This research presents a tracking formation by multiple mobile robots. The formation used is leader follower approach. Formation control is designed based on the robot kinematics model. Follower is ...controlled to track the position of the specified formation. Triangle shape is used to the goal formation. Experiments carried out with two scenarios. First, leader moves to a point with linear motion. Second, leader moves along the circular trajectory. Leader motion is constantly with the aim that the formation is rigidly formed while moving towards the goal. Experiments show that robots can perform and maintain formation while achieving goals.
In this investigation, we aimed to fabricate easy separable composite microbeads for efficient adsorption of tetracycline (TC) drug. MIL-125(Ti)/MIL-53(Fe) binary metal organic framework (MOF) was ...synthetized and incorporated with carbon nanotube (CNT) into alginate (Alg) microbeads to form MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads. Various tools including FTIR, XRD, SEM, BET, Zeta potential and XPS were applied to characterize the composite microbeads. It was found that the specific surface area of MIL-125(Ti)/MIL-53(Fe)/CNT@Alg microbeads was 273.77 m
/g. The results revealed that the adsorption of TC augmented with rising CNT proportion up to 15 wt% in the microbeads matrix. In addition, the adsorption process followed the pseudo-second-order and well-fitted to Freundlich and Langmuir models with a maximum adsorption capacity of 294.12 mg/g at 25 ◦C and pH 6. Furthermore, thermodynamic study clarified that the TC adsorption process was endothermic, random and spontaneous. Besides, reusability test signified that MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads retained superb adsorption properties for six consecutive cycles, emphasizing its potentiality for removing of pharmaceutical residues.
•Faster decolorization of AB-14 dye by AO and EC and follow pseudo-first order kinetic.•Faster and similar decolorization by EC and AO due to the generation of strong oxidant OH in the bulk.•Current ...density (j), Initial dye conc. (Co), NaCl conc. (CN), and pH affect the oxidation efficiency.•Synergy between coagulation and oxidation by OH and active chlorine species.
In this study, a laboratory scale for the treatment of a recalcitrant and toxic synthetic wastewater containing diazo dye, acid brown 14 (AB-14) has been comparatively performed by two electro-catalytic treatment processes, namely anodic oxidation (AO) and electrocoagulation (EC) using a new batch electrochemical cell. Additionally, the influence of several operating parameters such as; current density (j), initial dye concentration (Co), NaCl concentration (CN), and pH on the color removal efficiency and chemical oxygen demand (COD) are evaluated. The powerful capability of the AO and EC of AB-14 which related to the mechanistic reaction pathway is shown. The poor degradation is ascribed to higher Co and pH, while the enhancement of j and CN is responsible for better degradation of AB-14 dye. The results indicate that the EC is more effective than AO under the same operational condition. A kinetic model is developed for evaluation of the pseudo-first-order-rate constant (kapp) as a function of various operational parameters. The results emphasize the high efficiency of AO and EC and the clean processes which are hopeful alternative for the treatment of the large volume wastewater of the textile industry.
Co‐infections commonly arise when two or multiple different pathogens infect the same host, either as simultaneous or as secondary concurrent infection. This potentiates their pathogenic effects and ...leads to serious negative consequences on the exposed host. Numerous studies on the occurrence of the bacterial, parasitic, fungal and viral co‐infections were conducted in various tilapia species. Co‐infections have been associated with serious negative impacts on susceptible fish because they increase the fish susceptibility to diseases and the likelihood of outbreaks in the affected fish. Co‐infections can alter the disease course and increase the severity of disease through synergistic and, more rarely, antagonistic interactions. In this review, reports on the synergistic co‐infections and their impacts on the affected tilapia species are highlighted. Additionally, their pathogenic mechanisms are briefly discussed. Tilapia producers should be aware of the possible occurrence of co‐infections and their effects on the affected tilapia species and in particular of the clinical signs and course of the disease. To date, there is still limited information regarding the pathogenicity mechanisms and pathogen interactions during these co‐infections. This is generally due to low awareness regarding co‐infections, and in many cases, a dominant pathogen is perceived to be of vital importance and hence becomes the target of treatment while the treatment of the co‐infectious agents is neglected. This review article aimed at raising awareness regarding co‐infections and helping researchers and fish health specialists pay greater attention to these natural cases, leading to increased research and more consistent diagnosis of co‐infectious outbreaks in order to improve control strategies to protect tilapia when infected with multiple pathogens.
Supermassive black holes are not only common in the present-day galaxies, but billion solar masses black holes also powered z ≥ 6 quasars. One efficient way to form such black holes is the collapse ...of a massive primordial gas cloud into a so-called direct collapse black hole. The main requirement for this scenario is the presence of large accretion rates of ≥ 0.1 M⊙ yr− 1 to form a supermassive star. It is not yet clear how and under what conditions such accretion rates can be obtained. The prime aim of this work is to determine the mass accretion rates under non-isothermal collapse conditions. We perform high-resolution cosmological simulations for three primordial haloes of a few times 107 M⊙ illuminated by an external UV flux, J
21 = 100–1000. We find that a rotationally supported structure of about parsec size is assembled, with an aspect ratio between 0.25 and 1 depending upon the thermodynamical properties. Rotational support, however, does not halt collapse, and mass inflow rates of ∼ 0.1 M⊙ yr− 1 can be obtained in the presence of even a moderate UV background flux of strength J
21 ≥ 100. To assess whether such large accretion rates can be maintained over longer time-scales, we employed sink particles, confirming the persistence of accretion rates of ∼ 0.1 M⊙ yr− 1. We propose that complete isothermal collapse and molecular hydrogen suppression may not always be necessary to form supermassive stars, precursors of black hole seeds. Sufficiently high inflow rates can be obtained for UV flux J
21 = 500–1000, at least for some cases. This value brings the estimate of the abundance of direct collapse black hole seeds closer to that high-redshift quasars.
Immobilized eggshell with a polymer mixture of alginate and polyvinyl alcohol was applied as a biocomposite adsorbent (ESC) for the adsorption of C.I. Remazol Reactive Red 198 from aqueous solution. ...ESC was characterized using XRD, TGA, FTIR and SEM. The Red dye adsorption onto the ESC was investigated in a batch system with respect to initial dye concentration, pH, contact time, agitation speed, solution temperature and biocomposite dosage. The prepared biocomposite exhibits high efficiency for red dye adsorption and the equilibrium states could be achieved in 3
h for the different studied initial dye concentrations. The equilibrium isotherm study indicated that sorption data were analyzed and fitted well by both Langmuir and Temkin models compared to Freundlich model. The maximum monolayer dye adsorption capacity (at the optimum pH 1.0) was estimated to be 46.9
mg/g at 22
°C. The kinetic study revealed that pseudo-second order model fitted well the kinetic data, while both the intraparticle diffusion and Boyd kinetic model indicated that intraparticle diffusion was the main rate determining step in the biosorption process. The negative values of both the enthalpy (ΔH°) and Gibbs free energy (ΔG°) changes indicate exothermic as well as feasible and spontaneous nature of the biosorption process respectively.
► Biocomposite eggshell was applied for the adsorption of Reactive dye. ► The sorption data were fitted well by both Langmuir and Temkin models. ► The kinetic data was fitted well with pseudo-second order model. ► Intraparticle diffusion was the main rate determining step. ► The negative values of ΔH° and ΔG° indicate exothermic and spontaneous nature.
Extraordinarily strong El Niño events, such as those of 1982/1983 and 1997/1998, have been poorly predicted by operational seasonal forecasts made before boreal spring, despite significant advances ...in understanding, improved models, and enhanced observational networks. The Equatorial Atlantic Zonal Mode—a phenomenon similar to El Niño but much weaker and peaking in boreal summer—impacts winds over the Pacific, and hence affects El Niño, and also potentially its predictability. Here we use a climate model to perform a suite of seasonal predictions with and without sea surface temperature (SST) in the Atlantic restored to observations. We show for the first time that knowledge of equatorial Atlantic SST significantly improves the prediction across boreal spring of major El Niño events and also weaker variability. This is because Atlantic SST acts to modulate El Niño variability, rather than triggering events. Our results suggest that better prediction of major El Niño events might be achieved through model improvement in the equatorial Atlantic.
Key Points
Observed equatorial Atlantic SST variability improves El Nino predictionMajor El Nino events better predicted, partly overcoming the spring barrierMotivates strongly the need to improve climate models in the tropical Atlantic
The early 21st century was marked by several severe winters over Central Eurasia linked to a blocking anti-cyclone centered south of the Barents Sea. Severe winters in Central Eurasia were frequent ...in the 1960s when Arctic sea ice cover was anomalously large, and rare in the 1990s featuring considerably less sea ice cover; the 1960s being characterized by a low, the 1990s by a high phase of the North Atlantic Oscillation, the major driver of surface climate variability in Central Eurasia. We performed ensemble simulations with an atmospheric general circulation model using a set of multi-year Arctic sea ice climatologies corresponding to different periods during 1966-2012. The atmospheric response to the strongly reduced sea ice cover of 2005-2012 exhibits a statistically significant anti-cyclonic surface pressure anomaly which is similar to that observed. A similar response is found when the strongly positive sea ice cover anomaly of 1966-1969 drives the model. Basically no significant atmospheric circulation response was simulated when the model was forced by the sea ice cover anomaly of 1990-1995. The results suggest that sea ice cover reduction, through a changed atmospheric circulation, considerably contributed to the recent anomalously cold winters in Central Eurasia. Further, a nonlinear atmospheric circulation response to shrinking sea ice cover is suggested that depends on the background sea ice cover.
The El Niño/Southern Oscillation (ENSO) phenomenon, originating in the Tropical Pacific, is the strongest natural interannual climate signal and has widespread effects on the global climate system ...and the ecology of the Tropical Pacific. Any strong change in ENSO statistics will therefore have serious climatic and ecological consequences. Most global climate models do simulate ENSO, although large biases exist with respect to its characteristics. The ENSO response to global warming differs strongly from model to model and is thus highly uncertain. Some models simulate an increase in ENSO amplitude, others a decrease, and others virtually no change. Extremely strong changes constituting tipping point behavior are not simulated by any of the models. Nevertheless, some interesting changes in ENSO dynamics can be inferred from observations and model integrations. Although no tipping point behavior is envisaged in the physical climate system, smooth transitions in it may give rise to tipping point behavior in the biological, chemical, and even socioeconomic systems. For example, the simulated weakening of the Pacific zonal sea surface temperature gradient in the Hadley Centre model (with dynamic vegetation included) caused rapid Amazon forest die-back in the mid-twenty-first century, which in turn drove a nonlinear increase in atmospheric CO₂, accelerating global warming.
PDF
