An Improved Unscented Kalman Filter for Discrete Nonlinear Systems with Random Parameters

This paper investigates the nonlinear unscented Kalman filtering (UKF) problem for discrete nonlinear dynamic systems with random parameters. We develop an improved unscented transformation by incorporating the random parameters into the state vector to enlarge the number of sigma points. The theoretical analysis reveals that the approximated mean and covariance via the improved unscented transformation match the true values correctly up to the third order of Taylor series expansion. Based on the improved unscented transformation, an improved UKF method is proposed to expand the application of the UKF for nonlinear systems with random parameters. An application to the mobile source localization with time difference of arrival (TDOA) measurements and sensor position uncertainties is provided where the simulation results illustrate that the improved UKF method leads to a superior performance in comparison with the normal UKF method

Responsive aqueous foams stabilized by silica nanoparticles hydrophobized in situ with a conventional surfactant

In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report a facile protocol to obtain responsive surface-active nanoparticles and their use in preparing responsive particle-stabilized foams. Hydrophilic silica nanoparticles are initially hydrophobized in situ with a trace amount of a conventional cationic surfactant in water, rendering them surface-active such that they stabilize aqueous foams. The latter can then be destabilized by adding equal moles of an anionic surfactant, and restabilized by adding another trace amount of the cationic surfactant followed by shaking. The stabilization–destabilization of the foams can be cycled many times at room temperature. The trigger is the stronger electrostatic interaction between the oppositely charged surfactants than that between the cationic surfactant and the negatively charged particles. The added anionic surfactant tends to form ion pairs with the cationic surfactant, leading to desorption of the latter from particle surfaces and dehydrophobization of the particles. Upon addition of another trace amount of cationic surfactant, the particles are rehydrophobized in situ and can then stabilize foams again. This principle makes it possible to obtain responsive surface-active particles using commercially available inorganic nanoparticles and conventional surfactants

Feed types driven differentiation of microbial community and functionality in marine integrated multitrophic aquaculture system

Integrated multi trophic aquaculture (IMTA) improves the production of aquatic animals by promoting nutrient utilization through different tropical levels. Microorganisms play an important role in elements cycling, energy flow and farmed-species health. The aim of this study was to evaluate how feed types, fresh frozen fish diet (FFD) or formulated diet (FD), influence the microbial community diversity and functionality in both water and sediment in a marine IMTA system. Preferable water quality, higher animal yields and higher cost efficiency were achieved in the FD pond. Feed types changed the pond bacterial community distribution, especially in the rearing water. The FFD pond was dominated with Cyanobacteria in the water, which played an important role in nitrogen fixation through photosynthesis due to the high nitrogen input of the frozen fish diet. The high carbohydrate composition in the formulated diet triggered higher metabolic pathways related to carbon and lipid metabolism in the water of the FD pond. Sediment had significantly higher microbial diversity than the rearing water. In sediment, the dominating genus, Sulfurovum and Desulfobulbus, were found to be positively correlated by network analysis, which had similar functionality in sulfur transformation. The relatively higher rates of antibiotic biosynthesis in the FFD sediment might be related to the pathogenic bacteria introduced by the trash fish diet. The difference in microbial community composition and metabolic pathways may be associated with the different pathways for nutrient cycling and animal growth performance. The formulated diet was determined to be more ecologically and economically sustainable than the frozen fish diet for marine IMTA pond systems.</p

Research on the Concentration Prediction of Nitrogen in Red Tide Based on an Optimal Grey Verhulst Model

In order to reduce the harm of red tide to marine ecological balance, marine fisheries, aquatic resources, and human health, an optimal Grey Verhulst model is proposed to predict the concentration of nitrogen in seawater, which is the key factor in red tide. The Grey Verhulst model is established according to the existing concentration data series of nitrogen in seawater, which is then optimized based on background value and time response formula to predict the future changes in the nitrogen concentration in seawater. Finally, the accuracy of the model is tested by the posterior test. The results show that the prediction value based on the optimal Grey Verhulst model is in good agreement with the measured nitrogen concentration in seawater, which proves the effectiveness of the optimal Grey Verhulst model in the forecast of red tide

Research on the Concentration Prediction of Nitrogen in Red Tide Based on an Optimal Grey Verhulst Model

In order to reduce the harm of red tide to marine ecological balance, marine fisheries, aquatic resources, and human health, an optimal Grey Verhulst model is proposed to predict the concentration of nitrogen in seawater, which is the key factor in red tide. The Grey Verhulst model is established according to the existing concentration data series of nitrogen in seawater, which is then optimized based on background value and time response formula to predict the future changes in the nitrogen concentration in seawater. Finally, the accuracy of the model is tested by the posterior test. The results show that the prediction value based on the optimal Grey Verhulst model is in good agreement with the measured nitrogen concentration in seawater, which proves the effectiveness of the optimal Grey Verhulst model in the forecast of red tide

Thermoresponsive Pickering emulsions stabilized by silica nanoparticles in combination with alkyl polyoxyethylene ether nonionic surfactant

We put forward a simple protocol to prepare thermo-responsive Pickering emulsions. Using hydrophilic silica nanoparticles in combination with a low concentration of alkyl polyoxyethylene monododecyl ether (C12En) nonionic surfactant as emulsifier, oil-in-water (o/w) emulsions can be obtained which are stable at room temperature but demulsified at elevated temperature. The stabilization can be restored once the separated mixture is cooled and re-homogenized, and this stabilization-destabilization behavior can be cycled many times. It is found that the adsorption of nonionic surfactant at the silica nanoparticle-water interface via hydrogen bonding between the oxygen atoms in the polyoxyethylene headgroup and the SiOH groups on particle surfaces at low temperature is responsible for the in situ hydrophobization of the particles rendering them surface-active. De-hydrophobization can be achieved at elevated temperature due to weakening or loss of this hydrogen bonding. The time required for demulsification decreases with increasing temperature and the temperature interval between stabilization and destabilization of the emulsions is affected by the surfactant headgroup length. Experimental evidence including microscopy, adsorption isotherms and three-phase contact angles is provided to support the mechanism

Intestinal microbiota: a new perspective on delaying aging?

The global aging situation is severe, and the medical pressures associated with aging issues should not be underestimated. The need and feasibility of studying aging and intervening in aging have been confirmed. Aging is a complex natural physiological progression, which involves the irreversible deterioration of body cells, tissues, and organs with age, leading to enhanced risk of disease and ultimately death. The intestinal microbiota has a significant role in sustaining host dynamic balance, and the study of bidirectional communication networks such as the brain–gut axis provides important directions for human disease research. Moreover, the intestinal microbiota is intimately linked to aging. This review describes the intestinal microbiota changes in human aging and analyzes the causal controversy between gut microbiota changes and aging, which are believed to be mutually causal, mutually reinforcing, and inextricably linked. Finally, from an anti-aging perspective, this study summarizes how to achieve delayed aging by targeting the intestinal microbiota. Accordingly, the study aims to provide guidance for further research on the intestinal microbiota and aging

Translation, adaptation, and initial evaluation of a guided self-help intervention to reduce psychological distress among nurses during COVID-19 in China

BackgroundThis study aimed to reduce the unprecedented and intense psychological distress that nurses were forced to experience during the COVID-19 pandemic. A Chinese version of the World Health Organization's Self-Help Plus (SH+) intervention guide was adapted and tested among nurses. The objective of this study was to translate and adapt the SH+ guideline into the Chinese version and to test its feasibility in reducing psychological distress among nurses during COVID-19.MethodsA staged approach comprising translation, adaptations, initial evaluation by pilot implementation, and a qualitative process evaluation was conducted in two hospitals in Xi'an, China. The translation of the Chinese version was authorized by the World Health Organization. We adapted SH+ for use among clinical nurses working during the pandemic in China through a qualitative process evaluation, which was guided by the descriptive phenomenological study design. The outcomes of the pilot included psychological distress, psychological flexibility, depressive and anxiety symptoms, post-traumatic stress disorder (PTSD) symptoms, and subjective psychological wellbeing, which were assessed using the Kessler 6 symptom checklist, the Comprehensive Assessment of ACT Process (CompACT), the Patient Health Questionnaire-9 (PHQ-9), the Generalized Anxiety Disorder scale (GAD-7), the PTSD Checklist-Civilian Version (PCL-C), and the Index of Wellbeing (IWB), respectively.ResultsThe SH+ materials, including audio-recorded sessions and an accompanying illustrated manual, were translated into Chinese and adapted in line with feedback from the nurses. An uncontrolled pilot study (n = 28) for 5 weeks showed a statistically significant reduction of psychological distress (mean difference in Kessler 6 score, −2.74; 95% CI [−3.71, −1.78]; p &lt; 0.001). We also found improvements in psychological flexibility (mean difference in CompACT score, 6.89; 95% CI [−12.35, −4.47]; p &lt; 0.001), subjective psychological wellbeing (mean difference in IWB score, 0.86; 95% CI [0.07, 1.65]; p &lt; 0.05), and depressive symptoms (mean difference in PHQ-9 score, −1.52; 95% CI [−2.78, −0.26]; p &lt; 0.05). The process evaluation showed that nurses found the SH+ program very useful but difficult to adhere to.ConclusionWe found that the translated Chinese version of SH+ was applicable and feasible in the Chinese cultural context. There was a potential effect of adapted SH + in reducing nurses' psychological distress during COVID-19 and suggested the value of exploring strategies to increase adherence to the program