A study of 1304 data points collated over 266 papers statistically evaluates the relationships between carbon nanotube (CNT) material characteristics, including: electrical, mechanical, and thermal ...properties; ampacity; density; purity; microstructure alignment; molecular dimensions and graphitic perfection; and doping. Compared to conductive polymers and graphitic intercalation compounds, which have exceeded the electrical conductivity of copper, CNT materials are currently one‐sixth of copper's conductivity, mechanically on‐par with synthetic or carbon fibers, and exceed all the other materials in terms of a multifunctional metric. Doped, aligned few‐wall CNTs (FWCNTs) are the most superior CNT category; from this, the acid‐spun fiber subset are the most conductive, and the subset of fibers directly spun from floating catalyst chemical vapor deposition are strongest on a weight basis. The thermal conductivity of multiwall CNT material rivals that of FWCNT materials. Ampacity follows a diameter‐dependent power‐law from nanometer to millimeter scales. Undoped, aligned FWCNT material reaches the intrinsic conductivity of CNT bundles and single‐crystal graphite, illustrating an intrinsic limit requiring doping for copper‐level conductivities. Comparing an assembly of CNTs (forming mesoscopic bundles, then macroscopic material) to an assembly of graphene (forming single‐crystal graphite crystallites, then carbon fiber), the ≈1 µm room‐temperature, phonon‐limited mean‐free‐path shared between graphene, metallic CNTs, and activated semiconducting CNTs is highlighted, deemphasizing all metallic helicities for CNT power transmission applications.
A meta‐analysis of 1304 data points collated over 266 papers statistically evaluates the relationships between carbon nanotube (CNT) material characteristics, at an extrinsic and intrinsic level, and compares them to graphitic intercalation compounds and conductive polymers. An unrivaled deep dive into the state‐of‐the‐art, it provides a roadmap to developing advanced CNT conductors simultaneously competitive with copper and carbon fiber.
Key points
Exercise elicits circadian phase‐shifting effects, but additional information is needed.
The phase–response curve describing the magnitude and direction of circadian rhythm phase shifts, ...depending on the time of the zeigeber (time cue) stimulus, is the most fundamental chronobiological tool for alleviating circadian misalignment and related morbidity.
Fifty‐one older and 48 young adults followed a circadian rhythms measurement protocol for up to 5.5 days, and performed 1 h of moderate treadmill exercise for 3 consecutive days at one of eight times of the day/night.
Temporal changes in the phase of 6‐sulphatoxymelatonin (aMT6s) were measured from evening onset, cosine acrophase, morning offset and duration of excretion. Significant phase–response curves were established for aMT6 onset and acrophase with large phase delays from 7:00 pm to 10:00 pm and large phase advances at both 7:00 am and from 1:00 pm to 4:00 pm. Delays or advances would be desired, for example, for adjustment to westward or eastward air travel, respectively.
Along with known synergism with bright light, the above PRCs with a second phase advance region (afternoon) could support both practical and clinical applications.
Although bright light is regarded as the primary circadian zeitgeber, its limitations support exploring alternative zeitgebers. Exercise elicits significant circadian phase‐shifting effects, but fundamental information regarding these effects is needed. The primary aim of the present study was to establish phase–response curves (PRCs) documenting the size and direction of phase shifts in relation to the circadian time of exercise. Aerobically fit older (n = 51; 59–75 years) and young adults (n = 48; 18–30 years) followed a 90 min laboratory ultrashort sleep–wake cycle (60 min wake/30 min sleep) for up to 5½ days. At the same clock time on three consecutive days, each participant performed 60 min of moderate treadmill exercise (65–75% of heart rate reserve) at one of eight times of day/night. To describe PRCs, phase shifts were measured for the cosine‐fitted acrophase of urinary 6‐sulphatoxymelatonin (aMT6s), as well as for the evening rise, morning decline and change in duration of aMT6s excretion. Significant PRCs were found for aMT6s acrophase, onset and duration, with peak phase advances corresponding to clock times of 7:00 am and from 1:00 pm to 4:00 pm, delays from 7:00 pm to 10:00 pm, and minimal shifts around 4:00 pm and 2:00 am. There were no significant age or sex differences. The amplitudes of the aMT6s onset and acrophase PRCs are comparable to expectations for bright light of equal duration. The phase advance to afternoon exercise and the exercise‐induced PRC for change in aMT6s duration are novel findings. The results support further research exploring additive phase‐shifting effects of bright light and exercise and health benefits.
Key points
Exercise elicits circadian phase‐shifting effects, but additional information is needed.
The phase–response curve describing the magnitude and direction of circadian rhythm phase shifts, depending on the time of the zeigeber (time cue) stimulus, is the most fundamental chronobiological tool for alleviating circadian misalignment and related morbidity.
Fifty‐one older and 48 young adults followed a circadian rhythms measurement protocol for up to 5.5 days, and performed 1 h of moderate treadmill exercise for 3 consecutive days at one of eight times of the day/night.
Temporal changes in the phase of 6‐sulphatoxymelatonin (aMT6s) were measured from evening onset, cosine acrophase, morning offset and duration of excretion. Significant phase–response curves were established for aMT6 onset and acrophase with large phase delays from 7:00 pm to 10:00 pm and large phase advances at both 7:00 am and from 1:00 pm to 4:00 pm. Delays or advances would be desired, for example, for adjustment to westward or eastward air travel, respectively.
Along with known synergism with bright light, the above PRCs with a second phase advance region (afternoon) could support both practical and clinical applications.
Some notable exceptions aside, eukaryotic genomes are distinguished from those of Bacteria and Archaea in a number of ways, including chromosome structure and number, repetitive DNA content, and the ...presence of introns in protein-coding regions. One of the most notable differences between eukaryotic and prokaryotic genomes is in size. Unlike their prokaryotic counterparts, eukaryotes exhibit enormous (more than 60 000-fold) variability in genome size which is not explained by differences in gene number. Genome size is known to correlate with cell size and division rate, and by extension with numerous organism-level traits such as metabolism, developmental rate or body size. Less well described are the relationships between genome size and other properties of the genome, such as gene content, transposable element content, base pair composition and related features. The rapid expansion of ‘complete’ genome sequencing projects has, for the first time, made it possible to examine these relationships across a wide range of eukaryotes in order to shed new light on the causes and correlates of genome size diversity. This study presents the results of phylogenetically informed comparisons of genome data for more than 500 species of eukaryotes. Several relationships are described between genome size and other genomic parameters, and some recommendations are presented for how these insights can be extended even more broadly in the future.
Gibbsian Surface Thermodynamics Elliott, Janet A. W
The journal of physical chemistry. B,
12/2020, Letnik:
124, Številka:
48
Journal Article
Recenzirano
Odprti dostop
Gibbsian composite-system thermodynamics is the framework governing the equilibrium of composite systems, including systems that at equilibrium have more than one value of pressure because of the ...action of surface tension, semipermeable membranes, or fields, and thus cannot be treated as simple systems. J. W. Gibbs’s paper that lays out composite-system thermodynamics, “On the Equilibrium of Heterogeneous Substances”, communicated in two parts in 1876 and 1878, is widely regarded as one of the most important pieces of scientific literature of its century. Many scientists adopted and stressed the importance of Gibbsian thermodynamics. In 1960, H. B. Callen wrote a textbook that made Gibbsian composite-system thermodynamics more accessible to thermodynamicists. However, Callen’s book left out Gibbs’s work on curved fluid interfaces and did not treat the complicated nonideal systems of interest to today’s thermodynamicists. In this Feature Article, I have attempted to convey in a comprehensive manner the framework of Gibbsian composite-system thermodynamics including in detail the treatment of systems with interface effects and with nonideal, multicomponent phases. This work lays out the relationships between important equilibrium equations including the following: the Gibbs–Duhem equation, the Gibbs adsorption equation, the Young–Laplace equation, the Young equation, the Cassie–Baxter equation, the Wenzel equation, the Kelvin equation, the Gibbs–Thompson equation, and the Ostwald–Freundlich equation, including nonideal and multicomponent forms. Equations of state that are often useful for Gibbsian composite-system thermodynamics are reviewed including adsorption isotherms and our own work on two semiempirical equations of state: the Elliott et al. form of the osmotic virial equation and the Shardt–Elliott–Connors–Wright equation for the temperature and composition dependence of surface tension. I summarize the work of our group developing Gibbisan composite-system thermodynamics including new equations for such things as the curvature-induced depression of the eutectic temperature or the removal of azeotropes by nanoscale fluid interface curvature. Gibbsian composite-system thermodynamics has broad applications in biotechnology, nanostructured materials, surface textures and coatings, microfluidics, nanoscience, atmospheric and environmental physics, among others.
Australian dinosaurs have played a rare but controversial role in the debate surrounding the effect of Gondwanan break-up on Cretaceous dinosaur distribution. Major spatiotemporal gaps in the ...Gondwanan Cretaceous fossil record, coupled with taxon incompleteness, have hindered research on this effect, especially in Australia. Here we report on two new sauropod specimens from the early Late Cretaceous of Queensland, Australia, that have important implications for Cretaceous dinosaur palaeobiogeography. Savannasaurus elliottorum gen. et sp. nov. comprises one of the most complete Cretaceous sauropod skeletons ever found in Australia, whereas a new specimen of Diamantinasaurus matildae includes the first ever cranial remains of an Australian sauropod. The results of a new phylogenetic analysis, in which both Savannasaurus and Diamantinasaurus are recovered within Titanosauria, were used as the basis for a quantitative palaeobiogeographical analysis of macronarian sauropods. Titanosaurs achieved a worldwide distribution by at least 125 million years ago, suggesting that mid-Cretaceous Australian sauropods represent remnants of clades which were widespread during the Early Cretaceous. These lineages would have entered Australasia via dispersal from South America, presumably across Antarctica. High latitude sauropod dispersal might have been facilitated by Albian-Turonian warming that lifted a palaeoclimatic dispersal barrier between Antarctica and South America.
The Australian pterosaur record is poor by world standards, comprising fewer than 20 fragmentary specimens. Herein, we describe the new genus and species Ferrodraco lentoni gen. et sp. nov., based on ...the most complete pterosaur specimen ever found in Australia, and the first reported from the Winton Formation (Cenomanian-lower Turonian). The presence of premaxillary and mandibular crests, and spike-shaped teeth with subcircular bases, enable Ferrodraco to be referred to Anhangueria. Ferrodraco can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the first premaxillary and mandibular tooth pairs are small; and the fourth-seventh tooth pairs are smaller than the third and eighth ones. Ferrodraco was included in a phylogenetic analysis of Pterosauria and resolved as the sister taxon to Mythunga camara (upper Albian Toolebuc Formation, Australia), with that clade occupying the most derived position within Ornithocheiridae. Ornithocheirus simus (Albian Cambridge Greensand, England), Coloborhynchus clavirostris (Valanginian Hastings Sands, England), and Tropeognathus mesembrinus (upper Aptian-lower Albian Romualdo Formation, Brazil) were resolved as successive sister taxa, which suggests that ornithocheirids were cosmopolitan during the Albian-Cenomanian. Furthermore, the stratigraphic age of Ferrodraco lentoni (Cenomanian-lower Turonian) implies that anhanguerians might have survived later in Australia than elsewhere.
Surface thermodynamics at the nanoscale
Journal of chemical physics online/The Journal of chemical physics/Journal of chemical physics,
05/2021
Journal Article
There are well-established measurement standards for the rating of impact noise reduction provided by floor coverings in relation to structurally transmitted impact noise, e.g. BS EN ISO 10140-3 and ...ASTM E492 are widely used in Europe and North America Respectively. Standardisation for “in-room” impact noise transmitted by an airborne path is however less well established. At the current time the standard used for rating the “in-room” impact sound reduction is BS EN 16205:2013 which focuses primarily on walking noise as a the impact source. This standard employs the same tapping machine used for impact improvement testing in BS EN ISO 10140-3 but has been found not to be ideal due to the mechanical noise it produces and because it is not fully representative of the walking loads that the standard primarily aims to address. There is currently no standard that deals with “in room” impact noise from falling objects which may be a greater concern than walking noise, for example in a healthcare or education setting. Thus, presented in the paper are the findings from a large measurement survey conducted to investigate the influence of impactor mass, hardness and velocity on measured “in room” impact noise reductions. Other measurands such as the reduction in impact force and floor acceleration are also considered. It is discussed in the paper how ‘In-room’ impact noise differs from transmitted impact noise and this is demonstrated by performing a transfer path analysis to separate out the impact noise contributions from a falling object and from the floor. The key finding of the study is that the whilst the impact noise reduction achieved by different floor coverings varies wildly for different impactor types the rank order of the floor coverings tested in terms of Impact noise reduction did not. Thus, the ideal test method may not be the one that simulates best the type of impacts a floor is likely to be subjected to, but rather, it ought to be the one that gives the biggest differences between similar floor coverings so as to highlight most clearly the differences between them.
When a drop is in contact with a rough surface, it can rest on top of the rough features (the Cassie–Baxter state) or it can completely fill the rough structure (the Wenzel state). The contact angle ...(θ) of a drop in these states is commonly predicted by the Cassie–Baxter or Wenzel equations, respectively, but the accuracy of these equations has been debated. Previously, we used fundamental Gibbsian composite-system thermodynamics to rigorously derive the Cassie–Baxter equation, and we found that the contact line determined the macroscopic contact angle, not the contact area that was originally proposed. Herein, to address the various perspectives on the Wenzel equation, we apply Gibbsian composite-system thermodynamics to derive the complete set of equilibrium conditions (thermal, chemical, and mechanical) for a liquid drop resting on a homogeneous rough solid substrate in the Wenzel mode of wetting. Through this derivation, we show that the roughness must be evaluated at the contact line, not over the whole interfacial area, and we propose a new Wenzel equation for a surface with pillars of equal height. We define a new dimensionless number H = h(1 – λsolid)/R to quantify when the drop’s radius of curvature (R) is large enough compared to the size of the pillars for the new Wenzel equation to be simplified (h is the pillar height; λsolid is the line fraction of the spherical cap’s circumference that is on the pillars). Our new line-roughness Wenzel equation can be simplified to cos θW = ρ cos θY when H ≪ 1, where ρ is the line roughness. We also perform a thermodynamic free-energy analysis to determine the stability of the equilibrium states that are predicted by our new Wenzel equation.
Low-impact development urban stormwater drainage systems (LID) are an increasingly popular method to reduce the adverse hydrologic and water quality effects of urbanisation. In this review, ten ...existing stormwater models are compared in relation to attributes relevant to modelling LID. The models are all based on conventional methods for runoff generation and routing, but half of the models add a groundwater/baseflow component and several include infiltration from LID devices. The models also use conventional methods for contaminant generation and treatment such as buildup-washoff conceptual models and first order decay processes, although some models add treatment mechanisms specific to particular types of LID device. Several models are capable of modelling distributed on-site devices with a fine temporal resolution and continuous simulation, yet the need for such temporal and spatial detail needs to be established. There is a trend towards incorporation of more types of LID into stormwater models, and some recent models incorporate a wide range of LID devices or measures. Despite this progress, there are many areas for further model development, many of which relate to stormwater models in general, including: broadening the range of contaminants; improving the representation of contaminant transport in streams and within treatment devices; treating baseflow components and runoff from pervious surfaces more thoroughly; linkage to habitat and toxicity models; linkage to automated calibration and prediction uncertainty models; investigating up-scaling for representation of on-site devices at a catchment level; and catchment scale testing of model predictions.
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