One common approach for solving collisions between protoplanets in simulations of planet formation is to employ analytical scaling laws. The most widely used one was developed by Leinhardt & Stewart ...(2012, ApJ, 745, 79) from a catalog of ~180 N -body simulations of rubble–pile collisions. In this work, we use a new catalogue of more than 20 000 SPH simulations to test the validity and the prediction capability of Leinhardt & Stewart (2012, ApJ, 745, 79) scaling laws. We find that these laws overestimate the fragmentation efficiency in the merging regime and they are not able to properly reproduce the collision outcomes in the super-catastrophic regime. In the merging regime, we also notice a significant dependence between the collision outcome, in terms of the largest remnant mass, and the relative mass of the colliding protoplanets. Here, we present a new set of scaling laws that are able to better predict the collision outcome in all regimes and it is also able to reproduce the observed dependence on the mass ratio. We compare our new scaling laws against a machine learning approach and obtain similar prediction efficiency.
Synthetic molecular machines hold tremendous potential to revolutionize chemical and materials sciences. Their autonomous motion controlled by external stimuli allows to develop smart materials whose ...properties can be adapted on command. For the realisation of more complex molecular machines, it is crucial to design building blocks whose properties can be controlled by multiple orthogonal stimuli. A major challenge is to reversibly switch from forward to backward and again forward light-driven rotary motion using external stimuli. Here we report a push-pull substituted photo-responsive overcrowded alkene whose function can be toggled between that of a unidirectional 2
generation rotary motor and a molecular switch depending on its protonation and the polarity of its environment. With its simplicity in design, easy preparation, outstanding stability and orthogonal control of distinct forward and backward motions, we believe that the present concept paves the way for creating more advanced molecular machines.
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•The bioconversion of citrus effluents into H2 had not been tested previously.•The integrated management of sewage sludge and citrus effluents was performed.•Anaerobic digestion ...promotes the simultaneous effluent treatment and energy recovery.•Citrus effluents have remarkable potential as feedstock to clean energy production.•BioH2 may be a sustainable and cost-effective option for local energy supply.
Citrus crops are among the most abundant crops in the world, which processing is mainly based on juice extraction, generating large amounts of effluents with properties that turn them into potential pollution sources if they are improperly discarded. This study evaluated the potential for bioconversion of effluents from citrus-processing industry (wastewater and vinasse) into hydrogen through the dark fermentation process, by applying anaerobic sewage sludge as inoculum. The inoculum was previously heat treated to eliminate H2-consumers microorganisms and improve its activity. Anaerobic batch reactors were operated in triplicate with increasing proportions (50, 80 and 100%) of each effluent as substrate at 37°C, pH 5.5. Citrus effluents had different effects on inoculum growth and H2 yields, demonstrated by profiles of acetic acid, butyric acid, propionic acid and ethanol, the main by-products generated. It was verified that there was an increase in the production of biogas with the additions of either wastewater (7.3, 33.4 and 85.3mmolL−1) or vinasse (8.8, 12.7 and 13.4mmolL−1) in substrate. These effluents demonstrated remarkable energetic reuse perspectives: 24.0MJm−3 and 4.0MJm−3, respectively. Besides promoting the integrated management and mitigation of anaerobic sludge and effluents from citrus industry, the biohydrogen production may be an alternative for the local energy supply, reducing the operational costs in their own facilities, while enabling a better utilization of the biological potential contained in sewage sludges.
In adults, partial damage to V1 or optic radiations abolishes perception in the corresponding part of the visual field, causing a scotoma. However, it is widely accepted that the developing cortex ...has superior capacities to reorganize following an early lesion to endorse adaptive plasticity. Here we report a single patient case (G.S.) with near normal central field vision despite a massive unilateral lesion to the optic radiations acquired early in life. The patient underwent surgical removal of a right hemisphere parieto-temporal-occipital atypical choroid plexus papilloma of the right lateral ventricle at four months of age, which presumably altered the visual pathways during in utero development. Both the tumor and surgery severely compromised the optic radiations. Residual vision of G.S. was tested psychophysically when the patient was 7 years old. We found a close-to-normal visual acuity and contrast sensitivity within the central 25° and a great impairment in form and contrast vision in the far periphery (40–50°) of the left visual hemifield. BOLD response to full field luminance flicker was recorded from the primary visual cortex (V1) and in a region in the residual temporal-occipital region, presumably corresponding to the middle temporal complex (MT+), of the lesioned (right) hemisphere. A population receptive field analysis of the BOLD responses to contrast modulated stimuli revealed a retinotopic organization just for the MT+ region but not for the calcarine regions. Interestingly, consistent islands of ipsilateral activity were found in MT+ and in the parieto-occipital sulcus (POS) of the intact hemisphere. Probabilistic tractography revealed that optic radiations between LGN and V1 were very sparse in the lesioned hemisphere consistently with the post-surgery cerebral resection, while normal in the intact hemisphere. On the other hand, strong structural connections between MT+ and LGN were found in the lesioned hemisphere, while the equivalent tract in the spared hemisphere showed minimal structural connectivity. These results suggest that during development of the pathological brain, abnormal thalamic projections can lead to functional cortical changes, which may mediate functional recovery of vision.
•G.S. has near normal central field vision despite an early lesion to the right optic radiation.•LGN-V1 connectivity is minimal in the right hemisphere, while normal in the left.•There is enhanced LGN-MT+ connectivity in the right hemisphere, compared to the left.•During pathological brain development, abnormal thalamic projections mediate recovery of vision.
Human population growth, high consumption and unsustainable management of products and services are exceeding the sustainable use of natural resources. The use of disposable diapers, not only baby ...but also geriatric ones, reaches a high value, increasing considerably the urban solid residue generation. Currently, all this urban solid residue goes to landfills, taking up to 400 years to decompose, as most of its components are derived from oil. Its use as energy source, as it is already done with the cane bagasse, would bring great benefits, such as power generation and waste reduction. The objectives of this work were to identify the composition of each layer of a disposable diaper for babies and estimate the potential energy through combustion, employing the thermal analytical techniques TG/DTG/DTA, aiming at the reduction in the waste disposed in landfills, contributing in this way to an effective solid waste residue management. The layer 1 presented an endothermic peak at 165 °C, suggesting the presence of polypropylene, and layer 2 presented an endothermic peak at 130 °C, possibly consistent presence of polyethylene according to the manufacturer’s information and infrared analyses. Through the DTA curves of layers 4, 5 and sodium polyacrylate (PSA), it is observed that the fusion temperatures of the polymer are around 425 °C indicating the presence of PSA in both layers. The disposable diaper combustion releases approximately 12 kJg
−1
, lower than the heat released from sugarcane that is around 17 kJg
−1
; if used to obtain energy would help the removal of the diaper from the environment by reducing space occupied by that residue in landfills, contributing to environmental sustainability.
Transitional millisecond pulsars are an emerging class of sources that link low-mass X-ray binaries to millisecond radio pulsars in binary systems. These pulsars alternate between a radio pulsar ...state and an active low-luminosity X-ray disc state. During the active state, these sources exhibit two distinct emission modes (high and low) that alternate unpredictably, abruptly, and incessantly. X-ray to optical pulsations are observed only during the high mode. The root cause of this puzzling behaviour remains elusive. This paper presents the results of the most extensive multi-wavelength campaign ever conducted on the transitional pulsar prototype, PSR J1023+0038, covering from the radio to X-rays. The campaign was carried out over two nights in June 2021 and involved 12 different telescopes and instruments, including
XMM-Newton
, HST, VLT/FORS2 (in polarimetric mode), ALMA, VLA, and FAST. By modelling the broadband spectral energy distributions in both emission modes, we show that the mode switches are caused by changes in the innermost region of the accretion disc. These changes trigger the emission of discrete mass ejections, which occur on top of a compact jet, as testified by the detection of at least one short-duration millimetre flare with ALMA at the high-to-low mode switch. The pulsar is subsequently re-enshrouded, completing our picture of the mode switches.
We report on an optical photometric and polarimetric campaign on the accreting millisecond X-ray pulsar (AMXP) SAX J1808.4-3658 during its 2019 outburst. The emergence of a low-frequency excess in ...the spectral energy distribution in the form of a red excess above the disk spectrum (seen most prominently in the z, i, and R bands) is observed as the outburst evolves. This is indicative of optically thin synchrotron emission due to a jet, as seen previously in this source and in other AMXPs during outburst. At the end of the outburst decay, the source enters a reflaring state. The low-frequency excess is still observed during the reflares. Our optical (BVRI) polarimetric campaign shows variable linear polarization (LP) throughout the outburst. We show that this is intrinsic to the source, with low-level but significant detections (0.2%-2%) in all bands. The LP spectrum is red during both the main outburst and the reflaring state, favoring a jet origin for this variable polarization over other interpretations, such as Thomson scattering with free electrons from the disk or the propelled matter. During the reflaring state, a few episodes with stronger LP levels (1%-2%) are observed. The low-level, variable LP is suggestive of strongly tangled magnetic fields near the base of the jet. These results clearly demonstrate how polarimetry is a powerful tool for probing the magnetic field structure in X-ray binary jets, as for active galactic nuclei jets.
Mixture of biomass to energy reuse Nozela, W. C.; Braz, C. E. M.; Almeida, S. ...
Journal of thermal analysis and calorimetry,
2018/1, Letnik:
131, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Focusing on the reuse of the energy and aiming at the thermal and kinetic characterization of sewage sludge and its mixture, with pruning residues (50 mass%), the thermogravimetry was used. The ...kinetic study was elaborated from the local isoconversional integral method in heating rates 10.0, 20.0 and 30.0 °C min
−1
at a temperature ranging from 219 to 386 °C at nitrogen atmosphere, in a flow of 100 mL min
−1
. The average activation energy of sewage sludge sample revealed the value of 219 kJ mol
−1
and that of the mixture 161 kJ mol
−1
, supporting the incorporation of pruning residues in the sewage sludge. During the degradation process, a remarkable increase in activation energy was noticed that ranged from 20 to 70% conversion in the sewage sludge sample, and regarding the mixture, an almost linear behavior was observed during the decomposition reaction. There was no evidence of kinetic compensation effect in the performed studies. The evaluation of the thermal characteristics, as well as the kinetic study of the degradation of sewage sludge and its mixture with pruning residues, can lead to important insights and contribute to a better use of energy regarding the environmental issues.
The application of granular sludge from biological treatment plants can become an economically and environmentally viable process as a renewable source of energy. It is available in most countries, ...and its application can diversify the local energy potential. However, in order to achieve such benefits and make possible the development of more efficient conversion processes, prior knowledge of the composition of these materials is essential. In this sense, samples of granular sludge were obtained from upflow anaerobic sludge blanket reactors for the treatment of: (1) poultry slaughterhouse waste (Tietê—SP); (2) poultry slaughterhouse waste (Pereiras—SP); (3) wastewater treatment plant (São Carlos—SP) and (4) a mix of sludges 1, 2 and 3. Biogas generation tests in anaerobic batch reactors fed with sodium acetate and glucose separately as carbon sources were performed with samples 1, 2, 3 and 4, at initial pH 7.0 and 30 °C. Characteristic decomposition profiles were observed in the granular sludge tested. The two poultry slaughterhouse waste (samples 1 and 2) presented higher proportions of organic substrate molecules for the methanogenesis than the sanitary sewage sludge (sample 3), thus facilitating the production of the highest biogas, as verified in the tests carried out. The thermal characterization of the samples was relevant to the methane generation tests demonstrating the potential for the generation of this fuel.
In sports, as in other activities and knowledge domains, expertise is a highly valuable asset. We assessed whether expertise in billiards is associated with specific patterns of eye movements in a ...visual prediction task. Professional players and novices were presented a number of simplified billiard shots on a computer screen, previously filmed in a real set, with the last part of the ball trajectory occluded. They had to predict whether or not the ball would have hit the central skittle. Experts performed better than novices, in terms of both accuracy and response time. By analyzing eye movements, we found that during occlusion, experts rarely extrapolated with the gaze the occluded part of the ball trajectory-a behavior that was widely diffused in novices-even when the unseen path was long and with two bounces interposed. Rather, they looked selectively at specific diagnostic points on the cushions along the ball's visible trajectory, in accordance with a formal metrical system used by professional players to calculate the shot coordinates. Thus, the eye movements of expert observers contained a clear signature of billiard expertise and documented empirically a strategy upgrade in visual problem solving from dynamic, analog simulation in imagery to more efficient rule-based, conceptual knowledge.
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