Modeling ammonia emissions from dairy production systems in the United States

Dairy production systems are hot spots of ammonia (NH3) emission. However, there remains large uncertainty in quantifying and mitigating NH3 emissions from dairy farms due to the lack of both long-term field measurements and reliable methods for extrapolating these measurements. In this study, a process-based biogeochemical model, Manure-DNDC, was tested against measurements of NH3 fluxes from five barns and one lagoon in four dairy farms over a range of environmental conditions and management practices in the United States. Results from the validation tests indicate that the magnitudes and seasonal patterns of NH3 fluxes simulated by Manure-DNDC were in agreement with the observations across the sites. The model was then applied to assess impacts of alternative management practices on NH3 emissions at the farm scale. The alternatives included reduction of crude protein content in feed, replacement of scraping with flushing for removal of manure from barn, lagoon coverage, increase in frequency for removal of slurry from lagoon, and replacement of surface spreading with incorporation for manure land application. The simulations demonstrate that: (a) all the tested alternative management practices decreased the NH3 emissions although the efficiency of mitigation varied; (b) a change of management in an upstream facility affected the NH3 emissions from all downstream facilities; and (c) an optimized strategy by combining the alternative practices on feed, manure removal, manure storage, and land application could reduce the farm-scale NH3 emission by up to 50%. The results from this study may provide useful information for mitigating NH3 emissions from dairy production systems and emphasize the necessity of whole-farm perspectives on the assessment of potential technical options for NH3 mitigation. This study also demonstrates the potential of utilizing process-based models, such as Manure-DNDC, to quantify and mitigate NH3 emissions from dairy farms

Investor Sentiment and Assets Valuation

AbstractUsing the Chinese stock market data as sample, this paper investigates the impact of investor sentiment on the assets valuation. In order to classify stocks objectively, our sample stocks are sorted by double indicators (B/M and PE). In the portfolio, we find stocks with low B/M and high PE are sensitive to investor sentiment, which are considered to be costly to arbitrage. Investor sentiment has incremental power to explain stock return co-movements, which indicates that these stocks would perform higher (lower) excess returns when investors are bullish (bearish).Our findings support a role for investor sentiment in the formation of return and the change of investor sentiment should be taken as an important systemic risk in asset pricing and portfolio management

Effect of combination of botulinum toxin and electromyographic biofeedback therapy on post-stroke patients with lower limb muscle spasticity

Purpose: To investigate the clinical effect of combined use of botulinum toxin type A and electromyographic biofeedback therapy (EMGBFT) on post-stroke patients with lower limb muscle spasticity. Methods: The data of 91 post-stroke patients with lower limb muscle spasticity who were admitted to Shanghai Seventh People’s Hospital (January 2020 -January 2021) were retrospectively analyzed, and they were divided into control group (COG, n = 45) and study group (STG, n = 46) based on the treatments given. All patients received conventional rehabilitation and training. Patients in COG were treated with EMGBFT, whereas those in STG received botulinum toxin type A as well as EMGBFT. The parameters determined in the two groups were degree of spasticity, lower limb motor function [3m-Timed Up and Go (3m - TUG) and 10m - Walk Test (10 m - WT)], active range of motion (AROM) of ankle dorsiflexion, ability of daily living (based on Barthel Index, BI), and adverse reactions before and after treatment. Results: The effectiveness of the treatments on spasticity was higher in STG than in COG (p < 0.05). After treatment, the times taken for 3m-TUG and 10m-WT were significantly shorter in STG than in COG (p < 0.05). The AROM of patients in both groups was expanded, but the expansion was significantly greater in STG than in COG (p < 0.05). Conclusion: Combined therapy using botulinum toxin and EMGBFT effectively relieved lower limb muscle spasticity of post-stroke patients, and also improved their lower limb motion function and daily living ability. Thus, the combined therapy provided better management of lower limb spasticity. However, further clinical trials are required prior to its adoption in clinical practice

Modeling nitrogen loadings from agricultural soils in southwest China with modified DNDC

Degradation of water quality has been widely observed in China, and loadings of nitrogen (N) and other nutrients from agricultural systems play a key role in the water contamination. Process‐based biogeochemical models have been applied to quantify nutrient loading from nonpoint sources at the watershed scale. However, this effort is often hindered by the fact that few existing biogeochemical models of nutrient cycling are able to simulate the two‐dimensional soil hydrology. To overcome this challenge, we launched a new attempt to incorporate two fundamental hydrologic features, the Soil Conservation Service curve and the Modified Universal Soil Loss Equation functions, into a biogeochemistry model, Denitrification‐Decomposition (DNDC). These two features have been widely utilized to quantify surface runoff and soil erosion in a suite of hydrologic models. We incorporated these features in the DNDC model to allow the biogeochemical and hydrologic processes to exchange data at a daily time step. By including the new features, DNDC gained the additional ability to simulate both horizontal and vertical movements of water and nutrients. The revised DNDC was tested against data sets observed in a small watershed dominated by farmlands in a mountainous area of southwest China. The modeled surface runoff flow, subsurface drainage flow, sediment yield, and N loading were in agreement with observations. To further observe the behaviors of the new model, we conducted a sensitivity test with varied climate, soil, and management conditions. The results indicated that precipitation was the most sensitive factor determining the rate of N loading from the tested site. A Monte Carlo test was conducted to quantify the potential uncertainty derived by variations in four selected input parameters. This study demonstrates that it is feasible and effective to use enhanced biogeochemical models such as DNDC for quantifying N loadings by incorporating basic hydrological features into the model framework

Modeling nitrogen loading in a small watershed in southwest China using a DNDC model with hydrological enhancements

The degradation of water quality has been observed worldwide, and inputs of nitrogen (N), along with other nutrients, play a key role in the process of contamination. The quantification of N loading from non-point sources at a watershed scale has long been a challenge. Process-based models have been developed to address this problem. Because N loading from non-point sources result from interactions between biogeochemical and hydrological processes, a model framework must include both types of processes if it is to be useful. This paper reports the results of a study in which we integrated two fundamental hydrologic features, the SCS (Soil Conservation Service) curve function and the MUSLE (Modified Universal Soil Loss), into a biogeochemical model, the DNDC. The SCS curve equation and the MUSLE are widely used in hydrological models for calculating surface runoff and soil erosion. Equipped with the new added hydrologic features, DNDC was substantially enhanced with the new capacity of simulating both vertical and horizontal movements of water and N at a watershed scale. A long-term experimental watershed in Southwest China was selected to test the new version of the DNDC. The target watershed\u27s 35.1 ha of territory encompass 19.3 ha of croplands, 11.0 ha of forest lands, 1.1 ha of grassplots, and 3.7 ha of residential areas. An input database containing topographic data, meteorological conditions, soil properties, vegetation information, and management applications was established and linked to the enhanced DNDC. Driven by the input database, the DNDC simulated the surface runoff flow, the subsurface leaching flow, the soil erosion, and the N loadings from the target watershed. The modeled water flow, sediment yield, and N loading from the entire watershed were compared with observations from the watershed and yielded encouraging results. The sources of N loading were identified by using the results of the model. In 2008, the modeled runoff-induced loss of total N from the watershed was 904 kg N yr−1, of which approximately 67 % came from the croplands. The enhanced DNDC model also estimated the watershed-scale N losses (1391 kg N yr−1) from the emissions of the N-containing gases (ammonia, nitrous oxide, nitric oxide, and dinitrogen). Ammonia volatilization (1299 kg N yr−1) dominated the gaseous N losses. The study indicated that process-based biogeochemical models such as the DNDC could contribute more effectively to watershed N loading studies if the hydrological components of the models were appropriately enhanced

Clinical significance of obstructive sleep apnea in patients with acute coronary syndrome in relation to diabetes status.

Objective: The prognostic significance of obstructive sleep apnea (OSA) in patients with acute coronary syndrome (ACS) according to diabetes mellitus (DM) status remains unclear. We aimed to elucidate the association of OSA with subsequent cardiovascular events in patients with ACS with or without DM. Research design and methods: In this prospective cohort study, consecutive eligible patients with ACS underwent cardiorespiratory polygraphy between June 2015 and May 2017. OSA was defined as an Apnea Hypopnea Index ≥15 events/hour. The primary end point was major adverse cardiovascular and cerebrovascular events (MACCEs), including cardiovascular death, myocardial infarction, stroke, ischemia-driven revascularization, or hospitalization for unstable angina or heart failure. Results: Among 804 patients, 248 (30.8%) had DM and 403 (50.1%) had OSA. OSA was associated with 2.5 times the risk of 1 year MACCE in patients with DM (22.3% vs 7.1% in the non-OSA group; adjusted HR (HR)=2.49, 95% CI 1.16 to 5.35, p=0.019), but not in patients without DM (8.5% vs 7.7% in the non-OSA group, adjusted HR=0.94, 95% CI 0.51 to 1.75, p=0.85). Patients with DM without OSA had a similar 1 year MACCE rate as patients without DM. The increased risk of events was predominately isolated to patients with OSA with baseline glucose or hemoglobin A1c levels above the median. Combined OSA and longer hypoxia duration (time with arterial oxygen saturation22 min) further increased the MACCE rate to 31.0% in patients with DM. Conclusions: OSA was associated with increased risk of 1 year MACCE following ACS in patients with DM, but not in non-DM patients. Further trials exploring the efficacy of OSA treatment in high-risk patients with ACS and DM are warranted

Synergistic Gelation Properties of Gelatin and Polysaccharide Aqueous Mixtures

RÉSUMÉ: Les protéines et les polysaccharides sont deux composants essentiels de la nourriture qui contribuent à leurs microstructures et textures. En conséquence, des gels composés de mélanges de protéines et de polysaccharides sont actuellement développés et utilisés, à des fins de recherche, en tant que modèles pour comprendre la structure et les propriétés des aliments réels. Récemment, ces gels multicomposants ont également attiré beaucoup d'attention comme systèmes d'encapsulation et de distribution de molécules bioactives, car la gélification peut se produire sans l'utilisation d'agents de réticulation, d'enzyme, ou de traitement thermique. Les gels composés de mélanges de protéines et de polysaccharides, ou gels mixtes, peuvent souvent être formés à des concentrations beaucoup plus faibles et affichent des propriétés mécaniques améliorées par rapport aux gels composés d'un seul composant. Ces gels mixtes sont connus pour être sensibles à des facteurs environnementaux tels que le pH, la force ionique, le rapport massique protéine/polysaccharide et les caractéristiques intrinsèques des biopolymères (type de polysaccharide, poids moléculaire, etc.). Par conséquent, une compréhension fondamentale des interactions entre protéines et polysaccharides en solutions est nécessaire pour concevoir de nouveaux épaississants et/ou gélifiants, systèmes d'encapsulation et de livraison. Dans ce projet, nous avons systématiquement étudié le comportement gélifiant de mélanges binaires composés de quatre types de gélatine (la protéine gélifiante la plus connue et l'une des plus utilisées) et de deux polysaccharides aux charges opposées: le chitosane, à charge positive (le deuxième biopolymère naturel le plus abondant) et la gomme de xanthane, chargée négativement (XG) (en raison de ses applications importantes dans les industries alimentaire, cosmétique et pharmaceutique). L'objectif général de cette thèse est de comprendre et de proposer un mécanisme général de gélification pour des mélanges de gélatine et de polysaccharides. La première partie de cette thèse démontre qu'un équilibre délicat des charges est nécessaire pour former un gel mixte de gélatine et de gomme de xanthane à des concentrations très diluées (à une concentration environ 10 fois moindre par rapport à la concentration de gélification critique de la gélatine B uniquement) - illustrant le rôle important des interactions électrostatiques dans ces systèmes. Les expériences de rhéométrie ont montré que des systèmes composés de gélatine B de faible indice de Bloom (L-GB) et de XG gélifient légèrement au-dessus du point isoélectrique (pI) de L-GB (pI = 5.3) et affichent un module de stockage beaucoup plus élevé (G') par rapport à des solutions composées de XG ou de L-GB uniquement, avec G' atteignant un maximum à pH 5.5. v En outre, l'addition de sel entraîne une diminution significative de G' en raison de l'écrantage des charges. En outre, la microscopie confocale à balayage laser (CLSM) a révélé que la L-GB et le XG forment des agrégats dispersés à des pH inférieurs à 5.0, des réseaux colocalisés à pH 5.5 et enfin des réseaux complémentaires à des pH plus élevés (par exemple pH 8.0) - la structure du réseau se brisant avec l'addition de sel. Ces microstructures corrèlent avec les résultats de rhéologie et de potentiel zêta. Enfin, comme pour les gels de gélatine purs, les gels mixtes sont thermoréversibles, ce qui indique que les liaisons hydrogène jouent également un rôle important pendant le processus de gélification. Dans la deuxième partie de cette thèse, nous avons étudié les effets de l'indice de Bloom pour la GB, du rapport GB à XG, et du poids moléculaire de la XG sur les propriétés de gélification des mélanges GB/XG. Comme pour les mélanges L-GB/XG (faible indice de Bloom), les mélanges composés de GB à indice de Bloom élevé H-GB/XG présentent un G' maximum à un pH proche du pI de H-GB. Les mélanges (L- et H-GB)/XG possèdent des compositions optimales au-delà desquelles G' diminue. L'augmentation de l'indice de Bloom entraîne l'augmentation de G', alors que l'augmentation du poids moléculaire de la XG provoque l'effet inverse (ce qui peut sembler contre-intuitif) en raison des limitations de transfert de masse (diffusion). En fait, au pH optimal, le CLSM révèle que les mélanges GB/XG présentent également des transitions microstructurales reliées à la composition: d'agrégats discontinus (rapport GB/XG ≤ 1) à des réseaux superposés de GB et XG (ratio = 2-6), puis finalement une fragmentation du réseau (ratio = 8-10). Ces transitions microstructurales sont également corrélées aux propriétés rhéologiques mesurées. La micro-calorimétrie (micro-DSC) a finalement révélé que la XG adopte une conformation moléculaire plus stable avec l'addition de GB, ce qui augmente la gélification GB par la formation de triples hélices, comme l'indiquent la position et la surface des pics de transition. Dans la troisième partie de cette thèse, nous avons étendu notre étude en analysant les effets des types de gélatine (type A et B) et de la charge des polysaccharides (XG chargé négativement, chitosane chargé positivement (CHI)), afin d'évaluer si les caractéristiques observées dans les systèmes GB/XG constituent un comportement général, ou sont spécifiques à cette combinaison protéine/polysaccharide. Les deux types de gélatine ont des compositions différentes en acides aminés, et donc différents points isoélectriques. Les mélanges GB/polysaccharides présentent toujours un G' à un pH sensiblement supérieur au pI, tandis que les mélanges gélatine A vi (GA)/polysaccharides se comportent quelque peu différemment. Par exemple, les mélanges GA/XG montrent un G' maximum à un pH bien au-dessous du pI de GA (un résultat qui, nous soupçonnons, pourrait être dû à la distribution des charges dans la molécule de GA, mais cette hypothèse reste à être validée), tandis que les systèmes GA/CHI montrent une augmentation monotone de G' avec le pH, jusqu'à ce que le chitosane ne soit plus soluble en solution (au-delà de pH 6,0-6,5). Dans tous les cas, les microstructures des gels mixtes, dans les conditions optimales, sont caractérisées par des domaines pauvres et riches en biopolymères, et les résultats de micro-DSC révèlent que l'ajout des polysaccharides mène à l'augmentation de la formation de triples hélices de gélatine. La synthèse des résultats suggère que le mécanisme de gélification des systèmes mixtes de gélatine/polysaccharide peut être divisé en trois étapes principales: 1) la formation de complexes de gélatine/polysaccharide par attraction électrostatique à une température initialement élevée (au-dessus de la température de transition pelote/hélice de la gélatine); 2) la réduction de la distance entre les molécules de polysaccharide avec une modification de la conformation du polysaccharide, à des températures intermédiaires; 3) l'augmentation de la concentration locale en biopolymères due à un effet de pontage provoqué par la formation de triples hélices de la gélatine, sous la température de transition pelote-hélice de la gélatine, ainsi que la formation d'un réseau. Enfin, dans la quatrième et dernière partie de ce projet, nous avons commencé à étudier l'impact de la cinétique de gélification et du pH initial en comparant les propriétés des gels de gélatine/polysaccharide préparés selon 3 méthodes différentes: 1) par addition de HCl ou de NaOH en solution - c'est-à-dire par titration, un processus très rapide (~ 1 s) qui a été utilisé dans les trois premières parties de cette thèse; 2) par l'addition de glucono delta-lactone (GDL), ce qui ralentit l'acidification du milieu (~ 4-5 h); 3) par gélification induite par une phase vapeur (acidification très lente sans agitation, ~ 24 h). Nous avons constaté que les procédés d'acidification lente étendent significativement la gamme des compositions et des pH pour la formation de gels. Les gels mixtes obtenus par exposition à une vapeur d'acide présentent les meilleures propriétés mécaniques. Il apparaît que le processus de gélification est affecté par l'agitation, le taux d'acidification, le pH initial et le pH final. Ce projet a utilisé une gamme de techniques complémentaires incluant la rhéométrie, la calorimétrie et la microscopie, qui pourraient être utilisées pour explorer et comprendre le mécanisme de gélification propre à d'autres mélanges aqueux de protéines linéaires ou globulaires, et de polysaccharides. Il ouvre la voie à l'exploration et à la compréhension du comportement de systèmes plus complexes, tels que des émulsions préparées avec des mélanges aqueux de protéines et de polysaccharides. En résumé, ce projet fournit un ensemble de lignes directrices fondamentales pour la conception de nouveaux épaississants et/ou gélifiants à base de protéines et de polysaccharides, pour des applications alimentaires ou pharmaceutiques. ABSTRACT: Proteins and polysaccharides are two essential components in food, which contribute to structural and textural properties. As a result, gels comprising mixtures of proteins and polysaccharides are currently used, for research purposes, as models of multicomponent structures found in real foods. Recently, these multicomponent gels have attracted much attention for the protection of bioactive molecules when used as encapsulation and delivery systems, since gelation can occur without the use of crosslinking agents, heating or enzymes. Proteins/polysaccharides mixed gels can often be formed at much lower concentrations, and display enhanced mechanical properties compared to gels composed of only one component. These mixed gels are known to be sensitive to environmental factors like pH, ionic strength, protein to polysaccharide ratio, and biopolymer intrinsic characteristics (polysaccharide type, molecular weight, etc.). Therefore, a fundamental understanding of the interactions between proteins and polysaccharides in solutions is required to provide the guidelines to design such novel thickeners and/or gelling agents, encapsulation and delivery systems. In this project, we have systematically investigated the gelation behavior of binary mixtures comprising four types of gelatin (the most well-known and employed gelling protein), and two oppositely charged polysaccharides: the positively charged chitosan (the second most abundant natural biopolymer), and the negatively charged xanthan gum (XG) (due to its extensive applications in food, cosmetics and pharmaceutical industries). The general objective of this thesis is to understand and to propose a general gelation mechanism for gelatin/polysaccharide mixtures. The first part of this thesis demonstrates that a delicate charge balance is required to form a mixed gel of gelatin and xanthan gum at very dilute concentrations (about 10 times less concentrated compared to the critical gelling concentration of gelatin B (GB) alone) – illustrating the important role of electrostatic interactions in these systems. Rheometry experiments showed that mixed gels comprised of low Bloom index gelatin B (L-GB) and XG form slightly above the isoelectric point (pI) of L-GB (pI = 5.3) and display much higher storage modulus (G') compared to neat XG and L-GB solutions, with G' reaching a maximum at pH 5.5. Furthermore, salt addition causes a significant decrease in G' due to charge screening. Moreover, confocal laser scanning microscopy (CLSM) has revealed that L-GB and XG form dispersed aggregates at pH 5.0 and below, colocalized networks at pH 5.5, and finally complementary networks at higher pHs (e.g. pH 8.0) - the network structure however breaks down when salt is added. These microstructures correlate ix well with rheology and zeta potential results. Finally, like pure gelatin gels, mixed L-GB and XG gels are thermoreversible, indicating that hydrogen bonding also plays an important role during the gelling process. In the second part of this thesis, we further investigated the effects of GB Bloom index, GB to XG ratio, and XG molecular weight on the gelation properties of GB/XG mixtures. Similar to L-GB/XG, high Bloom index gelatin B (H-GB)/XG mixtures exhibit a maximum G' at a pH near the pI of H-GB. Both (L- and H-GB)/XG mixtures possess optimal compositions, beyond which G' decreases. Increasing the GB Bloom index results in a higher G', whereas increasing XG molecular weight causes the opposite effect (which might seem counter-intuitive) due to mass transfer (diffusion) limitations. In fact, at the optimum pH, CLSM reveals that GB/XG mixtures also display composition-dependent microstructural transitions: from discontinuous aggregates (GB/XG ratio ≤ 1) to continuous GB and XG colocalized networks (ratio = 2-6), followed by a fragmentation of the network (ratio = 8-10). These microstructural transitions also correlate well with the measured rheological properties. Micro-calorimetry (micro-DSC) finally revealed that XG adopts a more stable molecular conformation with the addition of GB, which in turn enhances GB gelling by triple helix formation, as indicated by the position and area of the transition peaks. In the third part of this thesis, we extended our investigation by analyzing the effects of gelatin types (Type A and B) and polysaccharide charge (negatively charged XG, positively charged chitosan (CHI)), to assess whether or not the observed features observed in GB/XG systems constitute a general behavior, or are particular to this protein/polysaccharide combination. The two types of gelatin have different compositions of amino acids, and thus isoelectric point. Gelatin B (GB)/polysaccharides mixtures always exhibit the highest G' at a pH near the pI of GB, whereas gelatin A (GA)/polysaccharides mixtures behave somewhat differently. For example, GA/XG displays the highest G' at a pH far below the pI of GA (a result which we suspect could be due to the charge distribution in GA at a molecular level, but that remains to be validated), while GA/CHI shows a monotonous increase in G' with pH, until chitosan is no longer soluble over pH (~6.0-6.5). In all cases, the microstructures of the mixed gels under the optimal conditions are characterized by biopolymer-rich and biopolymer-poor domains, and micro-DSC results reveal that both polysaccharides always enhance gelatin gelling by triple helix formation. x Overall, our results indicate that the gelation mechanism of gelatin/polysaccharide mixed systems can be divided into three main steps: 1) the formation of gelatin/polysaccharide complexes via electrostatic attraction at an initially elevated temperature (above the coil-to-helix transition temperature of gelatin); 2) the reduction of the distance between polysaccharide molecules along with a change in polysaccharide conformation at intermediate temperatures; 3) the increase in local biopolymer concentration due to a bridging effect caused by gelatin triple helices formation below the coil-to-helix transition temperature of gelatin, along with a network formation. Finally, in the fourth and last part of this project, we have started to investigate the impact of the gelling kinetics and initial starting pH by comparing the properties of gelatin/polysaccharide gels prepared following 3 different methods: 1) by the addition of HCl or NaOH solutions – i.e. titration, a very fast process (~ 1 s), which was used in the first three parts of this thesis; 2) by the addition of glucono delta-lactone (GDL), which slows down the acidification of the medium ( 4-5 hrs); 3) by vapor-induced gelification (very slow acidification without stirring, 24 hrs). It was found that slow acidification methods extend the range of compositions and pHs for gel formation. The vapor-induced mixed gels display the best mechanical properties. The gelation process is affected by stirring, acidification rate, initial pH and final pH. This project has used an extensive array of techniques including rheometry, calorimetry and microscopy, which could be used to explore and understand the gelation mechanism of other linear protein/polysaccharide or globular protein/polysaccharide aqueous mixtures. It paves the way to understand the behavior of more complicated systems, such as emulsions prepared by protein/polysaccharide aqueous mixtures. In summary, this project provides a set of fundamental guidelines to design novel thickeners and/or gelling agents based on proteins and polysaccharides, for food or pharmaceutical applications