A Multilevel Study Of Supportive Leadership And Individual Work Outcomes: The Mediating Roles Of Team Cooperation, Job Satisfaction, And Team Commitment

Due to increasing empowerment in work teams, team leaders’ supportive role in helping team members perform their tasks is deemed important. The present study aimed at exploring the multilevel dynamics involving team leaders’ supportive leadership and individual work outcomes. Longitudinal survey data were collected from 536 employees in 69 teams of a large engineering company located in South Korea. The results of multilevel structural equation modeling showed that individuals’ perceptions of supportive leadership were positively related to their subsequent task performance, and that this relationship was mediated by team commitment. The relationship between individual-level perceptions of supportive leadership and organizational citizenship behavior (OCB) was mediated by job satisfaction and team commitment. On the other hand, team cooperation mediated the relationship between team-level perceptions of supportive leadership and OCB. These findings provide meaningful insights into multilevel mediation processes involving different levels of supportive leadership perceptions

Transcriptional Profiles of Treponema denticola in Response to Environmental Conditions

The periodontal pathogen T. denticola resides in a stressful environment rife with challenges, the human oral cavity. Knowledge of the stress response capabilities of this invasive spirochete is currently very limited. Whole genome expression profiles in response to different suspected stresses including heat shock, osmotic downshift, oxygen and blood exposure were examined. Most of the genes predicted to encode conserved heat shock proteins (HSPs) were found to be induced under heat and oxygen stress. Several of these HSPs also seem to be important for survival in hypotonic solutions and blood. In addition to HSPs, differential regulation of many genes encoding metabolic proteins, hypothetical proteins, transcriptional regulators and transporters was observed in patterns that could betoken functional associations. In summary, stress responses in T. denticola exhibit many similarities to the corresponding stress responses in other organisms but also employ unique components including the induction of hypothetical proteins

Akkermansia muciniphila-derived extracellular vesicles influence gut permeability through the regulation of tight junctions

The gut microbiota has an important role in the gut barrier, inflammation and metabolic functions. Studies have identified a close association between the intestinal barrier and metabolic diseases, including obesity and type 2 diabetes (T2D). Recently, Akkermansia muciniphila has been reported as a beneficial bacterium that reduces gut barrier disruption and insulin resistance. Here we evaluated the role of A. muciniphila-derived extracellular vesicles (AmEVs) in the regulation of gut permeability. We found that there are more AmEVs in the fecal samples of healthy controls compared with those of patients with T2D. In addition, AmEV administration enhanced tight junction function, reduced body weight gain and improved glucose tolerance in high-fat diet (HFD)-induced diabetic mice. To test the direct effect of AmEVs on human epithelial cells, cultured Caco-2 cells were treated with these vesicles. AmEVs decreased the gut permeability of lipopolysaccharide-treated Caco-2 cells, whereas Escherichia coli-derived EVs had no significant effect. Interestingly, the expression of occludin was increased by AmEV treatment. Overall, these results imply that AmEVs may act as a functional moiety for controlling gut permeability and that the regulation of intestinal barrier integrity can improve metabolic functions in HFD-fed mice.11Ysciescopuskc

Construction and Characterization of a cheA Mutant of Treponema denticola

The Treponema denticola cheA gene, encoding the central kinase of the general chemotaxis pathway, was analyzed for its role in chemotaxis and tissue penetration. The cheA gene was interrupted by insertion of an ermF-ermAM gene cassette. Reverse transcription-PCR confirmed that the other downstream chemotaxis genes within the same operon (cheW, cheX, and cheY) were still expressed in the cheA mutant strain. Lack of cheA resulted in decreased swarming on soft-agar swarm plates and failure to respond chemotactically to a mixture of nutrients. Behavioral analyses using video microscopy revealed that the cheA mutant exhibited coordinated cell movement. The cellular reversal frequency, however, was severely reduced, indicating that CheA in T. denticola mainly controls cellular reversal and that active chemotaxis signaling input is not required for coordination of flagellar rotation at both cell poles

Transcriptional profiles of Treponema denticola in response to environmental conditions.

The periodontal pathogen T. denticola resides in a stressful environment rife with challenges, the human oral cavity. Knowledge of the stress response capabilities of this invasive spirochete is currently very limited. Whole genome expression profiles in response to different suspected stresses including heat shock, osmotic downshift, oxygen and blood exposure were examined. Most of the genes predicted to encode conserved heat shock proteins (HSPs) were found to be induced under heat and oxygen stress. Several of these HSPs also seem to be important for survival in hypotonic solutions and blood. In addition to HSPs, differential regulation of many genes encoding metabolic proteins, hypothetical proteins, transcriptional regulators and transporters was observed in patterns that could betoken functional associations. In summary, stress responses in T. denticola exhibit many similarities to the corresponding stress responses in other organisms but also employ unique components including the induction of hypothetical proteins

Switching Modulation Method for Current-Fed Dual-Active-Bridge Converter to Improve Power Conversion Efficiency

A current-fed dual active bridge (CF-DAB) converter has attracted much attention in battery applications and energy storage systems (ESS) because of their zero-voltage-switching (ZVS) capability and high performance due to the high control degree of freedom. However, conventional switching algorithms cannot reduce the high current in low-side switches under the heavy load condition. It causes high conduction loss which decreases power conversion efficiency. In this paper, a new switching modulation method of the CF-DAB converter for the ESS application is proposed to improve the power conversion efficiency by reducing the conduction loss. The relationship between the pulse width modulation (PWM) and the phase shift modulation (PSM) is investigated and a PWM-plus-PSM modulation method is proposed to reduce the conduction loss. A 1-kW prototype CF-DAB converter is used to verify the effectiveness of the proposed switching modulation method

High Power Density Bidirectional Three-Port DC-DC Converter for Battery Applications in DC Microgrids

DC microgrids, which have a variety of energy sources must need energy storage systems (ESS)to stabilize the grid systems. A triple active bridge (TAB)converter has advantages of galvanic isolation, bidirectional power transfer, and small quantity of components. However, the conventional TAB converter requires power decoupling control to remove power correlation between ports, which brings complexity in control manner. In addition, it induces circulating current in the ESS port even when it is not used, which decreases the total power conversion efficiency. This paper presents an isolated bidirectional three-port DC-DC converter that has high power density, absence of the power decoupling control and the low circulating current in the ESS port remaining at zero power. All the functionality and performance of the proposed converter are verified by PSIM simulation and experiments with a 5-kW prototype converte

Interlink Three-Level Bidirectional DC-DC Converter with Asymmetrical Load Conditions

Due to dc based electric loads and renewable sources, the dc distribution system is an alternative future solution. Among the dc distribution systems, the bipolar dc type has higher performance and reliability than the unipolar one. To interlink two dc buses, an isolated bidirectional DC-DC converter is needed. A three-level dual-active-bridge DC-DC converter is proposed to interlink two bipolar de buses. Between two dc buses, a galvanic isolation is provided by the high frequency transformer of the three-level dual-active-bridge. Besides, an asymmetrical switching modulation is proposed to compensate asymmetrical load condition of the bipolar dc bus system. Finally, a 1-kW prototype is built to verify the proposed converter

Experimental and Digimat-FE Based Representative Volume Element Analysis of Dye-Mixed Colored Resin and Carbon Fiber

Recently, the automobile industry has demanded weight reduction, so research on materials is being actively conducted. Among this research, carbon fiber-reinforced composite materials are being studied a lot in the automobile industry due to their excellent mechanical properties, chemical resistance, and heat resistance. However, carbon fiber-reinforced composite materials have disadvantages, in that they are not free from color selection, and have weak interfacial bonding strength. In this study, a colored epoxy resin was prepared by mixing epoxy—which is a thermosetting resin according to the pigment concentration (0.1, 0.3, 0.5, 1.0 wt%)—and curing shrinkage. Thermal expansion characteristics were analyzed and the concentration of 0.5 wt% pigment showed the lowest shrinkage and thermal expansion characteristics. In addition, to measure the interfacial shear strength (IFSS) of the carbon fiber and the colored epoxy resin, the IFSS was obtained by performing a microdroplet debonding test, and the strength of the pigment concentration of 0.5 wt% was reduced to a relatively low level. Through these experiments, it was determined that an epoxy resin in which 0.5 wt% pigment is mixed is the optimal condition. Finally, using the composite material modeling software (Digimat 2020.0), the representative volume element (RVE) of the meso-scale was set, and interfacial properties of carbon fibers and colored epoxy resins were analyzed by interworking with general-purpose finite element analysis software (Abaqus CAE)