Robust assignment of airport gates with operational safety constraints

This paper reviews existing approaches to the airport gate assignment problem (AGAP) and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize the dispersion of gate idle time periods (to get robust optimization) while ensuring appropriate matching between the size of each aircraft and its assigned gate type and avoiding the potential hazard caused by gate apron operational conflict. Genetic algorithm is adopted to solve the problem. An illustrative example is given to show the effectiveness and efficiency of the algorithm. The algorithm performance is further demonstrated using data of a terminal from Beijing Capital International Airport (PEK)

Pd nanocrystals with continuously tunable high-index facets as a model nanocatalyst

Knowledge of the structure–reactivity relationship of catalysts is usually gained through using well-defined bulk single-crystal planes as model catalysts. However, there exists a huge gap between bulk single-crystal planes and practical nanocatalysts in terms of size, structural complexity, and local environment. Herein, we efficiently bridged this gap by developing a model nanocatalyst based on nanocrystals with continuously tunable surface structures. Pd nanocrystals with finely tunable facets, ranging from a flat {100} low-index facet to a series of {hk0} high-index facets, were prepared by an electrochemical square-wave potential method. The validity of the Pd model nanocatalyst has been demonstrated by structure–reactivity studies of electrocatalytic oxidation of small organic molecules. We further observed that Pd nanocrystals exhibited catalytic performance considerably different from bulk Pd single-crystal planes with the same Miller indices. Such differences were attributed to special catalytic functions conferred by nanocrystal edges. This study paves a promising route for investigating catalytic reactions effectively at the atomic level and nanoscales

A Quantitative Mass Spectrometry-Based Approach for Assessing the Repair of 8‑Methoxypsoralen-Induced DNA Interstrand Cross-Links and Monoadducts in Mammalian Cells

Interstrand cross-links (ICLs) are highly toxic DNA lesions that block transcription and replication by preventing strand separation. ICL-inducing agents were among the earliest and are still the most widely used forms of chemotherapeutic drugs. Because of the repair of DNA ICLs, the therapeutic efficacy of the DNA cross-linking agents is often reduced by the development of chemoresistance in patients. Thus, it is very important to understand how various DNA ICLs are repaired. Such studies are currently hampered by the lack of an analytical method for monitoring directly the repair of DNA ICLs in cells. Here we report a high-performance liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method, together with the isotope dilution technique, for assessing the repair of 8-methoxypsoralen (8-MOP)-induced DNA ICLs, as well as monoadducts (MAs), in cultured mammalian cells. We found that, while there were substantial decreases in the levels of ICL and MAs in repair-competent cells 24 h after 8-MOP/UVA treatment, there was little repair of 8-MOP-ICLs and -MAs in xeroderma pigmentosum, complementation group A-deficient human skin fibroblasts and excision repair cross-complementing rodent repair deficiency, complementation group 1-deficient Chinese hamster ovary cells over a 24 h period. This result provided unequivocal evidence supporting the notion that the 8-MOP photoadducts are substrates for nucleotide excision repair in mammalian cells. This is one of the first few reports about the application of LC–MS/MS for assessing the repair of DNA ICLs. The analytical method developed here, when combined with genetic manipulation, will also facilitate the assessment of the roles of other DNA repair pathways in removing these DNA lesions, and the method can also be generally applicable for investigating the repair of other types of DNA ICLs in mammalian cells

Effect of Fabrication-Dependent Shape and Composition of Solid-State Nanopores on Single Nanoparticle Detection

Solid-state nanopores can be fabricated in a variety of ways and form the basis for label-free sensing of single nanoparticles: as individual nanoparticles traverse the nanopore, they alter the ionic current across it in a characteristic way. Typically, nanopores are described by the diameter of their limiting aperture, and less attention has been paid to other, fabrication-dependent parameters. Here, we report a comprehensive analysis of the properties and sensing performance of three types of nanopore with identical 50 nm aperture, but fabricated using three different techniques: direct ion beam milling, ion beam sculpting, and electron beam sculpting. The nanopores differ substantially in physical shape and chemical composition as identified by ion-beam assisted cross-sectioning and energy dispersive X-ray spectroscopy. Concomitant differences in electrical sensing of single 30 nm beads, such as variations in blockade depth, duration, and electric field dependence, are observed and modeled using hydrodynamic simulations. The excellent agreement between experiment and physical modeling shows that the physical properties (shape) and not the chemical surface composition determine the sensing performance of a solid-state nanopore in the absence of deliberate surface modification. Consequently, nanoparticle sensing performance can be accurately predicted once the full three-dimensional structure of the nanopore is known

Synthesis of α‑Amino Phosphonates under a Neat Condition Catalyzed by Multiple-Acidic Ionic Liquids

A simple and efficient method for the synthesis of α-amino phosphonates has been accomplished from aromatic aldehydes, diethyl phosphite, and aromatic amines using multiple-acidic ionic liquids catalysts under solvent-free conditions at room temperature, and these compounds were characterized by H–H correlation spectroscopy (COSY)

Spectral Identification of Methanol on TiO₂(110) Surfaces with Sum Frequency Generation in the C–H Stretching Region

In order to understand the adsorption behavior and photocatalytic reactions of organic molecules on titanium dioxide, TiO₂, at the molecular level, we have studied the vibrational spectra of methanol on TiO₂(110) by using surface-specific broadband infrared (IR) sum frequency generation (SFG) in combination with ultrahigh vacuum technique. As compared to vapor/liquid methanol interface, methanol on TiO₂(110) exhibits a much more complicated spectrum due to its molecular and dissociative adsorption (methoxy) on TiO₂(110). Furthermore, different sites are available for the methanol adsorption, including five-coordinated titanium (Ti_5c) and bridge-bonded oxygen (O_br). The methyl group of these species has symmetric stretching and Fermi resonance modes similar to those at the air/liquid methanol interface, and also presents intense antisymmetric stretching modes. These resonances of both molecular and dissociative methanol have been well resolved and assigned by means of polarization-dependent and methanol coverage-dependent SFG measurements, as well as ultraviolet (UV) irradiation treatments. This work lays the foundation for further in situ studies of the surface chemistry of methanol on TiO₂(110). The results also demonstrate the ability of SFG vibrational spectroscopy for investigating complicated structures of adsorbates on single crystal oxides

Visualization1.avi

Monitoring result of mouse osteoblastic MC3T3-E1 living cell

Risk of bias.

<p>Green indicates low risk; yellow indicates unclear risk; red indicates high risk.</p

Forest plot.

<p>Forest plot.</p

Funnel plot.

<p>Funnel plot.</p