation and activation of ERK1/2 in the OPN RNAi group reduced significantly than the negative control groups. In Conclusion, the proliferation and migration of human ESCC can be inhibited by RNAi-targeting OPN. OPN can promote the expression of MMP2 through the ERK signaling pathways. OPN could serve as a potential therapeutic target for human ESCC.
The development of conductometric sensors for high sensing and selective detection of very toxic and explosive hydrazine gas remains urgent challenge. Herein, waste and reproducible willow catkins ...were chosen as biotemplate and simply immersed into mixed Ni(NO3)2/Zn(NO3)2 solution with different Ni/Zn ratios. Afterwards, the isolated precursors were calcined at 500 ℃ in air to generate three biomorphic NiO/ZnO hetero-tubes, which were all replicated from small-size nanoparticles with good crystallinity. Amongst, 6.1 wt% NiO/ZnO composite achieves high sensing and rapid detection of trace N2H4. At 92 °C, its response value (S = 443) to 100 ppm N2H4 is significantly higher than those of 3.7 wt% NiO/ZnO (S = 113) and 7.2 wt% NiO/ZnO (S = 210). Especially, its response value is the highest among reported metal oxide-based sensors. Meanwhile, it also has short response time (6 s), low practical detection limit (10 ppb) along with satisfactory stability and moisture tolerance. Such well over-all sensing performance roots from the synergism of mesoporous hetero-tubes assembled by small-size nanoparticles, proper tube thickness, high concentration of Ni3+ Lewis acid, as well as rich oxygen vacancy defects. Moreover, the mechanism for enhanced N2H4 sensing performance was also discussed in detail.
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•NiO/ZnO tubes rich in oxygen vacancies were simply and controllably prepared using waste willow catkins as biotemplate.•Synergy of rich oxygen vacancies, high Ni3+ concentration and mesoporous hetero-tubes leads to excellent sensing performance.•6.1 wt% NiO/ZnO sensor exhibits the highest response to trace N2H4 at 92 °C among all reported metal oxide-based sensors.•The simple and sustainable biotemplate method provides a new inspiration for preparing other tube-like metal oxides.
The development of gas sensors with high selectivity to volatile ketones at low temperature has recently been a hot topic. However, the reported good response to butanone is usually achieved above ...200 °C. Herein, based on the conception of biomimicry, we chose waste phoenix tree leaves (PTL) as template and simply immersed them in iron nitrate solution. Subsequently, biomorphic Fe2O3 nanosheets were controllably replicated by calcining immersed PTL precursor in air. Thereinto, Fe2O3-600 nanosheets obtained by calcining precursor at 600 °C are cross-linked by nanoparticles and have broad pore structure and large surface area. Such unique microstructure induced by bio-template imprinting not only facilitates the fast gas diffusion, but also exposes more active sites to accelerate gas adsorption and its chemical reaction with adsorbed oxygen species. In this sense, it firstly realizes the highly selective detection of Fe2O3-based material to trace butanone. At 170 °C, Fe2O3-600 sensor shows high sensing response (S = 25.8) and short response time (Tres = 5 s) to 100 ppm butanone vapor. This sensor still possesses small detection limit (100 ppb), good reversibility and anti-humidity. In addition, we explored the sensing mechanism of Fe2O3-600 nanosheets to butanone by O2-TPD, XPS and GC-MS techniques.
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•Fe2O3 nanosheets were simply synthesized using phoenix tree leaves as bio-template.•Fe2O3-600 sensor shows high sensing ability to butanone at low working temperature.•The low-cost PTL-template method provides a new vision for preparing metal oxides.
First-generation EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib have significant activity in NSCLC patients with activating EGFR mutations. However, EGFR-TKI resistance inevitably occurs ...after approximately 12 months of treatment. Acquired mechanisms of resistance, other than secondary mutations in EGFR (T790 M) which account for 50–60%, are less well understood. Here, we identified lncRNA H19 as a significantly downregulated lncRNA in vitro models and clinical specimens with acquired EGFR-TKI resistance, H19 knockdown or overexpression conferred resistance or sensitivity, respectively, both in vitro and in vivo models. H19 downregulation contributed to erlotinib resistance through interaction and upregulation of PKM2, which enhanced the phosphorylation of AKT. AKT inhibitors restored the sensitivity of erlotinib-resistant cells to erlotinib. In EGFR-mutant patients treated with EGFR-TKIs, low H19 levels were associated with a shorter progression-free survival (PFS) (P = 0.021). These findings revealed a novel mechanism of low-level H19 in the regulation of erlotinib resistance in EGFR-mutant lung cancers. Combination of AKT inhibitors and EGFR-TKIs could be a rational therapeutic approach for some subgroups of EGFR-mutant lung cancer patients.
•LncRNA H19 is downregulated in vitro models and clinical specimens with acquired EGFR-TKI resistance.•H19 knockdown or overexpression confers resistance or sensitivity, respectively, both in vitro and in vivo models.•H19 regulates EGFR-TKI resistance by interacting with PKM2, which mediates AKT activation.•AKT inhibitors restore the sensitivity of erlotinib-resistant cells to erlotinib.
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•Property and bioactivity of Hericium coralloides polysaccharide from nine extraction methods were evaluated.•Notable variations were found in yields, chemical compositions, and Mw of ...the nine polysaccharides.•Polysaccharide obtained by heat reflux extraction exhibiting the highest yield and the strongest bioactivity.•Monosaccharide composition and total polyphenol content significantly affected the bioactivity.
In current study, polysaccharides from Hericium coralloides were extracted by heat reflux, acid-assisted, alkali-assisted, enzyme-assisted, ultrasonic-assisted, cold water, pressurized hot water, hydrogen peroxide/ascorbic acid system and acid-chlorite delignification methods, which were named as HRE-P, ACE-P, AAE-P, EAE-P, UAE-P, CWE-P, PHE-P, HAE-P, and ACD-P, respectively. Their physicochemical properties, structural characteristics, and antioxidant activities were investigated and compared. Experimental outcomes indicated notable variations in the extraction yields, chemical compositions, monosaccharide constituents and molecular weights of the obtained nine polysaccharides. HRE-P demonstrated the highest activity against ABTS and OH radicals, CWE-P against ABTS, DPPH, and superoxide radicals, and UAE-P against DPPH radicals. In addition, UAE-P, CWE-P, and HAE-P exhibited better protective effects on L929 cells, when compared to the other obtained polysaccharides. Additionally, correlation analysis indicated that monosaccharide composition and total polyphenol content were two prominent variables influencing the bioactivity of H. coralloides polysaccharides.
