Porosity and water vapor conductance of two Troodon formosus eggs: an assessment of incubation strategy in a maniraptoran dinosaur

Paleobiology ◽  
10.1666/11042 ◽  
2013 ◽  
Vol 39 (2) ◽  
pp. 278-296 ◽  
Author(s):  
David J. Varricchio ◽  
Frankie D. Jackson ◽  
Robert A. Jackson ◽  
Darla K. Zelenitsky
Keyword(s):  
Water Vapor ◽  
Surface Area ◽  
Geometric Modeling ◽  
Geometric Model ◽  
Thin Sections ◽  
Surface Areas ◽  
The North ◽  
Subaerial Exposure ◽  
Total Conductance ◽  
Egg Shape

Using tangential thin sections, we examined variation in porosity and water vapor conductance across two eggs of Troodon formosus, a small (∼50 kg) theropod dinosaur from the North American Upper Cretaceous, testing two hypotheses of egg incubation: (1) full burial within sediments or vegetation and (2) partial burial with exposed upper egg portions. We divided and sampled the eggs in five zones, 1 through 5 from blunt top to more pointed bottom. A geometric model composed of a hemisphere, cone, and paraboloid was used to estimate total and zonal volumes and surface areas. The 138 × 67 mm idealized Troodon egg has a volume, surface area, and mass of 296.4 cm3, 239.23 cm2, and 314.2 g, respectively. Zonal surface areas and volumes highlight the strongly asymmetric and elongate form of the Troodon egg. Geometric modeling provides better estimates of volume and surface area where egg shape diverges markedly from that of a typical bird egg. Porosity varies significantly across both Troodon eggs, with zones 2 and 3 having the largest pores and a majority (70–78%) of total conductance, whereas zone 5 has very low conductance. Total water vapor conductance in the two eggs are 31.85 and 40.62 mg H2O day− Torr−, values 76% and 97% of those predicted for an avian egg of similar size. Low total conductance compares favorably to values in extant birds and non-avian reptiles that incubate in open nests, arguing against full burial incubation. Together with nesting site evidence, low conductance values favor partial burial and incubation by a Troodon adult. Asymmetric egg shape concentrates volume, surface area, and conductance near or at the point of subaerial exposure. Among non-avian dinosaurs, the eggs of Troodon and troodontids are most similar to those of modern birds in having an asymmetric shape, low porosity, no ornamentation, and three structural eggshell layers.

Efficiency of the Conversion of Work of Drainage to Surface Energy for Sandstone and Carbonate

2007 ◽  
Vol 10 (04) ◽  
pp. 338-347 ◽  
Author(s):  
Siddhartha Seth ◽  
Norman R. Morrow
Keyword(s):  
Surface Energy ◽  
Capillary Pressure ◽  
Surface Area ◽  
Pressure Curve ◽  
Thin Sections ◽  
Surface Areas ◽  
Capillary Pressure Curve ◽  
Phase Saturation ◽  
Interfacial Areas ◽  
Random Packings

Summary The increase in surface energy resulting from drainage of a wetting phase from a porous medium is often equated to the work of displacement determined from the area under its capillary pressure curve. However, capillary pressure vs. saturation relationships are not reversible and do not represent quasistatic displacement. The increase in surface energy is less than the work done because of inherent capillary instabilities that are the basic cause of capillary pressure hysteresis. Nevertheless, relating the area under a capillary pressure curve to the thermodynamic work of displacement can be justified by interpreting the curve as a series of alternating isons (reversible displacements) and rheons (spontaneous redistribution at constant saturation). The efficiency of conversion of work to surface energy, Ed, depends on the increase in surface area that accompanies drainage. Surface areas of nonwetting phase/solid and nonwetting phase/wetting phase have been determined through displacement of a colored low-viscosity liquid resin that can be solidified so that thin sections reveal the distribution of phases and surfaces within the pore space of the rock. Two-dimensional images obtained from thin sections were analyzed using stereology to obtain estimates of saturations and interfacial areas in three dimensions. For drainage of Berea sandstone to 20% wetting-phase saturation, Ed was 36%, which was less than one-half of the efficiency of 85% for the same range of change in saturation determined previously for random packings of equal spheres. Values of Ed for the tested carbonate were approximately one-half of those for sandstone. The wide variation is explained in terms of a simple pore model that relates Ed to aspect ratio. Introduction Changes in fluid saturations during multiphase displacements in porous media are accompanied by changes in interfacial surface area between the phases. Interfacial areas are directly related to surface energy and are fundamental to spontaneous-imbibition phenomena, to multiphase transport properties such as relative permeability, and to processes that involve mass transfer between phases (Haines 1930; Leverett 1941; Rapoport and Leas 1951; Payne 1953; Rootare and Prenzlow 1967; Hassanizadeh and Gray 1993; Reeves and Celia 1996; Kim et al. 1997; Alpak et al. 1999; Schaefer et al. 2000a, 2000b; Beliaev and Hassanizadeh 2001; Wan and Tokunaga 2002; Jain et al. 2003; Cheng et al. 2004). The relationship between work of displacement from capillary pressure data to changes in surface energy from direct measurements of surface areas has been reported in detail for drainage, imbibition, and secondary drainage for random packings of equal spheres (Morrow 1970a). The first measurements of relationships between work and increase in surface energy for porous rocks are reported here for primary drainage of a sandstone and a limestone.

MICROCALORIMETRY OF THE ADSORPTION OF WATER VAPOR ON SODIUM CHLORIDE

1958 ◽  
Vol 36 (10) ◽  
pp. 1338-1345 ◽  
Author(s):  
Henry M. Papée ◽  
Keith J. Laidler
Keyword(s):  
Water Vapor ◽  
Sodium Chloride ◽  
Surface Area ◽  
Heat Production ◽  
No Adsorption ◽  
Heats Of Adsorption ◽  
Second Stage ◽  
Surface Areas ◽  
Adsorption Of Water ◽  
Adsorption Of Water Vapor

Using a microcalorimeter of the Calvet type, measurements have been made of the heats of adsorption of water vapor on microcrystals of sodium chloride, the rate of heat production being followed as a function of time. With crystals of surface areas between 1 and 15 square meters per gram it was found that three distinct processes occurred, in the following order: (1) simple adsorption of water on the surface, (2) decrease in the surface area, and (3) penetration of water into the lattice. During the second stage no adsorption could be detected. On crystals with larger surface areas there was considerable overlapping of the three phenomena, but the general mechanisms appear to be the same.

The Effect of Specific Surface Area on Radionuclide Sorption on Crushed Crystalline Rock

1996 ◽  
Vol 465 ◽  
Author(s):  
P. Hölttä ◽  
M. Siitari-Kauppi ◽  
P. Huihuri ◽  
A. Lindberg ◽  
A. Hautojärvt
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Mass Distribution ◽  
Specific Surface Area ◽  
Crystalline Rock ◽  
Crushed Rock ◽  
Surface Irregularity ◽  
Adsorption Method ◽  
Thin Sections ◽  
Surface Areas

ABSTRACTThe sorption of sodium (22Na), calcium (45Ca) and strontium (85Sr) was studied on mica gneiss, unaltered, moderately altered and strongly altered tonalite samples taken from hole SY-KR7 drilled in the Syyry area in Sievi, Western Finland. The crushed rock samples were sieved into six fractions from 71 μm to 1250 μm. A proportional mineral composition for the different fractions were estimated by X-ray diffraction. The specific fraction surface areas were determined by the BET nitrogen adsorption method. The fractal method was applied to characterize rocks and to describe quantitatively surface irregularity. The mass distribution ratio values for each fraction were determined using the static batch method. The sorption of tracers onto different minerals was observed using rock thin sections. Kd-values calculated from thin section Ka-values and Kd revalues obtained from batch experiments were in good agreement. Mass distribution ratios for different size fractions are given, and the effect of the specific surface area is discussed. Owing to larger specific surface areas considerably higher sorption on smaller fractions was found for altered tonalites.

Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts

1987 ◽  
Vol 45 ◽  
pp. 588-589
Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons
Keyword(s):  
Surface Area ◽  
Electron Micrographs ◽  
Cell Morphology ◽  
Individual Variation ◽  
Serial Section ◽  
Stereo Pair ◽  
Complex Structures ◽  
Serial Sections ◽  
Surface Areas ◽  
Computer Based

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.

scholarly journals Tuning the hierarchical pore structure of graphene oxide through dual thermal activation for high-performance supercapacitor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jeongpil Kim ◽  
Jeong-Hyun Eum ◽  
Junhyeok Kang ◽  
Ohchan Kwon ◽  
Hansung Kim ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Pore Structure ◽  
Specific Capacitance ◽  
Surface Area ◽  
Thermal Annealing ◽  
High Performance ◽  
Annealing Process ◽  
Supercapacitor Electrode ◽  
Simple Method ◽  
Surface Areas

AbstractHerein, we introduce a simple method to prepare hierarchical graphene with a tunable pore structure by activating graphene oxide (GO) with a two-step thermal annealing process. First, GO was treated at 600 °C by rapid thermal annealing in air, followed by subsequent thermal annealing in N2. The prepared graphene powder comprised abundant slit nanopores and micropores, showing a large specific surface area of 653.2 m2/g with a microporous surface area of 367.2 m2/g under optimized conditions. The pore structure was easily tunable by controlling the oxidation degree of GO and by the second annealing process. When the graphene powder was used as the supercapacitor electrode, a specific capacitance of 372.1 F/g was achieved at 0.5 A/g in 1 M H2SO4 electrolyte, which is a significantly enhanced value compared to that obtained using activated carbon and commercial reduced GO. The performance of the supercapacitor was highly stable, showing 103.8% retention of specific capacitance after 10,000 cycles at 10 A/g. The influence of pore structure on the supercapacitor performance was systematically investigated by varying the ratio of micro- and external surface areas of graphene.

The new face of large dams in the 21st century

2021 ◽  
Author(s):  
Atal Ahmadzai
Keyword(s):  
Surface Area ◽  
Aquatic Ecosystems ◽  
Energy Demand ◽  
Environmental Aspects ◽  
Water Insecurity ◽  
Surface Areas ◽  
Large Dams ◽  
Physical Attributes ◽  
Under Construction ◽  
Ecological Disturbances

Alerted by increasing water insecurity and energy demand, countries, mainly in the Global South, are building dams of unprecedented magnitude. Hundreds of large dams (≥ 100 metres) have been constructed since 2000, with hundreds more under construction. Analyses of the physical attributes of these dams present a concerning image. While they create expansive reservoirs with large surface areas, they have inefficient surface area-to-volume ratios ('S2VR'). Their unprecedented size and the reservoirs’ expansive surface area, indicate severe environmental costs, mainly through ecological disturbances to the (riverine) aquatic ecosystems; and greenhouse gas emissions (GHG). Other ecological costs due to the larger S2VR include a high evaporation rate and compromised biodiversity of a wider area, both up- and downstream. The safety and environmental aspects of these large dams should be robustly scrutinised.

scholarly journals The Effects of Methane Storage Capacity Using Upgraded Activated Carbon by KOH

2018 ◽  
Vol 8 (9) ◽  
pp. 1596 ◽  
Author(s):  
Jung Park ◽  
Gi Lee ◽  
Sang Hwang ◽  
Ji Kim ◽  
Bum Hong ◽  
...  
Keyword(s):  
Surface Area ◽  
Storage Capacity ◽  
Activated Carbons ◽  
Chemical Activation ◽  
High Surface ◽  
Heat Of Adsorption ◽  
Low Grade ◽  
Surface Areas ◽  
Ch4 Adsorption ◽  
Ch4 Storage

In this study, a feasible experiment on adsorbed natural gas (ANG) was performed using activated carbons (ACs) with high surface areas. Upgraded ACs were prepared using chemical activation with potassium hydroxide, and were then applied as adsorbents for methane (CH4) storage. This study had three principal objectives: (i) upgrade ACs with high surface areas; (ii) evaluate the factors regulating CH4 adsorption capacity; and (iii) assess discharge conditions for the delivery of CH4. The results showed that upgraded ACs with surface areas of 3052 m2/g had the highest CH4 storage capacity (0.32 g-CH4/g-ACs at 3.5 MPa), which was over two times higher than the surface area and storage capacity of low-grade ACs (surface area = 1152 m2/g, 0.10 g-CH4/g-ACs). Among the factors such as surface area, packing density, and heat of adsorption in the ANG system, the heat of adsorption played an important role in controlling CH4 adsorption. The released heat also affected the CH4 storage and enhanced available applications. During the discharge of gas from the ANG system, the residual amount of CH4 increased as the temperature decreased. The amount of delivered gas was confirmed using different evacuation flow rates at 0.4 MPa, and the highest efficiency of delivery was 98% at 0.1 L/min. The results of this research strongly suggested that the heat of adsorption should be controlled by both recharging and discharging processes to prevent rapid temperature change in the adsorbent bed.

scholarly journals Effect of tropical cyclones on the Stratosphere-Troposphere Exchange observed using satellite observations over north Indian Ocean

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
S. Ravindra Babu ◽  
S. S. Das ◽  
Ghouse Basha ◽  
B. V. Krishnamurthy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Lower Stratosphere ◽  
North Indian Ocean ◽  
Satellite Observations ◽  
Upper Troposphere ◽  
North West ◽  
The North ◽  
The Impact

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere-troposphere exchange (STE) process in the Upper Troposphere and Lower Stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the North Indian Ocean during 2007–2013 on the STE process is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) Radio Occultation (RO) measurements and ozone and water vapor concentrations in UTLS region are obtained from Aura-Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km from the centre of cyclone. In our earlier study we have observed decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K) and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within the 500 km from the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from cyclone centre whereas the enhancement in the water vapor in the lower stratosphere is more significant on south-east side extending from 500–1000 km away from the cyclone centre. We estimated the cross-tropopause mass flux for different intensities of cyclones and found that the mean flux from stratosphere to troposphere for cyclonic stroms is 0.05 ± 0.29 × 10−3 kg m−2 and for very severe cyclonic stroms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed in the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget and consequentially the STE in the UTLS region.

scholarly journals The Peroneus Brevis and Plantar Fascia Insertions Are Related to Proximal Fifth Metatarsal Fractures

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0001
Author(s):  
Ali Hosseini ◽  
Pim Van Dijk ◽  
Sofie Breuking ◽  
Bryan Vopat ◽  
Daniel Guss ◽  
...  
Keyword(s):  
Surface Area ◽  
Fracture Mechanism ◽  
Soft Tissues ◽  
Plantar Fascia ◽  
Dorsal Side ◽  
Fracture Zones ◽  
Surface Areas ◽  
Metatarsal Bones ◽  
Metatarsal Fractures ◽  
Peroneus Brevis

Category: Midfoot/Forefoot Introduction/Purpose: Proximal fifth metatarsal fractures (PFMF) are among the most common fractures in the foot and can be categorized into three fracture zones [1]. To investigate the fracture mechanism of PFMF in different zones, a better understanding of the anatomy of the bone and its surrounding soft tissues is required. Both the plantar fascia (PF) and the peroneus brevis (PB) tendon insertions are at the base of the fifth metatarsal, and may contribute to the pathophysiology of PFMF. However, the role of the PB and PF insertions in the pathogenesis of PFMF remains unclear. The purpose of this study was to accurately define the footprint of the PB and PF insertions of the base of the 5th metatarsal in relation to the different zones of PFMF. Methods: 21 cadaveric fifth metatarsal bones were harvested from cadaveric feet. All bones were freed of any remaining soft tissue adherence, except for the PB and the PF insertions. Three reference screws with a diameter of 1 mm were placed and secured on each bone with 2 screws distally and 1 screw proximally for registration. All bones were CT scanned to create a 3D bone reconstruction. Next, the insertions of the PB and PF and the reference screws of each bone were digitized and then mapped to its corresponding 3D bone model. In order to describe the three different fracture zones of the 5th metatarsal, an established coordinate system was made for each bone to simulate separate fracture zones (Figure a) based on Lawrence guideline [1]. The shape, location and surface areas of both insertions and their relation to the different fractures zones were determined (Figure b). Results: The insertion of the PB was oval shaped and located on the dorsal side of the base, with a mean surface area of 88.1 ± 46.4 mm2. The PF was oval shaped and situated around the tip of tuberosity, with a mean surface area of 150.7±53.5 mm2. The PB insertion was present in zone 1 fractures in 100% (21/21) of the 5th metatarsal models and 29% (6/21) of the models for zone 2 fractures. The PF insertion was involved in 100% (21/21) of the 5th metatarsal models for zone 1 fractures and 43% (9/21) of the models for zone 2 fractures. Conclusion: Results of this study demonstrate that the insertion of both the PB and PF are involved in all zone 1 PFMF and a significant percentage of zone 2 PFMF. The location of tendon insertions affect the forces exerted on the bone, which may indicate a relation of the insertions of both the PB and the PF with the fracture mechanism of many zone 1 and 2 PFMF. Moreover, in the treatment of these fractures, care should be taken to maintain or restore the anatomy of these insertions to maximize functional outcomes.

The Relation of Vibrator Surface Area and Static Application Force to the Vibrator-to-Head Coupling

1968 ◽  
Vol 11 (4) ◽  
pp. 805-810 ◽  
Author(s):  
E. R. Nilo
Keyword(s):  
Young Adult ◽  
Surface Area ◽  
Unit Area ◽  
Bone Conduction ◽  
Pressure Force ◽  
Adult Men ◽  
Surface Areas ◽  
History Of ◽  
Preliminary Study ◽  
Bone Conduction Hearing

Twelve young adult men with normal hearing and no history of ear disease took part in our study of the relation of vibrator surface area and static application force to the vibrator-to-head coupling. For vibrator surface areas of 1.125, 2.25, and 4.5 cm 2 coupled to the forehead under static forces of 150, 300, and 600 gm, monaural thresholds of bone-conduction hearing were determined at frequencies 250, 500, 1000, and 2000 Hz. With surface area constant, threshold improvement was frequency dependent. It decreased with increasing frequency until at 2000 Hz it was minimal. In contrast to this, with force constant, the influence of surface area was observed to begin at 2000 Hz. Preliminary study suggests this influence would extend to 4000 Hz. In view of the respective influence of application force and surface area to bone-conduction hearing, equating vibrator-to-head coupling on the basis of pressure (force per unit area), when there are two or more vibrators, may not represent an adequate control.

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