Crystal Face-Dependent Behavior of Single-Atom Pt: Construct of SA-FLP Dual Active Sites for Efficient NO2 Detection.

The strong potential of platinum single atom (PtSA) in gas sensor technology is primarily attributed to its high atomic economy. Nevertheless, it is imperative to conduct further exploration to understand the impact of PtSA on the active sites. In this study, the evolution of PtSA on (100)CeO2 and (111)CeO2 is examined, revealing notable disparities in the position and activity of surface PtSA on different crystal planes. The PtSA in (100)CeO2 surface can enhance the stability of Ce3+ and construct a frustrated Lewis pair (FLP) to form a double active site by combining the steric hindrance effect of oxygen vacancies, which increases the response value from 1.8 to 27 and reduce the response-recovery time from 140-192 s to 25-26 s toward five ppm NO2 at room temperature. Conversely, PtSA tends to bind to terminal oxygen on the surface of (111)CeO2 and become an independent reaction site. The response value of PtSA-(111)CeO2 surface only increased from 1.6 to 3.8. This research underscores the correlation between single atoms and crystal plane effects, laying the groundwork for designing and synthesizing ultra-stable and efficient gas sensors.

Tandem Electric-Fields Prolong Energetic Hot Electrons Lifetime for Ultra-Fast and Stable NO2 Detection.

Prolonging energetic hot electrons lifetimes and surface activity in the reactive site can overcome the slow kinetics and unfavorable thermodynamics of photo-activated gas sensors. However, bulk and surface recombination limit the simultaneous optimization of both kinetics and thermodynamics. Here tandem electric fields are deployed at (111)/(100)Au-CeO2 to ensure a sufficient driving force for carrier transfer and elucidate the mechanism of the relationship between charge transport and gas-sensing performance. The asymmetric structure of the (111)/(100)CeO2 facet junction provides interior electric fields, which facilitates electron transfer from the (100)face to the (111)face. This separation of reduction and oxidation reaction sites across different crystal faces helps inhibit surface recombination. The increased electron concentration at the (111)face intensifies the interface electric field, which promotes electron transfer to the Au site. The local electric field generated by the surface plasmon resonance effect promotes the generation of high-energy energy hot-electrons, which maintains charge concentration in the interface field by injecting into (111)/(100)CeO2, thereby provide thermodynamic contributions and inhibit bulk recombination. The tandem electric fields enable the (111)/(100)Au-CeO2 to rapidly detect 5 ppm of NO2 at room temperature with stability maintained within 20 s.

Achieving Molecular-Level Selective Detection of Volatile Organic Compounds through a Strong Coupling Effect of Ultrathin Nanosheets and Au Nanoparticles.

The high density of surface active sites, high efficiency of interfacial carrier transport, and molecular diffusion path determine the efficiency of the electrochemical sensors. The ultrathin structures have atomic-level thickness, carrier migration and heat diffusion are limited in the two-dimensional plane, resulting in excellent conductivity and high carrier concentration. A one-step chemical method is applied to synthesize defect-rich Au-SnO2 in an ultrathin nanosheet form (thickness of 2-3 nm). The strong interaction between Au and SnO2 via the Au-O-Sn bonding and the catalytic effect of Au can prolong the service life via decreasing the optimal operating temperature (55 °C) and promote the Au-SnO2 sensor to exclusively detect formaldehyde at the ppb level (300 ppb). The experimental findings along with theoretical study reveal that Au nanoparticles have a different effect on the competitive adsorption and chemical reaction over the surface of the Au-SnO2 with formaldehyde and other interfering VOC gases, such as methanol, ethanol, and acetone. This study provides mechanistic insights into the correlation between operating temperature and the performance of the Au-SnO2 chemiresistive sensor. This work allows the development of highly efficient and stable electrochemical sensors to detect VOC gases at room temperature in the future.

Effect of support foot placement on football instep kick performance.

Although the support foot plays an important role in kicking a football, there has been a paucity of research exploring the effect of the placement of the support foot on kicking performance. To investigate the kick performance under different support foot positions, ten male footballers were recruited to participate in two experiments: one determining the maximum ball speed and the second determining accuracy. The participants were instructed to plant their support foot on one of nine different spots marked in the form of a 3 × 3 shape on a piece of artificial grass and asked to kick the ball. In the first (maximum speed) test, the participants tried their best to kick the ball at the maximum ball speed from nine different support foot positions. In the second (accuracy) test, the participants kicked the ball toward the target area without restricting the support foot position. The ball speed, as well as the success rate, were recorded from each support foot position. Significantly higher ball speed and accuracy were obtained at medial positions than was the case at lateral positions from the nine spots. It was concluded that although footballers may choose different positions for support foot placement, the maximum ball speed and better accuracy could be expected when the support foot was next to or slightly in front of the ball centre without too much side-by-side separation (27-37 cm).

Anchoring Platinum Clusters onto Oxygen Vacancy-Modified In2O3 for Ultraefficient, Low-Temperature, Highly Sensitive, and Stable Detection of Formaldehyde.

To avoid carcinogenicity, formaldehyde gas, currently being only detected at higher operating temperatures, should be selectively detected in time with ppb concentration sensitivity in a room-temperature indoor environment. This is achieved in this work through introducing oxygen vacancies and Pt clusters on the surface of In2O3 to reduce the optimal operating temperature from 120 to 40 °C. Previous studies have shown that only water participates in the competitive adsorption on the sensor surface. Here, we experimentally confirm that the adsorbed water on the fabricated sensor surface is consumed via a chemical reaction due to the strong interaction between the oxygen vacancies and Pt clusters. Therefore, the long-term stability of formaldehyde gas detection is improved. The results of theoretical calculations in this work reveal that the excellent formaldehyde gas detection of Pt/In2O3-x originates from the electron enrichment due to the surface oxygen vacancies and the molecular adsorption and activation ability of Pt clusters on the surface. The developed Pt/In2O3-x sensor has potential use in the ultraefficient, low-temperature, highly sensitive, and stable detection of indoor formaldehyde at an operating temperature as low as room temperature.

Magnetically separable Fe-MIL-88B_NH2 carbonaceous nanocomposites for efficient removal of sulfamethoxazole from aqueous solutions.

Extensive exposure to antibiotics could potentially be harmful to the environment and human health. The development of effective and convenient technologies to remove residual antibiotics from water is imperative. Herein, we successfully developed a facile method via pyrolysis of Fe-MIL-88B_NH2 to synthesize magnetic nanocomposites (MNC) as potential adsorbents, which exhibited cluster-shape structure and excellent magnetic response. Magnetic nanocomposites carbonized at 700 °C showed high efficiency for sulfamethoxazole (SMX) adsorption (73.53 mg/g). Some experimental conditions including solution pH, ionic strength, coexisting ions and SMX concentration were systematically investigated. The adsorption isotherm and kinetic followed Langmuir and the pseudo-second-order models, and the adsorption process was dependent on the solution pH. The adsorption mechanism hypothesis was pore filling effect, π-π EDA and electrostatic interactions. Moreover, MNC-700 exhibited good reusability and magnetic separation properties, being reused six times without significant loss in adsorption capacity.

Guidance of neural regeneration on the biomimetic nanostructured matrix.

Biomimetic materials are used for creating microsystems to control cell growth spatially and elicit specific cellular responses by combining complex biomolecules with nanostructured surfaces. Intercellular cell-to-cell and cell-to-extracellular matrix (ECM) interactions in biomimetic materials have demonstrated potential in the development of drug discovery platforms and regeneration medicine. In this study, we developed a biomimetic nanostructured matrix by using various ECM molecular layers to create a biomimetic and biocompatible environment for realizing neuronal guidance in neural regeneration medicine. Silicon-based substrates possessing nanostructures were modified using different ECM proteins and peptides to develop a biomimetic and biocompatible environment for studying neural behaviors in adhesion, proliferation, and differentiation. The substrates were flat glass, flat silicon wafers (FWs), and nanorod-structured wafers prepared using wet etching. The three substrates were then functionalized using laminin-1 peptide, PA22-2-contained active isoleucine-lysine-valine-alanine-valine (IKVAV) peptide, and poly-d-lysine (PDL), separately. When PC12 cells were cultured and differentiated on the modified substrates, the cells were able to elongate the neurites on the glass and FW, which was coated with three types of peptide. More differentiated neurons were observed on the nanorod-structured wafers coated with laminin than on those coated with IKVAV or PDL. For achieving directional guidance of neurite outgrowth, substrates exhibiting a grating pattern of nanorods were partially collapsed by the pulling force of water, leaving few nanorods, which support the net form of laminin on the surface. Furthermore, we fabricated the topological nanostructure-patterned wafer coated with laminin and successfully manipulated the extension and direction of neurites by using more than 80 µm of a single soma. This approach demonstrates potential as a facile and efficient method for guiding the direction of single axons and for enhancing neurite outgrowth in studies on nerve regenerative medicine.

The micro patterning of glutaraldehyde (GA)-crosslinked gelatin and its application to cell-culture.

This paper proposes a novel technique for fabricating micro patterns of glutaraldehyde (GA)-crosslinked gelatin. It provides another means to crosslink gelatin other than using photo-sensitizing agents, and the micro patterns of GA-crosslinked gelatin can still be made successfully by accessing conventional photolithography. A much less toxic and increased biocompatible approach to strengthening the gelatin microstructures can be developed according to this idea. This paper also describes a potential methodology for using GA-crosslinked gelatin patterns as single-cell culture bases. The best spatial resolution of the micro gelatin bases can reach 10 microm, and the selective growing density of human Mesenchymal stem cells on the gelatin patterns surpasses the density on the glass substrate by 2-3 orders of magnitude.