Molecular Simulation Study of Oil Hydrocarbons, Dispersants and Other Organics in Atmospheric Air/Water Interfaces

The main objective of this dissertation is to study the interfacial properties of organic contaminants, in particular green leaf volatiles (GLVs), oil hydrocarbons [mainly intermediate-volatile organic compounds (IVOCs) and semi-volatile organic compounds (SVOCs)], as well as surfactant species (i.e. DOSS and Span 80) from Corexit dispersants at atmospheric air/water and air/seawater interfaces. All these compounds can significantly contribute to the formation of secondary organic aerosols (SOAs). Furthermore, our simulation work on IVOCs, SVOCs and Corexit surfactants, combining with experiments from the Valsaraj group, suggests that these compounds can be adsorbed on the surface of seawater droplets and aerosolized into the atmosphere. These results suggest that sea-spray aerosols are a significant transport pathway for oil spill matter into the atmosphere, which has not been studied in detail until our studies. Classical molecular dynamics (MD) simulations along with experimental research were conducted to investigate the characteristics of those organic compounds at water and seawater interfaces with air. Our free energy results through potential of mean force (PMF) calculation show good agreement with experimental results of the 1-octanol/water partition coefficients for the four GLVs we studied (i.e. 2-methyl-3-buten-2-ol, methyl salicylate, cis-3-hexen-1-ol and cis-3-hexenylacetate). Furthermore, our PMF results indicate that these GLVs have deep free energy minima at the air/water interfaces, which implies that these compounds have a thermodynamic preference to remain at the air/water interfaces. Likewise, previous studies also suggest that common atmospheric oxidants also prefer to remain at the surface of water droplets. Overall, these results suggest that the air/water interface is the most likely reaction site for GLVs and other atmospheric oxidants. The interactions between n-alkanes from oil and Corexit surfactants near air/seawater interfaces were also studied. PMF calculations show that the n-alkanes, Span 80 and DOSS exhibit strong preferences to stay at the air/seawater interfaces. Our results suggest that n-alkanes have deeper free energy minima when Span 80 is present at the interface, as compared to when DOSS or no surfactants are present. Therefore, these species are likely to be ejected to the atmosphere adsorbed on the surface of seawater droplets, which form in significant quantities in the sea surface

A novel RNA extraction method for cyanobacteria

Research on production of polyhydroxyalkanoates (PHA) by microorganisms has captured attention over the last two decades, since PHA have similar properties as petroleum-based thermoplastics, yet are close to carbon neutral and made from renewable sources. Cyanobacteria are considered to be good PHA producers because of their simple nutrient requirements (mainly water, sunlight and CO2) and fast cell growth. However, knowledge of metabolisms behind PHA production by cyanobacteria is limited. Therefore, gene expression analysis of cyanobacteria is required to get a thorough understanding at the molecular level, and gene expression analysis requires the extraction of high quality RNA. Extracting high quality intact RNA from cyanobacteria is problematic due to their complicated cell wall structure and excessive polysaccharides produced by cells. Previous work on RNA extraction from cyanobacteria is either strain-specific or involves handling of hazardous chemicals like toxic chaotropic agents, saturated hot phenol or liquid nitrogen. With this work, we developed a low-cost RNA extraction method using a simple CTAB extraction buffer. Three morphologically distinct cyanobacteria strains, Synechocystis sp. PCC 6803, Plectonema sp. strain UTEX 1541, and Nostoc muscorum UTEX 1037 were used to testify the validity of this new method. Two traditional extraction protocols, using the Qiagen RNeasy Mini kit and TRIzol Reagent respectively for cyanobacteria were also optimized and analyzed with the same species. The newly developed CTAB method successfully extracted total RNA of high quality and quantity from the three selected strains, and the extracted total RNA were of sufficient quantity and quality for RT-PCR after DNase I treatment. Compared to the two traditional extraction methods, both the purity and the yield of extracted total RNA were greatly improved when using CTAB method: yields was improved up to 13 times higher, and both the A260/A280 and A260/A230 ratio indicated less contaminations in extracted RNA. Furthermore, the experimental cost of CTAB method was significantly lowered by up to 83%, yet still easy to perform

Atypical imaging of spinal tuberculosis: a case report and review of literature

This is a case report of spinal tuberculosis combined with sacroiliac joint tuberculosis, pulmonary tuberculosis, chest wall tuberculosis and tuberculous pleurisy and the image of the patient is rare, special and not typical and it looks like a halo sign. It has an important reference value for the diagnosis of spine tuberculosis although it is a rare imaging manifestation and diagnosis was confirmed by pathology after the surgery. Therefore atypical imaging is often appeared in clinical practice and it is meaningful and necessary for the diagnosis of atypical spinal tuberculosis combined with multiple organ tuberculosis.Pan African Medical Journal 2016; 2

Efficacy of Wushaoshe Qufeng Tablet and leflunomide combination therapy in the management of rheumatoid arthritis, and its influence on incidence of adverse drug reactions

Purpose: To study the effectiveness and safety of combined use of Wushaoshe Qufeng tablets andleflunomide in the treatment of rheumatoid arthritis patients.Methods: A retrospective trial was conducted among 120 patients with rheumatoid arthritis hospitalized in Heyuan Hospital of Traditional Chinese Medicine, Heyuan, from February 2020 to February 2021. The patients were equally divided into study group (n = 60) and control group (n = 60). Both groups received conventional treatment. in addition, the control group received leflunomide, whereas the experimental group received Wushaoshe Qufeng tablets. The two groups were compared with respect to laboratory indicators, TCM syndrome scores, and adverse events.Results: The post-treatment TCM syndrome scores was lower in the experimental group versus control group (p < 0.001). After treatment, the study group was superior to the control group in terms of their biochemical indicators (p < 0.001). Safety profile was better in the study group than in the control group (p < 0.05). Treatment effectiveness was significantly higher in the study group than in the control group (p < 0.05).Conclusion: Combined treatment of rheumatoid arthritis patients with Wushaoshe Qufeng tablets and leflunomide shows improved biochemical indicators, mitigates clinical symptoms, and enhances treatment effectiveness. Moreover, the combination therapy is safe, and therefore, should be considered for the management of rheumatoid arthritis patients

Spectral Compressive Sensing with Model Selection

The performance of existing approaches to the recovery of frequency-sparse signals from compressed measurements is limited by the coherence of required sparsity dictionaries and the discretization of frequency parameter space. In this paper, we adopt a parametric joint recovery-estimation method based on model selection in spectral compressive sensing. Numerical experiments show that our approach outperforms most state-of-the-art spectral CS recovery approaches in fidelity, tolerance to noise and computation efficiency.Comment: 5 pages, 2 figures, 1 table, published in ICASSP 201

Effectiveness of Mobile Phone Customer Retention Strategies

Using the 419,194 customers of a mobile operator as the sample, this research investigates the effectiveness of the company’s retention strategies. It examines the effect of such strategies on extending customer life cycle. We find that the retention policies and the incremental average revenue per user (ARPU) in the retention period over the month prior are positively correlated. In addition, the correlation between the retention polices and the increments of consumer consumption variables, such as the number of calls, the number of short messages and the value-added services, are also positive. Moreover, the significantly positive interaction terms between the retention bonus and the consumption increments suggest that the bonus affects the relative ARPU through the consumption variables. Finally, the retention strategies demonstrate the different effectiveness according to the three different calling plans. The managerial implications of our findings are discussed

Evolution of magnetic correlation in an inhomogeneous square lattice

We explore the magnetic properties of a two-dimensional Hubbard model on an inhomogeneous square lattice, which provides a platform for tuning the bandwidth of the flat band. In its limit, this inhomogeneous square lattice turns into a Lieb lattice, and it exhibits abundant properties due to the flat band structure at the Fermi level. By using the determinant quantum Monte Carlo simulation, we calculate the spin susceptibility, double occupancy, magnetization, spin structure factor, and effective pairing interaction of the system. It is found that the antiferromagnetic correlation is suppressed by the inhomogeneous strength and that the ferromagnetic correlation is enhanced. Both the antiferromagnetic correlation and ferromagnetic correlation are enhanced as the interaction increases. It is also found that the effective $d$-wave pairing interaction is suppressed by the increasing inhomogeneity. In addition, we also study the thermodynamic properties of the inhomogeneous square lattice, and the calculation of specific heat provide good support for our point. Our intensive numerical results provide a rich magnetic phase diagram over both the inhomogeneity and interaction

Receding Horizon Trajectory Optimization with Terminal Impact Specifications

The trajectory optimization problem subject to terminal impact time and angle specifications can be reformulated as a nonlinear programming problem using the Gauss pseudospectral method. The cost function of the trajectory optimization problem is modified to reduce the terminal control energy. A receding horizon optimization strategy is implemented to reject the errors caused by the motion of a surface target. Several simulations were performed to validate the proposed method via the C programming language. The simulation results demonstrate the effectiveness of the proposed algorithm and that the real-time requirement can be easily achieved if the C programming language is used to realize it

Name Your Colour For the Task: Artificially Discover Colour Naming via Colour Quantisation Transformer

The long-standing theory that a colour-naming system evolves under dual pressure of efficient communication and perceptual mechanism is supported by more and more linguistic studies, including analysing four decades of diachronic data from the Nafaanra language. This inspires us to explore whether machine learning could evolve and discover a similar colour-naming system via optimising the communication efficiency represented by high-level recognition performance. Here, we propose a novel colour quantisation transformer, CQFormer, that quantises colour space while maintaining the accuracy of machine recognition on the quantised images. Given an RGB image, Annotation Branch maps it into an index map before generating the quantised image with a colour palette; meanwhile the Palette Branch utilises a key-point detection way to find proper colours in the palette among the whole colour space. By interacting with colour annotation, CQFormer is able to balance both the machine vision accuracy and colour perceptual structure such as distinct and stable colour distribution for discovered colour system. Very interestingly, we even observe the consistent evolution pattern between our artificial colour system and basic colour terms across human languages. Besides, our colour quantisation method also offers an efficient quantisation method that effectively compresses the image storage while maintaining high performance in high-level recognition tasks such as classification and detection. Extensive experiments demonstrate the superior performance of our method with extremely low bit-rate colours, showing potential to integrate into quantisation network to quantities from image to network activation. The source code is available at https://github.com/ryeocthiv/CQForme