Abstract
Bringing arts to the science classes remains as a challenging idea. The illustration of a concept with an original painting would bring unexpected advantages. Here we present the use of a ...painting of Frida Kahlo to illustrate the concept of the thermodynamic universe the surroundings. Such concept is not deeply treated in most textbooks, and it is essential now of analysis of a thermodynamic system. Because of the use of this visual aid, our students were able to distinguish several possible thermodynamic universes, depending on the objective of their study, gaining a more insightful approach than that usually obtained with classical pictographic representations in physical chemistry textbooks.
A study of plant defensive systemic responses induced by three plant growth promoting rhizobacteria (PGPR) on Arabidopsis thaliana Col 0 against Pseudomonas syringae pv. tomato DC3000 at the ...biochemical and transcriptional levels is reported in this paper. All three strains decreased disease severity when applied to A. thaliana prior to pathogen inoculation. At the biochemical level, each of the three strains induced ethylene (ET) when incubated with 1-amino-cyclopropane-1-carboxylic acid, and salicylic acid (SA) production in the plant. Plants treated with each of the three strains were also reduced in salicylic acid production after pathogen challenge compared to untreated controls. This effect was more marked in plants treated with Chryseobacterium balustinum AUR9, the strain most effective in decreasing disease severity. The expression level of PR1, a transcriptional marker of the SA-dependent pathway in C. balustinum AUR9-treated plants, is fourfold that of controls while the expression of PDF1.2, a transcriptional marker for the SA-independent pathway, is not induced. C. balustinum cell wall lipopolysaccharides, being putative bacterial elicitor molecules, are able to reproduce this systemic induction effect at low doses. From these observations, we hypothesize that certain PGPR strains are capable of stimulating different systemic responses in host plants. With C. balustinum AUR9, the SA-dependent pathway is stimulated first, as indicated by increases in SA levels and PR1 expression, followed by induction of the SA-independent pathway, as indicated by the increases in ET concentrations. The effects of both pathways combined with respect to disease suppression appear to be additive.
Spherically shaped pellets, usually discarded after use in fluidized-bed catalytic cracking units (FCCs), were converted to zeolite A-surface-enriched pellets. The final pellets were obtained through ...a two-step treatment consisting of: (1) alkaline thermal activation followed by (2) a hydrothermal crystallization in selected reaction conditions. The alkaline thermal activation provided pellets mainly constituted by silico-aluminate compounds. When the pellets are heated at 800 °C in contact with sodium carbonate, a structural rearrangement occurs which includes nepheline, crystalline aluminosilicate, and an amorphous fraction expected to be silicon-enriched, preserving the pellet original geometry. Afterward, reaction mixtures were prepared by adding sodium hydroxide solution to the heat-treated product. Then, commercial sodium aluminate was added. During the hydrothermal synthesis at 85 ± 3 °C, zeolite A was formed from the calcined product and NaAlSiO₄ turned out to be an intermediary crystalline compound. The LTA crystals were already observed for a reaction time of 0.5 h, but the highest conversion to pure zeolite A was reached after 6 h. Those final round solid pellets showed an external surface fully covered by well anchored zeolite A cubic crystals about 1–2 μm in size. Such materials may be very useful in ion exchange, molecular sieving, and adsorption processes. The crystalline ordering was followed by XRD, SEM, NMR, and water adsorption.
We explore the use of industrial sources of silicon and surfactant for obtaining low-cost MCM-41 materials and evaluate their performances as CO2 adsorbents. All of them presented a high specific ...surface area with different structural characteristics and textural properties. Interestingly, the MCM-41 manufactured with the most economical reagents presented a SBET of 1602 m2·g−1. The template was removed by using thermal treatments in an air atmosphere or a washing process. Preservation of silanol groups proved to be more effective under washing or mild thermal treatment conditions with the advantage of their lower cost and environmental benefit. Surface reactivity against CO2 was enhanced by anchoring APTS to silanol groups through wet grafting. All amino-functionalized materials showed a performance as CO2 adsorbents comparable to those reported in the literature, reaching values close to 30 cm3·g−1 at 25 °C and 760 mmHg. Samples with a higher concentration of silanol groups showed better performance. Our studies indicate that adsorbed CO2 is retained at least up to 50 °C, and the CO2 is chemisorbed on the silica modified with amine groups. The chemisorbed gas at very low pressures points to the potential use of these materials for CO2 storage.
Virtual presence describes a users’ perception of a virtual reality (VR) environment (VRE), specifically, of their involvement (sense of control within a virtual environment with minimal ...distractions) and immersion (multi-input sensory engagement providing apparent realism of objects and interactions). In education, virtual presence is a significant construct as highly immersive VREs have been linked to users reporting memorable and exciting teaching experiences. Prior research has described that adults and children report different levels of presence when subjected to identical VREs, suggesting cognition may play some role in users’ perceptions of presence. According to Piaget, concrete operational development is a watershed moment when adolescents develop the ability to understand abstract concepts and make assessments what is and is not reality. This period in cognitive development may influence children’s and adolescents’ perceptions of presence. This is an exploratory study of seventy-five 6th-grade and seventy-six 9th-grade students who participated in an instructional module about cardiac anatomy and physiology using a 3-D, haptic-enabled, VR technology. When surveyed on their perceptions of virtual presence, there were no reported differences between grade levels. When assessed using a Piagetian inventory of cognitive development, the analyses indicated that the sixth-grade students’ understanding of spatial rotation and angular geometry was positively correlated with the reported perceived control and negatively correlated with distraction. This study suggests that the spatial acuity of younger learners plays an important role when using VR technologies for science learning. This research raises questions about the relevance of users’ cognitive development when using emergent VR technologies in the K–12 science classroom.
This paper presents a practical fuzzy controller two axes solar tracking-based realization on digital FPGA hardware. The fuzzy logic control is based according to Mamdani rules, alpha levels, max–min ...operations and defuzzification method. Operations and algorithms are reduced using look-up tables for the membership values which are stored as digital values and accessed to the control process. The feasibility and versatility of the proposed technique as well as its potential as a low-cost design for solar tracking control on digital field-programmable gate array (FPGA) are shown by simulated and experimental results in a photovoltaic system under different operation conditions. The proposed realization exhibits good performance related to the control and efficiency.
•We propose a Duplex-constructed wetland (CW) for domestic wastewater treatment.•The Duplex-CW combines a vertical flow (VF) CW on top of a horizontal flow filter.•The VF CW contributed the most to ...the overall treatment.•Artificial aeration did not significantly improve the treatment efficiency.•A Duplex-CW is a compact system with an area requirement of 2.6–3.4m2PE−1.
Lack of space for a wastewater treatment plant is a common problem in many areas, especially in dense cities. Constructed wetlands (CWs) are efficient natural systems; however, they require large areas. The aim of this study is the development of a compact CW design for the treatment of domestic wastewater, the Duplex-CW: a hybrid system with a stacked design (vertical flow CW (VFCW) on top of a horizontal flow filter (HFF)). The performance of three different configurations of Duplex-CW, called fill and drain, stagnant batch and free drain, was compared. The VFCWs operated differently with the intention of creating different oxygen conditions, whereas the HFFs were operated identically. The Duplex-CWs were subjected to three different wastewater strengths, corresponding to designs of 7.9, 3.4 and 2.6m2PE−1. The highest strength was treated with and without artificial aeration of the VFCW of each configuration. The contribution to the total removal of each compartment (VFCW and HFF), the effects of the use of artificial aeration, the solids accumulation, above- and below-ground biomass and the footprint requirements of the three configurations tested were determined. The fill and drain configuration performed better than the other two, the VFCW compartment being more active in the treatment than the HFF. It achieved an area of 2.6–3.4m2PE−1 and it needed 2–3 times lower area than what a single VFCW would have needed to reach similar total nitrogen effluent concentrations. The Duplex-CW did not contribute to the footprint reduction, for other parameters (e.g. COD, TSS and total phosphorus).
We show that if a linear operator T and obeys a linear bound with respect to the A_2 with a function b will obey a quadratic bound with respect to the A_2th-order commutator T^k_b=b,T^{k-1}_b of the ...A_2 estimates. In particular these estimates hold for T constant of the weight for all 1<p<\infty , and all dimensions, as examples involving the Riesz transforms, power functions and power weights show.
The aim of this study was to evaluate the efficacy of autochthonous Pichia kudriavzevii as a novel bioadsorbent for aflatoxin B
(AFB
). The selection of this yeast was based on the AFB
adsorption ...capacity previously demonstrated in vitro (Magnoli et al. 2016). One-day-old Cobb broilers (n = 160) were randomly assigned to four dietary treatments (T1: basal diet (B); T2: B + 0.1% yeast; T3: B + AFB
, 100 μg/kg; T4: B + 0.1% yeast + AFB
, 100 μg/kg). Performance parameters (average daily weight gain body, average daily consumption, feed conversion ratio, carcass weight, and dead weight), biochemical parameters (albumin, globulin, and albumin/globulin), liver pathological changes, and AFB
residual levels in the liver and excreta were evaluated. Significant differences (P < 0.05) in performance parameters were observed among treatments and controls: T3 group showed the lowest average daily body weight gain value while in T4 group, the value of this parameter increased significantly (P < 0.05). T3 and T4 groups showed the lowest and highest values for average daily feed consumption, respectively. The feed conversion ratio (FC) showed no significant differences among treatments. T3 group showed the lowest dead weight and carcass weight compared with T1 group. The biochemical parameters showed no significant differences among treatments. T3 group showed macroscopic and microscopic liver changes compared to the control. Aflatoxin B
levels (μg/g) were detected in broiler livers and showed significant differences among treatments (P < 0.05). In conclusion, native P. kudriavzevii incorporation (0.1%) in broiler diets containing AFB
was shown to be effective in ameliorating the adverse effects of AFB
on production.
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