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Optimally increasing the catalytic activity of Co3O4‐based materials is crucial for promoting their practical applications for acetone detection; however, this still remains challenging. Herein, a strategy is proposed in this work to increase the catalytic activity of Co3O4 toward the oxidation of acetone through the synergistic effect of boron doping and chemical reduction, which can substantially improve the sensing performance for acetone detection. The characterization results confirm that the present strategy facilitates the formation of more oxygen vacancies and increases the content of Co2+ ions serving as active sites. As expected, the optimal sensor yields a higher response. To extend the practical application to the auxiliary diagnosis of diabetes through exhaled breath, the optimal sensors distinguished between acetone concentrations in the breath of healthy individuals and in the simulated breath of patients with diabetes. Detailed gas‐sensing measurements reveal that the enhanced acetone sensing performance is attributed to the increased catalytic activity of materials for oxidation of acetone by the Mars–van Krevelen, Langmuir–Hinshelwood, and Eley–Rideal mechanisms. This study provides new insights into the fabrication of high‐performance metal oxide‐based gas sensors by improving the catalytic activity of sensing materials. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO)-based materials are deemed as promising candidates for fabrication of room-temperature gas sensors, while a tougher challenge is to develop an effective strategy for improving gas responses. Here, a noble metal decoration strategy is developed to enhance NO2 responses of α-Fe2O3/SnO2–rGO hybrids. Noble metal decorated α-Fe2O3/SnO2–rGO hybrids were prepared by depositing noble metals onto α-Fe2O3/SnO2–rGO hybrids through reduction of noble metal ions by NaBH4. Most importantly, Pt modified α-Fe2O3/SnO2–rGO hybrids (designated as Pt-FSR) exhibit the highest response value of 21.3 toward 5 ppm NO2, which is much higher than that of α-Fe2O3/SnO2–rGO (8.8). Combined characterization studies indicate that the enhanced NO2 response of Pt-FSR is attributed to the narrow band gap of Pt-FSR, small particle size and excellent catalytic activity of Pt. The NO2 sensing mechanism is also investigated by FT-IR spectroscopy. The findings proposed in this work not only broaden the study of room-temperature gas sensors, but also provide suggestions for discovering the gas sensing mechanism. [ABSTRACT FROM AUTHOR]

Toluene is widely used as a solvent and reactant in a wide range of industrial fields; however, gaseous toluene is toxic to humans, causing severe acute respiratory effects. In this case, Co3O4-based chemiresistive gas sensors are promising candidates for monitoring toluene. However, it is challenging to prepare Co3O4-based sensing materials with good toluene sensing performances on a large-scale. In this study, oxygen vacancy-rich Co3O4 materials were successfully synthesized via the reduction of commercial Co3O4 using NaBH4 as the reducing agent (designated as Co3O4-R), and the oxygen vacancy concentrations in Co3O4-R materials were effectively modulated by regulating the NaBH4 concentration. With an increase in oxygen vacancies, the optimal Co3O4-R-5 samples displayed better sensing performances toward 100 ppm toluene at 190 °C than that of the pristine commercial Co3O4, including an enhanced response value of 3.18 (vs. 1.22 for commercial Co3O4) and fast response time of 48 s and recovery time of 38 s. The combination of band structure analysis and chemisorption analysis indicated that the enhanced toluene sensing performances of Co3O4-R is attributed to the synergistic effect of reducing the band gap and activating the surface oxygen species. This work demonstrates the first utilization of commercial Co3O4 for toluene sensing applications, providing a universal and high-throughput preparation method to prepare gas sensing materials using commercial metal oxides. [ABSTRACT FROM AUTHOR]

The high-pressure structures of alkaline earth metal hydride-fluorides (AHFs) (A = Ca, Sr, Ba) were investigated up to 8 GPa. While AHF adopts the fluorite-type structure (Fm3¯m) at ambient pressure without anion ordering, the PbCl2-type (cotunnite-type) structure (Pnma) is formed by pressurization, with a declining trend of critical pressure as the ionic radius of the A2+ cation increases. In contrast to PbCl2-type LaHO and LaOF whose anions are fully ordered, the H−/F− anions in the high-pressure polymorph of SrHF and BaHF are partially ordered, with a preferential occupation of H− at the square-pyramidal site (vs. tetrahedral site). First-principles calculations partially support the preferential anion occupation and suggest occupation switching at higher pressure. These results provide a strategy for controlling the anion ordering and local structure in mixed-anion compounds. [ABSTRACT FROM AUTHOR]

The high-pressure structures of alkaline earth metal hydride-fluorides (AHFs) (A = Ca, Sr, Ba) were investigated up to 8 GPa. While AHF adopts the fluorite-type structure (Fm3[combining macron]m) at ambient pressure without anion ordering, the PbCl2-type (cotunnite-type) structure (Pnma) is formed by pressurization, with a declining trend of critical pressure as the ionic radius of the A2+ cation increases. In contrast to PbCl2-type LaHO and LaOF whose anions are fully ordered, the H-/F- anions in the high-pressure polymorph of SrHF and BaHF are partially ordered, with a preferential occupation of H- at the square-pyramidal site (vs. tetrahedral site). First-principles calculations partially support the preferential anion occupation and suggest occupation switching at higher pressure. These results provide a strategy for controlling the anion ordering and local structure in mixed-anion compounds.

Purpose: The purpose of the study is to identify the Cancer Stem Cells (CSCs) and to determine their expression profiles in different pathological stages of liver cancer by using multiple markers Methods: In this study, the expression profiles of CD133 and CD13, along with those of stem cell markers Oct4 and SOX2, were analyzed using immunohistochemistry and immunoblotting to clarify the character of CSCs in different stages of liver cancer., Results: CD133 liver cancer cells were injected into mice, and the tissues were processed for histology. The histological data revealed the progression of liver cancer. Immunohistochemical analysis showed the strong expression of CD133 in metastatic cancer. In contrast, the expression of CD13 in both primary and metastatic liver cancer was found to be very strong. Interestingly, the expression levels of Oct4 and SOX2 were found to be upregulated in primary tumors, but, in the metastatic stage, their expression was downregulated. The immunoblot analysis also confirmed the same result., Conclusions: Our findings demonstrate that tumor-suppressor proteins Oct4 and SOX2 have a prominent expression profile in the primary stage of cancer, but, in the metastatic stage, their expression is downregulated, leading to the failure to prevent metastatic cancer.

Purpose: Gliomas are destructive malignancies affecting mainly the central nervous system. Gliomas constitute around 50% of all the central nervous system tumors. The purpose of this study was to examine the anticancer activity of cycloartenol against the glioma U87 cells and to investigate the underlying mechanisms., Methods: MTT and colony formation assay were used to determine the proliferation rate. Acridine orange/ethidium bromide (AO/EB) and annexin V/propidium iodide (PI) were used to determine apoptosis and cell cycle analysis was carried out by western blotting. Cell migration was checked by cell migration assay and immunoblotting was used for checking protein expressions., Results: The results revealed that cycloartenol inhibited the proliferation and the colony formation potential of the glioma U87 cells in a concentration-dependent manner. The antiproliferative effects were found to be due to induction of Sub-G1 cell cycle arrest and triggering of apoptosis. These effects were found to be dose-dependent. Cycloartenol also caused significant alteration in the expression of Bax and Bcl-2. Furthermore, cycloartenol inhibited the migration of glioma cells and suppressed the phosphorylation of the p38 MAP kinase., Conclusion: These findings indicate that cycloartenol may prove beneficial in the treatment of glioma and warrants further investigation.