In this technical note, an adaptive cooperative output regulation problem for a class of nonlinear multi-agent systems is considered. The cooperative output regulation problem is first converted into ...an adaptive stabilization problem for an augmented multi-agent system. A distributed adaptive control law with adoption of Nussbaum gain technique is then proposed to globally stabilize this augmented system. This control scheme is designed such that, in the presence of unknown control direction and large parameter variations in each agent, the closed-loop system maintains global stability and the output of each agent tracks a class of prescribed signals asymptotically.
The hierarchical aggregation of molecular nanostructures from multiple components is a grand synthetic challenge, which requires highly selective linkage control. We demonstrate how two orthogonal ...linkage groups, that is, organotin and lanthanide cations, can be used to drive the aggregation of a giant molecular metal oxide superstructure. The title compound {(Sn(CH3)2)2O4{CeW5O18 TeW4O16CeSn(CH3)24TeW8O314}2}46− (1 a) features dimensions of ca. 2.2×2.3×3.4 nm3 and a molecular weight of ca. 25 kDa. Structural analysis shows the hierarchical aggregation from several independent subunits. Initial biomedical tests show that 1 features an inhibitory effect on the proliferation of HeLa cells based on an apoptosis pathway. In vivo experiments in mice reveal the antiproliferative activity of 1 and open new paths for further development of this new compound class.
Hierarchical assembly of a giant heterometallic polyoxotungstate supercluster with a molecular weight of ca. 25 kDa is reported. Geometrically unrestricted cerium(III) and geometrically restricted dimethyl tin cation linkers are used to gain access to a giant molecular species featuring three different polyoxometalate building units. The compound demonstrates in vitro and in vivo antiproliferative activity against HeLa cervical cancer cell lines.
In the course of our observations of the transmission of COVID-19 around the world, we perceived substantial concern about imported cases versus cases of local transmission. This study, therefore, ...tries to isolate cases due to local transmission (also called community spread) from those due to externally introduced COVID-19 infection, which can be key to understanding the spread pattern of the pandemic. In particular, we offer a probabilistic perspective to estimate the scale of the outbreak at the epicenter of the COVID-19 epidemic with an environmental focus. First, this study proposes a novel explanation of the probability of COVID-19 cases in the local population of the target city, in which the chain of probability is based on the assumption of independent distribution. Then it conducts a spatial statistical analysis on the spread of COVID-19, using two model specifications to identify the spatial dependence, more commonly known as the spillover effect. The results are found to have strong spatial dependence. Finally, it confirms the significance of residential waste in the transmission of COVID-19, which indicates that the fight against COVID-19 requires us to pay close attention to environmental factors. The method shown in this study is critical and has high practical value, because it can be easily applied elsewhere and to other future pandemics.
Carboxysomes are a family of bacterial microcompartments (BMCs), present in all cyanobacteria and some proteobacteria, which encapsulate the primary CO2-fixing enzyme, Rubisco, within a virus-like ...polyhedral protein shell. Carboxysomes provide significantly elevated levels of CO2 around Rubisco to maximize carboxylation and reduce wasteful photorespiration, thus functioning as the central CO2-fixation organelles of bacterial CO2-concentration mechanisms. Their intriguing architectural features allow carboxysomes to make a vast contribution to carbon assimilation on a global scale. In this review, we discuss recent research progress that provides new insights into the mechanisms of how carboxysomes are assembled and functionally maintained in bacteria and recent advances in synthetic biology to repurpose the metabolic module in diverse applications.
CO2-concentrating mechanisms (CCMs) provide a means for accumulating CO2 around Rubisco to overcome the inherent limitations of Rubisco and enhance CO2 fixation.Carboxysomes are proteinaceous organelles in cyanobacteria and some proteobacteria which serve as the central CO2-fixing factory of CCMs.Carboxysomes sequester the cellular Rubisco and carbonic anhydrase from the cytoplasm, using a selectively permeable shell that structurally resembles virus capsids.Great efforts have been made recently to advance our understanding of the molecular mechanisms underlying carboxysome structure, assembly, biogenesis, and physiology.Advances in fundamental knowledge about carboxysome assembly and function has stimulated rational design and engineering of the protein organelles for improving CO2 fixation and new functions.
Pyroptosis is a caspase-1 or caspase-4/5/11-dependent programmed cell death associated with inflammation, which is initiated by inflammasomes or cytosolic LPS in innate immunity. Sepsis is a ...life-threatening organ dysfunction caused by an imbalance in the body’s response to infection. It is a complex interaction between the pathogen and the host’s immune system. Neutrophils play the role of a double-edged sword in sepsis, and a number of studies have previously shown that regulation of neutrophils is the most crucial part of sepsis treatment. Pyroptosis is one of the important forms for neutrophils to function, which is increasingly understood as a host active immune response. There is ample evidence that neutrophil pyroptosis may play an important role in sepsis. In recent years, a breakthrough in pyroptosis research has revealed the main mechanism of pyroptosis. However, the potential value of neutrophil pyroptosis in the treatment of sepsis did not draw enough attention. A literature review was performed on the main mechanism of pyroptosis in sepsis and the potential value of neutrophils pyroptosis in sepsis, which may be suitable targets for sepsis treatment in future.
Under these rules, a newly emerged virus is normally assigned to a species based on phylogeny and taxonomy.4 Through DivErsity pArtitioning by hieRarchical Clustering-based analyses,5 the newly ...emerged coronavirus was deemed not sufficiently novel but is a sister virus to SARS-CoV, the primary viral isolate defining the species. For various reasons, the name of a disease and its causative viral pathogen can be different, as exemplified by acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV). Given that SARS-CoV-2 is already being used in the scientific literature, a name change at this stage would cause confusion in the scientific community.
Microbial biofilms are communities of aggregated microbial cells embedded in a self-produced matrix of extracellular polymeric substances (EPS). Biofilms are recalcitrant to extreme environments, and ...can protect microorganisms from ultraviolet (UV) radiation, extreme temperature, extreme pH, high salinity, high pressure, poor nutrients, antibiotics, etc., by acting as "protective clothing". In recent years, research works on biofilms have been mainly focused on biofilm-associated infections and strategies for combating microbial biofilms. In this review, we focus instead on the contemporary perspectives of biofilm formation in extreme environments, and describe the fundamental roles of biofilm in protecting microbial exposure to extreme environmental stresses and the regulatory factors involved in biofilm formation. Understanding the mechanisms of biofilm formation in extreme environments is essential for the employment of beneficial microorganisms and prevention of harmful microorganisms.
Brain injury is the main factor affecting the development and prognosis of the nervous system in premature infants. Early diagnosis and treatment are of great significance in reducing mortality and ...disability and improving the prognosis of premature infants. Craniocerebral ultrasound has become an important medical imaging method for evaluating the brain structure of premature infants due to its advantages of being non-invasive, cheap, simple, and bedside dynamic monitoring since it was applied to neonatal clinical practice. This article reviews the application of brain ultrasound to common brain injuries in premature infants.
The cyanobacterial thylakoid membrane represents a system that can carry out both oxygenic photosynthesis and respiration simultaneously. The organization, interactions and mobility of components of ...these two electron transport pathways are indispensable to the biosynthesis of thylakoid membrane modules and the optimization of bioenergetic electron flow in response to environmental changes. These are of fundamental importance to the metabolic robustness and plasticity of cyanobacteria. This review summarizes our current knowledge about the distribution and dynamics of electron transport components in cyanobacterial thylakoid membranes. Global understanding of the principles that govern the dynamic regulation of electron transport pathways in nature will provide a framework for the design and synthetic engineering of new bioenergetic machinery to improve photosynthesis and biofuel production. This article is part of a Special Issue entitled: Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux.
•Cyanobacterial thylakoid membranes carry out both oxygenic photosynthesis and respiration.•Electron transport components are located in the thylakoid membrane and functionally coordinate with each other.•Distribution and dynamics of electron transport components are physiologically regulated in response to environmental change.
Calcareous sands are known as problematic soils in nature and challenge geotechnical engineers in many practical projects. Microbially induced calcite precipitation (MICP) is an innovative soil ...improvement technique that uses biomineralisation processes to induce cementation in-situ. The work described in this paper investigates the strength, deformation, and microstructure characteristics of biocemented calcareous sand under different cementation solution to sample volume ratios. A series of laboratory experiments was conducted, including unconfined compressive strength tests, splitting, tensile (i.e., Brazilian) strength tests, and consolidated drained triaxial tests. The results indicate that an exponential function reasonably describes the unconfined compressive strength and splitting tensile strength with increasing cementation solution to sample volume ratios. The tangent modulus at 50% peak strength increases exponentially with an increase in cementation solution to sample volume ratio, whereas it increases linearly with an increase in strength. The strength parameters for this MICP-improved soil, including the peak cohesion and friction angle, are derived to facilitate engineering design. Microstructure analyses are used to illustrate the physical basis for the increase in strength and stiffness with increases in the calcite content, as demonstrated using the cementation solution to sample volume ratio.
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