Switchable metamaterial reflector/absorber for different polarized electromagnetic waves

We demonstrate a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes. Through biasing at different voltages to turn ON and OFF the diodes, we are able to switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave. By arranging orthogonally orientated resonant cells, the metamaterial can react to different polarized waves by selectively biasing the corresponding diodes. Both numerical simulations and microwave measurements have verified the performance.Comment: 11 pages, 4 figure

Carnitine metabolism to trimethylamine by an unusual Rieske-type oxygenase from human microbiota

Dietary intake of L-carnitine can promote cardiovascular diseases in humans through microbial production of trimethylamine (TMA) and its subsequent oxidation to trimethylamine N-oxide (TMAO) by hepatic flavin-containing monooxygenases. Although our microbiota are responsible for TMA formation from carnitine, the underpinning molecular and biochemical mechanisms remain unclear. In this study, using bioinformatics approaches, we first identified a two-component Rieske-type oxygenase/reductase (CntAB) and associated gene cluster proposed to be involved in carnitine metabolism in representative genomes of the human microbiota. CntA belongs to a group of previously uncharacterized Rieske-type proteins and has an unusual "bridging" glutamate but not the aspartate residue, which is believed to facilitate inter-subunit electron transfer between the Rieske centre and the catalytic mononuclear iron centre. Using Acinetobacter baumannii as the model, we then demonstrate that cntAB is essential in carnitine degradation to TMA. Heterologous overexpression of cntAB enables Escherichia coli to produce TMA, confirming that these genes are sufficient in TMA formation. Site-directed mutagenesis experiments have confirmed that this unusual "bridging glutamate" residue in CntA is essential in catalysis and neither mutant (E205D, E205A) is able to produce TMA. Together, our study reveals the molecular and biochemical mechanisms underpinning carnitine metabolism to TMA in human microbiota and assigns the role of this novel group of Rieske-type proteins in microbial carnitine metabolism

Exploring consumer online product returning behavior : Chinese e-consumers’ perspective

In the retail world, product returns are a common practice by consumers. Many businesses have been attempting to obtain more sales by providing customers with lenient return policies as well as customer-friendly return processes and procedures. Over the past decade, the issue of product returns by consumers is on the rise and drawing increased attention from practitioners and researchers. The objective of this thesis is to explore Chinese e-consumers’ perception of fraudulent returning behavior and identify the characteristics of Chinese consumers’ online returning behavior on fashion products, in the context of China’s thriving e-commerce market. Fashion products are the most popular items online, thus the thesis mainly focuses on fashion product returns. Mixed methods approach is employed in conducting the research. The author first conducts in-depth interviews with respondents, and then sends out an online survey. Both the qualitative and quantitative data are analyzed as to provide holistic results and findings for the thesis. Findings of this thesis provide an overview of Chinese consumers’ fashion product return motives, product return rates, demographical characteristics, and their attitudes towards fraudulent returning behavior. The theory of planned behavior proves to be suitable to explain the findings of this thesis and subsequently sheds light on the uniqueness of China’s online retail environment. Chinese online consumers are more critical of fraudulent returning behavior therefore the findings do not consider fraudulent returns as a problematic issue in China

Genetics and molecular mechanism of trimethylamine N-oxide demethylase of Methylocella silvestris BL2.

Methylocella silvestris, an alphaproteobacterium isolated from a forest soil, can grow on trimethylamine N-oxide (TMAO) as a sole nitrogen source, however, the molecular and biochemical mechanisms underpinning its growth remain unknown. Marker-exchange mutagenesis enabled the identification of several genes involved in TMAO metabolism, including Msil_3606, a permease of the amino acids-polyamine (APC) superfamily, and Msil_3603, consisting a N-terminal domain of unknown function (DUF1989) and a C-terminal tetrahydrofolate-binding domain. Null mutants of Msil_3603 and Msil_3606 can no longer grow on TMAO. Purified Msil_3603 from recombinant Escherichia coli can convert TMAO to dimethylamine and formaldehyde (1 TMAO ! 1 dimethylamine + 1 formaldehyde), confirming that it encodes a bona fide TMAO demethylase (Tdm). Site-directed mutagenesis, homology modelling and metal analyses by inorganic mass spectrometry have been applied to gain insight into metal stoichiometry and underlying catalytic mechanism of Tdm of M. silvestris. Herein, it is demonstrated that active Tdm has 1 molar equivalent of Zn2+ and 1 molar equivalent of non-haem Fe2+. Further investigation of Zn2+ and Fe2+-binding sites through homology modelling and site-directed mutagenesis revealed that Zn2+ is coordinated by a 3- sulfur-1-O motif. An aspartate residue (D198) likely bridges Fe2+ and Zn2+ centres. H276, and maybe H256, contribute to Fe2+ binding. Site-directed mutagenesis of Tdm also led to the identification of three hydrophobic aromatic residues likely involved in substrate coordination (F259, Y305, W321), potentially through a cation-π interaction. Furthermore, a cross-over experiment using a substrate intermediate analogue gave direct evidence that a trimethylamine-alike intermediate was produced during the Tdm catalytic cycle, suggesting TMAO has a dual role of being both a substrate and an oxygen donor for formaldehyde formation. In this thesis, I attempted to resolve 3D-structure of Tdm to investigate structure-function relationship. Various Tdm homologues and mutants have been screened for crystallisation. Tdm from Ruegeria pomeroyi DSS-3 forms small 2D plates, hence warrants further refinements. Although Tdm of R.pomeroyi has comparable activity to that of M. silvestris, it is different from the one of M.silvestris in that a trimer and more susceptible to EDTA chelator. Together, this study has contributed to the understanding of the genetic and biochemical mechanisms for TMAO degradation in M. silvestris, and provides novel insight into the role of Zn2+ and Fe2+ in the catalysis of TMAO demethylation by this unique oxygen-independent enzyme

The ∘\circ operation and ∗* operation of Cohen-Macaulay bipartite graphs

Let $G$ be a finite simple graph with the vertex set $V$ and let $I_G$ be its edge ideal in the polynomial ring $S=\mathbb{K}[x_V]$. In this paper, we compute the depth and the Castelnuovo--Mumford regularity of $S/I_G$ when $G=G_1\circ G_2$ or $G=G_1* G_2$ is a graph obtained from Cohen-Macaulay bipartite graphs $G_1$, $G_2$ by $\circ$ operation or $*$ operation, respectively.Comment: arXiv admin note: text overlap with arXiv:2308.0601

HCDG: A Hierarchical Consistency Framework for Domain Generalization on Medical Image Segmentation

Modern deep neural networks struggle to transfer knowledge and generalize across diverse domains when deployed to real-world applications. Currently, domain generalization (DG) is introduced to learn a universal representation from multiple domains to improve the network generalization ability on unseen domains. However, previous DG methods only focus on the data-level consistency scheme without considering the synergistic regularization among different consistency schemes. In this paper, we present a novel Hierarchical Consistency framework for Domain Generalization (HCDG) by integrating Extrinsic Consistency and Intrinsic Consistency synergistically. Particularly, for the Extrinsic Consistency, we leverage the knowledge across multiple source domains to enforce data-level consistency. To better enhance such consistency, we design a novel Amplitude Gaussian-mixing strategy into Fourier-based data augmentation called DomainUp. For the Intrinsic Consistency, we perform task-level consistency for the same instance under the dual-task scenario. We evaluate the proposed HCDG framework on two medical image segmentation tasks, i.e., optic cup/disc segmentation on fundus images and prostate MRI segmentation. Extensive experimental results manifest the effectiveness and versatility of our HCDG framework.Comment: this paper is currently not publishe

Molecular Hydrogen Therapy Ameliorates Organ Damage Induced by Sepsis

Since it was proposed in 2007, molecular hydrogen therapy has been widely concerned and researched. Many animal experiments were carried out in a variety of disease fields, such as cerebral infarction, ischemia reperfusion injury, Parkinson syndrome, type 2 diabetes mellitus, metabolic syndrome, chronic kidney disease, radiation injury, chronic hepatitis, rheumatoid arthritis, stress ulcer, acute sports injuries, mitochondrial and inflammatory disease, and acute erythema skin disease and other pathological processes or diseases. Molecular hydrogen therapy is pointed out as there is protective effect for sepsis patients, too. The impact of molecular hydrogen therapy against sepsis is shown from the aspects of basic vital signs, organ functions (brain, lung, liver, kidney, small intestine, etc.), survival rate, and so forth. Molecular hydrogen therapy is able to significantly reduce the release of inflammatory factors and oxidative stress injury. Thereby it can reduce damage of various organ functions from sepsis and improve survival rate. Molecular hydrogen therapy is a prospective method against sepsis