Optimal design for epoxy polymer concrete based on mechanical properties and durability aspects

Polymer concrete has shown a number of promising applications in building and construction, but its mix design process remains arbitrary due to lack of understanding of how constituent materials influence performance. This paper investigated the effect of resin-to-filler ratio and matrix-to-aggregate ratio on mechanical and durability properties of epoxy-based polymer concrete in order to optimise its mix design. A novel combination of fire-retardant, hollow microsphere and fly ash fillers were used and specimens were prepared using resin-to-filler ratios by volume from 100:0 to 40:60 at 10% increment. Another group of specimens were prepared using matrix-to-aggregate ratios from 1:0 decreasing to 1:0.45, 1:0.90 and 1:1.35 by weight at constant resin-to-filler ratio. The specimens were inspected and tested under compressive, tensile and flexural loading conditions. The epoxy polymer matrix shows excellent durability in air, water, saline solution, and hygrothermal environments. Results show that the resin-to-filler ratio has significant influence on the spatial distribution of aggregates. Severe segregation occurred when the matrix contained less than 40% filler while a uniform aggregate distribution was obtained when the matrix had at least 40% filler. Moreover, the tensile strength, flexural strength and ductility decreased with decrease in matrix-to-aggregate ratio. Empirical models for polymer concrete were proposed based on the experimental results. The optimal resin-to-filler ratio was 70:30 and 60:40 for non-uniform and uniform distribution of aggregates, respectively, while a matrix-to-aggregate ratio of 1:1.35 was optimal in terms of achieving a good balance between performance and cost

Antivortices due to competing orbital and paramagnetic pair-breaking effects

Thermodynamically stable vortex-antivortex structures in a quasi-two-dimensional superconductor in a tilted magnetic field are predicted. For this geometry, both orbital and spin pair-breaking effects exist, with their relative strength depending on the tilt angle \Theta. The spectrum of possible states contains as limits the ordinary vortex state (for large \Theta) and the Fulde-Ferrell-Larkin-Ovchinnikov state (for \Theta=0). The quasiclassical equations are solved near H_{c2} for arbitrary \Theta and it is shown that stable states with coexisting vortices and antivortices exist in a small interval close to \Theta=0. The results are compared with recent predictions of antivortices in mesoscopic samples.Comment: 11 pages, 3 figure

Exploring The Efficacy of Digital Meme Marketing Campaigns in Generating Leads Within the Generation Z Demographic

Quite recently, marketers have used memes because they entice customers’ attention. It serves as a means to have a dialogue between customers and companies. Some companies would even hire people to browse the internet for relevant memes. The emergence of Generation Z, who are digital natives, has brought significant changes to how businesses interact with their target audience. One potential strategy is to use digital memes as a marketing tool to engage them. The study, using 271 respondents, investigates the use of the aforementioned tool to determine its appropriateness in lead generation based on the Attention, Interest, Desire, Action (AIDA) model. Using the software Analysis of Moment Structures (AMOS), a descriptive exploratory design using Structural Equation Modeling (SEM) was used to investigate the relationship between the different variables in the study. The findings show that attention impacts interest, interest influences desire, and desire significantly affects action at a significance level of p < 0.01. The study revealed that Digital memes are an effective tool that can be utilized to generate leads. Businesses can use digital memes to engage with the Generation Z segment. However, prudence in creating memes must align the message with corporate values and be relevant to the target audience

A Two-dimensional Superconductor in a Tilted Magnetic Field - new states with finite Cooper-pair momentum

Varying the angle Theta between applied field and the conducting planes of a layered superconductor in a small interval close to the plane-parallel field direction, a large number of superconducting states with unusual properties may be produced. For these states, the pair breaking effect of the magnetic field affects both the orbital and the spin degree of freedom. This leads to pair wave functions with finite momentum, which are labeled by Landau quantum numbers 0<n<\infty. The stable order parameter structure and magnetic field distribution for these states is found by minimizing the quasiclassical free energy near H_{c2} including nonlinear terms. One finds states with coexisting line-like and point-like order parameter zeros and states with coexisting vortices and antivortices. The magnetic response may be diamagnetic or paramagnetic depending on the position within the unit cell. The structure of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states at Theta=0 is reconsidered. The transition n->\infty of the paramagnetic vortex states to the FFLO-limit is analyzed and the physical reason for the occupation of higher Landau levels is pointed out.Comment: 24 pages, 11 figure

Sex, pregnancy and aortic disease in Marfan syndrome

Background : Sex-related differences as well as the adverse effect of pregnancy on aortic disease outcome are well-established phenomena in humans with Marfan syndrome (MFS). The underlying mechanisms of these observations are largely unknown. Objectives : In an initial (pilot) step we aimed to confirm the differences between male and female MFS patients as well as between females with and without previous pregnancy. We then sought to evaluate whether these findings are recapitulated in a pre-clinical model and performed in-depth cardiovascular phenotyping of mutant male and both nulliparous and multiparous female Marfan mice. The effect of 17 beta-estradiol on fibrillin-1 protein synthesis was compared in vitro using human aortic smooth muscle cells and fibroblasts. Results : Our small retrospective study of aortic dimensions in a cohort of 10 men and 20 women with MFS (10 pregnant and 10 non-pregnant) confirmed that aortic root growth was significantly increased in the pregnant group compared to the non-pregnant group (0.64mm/year vs. 0.12mm/year, p = 0.018). Male MFS patients had significantly larger aortic root diameters compared to the non-pregnant and pregnant females at baseline and follow-up (p = 0.002 and p = 0.007, respectively), but no significant increase in aortic root growth was observed compared to the females after follow-up (p = 0.559 and p = 0.352). In the GT-8/+ MFS mouse model, multiparous female Marfan mice showed increased aortic diameters when compared to nulliparous females. Aortic dilatation in multiparous females was comparable to Marfan male mice. Moreover, increased aortic diameters were associated with more severe fragmentation of the elastic lamellae. In addition, 17 beta-estradiol was found to promote fibrillin-1 production by human aortic smooth muscle cells. Conclusions : Pregnancy-related changes influence aortic disease severity in otherwise protected female MFS mice and patients. There may be a role for estrogen in the female sex protective effect

Phonon Dynamics and Multipolar Isomorphic Transition in beta-pyrochlore KOs2O6

We investigate with a microscopic model anharmonic K-cation oscillation observed by neutron experiments in beta-pyrochlore superconductor KOs2O6, which also shows a mysterious first-order structural transition at Tp=7.5 K. We have identified a set of microscopic model parameters that successfully reproduce the observed temperature dependence and the superconducting transition temperature. Considering changes in the parameters at Tp, we can explain puzzling experimental results about electron-phonon coupling and neutron data. Our analysis demonstrates that the first-order transition is multipolar transition driven by the octupolar component of K-cation oscillations. The octupole moment does not change the symmetry and is characteristic to noncentrosymmetric K-cation potential.Comment: 5 pages, 4 figures, submitted to J. Phys. Soc. Jp

Superconductivity and Rattling under High Pressure in the beta-Pyrochlore Oxide RbOs2O6

Rattling-induced superconductivity in the beta-pyrochlore oxide RbOs2O6 is investigated under high pressures up to 6 GPa. Resistivity measurements in a high-quality single crystal show that the superconducting transition temperature Tc increases gradually from 6.3 K at ambient pressure to 8.8 K at 3.5 GPa, surprisingly remains almost constant at 8.8 \pm 0.1 K in a wide pressure range between 3.5 (Po) and 4.8 GPa, and suddenly drops to 6.3 K at Ps = 4.9 GPa, followed by a gradual decrease with further pressure increase. Two anomalies in the temperature dependence of the normal-state resistivity are observed at Po Ps, revealing the presence of two high-pressure phases corresponding to the changes in Tc. The rattling of the Rb ion inside a cage made of Os and O atoms may be slightly and seriously modified in these high-pressure phases that probably have cages of reduced symmetry, respectively, so that electron-rattler interactions that govern the superconducting and transport properties of beta-RbOs2O6 are significantly affected.Comment: arXiv admin note: text overlap with arXiv:1009.035

Infrared and optical properties of pure and cobalt-doped LuNi_2B_2C

We present optical conductivity data for Lu(Ni$_{1-x}$Co$_x$)$_2$B$_2$C over a wide range of frequencies and temperatures for x=0 and x=0.09. Both materials show evidence of being good Drude metals with the infrared data in reasonable agreement with dc resistivity measurements at low frequencies. An absorption threshold is seen at approximately 700 cm-1. In the cobalt-doped material we see a superconducting gap in the conductivity spectrum with an absorption onset at 24 +/- 2 cm-1 = 3.9$ +/- 0.4 k_BT_c suggestive of weak to moderately strong coupling. The pure material is in the clean limit and no gap can be seen. We discuss the data in terms of the electron-phonon interaction and find that it can be fit below 600 cm-1 with a plasma frequency of 3.3 eV and an electron-phonon coupling constant lambda_{tr}=0.33 using an alpha^{2}F(omega) spectrum fit to the resistivity.Comment: 10 pages with 10 embedded figures, submitted to PR

Diversity of Butterflies (Rhopalocera) inBulusukan (San Ildelfonso, Bulacan, Philippines)

There are 1,615 species and sub species of butterflies in the entire Philippines (C.R Baltazar, 1991), LUBG San Fernando La Union has 104 species recorded they belong to 6 families and 66 genera(Nacua et al2015).In Manila,Nacua (2016) 22 species of butterflies belong to 6 families 17 genera were also recorded. Thisstudyseeks to determine the species composition, conservation status, richness and abundance of butterflies in the town of Bulusukan, a community in San Ildefonso, Bulacan province (Luzon Island, Philippines). The opportunistic transect sampling method was used to collect butterflies. Collection was done at daytime on August 6, 2016 from 8 am up to 5 pm in areas with GPS of 15°04'26.0652"northand 121°02'39.9588"east near the vicinity of Bulusukan Cave.Species richness and butterfly diversity in all areas sampled was calculated. A dendogram showing 75% species abundance was accounted and comes mostly from the secondary dipterocarp forest. Graphium antiphates Cramer, Ypthima semperaand Ptychandra lorquini-lorquini were found to be endemic to Bulusukan. Butterflies were observed to be attracted to shady forest areas consisting of mosses clinging on metamorphic rocks along a river and includes species from the families Nymphalidae and Papilionidae. This study was able to identify 21 butterfly species with 19 genera 2 of them are rare and 2 endemic species of butterflies in Bulusukan. It is recommended to continue further study for wet and dry season

Structure-guided design and optimization of small molecules targeting the protein-protein interaction between the von hippel-lindau (VHL) E3 ubiquitin ligase and the hypoxia inducible factor (HIF) alpha subunit with in vitro nanomolar affinities

E3 ubiquitin ligases are attractive targets in the ubiquitin-proteasome system, however, the development of small-molecule ligands has been rewarded with limited success. The von Hippel-Lindau protein (pVHL) is the substrate recognition subunit of the VHL E3 ligase that targets HIF-1α for degradation. We recently reported inhibitors of the pVHL:HIF-1α interaction, however they exhibited moderate potency. Herein, we report the design and optimization, guided by X-ray crystal structures, of a ligand series with nanomolar binding affinities