Characterization of terrestrial organic carbon in the Amazon system: insights from biomarkers and their isotopic composition (δ13C and Δ14C)

The preservation of terrestrial organic carbon (OC) in marine sediments is a crucial component of global carbon cycle on geological timescale. Characterizing the origins and compositions of the terrestrial OC is critical for understanding the fate of terrestrial OC in marine sediments and constraining the terrestrial OC cycling. The amount of terrestrial OC discharged by the Amazon River to the Atlantic Ocean every year is about 8-10 % of the global annual input of terrestrial OC to oceans. Therefore, the terrestrial OC in the Amazon system has been extensively investigated. However, until now, many aspects regarding the origin and fate of terrestrial OC in the Amazon system are still ambiguous and need to be elucidated. Firstly, little is known about the disperse pattern of lignin (a major component of higher plants biomass and can serve as a biomarker of terrestrial OC) and the factors controlling the characteristics of terrestrial OC in the Amazon continental margin. Secondly, it is questionable whether the Amazon continental margin can efficiently store terrestrial OC or serve as a sedimentary OC incinerator. Thirdly, the response of vegetation to climate change during late Pleistocene is debated. To fill these knowledge gaps, lignin and its isotope compositions (13C and 14C) are used as the major tools to provide a better understanding of the origins, pattern of distribution, processing, composition and fate of terrestrial OC in the Amazon system. In the first part, the biogeochemical characteristics of terrestrial OC in the fluvial sediments from the Amazon drainage basin and in the adjacent marine sediments are compared. Total organic carbon (TOC) and lignin content exhibit positive correlations with aluminium to silicon ratios (Al/Si, indicative of the sediment grain size) implying that the grain size of sediment discharged by the Amazon River plays an important role in the preservation of TOC and leads to preferential preservation of lignin phenols in fine particles. Low δ13C values of bulk OC in the main tributaries consistently correspond with the dominance of C3 vegetation. Compositions of lignin, syringyl to vanillyl (S/V) and cinnamyl to vanillyl (C/V), suggest that non-woody angiosperm tissues are the dominant source of lignin in the Amazon basin. Although the Amazon basin hosts a rich diversity of vascular plant types, distinct regional lignin compositions are not observed. In the marine sediments, the distribution of δ13C values of bulk OC and lignin contents implies that terrestrial OC discharged by the Amazon River is transported northwestward by the North Brazil Current and mostly deposited on the inner shelf. The lignin compositions in offshore sediments under the influence of the Amazon plume are consistent with the riverbed samples suggesting that processing of terrestrial OC during offshore transport does not change the encoded source information. Therefore, the lignin compositions preserved in these offshore sediments can reliably reflect the vegetation in the Amazon River catchment. In sediments from the Amazon Fan, low lignin content, relatively low δ13C values of bulk OC and high degradation degree of lignin demonstrate that a significant fraction of the deposited terrestrial OC is derived from petrogenic (sourced from ancient rocks) sources. In the second part, a new method of assessing procedural blank for compound-specific 14C analysis is developed with a Bayesian model. This method is successfully used in the third part of this thesis, which is about radiocarbon dating of source-specific biomarkers (n-alkanoic acids and lignin phenols) in riverbed sediments from the lowland Amazon basin and offshore sediments. The results show that Δ14C values of terrestrial OC on the Amazon continental margin are substantially influenced by matrix association effects, where terrestrial OC associated with the finer-grained particles is better preserved and more resistant to decomposition during residence in intermediate reservoirs. The compoundspecific Δ14C values imply that as expected short-chain n-alkanoic acids represent recently biosynthesized organic matter from riverine or marine primary production whereas both long-chain nalkanoic acids and lignin phenols used as markers for land vegetation have pre-aged in soils where they resided attached to mineral surfaces. By using a ternary mixing model, a well-constrained quantitative estimate of the composition of sedimentary OC in riverbed and marine sediments is obtained. Despite the variable composition of sedimentary OC in the Amazon system, the burial of fossil rock-derived OC is relatively constant. Based on the absolute content of bulk terrestrial OC, lignin, and long-chain n-alkanoic acids and their 14C ages, half-lives of bulk terrestrial OC, lignin and long-chain n-alkanoic acids during transport are estimated to be about 2310 years, 13860 and 470 years, respectively. This suggests that the preservation of terrestrial OC in the mud belt on the Amazon shelf is more efficient than previously assumed. In the fourth part, the δ13C analysis of lignin phenols are applied in marine surface sediments from the Amazon shelf and sediment core GeoB16224-1 recovered from the continental margin NW of the Amazon mouth. The weighted average δ13C values of lignin indicate that the modern terrestrial OC on the Amazon shelf is dominated by C3 plants and the vegetation source remained constant over the past 12.8-50 kyr, in agreement with previous studies. A general pattern of phenolic δ13C values is observed with the acid monomers of V and S phenols displaying lower δ13C values than their aldehyde counterparts, while C phenols are always more enriched in 13C than V and S phenols. The lignin content and composition paired with δ13C of lignin are used to reconstruct the characteristics of terrestrial OC deposited on the continental margin NW of the Amazon mouth over the period 12.8-50 kyr. Lignin composition, δ13C values of lignin, BIT index, δ13C and δD values plant-wax lipids show clear in-phase variation. Therefore, it can be proposed that next to vegetation change, the variation of δ13C values of lignin and plant-wax lipids during HS could reflect either enhanced discharge of more degraded terrestrial OC and/or more contributions of terrestrial from high altitude regions. These two possible scenarios suggest that the Amazon basin was still a stable ecological system dominated by C3 forest and the increases of δ13C values of lignin and plant-wax lipids were actually the consequence of changes of sources of terrestrial OC through the late Pleistocene

High Throughput Screening for Enzyme Modulators Using Segmented Flow Coupled to Electrospray Ionization-Mass Spectrometry.

In drug discovery, it is important to use high throughput screening (HTS) technologies to rapidly identify active compounds for biological targets (usually enzymes) from large chemical libraries. The state of art strategy for HTS is coupling multiwell-plates (MWPs) to optical readers. Higher throughput, less reagent use and minimal labeling are always pursued in HTS. Mass spectrometry (MS) is a powerful label-free analyzer due to its high speed and sensitivity. Segmented flow (droplets) can reliably manipulate nanoliter samples and miniaturize reactions with high precision and automation. Novel high throughput screening systems have been developed by interfacing oil-segmented droplets to electrospray ionization (ESI)-MS. To miniaturize a screening, we designed an all-droplet system for conducting assays inside nanoliter droplets. A microfabricated reagent addition device was used for injecting multiple reagents into the droplet array of test compounds to initiate enzymatic reactions. The reaction droplets were directly analyzed by ESI-MS. This all-droplet system was demonstrated by a cathepsin B inhibitor screening with high reliability (Z-factor = 0.8), high analysis rate (0.8 Hz) and straightforward interpretation. Reagents consumption was at picomoles to femtomole level, which is 1000-fold less than the traditional MWP-based assays. Integrating droplet-ESI-MS with existing MWPs screening workflow can extend the application of both systems. With this concept, we developed a ‘MS plate reader’ (MSPR). It can reformat 3072 samples from eight 384-well plates into oil-segmented droplets in 13 min (4.5 Hz), and then analyze them in 30 min (up to 2 Hz). Using MSPR, a label-free screen for cathepsin B inhibitors against 1280 chemicals was completed in 45 min (triplicate assay, 1.6 Hz). 11 novel inhibitors were identified and validated. We also developed MS assays for two health beneficial enzymes: SIRT1 and SIRT6. Both assays are applicable to large-scale screenings using MSPR. An 80-compound pilot screening for SIRT1 modulators identified 4 strong inhibitors (> 50% inhibition), all of which were confirmed by dose-dependent experiments. A 25-compound test screening of SIRT6 modulators demonstrated the reliability of this assay by identifying the known activator (> 200% activation). It also showed that the single assay is as robust (Z-factor=0.6) as the replicated assay.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111582/1/shuwens_1.pd

Observer-based chaos synchronization for secure communications

Chaos, with reference to chaos theory, refers to an apparent lack of order in a system that, nevertheless, obeys particular laws or rules. The chaotic signals generated by chaotic systems have some properties such as randomness, complexity and sensitive dependence on initial conditions, which make them particularly suitable for secure communications. Since the 1990s, the problem of secure communication, based on chaos synchronization, has been thoroughly investigated and many methods, for instance, robust and adaptive control approaches, have been proposed to realize the chaos synchronization. However, from systems theory perspective, it may seem obvious that many robust and adaptive control methods could be considered for possible attacks against secure communication. In this thesis, we introduce the concept of secure chaos synchronization from the control theoretic view point. A new secure communication system, based on the chaos synchronization, is proposed and its security is analyzed, both theoretically and numerically

Research on Design Optimization and Simulation of Regenerative Braking Control Strategy for Pure Electric Vehicle Based on EMB Systems

The benefits of electromechanical braking (EMB) systems are short response time, high braking efficiency, ease of assembly and easy integration with other electronic control systems. Therefore, a model of an EMB system is developed based on which the braking stability, braking efficiency, and the regenerative braking energy recovery in electric vehicles are investigated. Electric vehicles can effectively increase their driving range by using a rational regenerative braking control strategy. Firstly, a fuzzy regenerative braking control strategy is developed for comparison, and an optimized regenerative braking control strategy is designed based on the NSGA-II algorithm. The technique for order preference by similarity to ideal solution (TOPSIS) is used to comprehensively evaluate the Pareto optimal solution set and to select an optimal solution for the optimization problem. Secondly, a Takagi-Sugeno fuzzy neural network is trained with the optimized discrete data, and then the braking force distribution controller is obtained. Simulink and AVL CRUISE are used to simulate the control strategy. The simulation results for variable intensity braking conditions and cyclic conditions NEDC, FTP75, and CLTC-P show that the optimized control strategy outperforms the fuzzy control strategy in braking stability and braking energy recovery

Label-Free Liver Tumor Segmentation

We demonstrate that AI models can accurately segment liver tumors without the need for manual annotation by using synthetic tumors in CT scans. Our synthetic tumors have two intriguing advantages: (I) realistic in shape and texture, which even medical professionals can confuse with real tumors; (II) effective for training AI models, which can perform liver tumor segmentation similarly to the model trained on real tumors -- this result is exciting because no existing work, using synthetic tumors only, has thus far reached a similar or even close performance to real tumors. This result also implies that manual efforts for annotating tumors voxel by voxel (which took years to create) can be significantly reduced in the future. Moreover, our synthetic tumors can automatically generate many examples of small (or even tiny) synthetic tumors and have the potential to improve the success rate of detecting small liver tumors, which is critical for detecting the early stages of cancer. In addition to enriching the training data, our synthesizing strategy also enables us to rigorously assess the AI robustness.Comment: CVPR 202

ILT4 drives B7-H3 expression via PI3K/AKT/mTOR signalling and ILT4/B7-H3 co-expression correlates with poor prognosis in non-small cell lung cancer

AbstractImmunoglobulin-like transcript (ILT) 4 is critical for the inhibitory function of certain immune cells. We previously demonstrated that ILT4 is over-expressed in human non-small cell lung cancer (NSCLC) cells and is involved in tumour evasion via an unknown mechanism. In this report, we demonstrate that ILT4 increases the expression of the co-inhibitory molecule B7-H3 through PI3K/AKT/mTOR signalling. In primary human NSCLC tissues, a significant positive relationship is observed between ILT4 and B7-H3 expression. ILT4/B7-H3 co-expression is significantly associated with a reduction in T infiltrating lymphoid cells and lower overall survival. In summary, ILT4 increases B7-H3 expression and ILT4/B7-H3 co-expression may be involved in NSCLC progression

Long-term trends in the incidence of depressive disorders in China, the United States, India and globally: A comparative study from 1990 to 2019

BackgroundDepressive disorders have become an increasingly significant public health issue. This study is intended to show the trend of the incidence of depressive disorders in China, the United States, India and the world from 1990 to 2019, as well as the impact of age, period and cohort on it.MethodsExtracting incidence data from the Global Burden of Disease Study 2019, we determined trends in the age-standardized incidence rate (ASIR) using Joinpoint regression. An age-period-cohort analysis was implemented to describe the effects of age, period, and cohort, as well as the long-term tendencies.ResultsFrom 1990 to 2019, the ASIR of depressive disorders in China was lower than that in the United States; India is lower than the United States in the first 5 years, showing a downward trend. The incidence in India and the United States is higher than the global average. The ASIR of women in the three countries is higher than that of men. In China, the elderly, early period and people born around 1954 have a higher risk of depressive disorders. In the United States, young people born around 1999 have a higher risk of depressive disorders. India is similar to China.ConclusionFrom 1990 to 2019, the age effect of China as a whole increased, and the period became stable, and the cohort effect declined. The overall age and period effects of the United States reduced, while the cohort effect increased. The age effect in India increased, while the period and cohort effects decreased. Depressive disorders are becoming ever more serious worldwide, and we’d better take measures to reduce its incidence according to the cohort effect of each age group

Sex Differences in Quality of Life and their Explanatory Variables in Patients with Non-Valvular Atrial Fibrillation

Background: Women with atrial fibrillation (AF) have poorer quality of life (QoL) than men; however, the factors contributing to the poorer QoL in women is unclear. Methods: We analyzed data for 3562 patients with non-valvular AF enrolled in the China Registry of Atrial Fibrillation. The Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) was used to evaluate QoL, which was compared between women and men. A multivariate logistic regression analysis model was used to explore factors potentially explaining the sex difference in QoL. Results: Overall, 43.3% of the cohort comprised women (n=1541) who were older than their male counterparts (72 ± 9.8 vs. 68 ± 11.9 years, P<0.001). Compared with men, women were more likely to have more symptoms, hypertension, diabetes mellitus, and heart failure. Women were less likely than men to receive catheter ablation (4.5% vs. 6.1%, P=0.044). Women also had lower physical component summary (PCS) scores (48 ± 9 vs. 51 ± 9, P<0.001) and mental component summary (MCS) scores (49 ± 10 vs. 51 ± 10, P<0.001) than men. In the multivariable analysis of the poorer PCS scores in women, patient age explained 32.9%, low socioeconomic status explained 20.0%, lifestyle explained 14.3%, cardiovascular comorbidities explained 15.7%, the presence of more symptoms explained 5.7%, and less catheter ablation explained 1.4%. These factors also explained similar proportions of the sex difference in MCS scores. Together, these factors explained 54.3% of the poorer physical function status and 46.8% of the poorer mental function status in women than men. Conclusions: Women with AF had poorer QoL than men. The following factors partly explained the poorer QoL in women: older age, low level of socioeconomic status, more cardiovascular comorbidities, less smoking and drinking, more symptoms, and less catheter ablation