The gastrointestinal (GI) tract represents a unique challenge to the mammalian immune system. It must tolerate the presence of the luminal microbiota and thus not respond to their products, but still ...protect the intestinal mucosa from potentially harmful dietary antigens and invading pathogens. The intestinal epithelium, composed of a single layer of cells, is crucial for preserving gut homeostasis and acts both as a physical barrier and as a coordinating hub for immune defense and crosstalk between bacteria and immune cells. We highlight here recent findings regarding communication between microbes and intestinal epithelial cells (IECs), as well as the immune mechanisms employed by distinct IEC subsets to promote homeostasis, emphasizing the central and active role that these cells play in host enteric defense.
The intestinal epithelium is an integral component of innate immunity, defending the host by actively responding through various mechanisms that protect the mucosal barrier.
IECs provide the first line of defense against noxious luminal stimuli, and professional immune cells are only activated once these defenses are overcome.
The epithelium primes and signals professional immune cells to promote an effective inflammatory/immune response.
The makeup of the intestinal epithelium is diverse and consists of multiple cell types (i.e., enterocytes, goblet cells, neuroendocrine cells, tuft cells, Paneth cells, and M cells), and these can develop further into specialized subsets.
Through their diverse functions, these different epithelial cell types work in concert to maintain intestinal homeostasis and promote host defense.
Catalysts for oxygen electrochemical processes are critical for the commercial viability of renewable energy storage and conversion devices such as fuel cells, artificial photosynthesis, and ...metal-air batteries. Transition metal oxides are an excellent system for developing scalable, non-noble-metal-based catalysts, especially for the oxygen evolution reaction (OER). Central to the rational design of novel catalysts is the development of quantitative structure–activity relationships, which correlate the desired catalytic behavior to structural and/or elemental descriptors of materials. The ultimate goal is to use these relationships to guide materials design. In this study, 101 intrinsic OER activities of 51 perovskites were compiled from five studies in literature and additional measurements made for this work. We explored the behavior and performance of 14 descriptors of the metal–oxygen bond strength using a number of statistical approaches, including factor analysis and linear regression models. We found that these descriptors can be classified into five descriptor families and identify electron occupancy and metal–oxygen covalency as the dominant influences on the OER activity. However, multiple descriptors still need to be considered in order to develop strong predictive relationships, largely outperforming the use of only one or two descriptors (as conventionally done in the field). We confirmed that the number of d electrons, charge-transfer energy (covalency), and optimality of eg occupancy play the important roles, but found that structural factors such as M–O–M bond angle and tolerance factor are relevant as well. With these tools, we demonstrate how statistical learning can be used to draw novel physical insights and combined with data mining to rapidly screen OER electrocatalysts across a wide chemical space.
Understanding elementary excitations and their couplings in condensed matter systems is critical for developing better energy-conversion devices. In thermoelectric materials, the heat-to-electricity ...conversion efficiency is directly improved by suppressing the propagation of phonon quasiparticles responsible for macroscopic thermal transport. The current record material for thermoelectric conversion efficiency, SnSe, has an ultralow thermal conductivity, but the mechanism behind the strong phonon scattering remains largely unknown. From inelastic neutron scattering measurements and first-principles simulations, we mapped the four-dimensional phonon dispersion surfaces of SnSe, and found the origin of the ionic-potential anharmonicity responsible for the unique properties of SnSe. We show that the giant phonon scattering arises from an unstable electronic structure, with orbital interactions leading to a ferroelectric-like lattice instability. The present results provide a microscopic picture connecting electronic structure and phonon anharmonicity in SnSe, and offers new insights on how electron-phonon and phonon-phonon interactions may lead to the realization of ultralow thermal conductivity.
Redox chemistry provides the fundamental basis for numerous energy-related electrochemical devices, among which are electrolysers,fuel cells and batteries. Throughout its history, Li-ion battery ...technology (LIB)has relied on cationic redox reactionsas the primary source of energy storage capacity. This is no longer true with the recent discovery of Li-driven reversible formation of (O2)n species in new layered oxides that have led to staggering increases in energy storage capacity. Such ndings could oer a transformative approach to creating advanced energy materials, not only for lithium storage but also for the oxygen evolution reaction (OER), as both involve (OO) bond formation. The exploration of these new opportunities calls for a better understanding and rationalization of the science underpinning anionic redox activity.In this Commentary, we aim to raise the energy communitys awareness of the benets that this new vision could bringto materials design for energy storage and conversion applications.
MOF-808, a Zr(IV)-based metal–organic framework, has been proven to be a very effective heterogeneous catalyst for the hydrolysis of the peptide bond in a wide range of peptides and in hen egg white ...lysozyme protein. The kinetic experiments with a series of Gly-X dipeptides with varying nature of amino acid side chain have shown that MOF-808 exhibits selectivity depending on the size and chemical nature of the X side chain. Dipeptides with smaller or hydrophilic residues were hydrolyzed faster than those with bulky and hydrophobic residues that lack electron rich functionalities which could engage in favorable intermolecular interactions with the btc linkers. Detailed kinetic studies performed by 1H NMR spectroscopy revealed that the rate of glycylglycine (Gly-Gly) hydrolysis at pD 7.4 and 60 °C was 2.69 × 10–4 s–1 (t 1/2 = 0.72 h), which is more than 4 orders of magnitude faster compared to the uncatalyzed reaction. Importantly, MOF-808 can be recycled several times without significantly compromising the catalytic activity. A detailed quantum-chemical study combined with experimental data allowed to unravel the role of the {Zr6O8} core of MOF-808 in accelerating Gly-Gly hydrolysis. A mechanism for the hydrolysis of Gly-Gly by MOF-808 is proposed in which Gly-Gly binds to two Zr(IV) centers of the {Zr6O8} core via the oxygen atom of the amide group and the N-terminus. The activity of MOF-808 was also demonstrated toward the hydrolysis of hen egg white lysozyme, a protein consisting of 129 amino acids. Selective fragmentation of the protein was observed with 55% yield after 25 h under physiological pH.
Purpose
The purpose of this paper is to explore the relationship between transformational leadership and employees’ work engagement based on fit theory. The paper reports an investigation into the ...way in which employees’ perceptions of transformational leadership and person-job fit affect their work engagement.
Design/methodology/approach
To test the authors’ hypotheses, the authors performed structure equation modeling with maximum likelihood estimation on Mplus with bootstrapping proposed by Hayes (2009) with data from 691 full-time employees in China.
Findings
The results indicate that transformational leadership has as significant influence on employees’ work engagement as person-job fit in China. Moreover, employees’ perception of person-job fit is found to partially mediate the relationship between transformational leadership and employees’ work engagement.
Research limitations/implications
There is a possible bias arising from the use of cross-sectional data. However, certain methods were implemented to minimize it, including survey design and data analysis.
Practical implications
The paper proposes a number of practical implications for policy makers, HR managers and transformational leaders relating to issues associated with improving levels of employee engagement.
Originality/value
The study contributes to developing leadership and engagement theory by examining a previously unexplored mediator – person-job fit – in a neglected cultural setting. This study promises to open new research avenues in this area.
Background
Dexmedetomidine has been shown to reduce pro‐inflammatory cytokine levels in rats with sepsis and in severely ill patients. The aim of this study was to document the effects of ...dexmedetomidine on inflammatory responses during and after surgery.
Materials and Methods
Patients undergoing laparoscopic cholecystectomy were enrolled. After induction of anaesthesia, patients in the dexmedetomidine group (n = 24, group D) received a loading dose of dexmedetomidine (1.0 μg/kg), followed by infusion of dexmedetomidine at 0.5 μg/kg/h. A saline‐treated group (n = 23, group S) served as a control. Intraoperative mean arterial pressure (MAP), heart rate (HR), and amount of rescue analgesic administered as post‐anaesthetic care were compared between the groups. The pro‐inflammatory cytokines tumour necrosis factor (TNF)‐α, interleukin (IL)‐1β, and IL‐6, and anti‐inflammatory cytokines IL‐4 and IL‐10 were quantified by sandwich enzyme‐linked immunoassay at three times: after anaesthesia induction (T0), at the end of peritoneal closure (T1), and 60 min after surgery (T2). The C‐reactive protein (CRP) level and leukocyte count were measured on post‐operative day 1.
Results
At time points T1 and T2, the IL‐1β, TNF‐α, and IL‐10 levels were lower in group D than in group S (P < 0.05). The CRP level and leukocyte count on post‐operative day 1 were also lower in group D (P < 0.05), as were intraoperative MAP, HR, and amount of rescue analgesic administered after surgery.
Conclusions
Dexmedetomidine administration during surgery reduced intraoperative and post‐operative secretion of cytokines, as well as post‐operative leukocyte count and CRP level.
•We show the advantage of the RHE reference in pH partial reaction order studies.•We discuss possible pH-dependent reaction steps for the oxygen evolution reaction.•A method to convert reaction ...orders from SHE to RHE reference is provided.•The reaction order with respect to RHE is measured for RuO2.•Dependencies of RHE reaction order on material properties are analyzed.
Understanding the mechanism of the oxygen evolution reaction (OER) is essential to develop better electrocatalysts for solar fuel generation. Measuring the pH dependence of the OER activity can provide insights on the reaction path that are otherwise difficult to access experimentally, in particular on the coupling of protons and electrons during the reaction. We argue that the use of a pH-dependent reference electrode, such as the reversible hydrogen electrode, is more suitable for these studies as it assures that the overpotential is fixed while varying the pH. We provide criteria for pH dependence when this reference is used and validate the existing results with our measurements on RuO2 powders. A statistical analysis of the existing results allows us to sketch trends in the reaction order on pH with respect to the number of d electrons, oxidation states, and crystal families, providing the groundwork for future OER mechanistic studies on oxides.
Having geographical proximity and a high volume of trade with China, the first country to record an outbreak of the new Coronavirus disease (COVID-19), Vietnam was expected to have a high risk of ...transmission. However, as of 4 April 2020, in comparison to attempts to containing the disease around the world, responses from Vietnam are seen as prompt and effective in protecting the interests of its citizens, with 239 confirmed cases and no fatalities. This study analyzes the situation in terms of Vietnam’s policy response, social media and science journalism. A self-made web crawl engine was used to scan and collect official media news related to COVID-19 between the beginning of January and April 4, yielding a comprehensive dataset of 14,952 news items. The findings shed light on how Vietnam—despite being under-resourced—has demonstrated political readiness to combat the emerging pandemic since the earliest days. Timely communication on any developments of the outbreak from the government and the media, combined with up-to-date research on the new virus by the Vietnamese science community, have altogether provided reliable sources of information. By emphasizing the need for immediate and genuine cooperation between government, civil society and private individuals, the case study offers valuable lessons for other nations concerning not only the concurrent fight against the COVID-19 pandemic but also the overall responses to a public health crisis.
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