Analysis of Yarrowia lipolytica Growth, Catabolism, and Terpenoid Biosynthesis during Utilization of Lipid-derived Feedstock

This study employs biomass growth analyses and 13C-isotope tracing to investigate lipid feedstock utilization by Yarrowia lipolytica. Compared to glucose, oil-feedstock in the minimal medium increases the yeast\u27s biomass yields and cell sizes, but decreases its protein content (\u3c20% of total biomass) and enzyme abundances for product synthesis. Labeling results indicate a segregated metabolic network (the glycolysis vs. the TCA cycle) during co-catabolism of sugars (glucose or glycerol) with fatty acid substrates, which facilitates resource allocations for biosynthesis without catabolite repressions. This study has also examined the performance of a β-carotene producing strain in different growth mediums. Canola oil-containing yeast-peptone (YP) has resulted in the best β-carotene titer (121 ± 13 mg/L), two-fold higher than the glucose based YP medium. These results highlight the potential of Y. lipolytica for the valorization of waste-derived lipid feedstock

Designing Artificial Two-Dimensional Landscapes via Room-Temperature Atomic-Layer Substitution

Manipulating materials with atomic-scale precision is essential for the development of next-generation material design toolbox. Tremendous efforts have been made to advance the compositional, structural, and spatial accuracy of material deposition and patterning. The family of 2D materials provides an ideal platform to realize atomic-level material architectures. The wide and rich physics of these materials have led to fabrication of heterostructures, superlattices, and twisted structures with breakthrough discoveries and applications. Here, we report a novel atomic-scale material design tool that selectively breaks and forms chemical bonds of 2D materials at room temperature, called atomic-layer substitution (ALS), through which we can substitute the top layer chalcogen atoms within the 3-atom-thick transition-metal dichalcogenides using arbitrary patterns. Flipping the layer via transfer allows us to perform the same procedure on the other side, yielding programmable in-plane multi-heterostructures with different out-of-plane crystal symmetry and electric polarization. First-principle calculations elucidate how the ALS process is overall exothermic in energy and only has a small reaction barrier, facilitating the reaction to occur at room temperature. Optical characterizations confirm the fidelity of this design approach, while TEM shows the direct evidence of Janus structure and suggests the atomic transition at the interface of designed heterostructure. Finally, transport and Kelvin probe measurements on MoXY (X,Y=S,Se; X and Y corresponding to the bottom and top layers) lateral multi-heterostructures reveal the surface potential and dipole orientation of each region, and the barrier height between them. Our approach for designing artificial 2D landscape down to a single layer of atoms can lead to unique electronic, photonic and mechanical properties previously not found in nature

Regulatory controls of duplicated gene expression during fiber development in allotetraploid cotton.

Polyploidy complicates transcriptional regulation and increases phenotypic diversity in organisms. The dynamics of genetic regulation of gene expression between coresident subgenomes in polyploids remains to be understood. Here we document the genetic regulation of fiber development in allotetraploid cotton Gossypium hirsutum by sequencing 376 genomes and 2,215 time-series transcriptomes. We characterize 1,258 genes comprising 36 genetic modules that control staged fiber development and uncover genetic components governing their partitioned expression relative to subgenomic duplicated genes (homoeologs). Only about 30% of fiber quality-related homoeologs show phenotypically favorable allele aggregation in cultivars, highlighting the potential for subgenome additivity in fiber improvement. We envision a genome-enabled breeding strategy, with particular attention to 48 favorable alleles related to fiber phenotypes that have been subjected to purifying selection during domestication. Our work delineates the dynamics of gene regulation during fiber development and highlights the potential of subgenomic coordination underpinning phenotypes in polyploid plants. [Abstract copyright: © 2023. The Author(s).

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Performance analysis of ship-to-ship communication using automatic identification system (AIS)

The Automatic Identification System (AIS) is a new type of marine navigation aid that can receive information from the very high frequency (VHF) band in real time. It is used for ship-to-ship/shore communication, effectively avoiding significant maritime accidents. Commercial available VHF/UHF can be used for short range communication and satellite services for longer range ones. This report focuses on the performance of ship-to-ship communication using AIS. The communication channel model using Matlab is developed and presented. The signal at transmitter is designed according to AIS frame structure. And the receiver is developed to test bit error rate through different non-coherent demodulation ways. The performance in this report of communication system is simulated by Monte Carlo method. Firstly, this report introduces AIS and its specific parameters in practical . Then the principle of GMSK modulation and demodulation is presented along with Matlab code list. Then communication channel model is developed and different parameters are set to test the performance. Finally, at the receiving end, we compute bit error rate of AWGN, Rician and Rayleigh channel and compare them. At the end of report, the recommendations for the future work to further improve the project is mentioned.Master of Science (Communications Engineering

Energy Absorption of Square Tubes Filled by Modularized Honeycombs with Multiple Gradients

The Uniform Honeycomb-filled Tube (UHT) is one of the composite structures that has shown huge potential in absorbing energy. In this paper, Uniform Honeycomb (UH) filler is replaced by an enhanced Modularized Honeycomb (MH). The biggest advantage of MH is that it can significantly enhance energy absorption without adding weight compared with its uniform counterpart. Finite element models are created, and then validated by theoretical models. The energy absorption of the Modularized Honeycomb-filled Tube (MHT) is compared with that of the empty tube and UHT. The results show that the MHT is superior to them in Specific Energy Absorption (SEA). It is also found that the tube can help the MH improve its deformation stability, which is the key of the MHT’s excellent energy absorption capacity. Then, effects of design parameters on the SEA of the MHT are investigated and discussed. The results show that the MH with a large graded coefficient is good for enhancing the SEA of the MHT. However, the SEA also relies on the match between the honeycomb filler and tube walls. The work could inspire designs of modularized filler with various types of cells and benefit the development of advanced energy absorbers with lighter weight and more excellent energy absorption capacity

Precision Compensation Method of Tooth Profile in Form Grinding of Modified Helical Gears

The coordinate equation of helical gear tooth profile modification and geometric algorithm of form grinding wheel dressing are established, and the section profile of grinding wheel after tooth profile modification is optimized. The coupling relation between machine position error and tooth profile error is obtained by the numerical simulation. A software for adjusting the precision of form grinding tooth profile is developed, and the forming sand profile and tooth profile precision adjustment parameters corresponding to the helical gear modification are calculated. Through the form grinding experiment of the modified helical gear, the correctness of sand contour trimming and the effectiveness of tooth profile adjustment are verified

One-pot hydrothermal synthesis of Al-doped MoS2@graphene aerogel nanocomposite electrocatalysts for enhanced hydrogen evolution reaction

Molybdenum disulfide (MoS2) has shown its promising performance for use as an electrocatalyst for hydrogen evolution reaction (HER). However, it has commonly suffered from limited edge active sites and stagnant conductivity in this regard. Therefore in the present work, with integrating graphene aerogel (GA) supporting and Al ions doping, we report for the first time one-pot hydrothermal synthesis of Al-doped MoS2@GA aerogel electrocatalysts with 3D porous network architecture. Vertical MoS2 ultrathin nanosheets with defect-rich structure are grown on graphene nanosheets at the optimum weight ratio of 5 wt% GA, leading to the enhancement of HER activity. Simultaneously Al doping of 0.77 at% further optimizes the number of exposed active sites and conductivity. The overpotential at a current of 10 mA·cm−2 was successfully reduced to 212 mV with a Tafel slope value down to 41 mV/dec, benefiting from synergistically structural and electronic modulating of MoS2. The study thus sheds light on designing and developing high-performance 3D network electrocatalysts for HER reaction. Keywords: Vertical MoS2, Graphene aerogel, 3D network, Hydrothermal synthesis, Current density, Hydrogen evolutio