Vapor Conductance Research Articles

Large dinosaur egg accumulations and their significance for understanding nesting behaviour

The accurate identification of dinosaur egg accumulations as nests or clutches is crucial for understanding the reproductive behaviour of these extinct species. However, existing methods often rely on the presence of complete eggs and embryo remains, and sedimentological criteria that are only applicable to well-structured sediments. In this study, we introduce an innovative approach to characterize egg accumulations in structureless sediments, where traditional nest structures may not be preserved. Our methodology employs a unique combination of sedimentological, taphonomic, geochemical, and geophysical proxies for the study of egg accumulations. We applied this approach to the egg accumulation from Paimogo (Jurassic, Portugal), traditionally interpreted as a nest. Our findings reveal that the Paimogo egg assemblage is a secondary deposit, resulting from a flooding event in a fluvial plain that dismantled several allosauroid and crocodylomorph clutches. The eggshell vapor conductance results, coupled with sedimentological evidence, suggest that allosauroid dinosaurs buried their eggs in the dry terrain of overbank areas close to a main channel during the breeding season, likely during the dry season to prevent the embryos from drowning. This research underscores the necessity of multidisciplinary approaches in interpreting egg accumulations and offers a novel methodology for studying these accumulations in structureless sediments. Our findings provide new insights into the breeding behaviour and nesting preferences of these extinct organisms, contributing to our understanding of dinosaur ecology.

On the Influence of Humidity on a Thermal Conductivity Sensor for the Detection of Hydrogen.

Thermal conductivity sensors face an omnipresent cross-influence through varying humidity levels in real-life applications. We present the results of investigations on the influence of humidity on a hydrogen thermal conductivity sensor and approaches for predicting the behavior of thermal conductivity towards humidity. A literature search and comparison of different mixing equations for binary gas mixtures were carried out. The theoretical results were compared with experimental results from three different thermal conductivity sensors with mixtures of water vapor in nitrogen. The mixing equations show a large discrepancy between each other. Some of the models predict a continuously decreasing thermal conductivity and some predict an increasing thermal conductivity for increasing levels of humidity. Our measurements indicate an increase in thermal conductivity followed by a decrease after reaching a peak value. It is shown that the measured behavior is reproducible with different sensors. Depending on the sensor, this corresponds to an error up to 2 vol.% in the measured hydrogen value. The measured behavior is consistent with only one of the three models. Compared to this model, our own sensor shows a maximum deviation of 1.4%. Mixing equations for gas mixtures must be chosen carefully, taking into consideration whether mixing partners include polar or non-polar molecules. Some simplified mixing equations cannot be used to calculate the thermal conductivity of water vapor in air or nitrogen.

Averaging or adding domain conductivities to calculate the unsaturated soil hydraulic conductivity

AbstractRecent models of the unsaturated hydraulic conductivity curve (UHCC) are the sum of separate UHCCs for domains of capillary water, film water, and water vapor. This requires parallel, noninteracting domains. A theoretical framework for aggregating domain conductivities to a bulk soil UHCC is presented to identify and possibly relax implicit assumptions about domain configuration. The paper develops arithmetic, harmonic, and geometric averages of the liquid‐water conductivities that can be arithmetically averaged with the vapor conductivity. However, current models for capillary and film conductivities are intrinsic, that is, valid within their respective domain. The vapor conductivity is a bulk conductivity, that is, it gives the conductivity of the gaseous domain as it manifests itself in the soil. Conversion relationships use the domain volume fractions as approximations of the as‐yet unknown weighting factors to convert between intrinsic and bulk conductivities. This facilitates consistent averaging of domain conductivities. Even with consistent averaging, a truly physically accurate model of the UHCC based on domain conductivities is fundamentally elusive. Nevertheless, models based on the three averages and the unweighted sum of the domain conductivities produce good fits to data for two soils but diverge in the dry range. The fitted curves for the capillary and film water depend on the averaging (or adding) method. Hence, they are not strictly characteristic of their respective domains. The true intrinsic domain conductivity functions may be impossible to determine.

Modeling hydraulic conductivity function of frozen soil

Hydraulic conductivity function for frozen soils (HCFF) is crucial for accurately simulating the water transfer process in cold regions, impacting hydrological states and frost heave diseases. However, the HCFF model capturing the relation between hydraulic conductivity and unfrozen water content (θ) or temperature (T) remains an open question. This study delves into HCFF encompassing both empirical and prediction models. This study begins with introducing θ-form and innovative T-form empirical HCFF models, showcasing their solid performance in fitting measured hydraulic conductivity data. Furthermore, the extension of the T-form empirical model to incorporate vapor flow and bimodal soils, through the introduction of maximum vapor conductivity and weighting factors, demonstrates a closer alignment with physical mechanisms and observed trends. In terms of predicting HCFF, the study provides a theoretical foundation through statistical hydraulic conductivity models and thermodynamic equilibrium in frozen soils. Additionally, it clarifies three routes for HCFF prediction—single Soil Freeze Characteristic Curve (SFCC), single Soil Water Characteristic Curve (SWCC), and a combination of the two—and validates their effectiveness through test results and comparison of HCFF prediction outcomes using SWCC and SFCC data from specific soil samples. In practice, the empirical and prediction models are recommended for available hydraulic conductivity data and available SFCC or SWCC data, respectively. Overall, this study not only lays the theoretical groundwork for most prediction models but also presents a valid empirical equation for modeling hydraulic conductivity function tailored specifically for frozen soils.

Water vapor transport through bioenergy grass residues and its effects on soil water evaporation

AbstractMiscanthus is a productive perennial grass that is suitable as a bioenergy crop in “marginal” lands (e.g., eroded soils) with low water holding capacity. However, little is known about the impact of miscanthus residues on vapor transport and soil water budgets. Laboratory experiments were conducted to measure the vapor conductance through miscanthus residues and its effect on soil water evaporation. The ranges for the length, width, and thickness of residue elements were 0.5–9.0, 0.1–0.5, and 0.1–0.5 cm, respectively. Average residue areal, bulk, and skeletal densities were 0.88 kg m−2, 24 kg m−3, and 1006 kg m−3, respectively, giving a porosity of 0.98 m3 m−3. A power function described the decrease in conductance with increasing residue load. The corresponding conductance for a residue load of 0.88 kg m−2 was 1.6 mm s−1. During the first days of a 60‐day drying experiment, cumulative evaporation showed logarithmic decay with increasing residue load. Conversely, cumulative evaporation during the last days of the study showed little difference between treatments. Measurements indicated that there is a “critical” residue load (∼1.0 kg m−2) beyond which evaporation no longer decreases appreciably when the soil is under the stage 1 evaporation regime. Results suggest that soil water conservation in marginal lands may be accomplished by maintaining moderate amounts of bioenergy grass residue covering the soil. Determining “critical” loads for different residue types is a knowledge gap that merits further research.

Do ontogenetic changes during incubation interfere with the interpretation of incubation mode in dinosaur eggs?

ABSTRACT Dinosaurs are oviparous reptiles that belong to Archosauria and whose closest modern relatives are crocodiles and birds. This is why, to shed light on the study of dinosaur reproduction, we conducted a test with the species Caiman latirostris (Crocodylia), a living archosaur. This paper focuses on the study of the embryos’ effect on the eggshells of Caiman latirostris during incubation. A total of 30 eggs from four nests including both embryonated and non-embryonated eggs were artificially incubated under the same conditions (incubation medium and temperature) to observe changes in eggshell structure throughout embryonic development. We found significant differences between eggs, in the embryonated eggshells we observed that the continuous calcium layer, became thinner, while at the same time we recorded an increase in the porosity of the eggshells both in the polar and equatorial regions. These changes could explain the variability recorded in fossil deposits with broods, where shells of the same oospecies were found at different levels and with differences in porosity and thickness. The results of this study will contribute to the methodology behind the inference of nesting environment and nesting strategies (buried, semi-buried or exposed) for fossil eggs, which typically utilises calculations of water vapour conductance.

Study on the water detection using the flowmeter method at low temperatures

To prepare for the lunar water exploration in the Chinese Lunar Exploration Project IV, a new apparatus for studying characteristics of the water vapor conductance and water detection at low temperatures was built based on the flowmeter method, and the performance of the miniature time-of-flight mass spectrometer (TOF-MS) for water detection in the range −20 to 20 °C was measured. The through-put within the range of 3 × 10−9–9 × 10−6 Pa m3 s−1 was provided at temperatures in the range −60 to 20 °C. The conductance of the orifice with a diameter of 21 µms for three gases (N2, Ar, and H2O) was measured at low temperatures. The diameter change of the metal orifice caused by the cold contraction in the molecular flow state is the main factor affecting the conductance, and the viscosity characteristic of gas in the viscous flow state is the main factor affecting the conductance. Therefore, the conductance of the orifice increases with the decreasing temperature when the through-put is high. In addition, the water vapor can be stably supplied by the orifice under low temperatures, and the conductance of water vapor through the orifice is measured through the on-line method and the time-ratio method. The adsorption rate and amount of water vapor on the metal surface increase with the decreasing temperature, hence the concentration of water molecules in the test dome significantly decreases as the temperature decreases. Finally, the through-put of water vapor of 8.75 × 10−8 Pa m3 s−1 was detected by the miniature TOF-MC at −20 °C on the apparatus.

Анализ особенностей процессов теплообмена при кристаллизации гранул алюминиевых сплавов в водной и водно-паровой среде

The result analysis of the created mathematical model application of a detailed change in the temperature field and analysis of phase transitions during cooling and crystallization of a melt drop under cooling conditions in an aqueous and water-vapor medium have been carried out. The presented mathematical model allows one not only to determine the temperature fields in the body of a drop or a granule, but also determines the speed of movement of a drop in the coolant at any given time, determines the intensity of heat removal, the cooling rate and the rate of crystallization of the melt at different points in the volume. All this, in the end, makes possible to predict the size of dendrites, properties and phase composition of material of the obtained granules. The mathematical model was tested in the process of granulation of high-doped aluminum alloys (alloys D1 and D16 of the Al—Cu—Mg system, alloys B95 and B96C of the Al—Zn—Mg—Cu system) obtained by the centrifugal melt spraying method and the drip method during cooling in an aqueous medium. The crystallization rate in full-scale samples was measured on the basis of the method of analysis of the dendritic parameter of the material structure. The mathematical model showed a high degree of convergence between the results of simulation modeling and the results of real experiments for obtaining granules. In particular, the model showed fairly accurate results for the formation of granules at ultra-high crystallization rates, in the absence of a «steam jacket», namely, a steam layer arising between the body of the granule and the coolant that prevents the intensity of heat removal, and is an obstacle to increasing the crystallization rate due to a lower thermal conductivity of water vapor.

Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

The unique structure of the egg allows for efficient reproduction on land. Although the functions of the egg are ensured by the concomitant cooperation of all its structures, the eggshell also plays a significant role. Apart from maintaining an aqueous environment within the egg along with controlled gas exchange, the color and pigmentation pattern of eggshell contributes to identification and protection. As a result of all these functions, the structure, shape, and pigmentation of eggshell greatly vary across the class of birds, and understanding these three variability-determining factors may aid in better interpretation of evolutionary mechanisms. In this study, we analyzed for the first time the structure, mineral composition, and characteristics of the pigmentation of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshells. The shell of blackbird eggs is much thicker compared to the shell of song thrush eggs which is due to a much thicker crystalline and palisade layers. In both species, strongly elongated mammillary knobs are observed, which create a large space between the mineralized shell and the egg membranes. The blackbird egg shell has a higher water vapor conductivity which is due to the larger diameter of the circle and the surface area of individual pores. The primary compound entering the mineral composition of the shell in both species is CaCO3 however, the thrush egg shells contained more Mg in all layers except the crystalline layer, and S in the crystalline and palisade layers. The two species clearly differ in the size and distribution of pigment spots on the eggshell. We suppose that the differences in shell structure and pigmentation presented in this study may in the future provide a basis for explaining the reasons for the much lower reproductive efficiency of song thrush compared to blackbird.

An Alternative Interpretation of the Franck-Hertz Experiment

An alternative interpretation of the general mechanism of generation of the cur-rent-voltage characteristic of the electronic conductivity of mercury vapor, formed from the standpoint of technical cybernetics, is considered. An original substantiation of the physical essence of the phenomenon under consideration is proposed, based on the relativistic model of spectral orbits of hydrogen-like systems.

Understanding the Effect of Intensified Heat Dissipation during Crystallization of High-Strength Aluminium Alloys of the Al – Zn – Mg – Cu System

This paper describes the results of a study that looked at granulated materials produced from high-strength aluminium alloys of the Al – Zn – Mg – Cu system by meltspinning. The concept of Steam Jacket is introduced, which stands for a layer of vapour that forms between the particle and the coolant and inhibits heat dissipation while also hindering the crystallization rate due to lower heat conductivity of water vapour. It was established that the vapour layer forms when the coolant comes in contact with the melt and heats up to the boiling point resulting in its transition from liquid phase to vapour. This paper describes how the particle crystallization rate can be increased by the vapour layer being constantly removed. The steam jacket that forms around a droplet gets removed due to a high speed with which the droplet travels through the coolant. What is crucial for industrial implementation of this process is not so much the design of the meltspinning unit but the velocity of the spray crucible. The paper describes the results of theoretical calculations, as well as proven experimental data, which can help determine what velocity a perforated cup should have to ensure sufficient initial speed of the droplet and constant removal of the steam jacket. It was established that by rising the rate of heat dissipation from solidified granules and, consequently, the crystallization rate one can enhance the strength of the resulting granulated aluminium alloys of the Al – Zn – Mg – Cu system. Thus, when dealing with Al – Zn – Mg – Cu alloys (such as ‘B95’, ‘В96ц’) with additional zirconium doping up to 0.5% for making pressed semi-finished products, the resultant material can have an up to 15% higher strength compared with similar granulated materials that are made using conventional processes and industrial solidification rates. It is pointed out that the technique that involves removal of the vapour layer around a forming granule is the only possible way to further raise the cooling rate and, consequently, the solidification rate. Bringing the granule size to the size of little powder particles can disrupt the following granule consolidation process meaning that it is not a feasible technique that could enhance the granulation process.

Properties, Genetics and Innate Immune Function of the Cuticle in Egg-Laying Species.

Cleidoic eggs possess very efficient and orchestrated systems to protect the embryo from external microbes until hatch. The cuticle is a proteinaceous layer on the shell surface in many bird and some reptile species. An intact cuticle forms a pore plug to occlude respiratory pores and is an effective physical and chemical barrier against microbial penetration. The interior of the egg is assumed to be normally sterile, while the outer eggshell cuticle hosts microbes. The diversity of the eggshell microbiome is derived from both maternal microbiota and those of the nesting environment. The surface characteristics of the egg, outer moisture layer and the presence of antimicrobial molecules composing the cuticle dictate constituents of the microbial communities on the eggshell surface. The avian cuticle affects eggshell wettability, water vapor conductance and regulates ultraviolet reflectance in various ground-nesting species; moreover, its composition, thickness and degree of coverage are dependent on species, hen age, and physiological stressors. Studies in domestic avian species have demonstrated that changes in the cuticle affect the food safety of eggs with respect to the risk of contamination by bacterial pathogens such as Salmonella and Escherichia coli. Moreover, preventing contamination of internal egg components is crucial to optimize hatching success in bird species. In chickens there is moderate heritability (38%) of cuticle deposition with a potential for genetic improvement. However, much less is known about other bird or reptile cuticles. This review synthesizes current knowledge of eggshell cuticle and provides insight into its evolution in the clade reptilia. The origin, composition and regulation of the eggshell microbiome and the potential function of the cuticle as the first barrier of egg defense are discussed in detail. We evaluate how changes in the cuticle affect the food safety of table eggs and vertical transmission of pathogens in the production chain with respect to the risk of contamination. Thus, this review provides insight into the physiological and microbiological characteristics of eggshell cuticle in relation to its protective function (innate immunity) in egg-laying birds and reptiles.

Combined in situ and in silico validation of a material model for hempcrete

Hempcrete is a very promising bio-based insulating material with a minor or even negative CO2 footprint and low thermal conductivity. To utilize it efficiently, it must be possible to make predictions regarding hempcrete hygrothermal performance and whether it is up to the modern standards—this requires a verified material model for use in numerical simulations. The results of ∼8 months of in situ temperature and relative humidity monitoring for a hempcrete wall are presented along with a documented manufacturing process, and the experiment is reproduced in silico, obtaining good agreement and observations in line with previous studies. Given the scarcity of in situ studies, the presented data could be used as a reference for simulations of moisture and heat transfer in building envelopes that contain hempcrete. Validation for hempcrete as a good insulating material for Latvian or similar climate conditions is also provided. Its high mold growth resistance even at high humidity is experimentally demonstrated. Combined with good water and vapor conductivity, this leads to consistently low mold growth risk as shown experimentally and in simulations.

Limited‐transpiration rate and plant conductance in a diverse sweet corn population

AbstractLimited‐transpiration rate at elevated vapor pressure deficit (VPD) can allow soil water conservation for use during late‐season drought, but it can also result in decreased crop yields under well‐watered conditions because of restricted crop gas exchange. Previous studies with sweet corn (Zea mays L.) have found the limited‐transpiration rate was quite common among commercial cultivars even though sweet corn is commonly grown under well‐watered conditions. This study was undertaken to identify possible genetic sources of sweet corn that were not encumbered by the limited‐transpiration trait. Additionally, data were obtained to compare the plant hydraulic conductance among the lines. Among the 26 sweet corn lines included in this study, only eight did not express the limited‐transpiration trait. Four of the lines not expressing the limited‐transpiration (IL395a, IL543c, P39, and SD245) had stomata vapor conductance values over the range of tested VPD similar to the values expressed by many of the limited‐transpiration lines only at low VPD. The eight lines not expressing the limited‐transpiration trait tended to have low plant hydraulic conductance. For those lines expressing the limited‐transpiration trait, there was a correlation between the VPD at initiation of limited transpiration and plant hydraulic conductance. Expression of the limited‐transpiration traits proved, however, to be temperature sensitive in 7 of 18 tested lines expressing the trait at 32 °C because they failed to express the trait at 38 °C. The genetic variation in expression of the limited‐transpiration trait and plant hydraulic conductance identified in this study offers specific candidate inbred lines that could be used as genetic resources for improving sweet corn growth and yield for well‐watered environments.

Investigation of the features of crystallization of granules of high-strength aluminum alloys of the Al-Zn-Mg-Cu system at ultra-high cooling rates

The article presents the results of studies of the process of obtaining granular materials from high-strength aluminum alloys of the Al - Zn - Mg - Cu system by centrifugation of the melt with ultra-high cooling rates of granules. The concept of a «steam jacket» is introduced, namely, a steam layer that occurs between the granule body and the cooling liquid, which prevents the intensity of heat removal and is an obstacle to increasing the crystallization rate due to the lower thermal conductivity of water vapor. It is established that the formation of a vapor layer always occurs due to the heating of the cooling liquid in contact with the melt drop to boiling temperatures and the transition of the cooler from the liquid phase to steam. The technology of increasing the rate of crystallization of granules due to the constant removal of the vapor layer is proposed. The removal (knocking down) of the vapor shell that occurs around the drop occurs due to the high speed of the drop movement in the cooling medium. Fundamentally important in the industrial implementation of this technology is not so much the design of the device for obtaining pellets by centrifugation of the melt, namely, the high required rotation speed of the spraying crucible of the device under consideration. The results of experimental data are presented to determine the necessary rotation speed of the perforated cup, which ensures the creation of a sufficient initial velocity of the drop movement, leading to a constant churning of the «steam jacket». It is determined that an increase in the rates of heat removal from the crystallized granules and, as a result, an increase in the crystallization rate leads to an increase in the strength characteristics of granular aluminum alloys of the Al-Zn-Mg-Cu system. In particular, in the production of pressed semi-finished products from alloys of the Al-Zn-Mg-Cu system, such as B95, B96c. the increase in the strength characteristics of the material of the press products is up to 15 % compared to the same granular materials obtained by traditional methods with industrial crystallization rates of melt droplets. It is established that this method, based on the removal of the vapor layer around the formed granule, is the only possible one for further increasing the cooling rate and, as a result, the crystallization rate. Reducing the size of granules to the size of powders leads to serious technological problems in the further consolidation of granules and, in fact, is a dead end branch of the further development of granulation methods.

Coordination of stomata and vein patterns with leaf width underpins water-use efficiency in a C4 crop.

Despite its importance for crop water use and productivity, especially in drought-affected environments, the underlying mechanisms of variation in intrinsic water-use efficiency (iWUE = net photosynthesis/stomatal conductance for water vapour, gsw ) are not well understood, especially in C4 plants. Recently, we discovered that leaf width (LW) correlated negatively with iWUE and positively with gsw across several C4 grasses. Here, we confirmed these relationships within 48 field-grown genotypes differing in LW in Sorghum bicolor, a C4 crop adapted to dry and hot conditions. We measured leaf gas exchange and modelled leaf energy balance three times a day, alongside anatomical traits as potential predictors of iWUE. LW correlated negatively with iWUE and stomatal density, but positively with gsw , interveinal distance of longitudinal veins, and the percentage of stomatal aperture relative to maximum. Energy balance modelling showed that wider leaves needed to open their stomata more to generate a more negative leaf-to-air temperature difference, especially at midday when air temperatures exceeded 40°C. These results highlight the important role that LW plays in shaping iWUE through coordination of vein and stomatal traits and by affecting stomatal aperture. Therefore, LW could be used as a predictor of higher iWUE among sorghum genotypes.

Theoretical method for the estimation of vapour conductivity for unsaturated soil

The liquid water movement is commonly considered in the seepage analysis related to the unsaturated soil (e.g, residual soil above the ground water table). The hydraulic conductivity of unsaturated soil is commonly considered to decrease with the increase in soil suction (or decrease in the degree of saturation). As a result, the estimated hydraulic conductivity of unsaturated soil from the conventional method is very low in the high suction range (i.e., beyond the residual suction). However, the experimental results from recent studies indicate that in the high suction zone, the hydraulic conductivity of unsaturated soil may increase with an increase in soil suction. In addition, recent studies also indicate that in the high suction zone (i.e., greater than 3100 kPa), water in soil moves mainly in the vapour form. As a result, the estimation of the hydraulic conductivity of unsaturated soil due to vapour flow in soil is crucial for engineers in the estimation of water transmission through a relative dry soil. In this note, the theoretical method is proposed for the estimation of vapour conductivity from the soil-water characteristic curve. The proposed method is rational and it has the theoretical basis without any empirical parameter. It is observed that the estimated results from the proposed method agree well with the results reported in the published literature.

Performance of nitrogen pulsating heat pipes as passive thermal switches in a redundant cryocooler application

A novel redundant cryocooler system, featuring two cryocooler cold heads linked via separate nitrogen pulsating heat pipe (PHP) thermal switches to a common cold plate, is developed and performance tested. The setup allows the cold plate to be maintained at the design temperature when one of the two cryocoolers is inactive by leveraging the low thermal conductivity of the static vapor in the associated dry PHP as insulation from the warm inactive cryocooler. The PHP thermal switches operate passively and require no mechanical actuation, inherently offering a highly reliable switching mechanism. PHP heat load, effective thermal conductivity, effective conductance, evaporator temperature, and condenser temperature measurements are presented for a range of fill ratios and applied cold plate heat loads. The tested PHPs can transfer at least 16 W before dryout and have effective thermal conductivities in the ON and OFF switch states ranging from 10,000 W/m-K to 55,000 W/m-K and 8 W/m-K to 50 W/m-K, respectively. Thermal switch performance is characterized by the switching ratio – the ratio of its effective conductance in the ON state to that in the OFF state – and is demonstrated to approach about 2500 for the tested PHPs. The parasitic heat load through the PHP switch in the OFF state (about 0.6 W) is found to be about 4 percent of its maximum tested ON state heat transfer capacity (about 16 W).

The eggshell structure in apteryx; form, function, and adaptation.

Apteryx is a genus of flightless birds endemic to New Zealand known to lay very large eggs in proportion to body weight. The eggshell of Apteryx is unusually thin and less porous than allometrically expected possibly as a compensation for a very long incubation period. Past studies have been carried out on Apteryx australis, a species which once comprised all kiwi with brown plumage, now separated into three distinct species. These species use different habitats and live at different latitudes and altitudes, therefore generating a need to revise our knowledge of the attributes of their eggshells. In this study, we measured the physical characteristics and water conductance on eggshell fragments of these three species and Great‐spotted Kiwi and relate them to the environmental conditions of their respective environments; we also measured the water vapor conductance of Brown Kiwi eggs of late stages of incubation. We found that several trade‐offs exist between incubation behavior, environmental conditions, and eggshell structure. We found differences between species in eggshell water vapor conductance seemingly related to altitude; Brown Kiwi and Rowi generally inhabiting lower altitudes had the highest conductance and Tokoeka, generally living in montane environments, the lowest. This is achieved by an increased eggshell thickness rather than a pore area reduction. Finally, the water vapor conductance late in incubation was 58% higher than infertile unincubated eggs, suggesting a drastic increase in conductance throughout the long incubation period. Using the values previously reported, we calculated the embryonic eggshell thinning to be 32.5% at the equatorial region of the eggshell. We describe several new features, such as triangular mineral particles in the cuticle, reported for the extinct Trigonoolithus amoei, and confirmed the existence of plugged pores. We suggest that these structures provide microbial protection needed by a burrow nesting species with a long incubation period.

Is the atomic metal vapor a dielectric state?

We propose a simple method for calculating the metal vapor conductivity at the critical point and near-critical isotherms This method is based on the hypothesis of an electron jellium’s existence as an origin of the conduction band in metal vapor’s gaseous phase. The hypothesis was suggested in our previous works, mentioned further in this article. Satisfactory agreement with the experimental data for alkali metals (Cs, Rb) allows us to conclude that, at the critical point and its vicinity, the atomic metal vapors should be considered as a gaseous metal, that is not a dielectric state of matter.