University of Macau

About: University of Macau is a education organization based out in Macao, Macau, China. It is known for research contribution in the topics: Computer science & Population. The organization has 6636 authors who have published 18324 publications receiving 327384 citations. The organization is also known as: UM & UMAC.

Highly dispersed graphene oxide electrodeposited carbon fiber reinforced cement-based materials with enhanced mechanical properties

Abstract: Mechanical behavior of carbon fiber (CF) reinforced cement-based materials greatly depends on the dispersion of CF and interfacial properties between the CF and cement matrix. In this study, graphene oxide (GO) was utilized to modify the surface properties of CF, including the roughness, wettability and chemical reactivity, and the graphene oxide/carbon fiber (GO/CF) hybrid fibers were fabricated by a newly designed electrophoretic depositing method. The scanning electron microscopy and contact angle measurement results indicated that GO/CF hybrid fibers not only had a rougher surface which was expected to improve the physical friction when CF was pulled out from cement matrix, but also had a higher wettability surface that made it easier to contact with cement hydrates as nucleation sites. In addition, GO/CF hybrid fibers were capable of high chemical reactivity due to the introduction of GO with many functional groups, which ensured them more likely to interact with cement hydrates due to the hydrogen bonding at interface and therefore benefited to strengthen the bonding between the CF and cement matrix. In terms of mechanical behavior, three-point bending test showed that compared with the CF reinforced cement paste, flexural strength of the GO/CF hybrid fibers reinforced cement paste was enhanced by 14.58%, and could be further improved by 10.53% when the GO/CF hybrid fibers were pre-dispersed in the GO solution and then mixed with cement powders. The larger electrostatic repulsion and steric stabilization led to the better dispersion of GO/CF hybrid fibers in GO solution, which were responsible for the further mechanical enhancement of cement paste. In conclusion, the research outcomes provided a novel way for utilizing GO as both of dispersant and surface modifier to improve the dispersion of CF in cement and strengthen its bonding with cement hydrates, consequently achieving a significant enhancement in the mechanical properties of cement paste.

Fuzzy Adaptive Inverse Compensation Method to Tracking Control of Uncertain Nonlinear Systems With Generalized Actuator Dead Zone

Abstract: This paper solves the problem of adaptive fuzzy inverse compensation control for an uncertain nonlinear system whose actuator is subjected to generalized dead-zone nonlinearity. By defining a continuous connection function and combining with the mean-value theorem, the generalized dead zone is first decomposed into a nominal asymmetric dead zone multiplying an uncertain continuous input function. Afterward, a smooth inversion and its parameterization are further proposed such that a new expression of adaptive asymmetric dead-zone compensation error is established in Theorems 1 and 2. With such an expression, the fuzzy systems can be successfully embedded into a compensation structure to indirectly handle uncertain input dynamics. In addition, a separation scheme is developed to construct two online estimators. Based on the above design procedure, an adaptive inverse compensator for generalized dead zone is built eventually. With the backstepping iteration design of compensator input, an adaptive fuzzy controller is developed to establish the closed-loop system stability. Finally, two simulations are conducted to illustrate the effectiveness and applicability of the proposed control scheme.

Discovery of pentacyclic triterpenoids as potential entry inhibitors of influenza viruses.

Abstract: Entry inhibitors are of particular importance in current efforts to develop a new generation of anti-influenza virus drugs. Here we report certain pentacyclic triterpenes exhibiting conserved structure features and with in vitro anti-influenza virus activity comparable to and even higher than that of oseltamivir. Mechanistic studies indicated that these lead triterpenoids bind tightly to the viral envelope hemagglutinin (HA), disrupting the interaction of HA with the sialic acid receptor and thus the attachment of viruses to host cells. Docking studies suggest that the binding pocket within HA for sialic acid receptor potentially acts as a targeting domain, and this is supported by structure–activity data, sialic acid competition studies, and broad anti-influenza spectrum as well as less induction of drug resistance. Our study might establish the importance of triterpenoids for development of entry inhibitors of influenza viruses.

Getting bank financing: A study of Vietnamese private firms

Abstract: Private firms in transition economies are operating in an extremely uncertain environment, with underdeveloped market institutions, poorly defined property rights, and absence of reliable business data. This raises a very basic question of how owners of these firms persuade bankers to make much needed loans. This study employs an institutional perspective and argues that firms' legitimacy positively influences their accessibility to bank financing. Specifically, this study develops a model that links networking, professional management practices, and growth stage with bank financing and tests that model using a sample of Vietnamese private firms. The results support the hypotheses that growth stage and networking greatly influence firms' accessibility to bank financing, and that the impact of networking on financing is contingent on the growth stage.

Longitudinal Associations between Parenting and Youth Adjustment in Twelve Cultural Groups: Cultural Normativeness of Parenting as a Moderator.

Abstract: To examine whether the cultural normativeness of parents' beliefs and behaviors moderates the links between those beliefs and behaviors and youths' adjustment, mothers, fathers, and children (N = 1,298 families) from 12 cultural groups in 9 countries (China, Colombia, Italy, Jordan, Kenya, Philippines, Sweden, Thailand, and the United States) were interviewed when children were, on average, 10 years old and again when children were 12 years old. Multilevel models examined 5 aspects of parenting (expectations regarding family obligations, monitoring, psychological control, behavioral control, warmth/affection) in relation to 5 aspects of youth adjustment (social competence, prosocial behavior, academic achievement, externalizing behavior, internalizing behavior). Interactions between family level and culture-level predictors were tested to examine whether cultural normativeness of parenting behaviors moderated the link between those behaviors and children's adjustment. More evidence was found for within- than between-culture differences in parenting predictors of youth adjustment. In 7 of the 8 instances in which cultural normativeness was found to moderate the link between parenting and youth adjustment, the link between a particular parenting behavior and youth adjustment was magnified in cultural contexts in which the parenting behavior was more normative. (PsycINFO Database Record