Supersaturation and condensation shock during flow of potassium vapor
Supersaturation and condensation shock during flow of potassium vapor
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Spontaneously supersaturated nucleation strategy for high reproducible and efficient perovskite solar cells
High-quality perovskite films are predominantly prepared by anti-solvent assisted spin-coating method. How- ever, small device size and narrow operation window limit their applications in practical and scalable production. Here, a spontaneously supersaturated nucleation strategy is developed to fabricate high-quality perovskite films without any antisolvents. The rapid precipitation behavior of the precursor solutions could be triggered by the volatilization of methylamine ethanol at the initial film formation stage, forming uniform and compact intermediate phase films. Mirror-like large area (10 cm × 10 cm) methylammonium lead triiodide (MAPbI 3 ) perovskite films with micrometer-sized grains can be achieved by phase transition via annealing. The average power conversion efficiency (PCE) of 19.4% is achieved for 0.1 cm 2 perovskite solar cells (PSCs). The 1 cm 2 device shows a PCE of 17.57% and retains 96.8% after aging for 39 days in the air with a relative humidity of 5–30%. The perovskite module based on the perovskite films prepared by our strategy exhibits a PCE of 13.13%. Here, the perovskite film fabrication method developed in this work shows high reproducibility of the fabrication process due to the spontaneous nucleation process. Meanwhile, it also exhibits significant potential in the application of scalable solution processing deposition techniques toward the commercialization of PSCs.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Deuterium supersaturated surface layer in tungsten: ion energy dependence
Abstract Properties of deuterium (D) supersaturated surface layers (DSSLs) formed in tungsten (W), such as thickness, internal microstructures, and D retention, are experimentally investigated as a function of the incident ion energy, E i . W samples were exposed to D plasmas in the PISCES-A linear plasma device in a range of E i ∼ 45–175 eV, while other plasma exposure parameters were fixed: sample temperature, T s , ∼423 K, ion flux, Γ i , ∼1.2 × 10 21 m −2 s −1 , and fluence, Φ i , ∼3.0 × 10 24 m −2 . High-resolution, cross-sectional, transmission electron microscopy observations confirm that (1) a DSSL forms even at the lowest E i ∼ 45 eV, (2) the DSSL thickness, Δ t DSSL , is found to decrease with decreasing E i from ∼11–12 nm at E i ∼ 175 eV to ∼5–6 nm at ∼45 eV, and to agree with approximately the maximum implantation depth calculated using SDTrimSP, and (3) high-density D nanobubbles with a diameter of ∼1 nm or less exist inside the DSSL, which is deemed to validate a theory-predicted vacancy stabilization process due to trapping of a solute D atom(s). Utilizing a D areal density of ∼4.2 × 10 19 m −2 in the first 14 nm from the surface at E i ∼ 75 eV from nuclear reaction analysis and the measured E i dependence of Δ t DSSL , our previous laser-induced breakdown spectroscopy data is updated: both dynamic and static D retention increase with decreasing E i , and the D/W atomic fraction during plasma exposure reaches ∼0.3 at E i ∼ 45 eV. A possible DSSL formation mechanism is proposed.
Physics↗
Reply to Comment on ‘Deuterium supersaturated surface layer in tungsten: ion energy dependence’
Abstract We reply to the comment by Li et al (submitted to Nucl. Fusion with this response) on our recent paper Nishijima et al (2023 Nucl. Fusion 63 126003). In this response, we address the existence of an incident ion energy, E i , threshold for the deuterium (D) supersaturated surface layer (DSSL) formation with a newly conducted D plasma exposure experiment at E i ∼ 20 eV. It is also further demonstrated, based on new experiments where the ion flux, fluence, and sample temperature are scanned, that non-kinetic (ballistic) processes play a role in the DSSL formation and growth. In addition, the effect of impurities in our plasma is discussed also with a new analysis of the surface composition made after a D plasma exposure.
Nishijima, D. (ORCID:0000000231194827)↗
Hydrogen-oxygen fuel cell system with reactant-supersaturated electrolyte feed Final report, 21 Nov. 1966 - 20 May 1967
Conceptual design analysis of hydrogen oxygen fuel cell system with reactant supersaturated electrolyte feed
Zaromb, S.↗
CCN-supersaturation spectra slopes (k)
Theoretically the slope k of a CCN-supesaturation spectrum should equal two thirds of the slope of the total (soluble) aerosol size distribution. Workshop results tended to verify this relation. The k values are markedly different depending on whether one is measuring ambient CCN concentrations at supersaturations S above or below approximately 0.1-0.2%. The larger k values for S approximately 0.1% is consistent with the greater decrease in large particle concentration with increasing size. It is concluded that over the S range of 0.02% to 2%, two power fits (and k values) may sometimes suffice for a reasonable approximation of the CCN distribution. At other times, and with laboratory generated aeosols, such an approach is inadequate and requires refinement.
Jiusto, J. E.↗
Response of cloud supersaturation to radiative forcing
Time-dependent solutions are obtained for droplet temperatures and supersaturation, in a study of the diffusional growth or evaporation of cloud droplets due to net emission or absorption of radiation, taking into account the partitioning of the net radiation budget between the droplets and the ambient air. Radiative perturbations are noted to result in very high rates of change in droplet temperatures. As the droplets evaporate or grow due to radiative effects, the saturation ratio of the ambient air adjusts in keeping with changes in the water vapor density and temperature of the air.
Davies, R.↗
Perennial N2 supersaturation in an Antarctic lake
The results of a study are reported which, for the first time, documents the supersaturation of N2 in a lake. Dissolved N2 levels of 145 percent and 163 percent were determined for Antarctica's Lake Hoare from samples taken just below the ice cover and at a depth of 12 m, respectively. The relative importance of biological and abiological sources is reflected in the ratio of N2 concentration to O2 concentration. In Lake Hoare this ratio was 1.20 at the ice/water interface and 1.05 at 12 m, considerably different from the ratio in equilibrium with air (about 1.8). Based on these results, it is determined that about half of the net O2 production in the lake is the result of biological processes. The significance of these results for the putative ice-covered paleolakes in the canyon regions of Mars is discussed.
Wharton, Robert A., Jr.↗
Supersaturation, droplet spectra, and turbulent mixing in clouds
Much effort has recently gone into explaining the observed broad precoalescence size distribution of droplets in cloud and fogs, because this differs from the results of condensational growth calculations which lead to much narrower distributions. A good example of droplet size-distribution broadening was observed on flight 17 (25 July) of the NRL tethered balloon during the 1987 FIRE San Nicolas Island IFO. These observations caused the interactions between cloud microphysics and turbulent mixing to be re-examined. The findings of Broadwell and Breidenthal (1982) who conducted laboratory and theoretical studies of mixing in shear flow, and those of Baker et al. (1984) who applied the earlier work to mixing in clouds, were used. Rather than looking at the 25 July case at SNI, earlier fog observations made at SUNY (6 Oct. 1982) which also indicated that shear-induced mixing was taking place, and which had a better collection of microphysical measurements including more precise supersaturation measurements and detailed vertical profiles of meteorological parameters were chosen instead.
Gerber, H.↗
Crystallization of proteins by dynamic control of supersaturation
The growth of protein crystals is known to be the limiting factor in the determination of the three-dimensional structures of most proteins. It is expected that the kinetics of supersaturation, which is directly related to solvent evaporation, will affect protein crystal growth and nucleation and accordingly determine the quality, number, size, and morphology of the crystals. With a technique that controls the evaporation of solvent from a protein solution with N2(g) it is possible to determine the effect of different evaporation profiles on hen egg white lysozyme crystals. Hen egg white lysozyme was chosen as the model protein because it crystallizes easily and has solubility data available for most salt, pH, and temperature ranges. Commercially available lysozyme was further purified by a number of methods. Crystals grown with the purified lysozyme and with the unpurified lysozyme in citrate buffer were different shapes but were found to be of the same symmetry space group by precession photos. Differences were seen in the lysozyme crystals grown using different evaporation rates. At three of the four initial conditions for lysozyme crystal growth, longer evaporation times yielded better crystals. The evaporation times required to see a change in the appearance of the crystals was much longer than expected. The number of rates studied so far represent only a small fraction of the ones now available with the gas evaporation device. The technique also provides for control of both solution pH and temperature which are related to the solubilities of proteins.
Wilson, Lori June↗
Oxygen supersaturation in ice-covered Antarctic lakes - Biological versus physical contributions
Lake Hoare is one of a number of ice-covered polar lakes in the Dry Valley Region of southern Victoria Land, Antarctica. Analysis of N2, O2, and Ar in bubbles from this lake's ice indicates that while O2 is about 2.4 times supersaturated in the water below the ice, only 11 percent of the O2 input to this lake is due to biological activity and the balance is derived from meltwater inflow. In Lake Hoare, as much as 70 percent of total gas loss may occur by advection through the ice cover; the remaining gas fractions are removed by respiration at the lower boundary in the case of O2, and by molecular exchange with the atmosphere in the peripheral summer moat around the ice.
Craig, H.↗
Some Aspects of PVT Low Supersaturation Nucleation and Contactless Crystal Growth
The basic principles of the contactless growth of crystals from the vapor in combination with the process of low-supersaturation nucleation are discussed. The mathematical formulation of the morphological stability criterion in vapor growth systems is given and its implications for contactless growth technique are analyzed. A diagram for selection of proper temperature conditions for growth of CdTe crystals is presented.
Grasza, K.↗
Experimental Study of the Low Supersaturation Nucleation in Crystal Growth by Contactless Physical Vapor Transport
The process of the development of the nuclei and of subsequent seeding in 'contactless' physical vapor transport is investigated experimentally. Consecutive stages of the Low Supersaturation Nucleation in 'contactless' geometry for growth of CdTe crystals from the vapor are shown. The effects of the temperature field, geometry of the system, and experimental procedures on the process are presented and discussed. The experimental results are found to be consistent with our earlier numerical modeling results.
Grasza, K.↗
Quantifying Main Trends in Lysozyme Nucleation: The Effects of Precipitant Concentration, Supersaturation and Impurities
Full factorial experimental design incorporating multi-linear regression analysis of the experimental data allows quick identification of main trends and effects using a limited number of experiments. In this study these techniques were employed to identify the effect of precipitant concentration, supersaturation, and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal forin of chicken egg white lysozyme. Decreasing precipitant concentration, increasing supers aturation, and increasing impurity, were found to increase crystal numbers. The crystal axial ratio decreased with increasing precipitant concentration, independent of impurity.
Burke, Michael W.↗
Occurrence of Ice Supersaturations, Ice Clouds, and Ternary Aerosols in the Arctic Lowermost Stratosphere
Relative humidity, aerosol concentration, and ice crystals all have important impacts on chemistry and radiative transfer in the lowermost stratosphere. In this study, we have combined SOLVE measurements with meteorological analyses to investigate the statistics of humidity, aerosols, and clouds in the arctic lower stratosphere. First, we will present a statistical analysis of relative humidity with respect to ice in the lowermost stratosphere, used on the DC-8 in situ measurements. We will show examples of ice supersaturation well within the stratosphere. Generally, these cases were associated with extremely low temperatures near the tropopause. Next, we will discuss the climatological occurrence frequency of tropopause temperatures low enough for ice saturation even with typically low stratospheric water vapor mixing ratios. Really, we will examine case studies of ice clouds observed in the lowermost stratosphere during SOLVE. We will discuss the possible origin of these clouds (i.e., precipitation from higher type II PSCs, injection of tropospheric air into the lower stratosphere, etc.).
Jensen, Eric↗
Understanding Ice Supersaturation, Particle Growth, and Number Concentration in Cirrus Clouds
Many factors control the ice supersaturation and microphysical properties in cirrus clouds. We explore the effects of dynamic forcing, ice nucleation mechanisms, and ice crystal growth rate on the evolution and distribution of water vapor and cloud properties in nighttime cirrus clouds using a one-dimensional cloud model with bin microphysics and remote sensing measurements obtained at the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility located near Lamont, OK. We forced the model using both large-scale vertical ascent and, for the first time, mean mesoscale velocity derived from radar Doppler velocity measurements. Both heterogeneous and homogeneous nucleation processes are explored, where a classical theory heterogeneous scheme is compared with empirical representations. We evaluated model simulations by examining both bulk cloud properties and distributions of measured radar reflectivity, lidar extinction, and water vapor profiles, as well as retrieved cloud microphysical properties. Our results suggest that mesoscale variability is the primary mechanism needed to reproduce observed quantities. Model sensitivity to the ice growth rate is also investigated. The most realistic simulations as compared with observations are forced using mesoscale waves, include fast ice crystal growth, and initiate ice by either homogeneous or heterogeneous nucleation. Simulated ice crystal number concentrations (tens to hundreds particles per liter) are typically two orders of magnitude smaller than previously published results based on aircraft measurements in cirrus clouds, although higher concentrations are possible in isolated pockets within the nucleation zone.
Comstock, Jennifer M.↗
Ambulation During Periods of Supersaturation Increase Decompression Stress in Spacewalk Simulations
Musculoskeletal activity accelerates inert gas elimination during oxygen breathing prior to decompression (prebreathe), but may also promote bubble formation (nucleation) and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of musculoskeletal activity and the level of tissue supersaturation are likely critical to the net effect. Understanding the relationships is important to evaluate exercise prebreathe protocols and quantify decompression risk in gravity and microgravity environments. The NASA Prebreathe Reduction Program (PRP) combined oxygen prebreathe and exercise preceding a low pressure (4.3 psia; altitude equivalent of 30,300 ft [9,235 m]) simulation exposure of non-ambulatory subjects (a microgravity analog) to produce two protocols now used by astronauts preparing for extravehicular activity. One protocol included both upright cycling and non-cycling exercise (CEVIS: 'cycle ergometer vibration isolation system') and one protocol relied on non-cycling exercise only (ISLE: 'in-suit light exercise'). CEVIS trial data serve as control data for the current study to investigate the influence of ambulation exercise in 1G environments on bubble formation and the subsequent risk of DCS.
Pollock, N. W.↗
Dynamical Conditions of Ice Supersaturation and Ice Nucleation in Convective Systems: A Comparative Analysis Between in Situ Aircraft Observations and WRF Simulations
Occurrence frequency and dynamical conditions of ice supersaturation (ISS, where relative humidity with respect to ice (RHi) greater than 100%) are examined in the upper troposphere around convective activity. Comparisons are conducted between in situ airborne observations and the Weather Research and Forecasting model simulations using four double-moment microphysical schemes at temperatures less than or or equal to -40degdegC. All four schemes capture both clear-sky and in-cloud ISS conditions. However, the clear-sky (in-cloud) ISS conditions are completely (significantly) limited to the RHi thresholds of the Cooper parameterization. In all of the simulations, ISS occurrence frequencies are higher by approximately 3-4 orders of magnitude at higher updraft speeds (greater than 1 m s(exp -1) than those at the lower updraft speeds when ice water content (IWC) greater than 0.01 gm(exp -3), while observations show smaller differences up to approximately 1-2 orders of magnitude. The simulated ISS also occurs less frequently at weaker updrafts and downdrafts than observed. These results indicate that the simulations have a greater dependence on stronger updrafts to maintain/generate ISS at higher IWC. At lower IWC (less than or equal or 0.01 gm(exp -3), simulations unexpectedly show lower ISS frequencies at stronger updrafts. Overall, the Thompson aerosol-aware scheme has the closest magnitudes and frequencies of ISS greater than 20% to the observations, and the modified Morrison has the closest correlations between ISS frequencies and vertical velocity at higher IWC and number density. The Cooper parameterization often generates excessive ice crystals and therefore suppresses the frequency and magnitude of ISS, indicating that it should be initiated at higher ISS (e.g.,lees than or equal to 25%).
D’Alessandro, John J.↗