Simulating and Validating the Traffic of Blackwall Tunnel Using TfL Jam Cam Data and Simulation of Urban Mobility (SUMO) (Short Paper)

Blackwall Tunnel is one of the most congested roadways in London. By simulating the tunnel and the connecting roads, information can be obtained about the traffic conditions and bottlenecks. In this paper, a model will be created using the Simulation of Urban Mobility (SUMO) tool and traffic flow data gathered from Transport for London (TfL) traffic cameras. The result from the simulation will be compared to the journey time data of Blackwall Tunnel in order to determine the accuracy of simulation

Instrumentation and Methods for Time-domain and In-cell Dynamic Nuclear Polarization

The application of dynamic nuclear polarization (DNP) and magic angle spinning (MAS) significantly improves the sensitivity of solid state nuclear magnetic resonance (NMR), making it a suitable tool to investigate structures and dynamics of complex biological systems. This dissertation describes the development of instrumentation and methods in various aspects with the goal of achieving time-domain and in-cell DNP NMR. In-cell NMR is necessary for obtaining functional structures and dynamics of proteins and interacting ligands in the native environment. Time-domain DNP could circumvent the cryogenic temperature restriction and permit DNP experiments at physiological temperatures, which is important for characterizing accurate in-cell conformations. This work describes a novel targeting, cell-penetrating, and fluorescent polarizing agent that was developed as a first step toward DNP inside living cells. High MAS frequencies, which can yield high spectral resolution, are exploited by designing and implementing spherical NMR rotors. Other strategies to improve DNP enhancement were also investigated, including the development of the frequency-agile, high-power gyrotron, which allows implementation of time-domain DNP and produce enhancement gain utilizing frequency-chirped microwave pulses. Lastly, the microwave simulation of MAS microwave resonators is presented, showing a high Q factor and drastically improved electron Rabi frequency, which could mitigate the limiting factor for time-domain DNP performance at high magnetic fields

Data-Driven Elucidation of Flavor Chemistry

Flavor molecules are commonly used in the food industry to enhance product quality and consumer experiences but are associated with potential human health risks, highlighting the need for safer alternatives. To address these health-associated challenges and promote reasonable application, several databases for flavor molecules have been constructed. However, no existing studies have comprehensively summarized these data resources according to quality, focused fields, and potential gaps. Here, we systematically summarized 25 flavor molecule databases published within the last 20 years and revealed that data inaccessibility, untimely updates, and nonstandard flavor descriptions are the main limitations of current studies. We examined the development of computational approaches (e.g., machine learning and molecular simulation) for the identification of novel flavor molecules and discussed their major challenges regarding throughput, model interpretability, and the lack of gold-standard data sets for equitable model evaluation. Additionally, we discussed future strategies for the mining and designing of novel flavor molecules based on multiomics and artificial intelligence to provide a new foundation for flavor science research.ISSN:0021-8561ISSN:1520-511

Response of Water Yield to Future Climate Change Based on InVEST and CMIP6—A Case Study of the Chaohu Lake Basin

The Chaohu Lake Basin (CLB) is the main flow area of the Yangtze River–Huaihe River Water Transfer Project in Central China. It is important to quantitatively evaluate the water resources in the CLB and predict their response to future climate change. This study simulated and calibrated the water yield in the CLB from 2000 to 2019 based on InVEST. We also analyzed the influence factor on the water yield and predicted the water yield in future years with CMIP6 data. The results demonstrate that: (1) The InVEST water production module had good applicability in this study region. There was a strong linear relationship between the simulated water yield and the observed surface runoff (y = 1.2363x − 8.6038, R2 = 0.868, p < 0.01); (2) The explanatory percentage of interaction between precipitation and land use/land cover for water yield in 2001, 2008, and 2016 reached 71%, 77%, and 85%, respectively, which were the two dominant factors affecting water yield in the CLB; and (3) The average annual water yield in the CLB increased under the SSP2-4.5, SSP3-7.0, and SSP5-8.5 future scenarios with increasing precipitation, increased with 71%, 139.8%, and 159.5% in 2100 compared with 2040, respectively. The overall trend of water production decreased with increases in carbon emission intensity

Improving the sensitivity of MAS spheres using a 9.5 mm spherical shell with 219 μL sample volume spinning in a spherical solenoid coil

Spherical rotors in magic angle spinning (MAS) nuclear magnetic resonance (NMR) experiments have potential advantages relative to cylindrical rotors in terms of ease of fabrication, low risk of rotor crash, easy sample exchange, and better microwave access. However, one major disadvantage so far of spherical rotors is poor NMR filling factor due to the small sample volume and large cylindrical radiofrequency (RF) coil. Here we present a novel NMR coil geometry in the form of a spherical coil. The spherical coil best fits the spherical sample to maximize sensitivity, while also providing excellent RF homogeneity. We further improve NMR sensitivity by employing a spherical shell as the rotor, thereby maximizing sample volume (219 μL in this case of 9.5 mm outer diameter spheres). The spinning gas is supplied by a 3D-printed ring stator external to the coil, thereby introducing a simplified form of MAS stators. In this apparatus, the RF field generated along the coil axis is perpendicular to the external magnetic field, regardless of rotor orientation. We observe a linear increase in sensitivity with increasing sample volume. We also simulate the RF performance of spherical and cylindrical solenoid coils with constant or variable pitch for spherical and cylindrical rotors, respectively. The simulation results show that spherical solenoid coils generate comparable B1 field intensities but have better homogeneity than cylindrical solenoid coils do.ISSN:1090-780

Two millimeter diameter spherical rotors spinning at 68 kHz for MAS NMR

Spherical rotors are a new paradigm in magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR). The simple geometry makes smaller diameter spheres and their utilization within narrow-bore NMR probes feasible. Here we report a 68 kHz spinning frequency of 2 mm diameter spheres using helium spinning gas outside the magnet and demonstrate the use of KMnO4 to adjust the magic angle at a spinning frequency of 59.3 kHz for MAS NMR. We observe third-order spinning sidebands in the 55Mn spectrum clearly showing the MAS frequency of 59.3 kHz, with KBr showing nearly no first-order spinning sidebands at a similar frequency. The spinning stability was ±0.5% during data acquisition without spinning regulation. To address concerns about the low NMR filling factor of MAS spheres, we employ a modified stator and a smaller coil and achieve three times higher NMR sensitivity then our previous coil geometries for MAS spheres. Advanced coil and rotor fabrication technologies are expected to further increase the spinning frequency and NMR sensitivity of MAS spheres

Response of Water Yield to Future Climate Change Based on InVEST and CMIP6—A Case Study of the Chaohu Lake Basin

The Chaohu Lake Basin (CLB) is the main flow area of the Yangtze River–Huaihe River Water Transfer Project in Central China. It is important to quantitatively evaluate the water resources in the CLB and predict their response to future climate change. This study simulated and calibrated the water yield in the CLB from 2000 to 2019 based on InVEST. We also analyzed the influence factor on the water yield and predicted the water yield in future years with CMIP6 data. The results demonstrate that: (1) The InVEST water production module had good applicability in this study region. There was a strong linear relationship between the simulated water yield and the observed surface runoff (y = 1.2363x − 8.6038, R2 = 0.868, p < 0.01); (2) The explanatory percentage of interaction between precipitation and land use/land cover for water yield in 2001, 2008, and 2016 reached 71%, 77%, and 85%, respectively, which were the two dominant factors affecting water yield in the CLB; and (3) The average annual water yield in the CLB increased under the SSP2-4.5, SSP3-7.0, and SSP5-8.5 future scenarios with increasing precipitation, increased with 71%, 139.8%, and 159.5% in 2100 compared with 2040, respectively. The overall trend of water production decreased with increases in carbon emission intensity

Pneumatic angle adjustment for magic angle spinning spherical rotors

Precise alignment of the sample's spinning axis is vital for many magic angle spinning solid state NMR experiments. Spherical rotors are a new paradigm for magic angle spinning NMR, having been demonstrated to spin stably with little risk of rotor crash, but like cylindrical rotors, they have previously only utilized a mechanical adjustment method to set the sample's rotation axis to the magic angle. Here we show that by using a second gas aperture within the stator, a spherical rotor's axis of rotation may be precisely pitched about the magic angle without mechanical adjustment or motion of the stator. The 2H MAS sideband lineshape of the carboxylic acid deuteron resonance in d4-malonic acid is used as a measure of the rotor's absolute deviation above or below the magic angle by comparing the experimental data to simulated lineshapes. We observe a linear, monotonic relationship between the angle adjustment gas flow rate and the rotor's pitch angle, which is also accompanied by an increase in spinning rate. Precise and in operando control of the spinning axis angle is expected to have considerable advantages to future implementation of MAS within narrow-bore magnets, and for variable angle spinning (VAS) and dynamic angle spinning (DAS) experiments

Characterization of Frequency-Chirped Dynamic Nuclear Polarization in Rotating Solids

Continuous wave (CW) dynamic nuclear polarization (DNP) is used with magic angle spinning (MAS) to enhance the typically poor sensitivity of nuclear magnetic resonance (NMR) by orders of magnitude. In a recent publication we show that further enhancement is obtained by using a frequency-agile gyrotron to chirp incident microwave frequency through the electron resonance frequency during DNP transfer. Here we characterize the effect of chirped MAS DNP by investigating the sweep time, sweep width, center-frequency, and electron Rabi frequency of the chirps. We show the advantages of chirped DNP with a trityl nitroxide biradical, and a lack of improvement with chirped DNP using AMUPol, a nitroxide biradical. Frequency-chirped DNP on a model system of urea in a cryoprotecting matrix yields an enhancement of 142, 21% greater than that obtained with CW DNP. We then go beyond this model system and apply chirped DNP to intact human cells. In human Jurkat cells, frequency-chirped DNP improves enhancement by 24% over CW DNP. The characterization of the chirped DNP effect reveals instrument limitations on sweep time and sweep width, promising even greater increases in sensitivity with further technology development. These improvements in gyrotron technology, frequency-agile methods, and in cell applications are expected to play a significant role in the advancement of MAS DNP.<br /