Drought Tolerance Dissection and Molecular Breeding in Alfalfa

Drought stress is one of the leading impediments that limit the productivity of global alfalfa (Medicago sativa). The underlying molecular and genetic mechanisms for drought tolerance in alfalfa remain largely unclear. In order to fully reveal the transcriptional changes of alfalfa in response to abiotic stress, the alfalfa transcriptome database under mannitol (simulated drought stress), NaCl (simulated salt stress), or exogenous ABA application was built via various RNA-seq technologies. Through further screening of the transcriptome database, a number of genes significantly induced by drought stress, such as the Nuclear Transport Factor 2-like (MsNTF2L), Drought-Induced Unknown Protein 1 (MsDIUP1), and MsNST1, were identified. These three genes were transferred into alfalfa by overexpression and RNAi techniques, and their physiological characteristics and transcriptional level response were synthetically studied. Alfalfa MsNTF2L-OE plants have been approved by the Ministry of Agriculture of China to carry out the field test in Gansu Province. Furthermore, we constructed a GWAS population and obtained 50 excellent plants with strong drought tolerance and high hay-yield. These studies provide a theoretical foundation for drought-tolerant molecular breeding of alfalfa

Beam energy distribution influences on density modulation efficiency in seeded free-electron lasers

The beam energy spread at the entrance of undulator system is of paramount importance for efficient density modulation in high-gain seeded free-electron lasers (FELs). In this paper, the dependences of high harmonic micro-bunching in the high-gain harmonic generation (HGHG), echo-enabled harmonic generation (EEHG) and phase-merging enhanced harmonic generation (PEHG) schemes on the electron energy spread distribution are studied. Theoretical investigations and multi-dimensional numerical simulations are applied to the cases of uniform and saddle beam energy distributions and compared to a traditional Gaussian distribution. It shows that the uniform and saddle electron energy distributions significantly enhance the performance of HGHG-FELs, while they almost have no influence on EEHG and PEHG schemes. A numerical example demonstrates that, with about 84keV RMS uniform and/or saddle slice energy spread, the 30th harmonic radiation can be directly generated by a single-stage seeding scheme for a soft x-ray FEL facility

Gait Cycle-Inspired Learning Strategy for Continuous Prediction of Knee Joint Trajectory from sEMG

Predicting lower limb motion intent is vital for controlling exoskeleton robots and prosthetic limbs. Surface electromyography (sEMG) attracts increasing attention in recent years as it enables ahead-of-time prediction of motion intentions before actual movement. However, the estimation performance of human joint trajectory remains a challenging problem due to the inter- and intra-subject variations. The former is related to physiological differences (such as height and weight) and preferred walking patterns of individuals, while the latter is mainly caused by irregular and gait-irrelevant muscle activity. This paper proposes a model integrating two gait cycle-inspired learning strategies to mitigate the challenge for predicting human knee joint trajectory. The first strategy is to decouple knee joint angles into motion patterns and amplitudes former exhibit low variability while latter show high variability among individuals. By learning through separate network entities, the model manages to capture both the common and personalized gait features. In the second, muscle principal activation masks are extracted from gait cycles in a prolonged walk. These masks are used to filter out components unrelated to walking from raw sEMG and provide auxiliary guidance to capture more gait-related features. Experimental results indicate that our model could predict knee angles with the average root mean square error (RMSE) of 3.03(0.49) degrees and 50ms ahead of time. To our knowledge this is the best performance in relevant literatures that has been reported, with reduced RMSE by at least 9.5%

Mixed plastics waste valorization through tandem chemical oxidation and biological funneling

115 p.-4 fig.-45 fig. supl.-14 tab supl.Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of thesematerials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either b-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products.Funding was provided by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO). This work was performed as part of the BOTTLE Consortium and was supported by AMO and BETO under contract no. DE-AC36- 08GO28308 with the National Renewable Energy Laboratory (NREL),operated by the Alliance for Sustainable Energy, LLC. The BOTTLE Consortium includes members from MIT, funded under contract no. DE-AC36-08GO28308 with NREL. Contributions by S.S.S. were supported by the US Department of Energy, Office of Basic Energy Sciences, under award no. DEFG02-05ER15690.Peer reviewe

A survey on heterogeneous face recognition: Sketch, infra-red, 3D and low-resolution

Heterogeneous face recognition (HFR) refers to matching face imagery across different domains. It has received much interest from the research community as a result of its profound implications in law enforcement. A wide variety of new invariant features, cross-modality matching models and heterogeneous datasets are being established in recent years. This survey provides a comprehensive review of established techniques and recent developments in HFR. Moreover, we offer a detailed account of datasets and benchmarks commonly used for evaluation. We finish by assessing the state of the field and discussing promising directions for future research

Development of Tandem Mass Spectrometric Methods for Characterizing Asphaltenes and Differentiating Small Organic Isomers

High-resolution mass spectrometry (MS) and tandem mass spectrometry (MS/MS) are powerful tools for the characterization of the molecular structures of components of both simple and complex mixtures. MS and MS/MS have played key roles in many fields, including proteomics, metabolomics, and petroleomics. This thesis focuses on the development of tandem mass spectrometric methods for the structural characterization of asphaltenes and small isomeric molecules. In addition, this thesis also presents a method to address a sampling bias in asphaltene analysis. Chapter 2 describes the fundamental aspects of the mass spectrometer used for the research discussed in this thesis. Chapter 3 presents an in-depth study on the determination of the relative abundances of single-core and multicore compounds in asphaltenes. A statistical sampling bias in many earlier asphaltene studies is discussed and a rapid and simple alternative method is introduced to address this sampling bias. Chapter 4 presents an investigation of the sizes of aromatic cores and lengths of alkyl chains in isobaric ions derived from asphaltenes by using an improved data analysis method. Chapter 5 presents a fundamental study on utilization of energy-resolved collision-activated dissociation (CAD) for the differentiation of isomeric ions. Energy-resolved CAD was used to compare the ability of two different activation methods to differentiate four sets of isomeric ions of aromatic hydrocarbons. The comparison suggests that medium-energy CAD (MCAD; commercially known as higher-energy collision dissociation, HCD) is more powerful in differentiation of the four sets of isomers than conventional ion trap CAD (ITCAD)

Biomarker discovery of thalassemia and sickle-cell disease from blood peptidome

This study aims to discover inherited blood disease biomarkers through peptidomic approaches, in order to develop faster and more economical diagnostic method suitable for population screening. 3 types of inherited blood diseases, thalassemia Hb CS, Hb E and sickle cell disease Hb S were included in this study. Hb CS markers were successfully identified through both MALDI-MS and LC-MS. 2 of the candidate markers were further analyzed by pseudo-MRM. Pseudo-MRM analysis demonstrated competitive sensitivity while further reduced total sample analysis time by approximately 25%. Hb E and Hb S markers were identified through LC-MS but not MALDI using same approaches. This study successfully identified several promising biomarkers for 3 different inherited blood diseases, thus provided support for biomarker discovery through peptidomic/degradomic approaches. Methods developed in this study could be readily expanded to biomarker discovery of other inherited blood diseases. Furthermore, as methods are compatible with MRM that is common in clinical laboratories, this study is readily converted to clinical applications.Doctor of Philosophy (SBS

Tandem Mass Spectrometric Evaluation of Core Structures of Aromatic Compounds after Catalytic Deoxygenation

Catalytic deoxygenation of coal enhances the stability and combustion performance of coal-derived liquids. However, determination of the selectivity of removal of oxygen atoms incorporated in or residing outside of aromatic rings is challenging. This limits the ability to evaluate the success of catalytic deoxygenation processes. A mass spectrometric method, in-source collision-activated dissociation (ISCAD), combined with high resolution product ion detection, is demonstrated to allow the determination of whether the oxygen atoms in aromatic compounds reside outside of aromatic rings or are part of the aromatic system, because alkyl chains can be removed from aromatic cores via ISCAD. Application of this method for the analysis of a subbituminous coal treated using a supported catalyst revealed that the catalytic treatment reduced the number of oxygen-containing heteroaromatic rings but not the number of oxygen atoms residing outside the aromatic rings.<br