Net Mass Research Articles

Estimating the environmental impact of disposable endoscopic equipment and endoscopes

ObjectiveProcedure-intense specialties, such as surgery or endoscopy, are a major contributor to the impact of the healthcare sector on the environment. We aimed to measure the amount of waste generated...

Thermal Atomic Layer Etching of Nickel Using Sequential Chlorination and Ligand-Addition Reactions

The thermal atomic layer etching (ALE) of nickel was demonstrated using sequential chlorination and ligand-addition reactions. Nickel chlorination was achieved using SO2Cl2 (sulfuryl chloride) as the chlorine reactant. PMe3 (trimethylphosphine) was employed as the ligand-addition reactant. Sequential exposures of SO2Cl2 and PMe3 led to Ni thermal ALE. This procedure was inspired by the covalent bond classification (CBC) method that categorizes the most common compounds of various metals. Based on the CBC method, the surface reactions during thermal Ni ALE were performed to form NiX2L2 products, where Cl is the X ligand and PMe3 is the L ligand. Using this strategy, thermal Ni ALE was observed at temperatures from 75–200 °C. The etch rates were determined from in situ quartz crystal microbalance (QCM) measurements. The average etch rates determined from the mass changes were 0.14 ± 0.13, 0.57 ± 0.36, 0.67 ± 0.45, 1.30 ± 0.68, and 3.07 ± 1.56 Å/cycle for the temperatures 75, 100, 125, 150, and 175 °C, respectively. The QCM investigations revealed that there was a mass increase on every SO2Cl2 exposure and a mass loss on every PMe3 exposure, resulting in a net mass loss. The amount of chlorination for a given SO2Cl2 exposure increased with increasing temperature. The amount of mass lost on each PMe3 exposure also increased with increasing temperature. The etch rates were also confirmed using ex situ X-ray reflectivity measurements on Ni films on silicon wafers. The etch rates varied from 0.39 ± 0.10 Å/cycle at 125 °C to 2.16 ± 0.47 Å/cycle at 200 °C. Mass spectrometry analysis revealed that the volatile etch product was NiCl2(PMe3)2 as expected from the CBC method. In addition, scanning electron microscopy revealed that the nickel surface morphology had negligible changes after ALE. Atomic force microscopy analysis showed that thin nickel films remained smooth during initial etching and may experience some slight roughening with progressive etching. Using the CBC method to create novel thermal ALE procedures can be generalized for the thermal ALE of many different metals.

Thermal imaging – A novel method for gas-liquid Interface conditions determination

We suggest monitoring of the interfacial mass transfer activity over the surface of the packing under distillation conditions by a thermal camera. Such a study should reveal zones with imperfect hydrodynamics and decreased mass-transfer intensity, enabling quantification of the fraction of the packing geometrical area, which is ineffective in the interfacial mass exchange.The objective of the present study is to validate that the temperature of a liquid surface measured by the camera is truly the temperature of the interface, which can substantially differ from the liquid bulk temperature under the non-zero heat and mass-transfer conditions. Validation experiments are performed using a water-air system with zero net mass transfer across the interface and non-zero heat transfer induced by cooling of the liquid phase and heating of the gas phase. The interface temperature is indirectly determined from the partial pressure of water in the air above the liquid level.The results show that the temperature reading of the thermal camera is up to 92% determined by the temperature of the interface. Its measurement opens the possibility of determining not only effective interfacial area but also local distribution of the mass-transfer and heat-transfer resistances between the phases.

Cycling-induced structural damage/degradation of electrode materials–microscopic viewpoint

Most analyses of the mechanical deformation of electrode materials of lithium-ion battery in the framework of continuum mechanics suggest the occurring of structural damage/degradation during the de-lithiation phase and cannot explain the lithiation-induced damage/degradation in electrode materials, as observed experimentally. In this work, we present first-principle analysis of the interaction between two adjacent silicon atoms from the Stillinger–Weber two-body potential and obtain the critical separation between the two silicon atoms for the rupture of Si–Si bonds. Simple calculation of the engineering-tensile strain for the formation of Li–Si intermetallic compounds from the lithiation of silicon reveals that cracking and cavitation in lithiated silicon can occur due to the formation of Li–Si intermetallic compounds. Assuming the proportionality between the net mass flux across the tip surface of a slit crack and the migration rate of the crack tip, we develop analytical formulas for the growth and healing of the slit crack controlled by lithiation and de-lithiation, respectively. It is the combinational effects of the state of charge, the radius of curvature of the crack tip and local electromotive force that determine the cycling-induced growth and healing of surface cracks in lithiated silicon.

Gas infall and radial transport in cosmological simulations of milky way-mass discs

ABSTRACT Observations indicate that a continuous supply of gas is needed to maintain observed star formation rates in large, discy galaxies. To fuel star formation, gas must reach the inner regions of such galaxies. Despite its crucial importance for galaxy evolution, how and where gas joins galaxies is poorly constrained observationally and rarely explored in fully cosmological simulations. To investigate gas accretion in the vicinity of galaxies at low redshift, we analyse the FIRE-2 cosmological zoom-in simulations for 4 Milky Way mass galaxies (Mhalo ∼ 1012M⊙), focusing on simulations with cosmic ray physics. We find that at z ∼ 0, gas approaches the disc with angular momentum similar to the gaseous disc edge and low radial velocities, piling-up near the edge and settling into full rotational support. Accreting gas moves predominately parallel to the disc and joins largely in the outskirts. Immediately prior to joining the disc, trajectories briefly become more vertical on average. Within the disc, gas motion is complex, being dominated by spiral arm induced oscillations and feedback. However, time and azimuthal averages show slow net radial infall with transport speeds of 1–3 km s−1 and net mass fluxes through the disc of ∼M⊙ yr−1, comparable to the galaxies’ star formation rates and decreasing towards galactic centre as gas is sunk into star formation. These rates are slightly higher in simulations without cosmic rays (1–7 km s−1, ∼4–5 M⊙ yr−1). We find overall consistency of our results with observational constraints and discuss prospects of future observations of gas flows in and around galaxies.

Active stiffening control by magnetically induced blocking in confined flow of fly ash pastes

Formwork leakage has become one of the important challenges of modern construction parallel to the increase in use of self-compacting cementitious materials. Excessive formwork pressure coupled with the highly flowable nature of these materials could lead to increased formwork leakage. This paper introduces a magnetic field-based active stiffening control methodology that could be beneficial for reducing formwork leakage during casting. As a demonstration of formwork leakage, pressure-driven flow through a narrow slit was investigated on magnetisable pastes containing 40% fly ash. The active stiffening control was incorporated by applying an external magnetic field at the outflow. The mass of the outflowing material was continuously recorded, and the flow rate and final net mass loss evaluated. Experimental results showed reduction in flow rate after applying the external magnetic field due to the agglomeration of magnetisable particles contained in the fly ash at the outflow region. It is concluded that the confined flow of pastes containing magnetisable particles can be actively controlled by the application of a magnetic field. The effectiveness of the introduced methodology is mainly dependent on the introduced magnetic field strength, paste viscosity, flow width to magnetisable particle size ratio and pressure level.

Prognostic Value of Dynamic Monoclonal Protein Pattern on Probability of Myeloma Progression from the Precursor State

Multiple Myeloma (MM) is a cancer of terminally differentiated plasma cell resides in bone marrow, which is always preceded by clinically asymptomatic precursor states. The process of malignant transformation however is not fully understood. Analyses of cells from precursor state have provided evidence that it is a genetically advanced lesion, wherein tumor cells carry many of the genetic changes found in MM cells. Furthermore, mice xenografts from patient (pt) with precursor disease showed progressive growth on its own suggesting progression potential is counteracted by active extrinsic restraints that prevent its progression to MM (Das R et al. Nature Medicine, 2016). Hence, precursor progression to MM can be viewed as a dynamic process in which the clonal mass is the net result of pro-growth, pro-survival replicative capacity of the myeloma clones vs. anti-tumor immunity.The change in the net clonal mass sometimes is large enough to be detected by measurable fluctuations in serum monoclonal protein spike (M-spike) levels and reflects a highly dynamic battle between plasma cell clone and cell-mediated anti-myeloma immunity among those pts. The prognostic value of this highly dynamic state on risk of progression to MM is largely unknown. In this study we sought to assess the association between the dynamic M-spike pattern and the risk of progression from a precursor clone to MM.Methods: All pts with positive serum electrophoresis (SPEP) values measured from January 2011 to January 2021 for our institution were included for this study. All pts that had <3 M-spike readings before requiring anti-myeloma regimen, received active treatment for MM within 90 days of the first positive SPEP, had M-spike values >3g/l or had clear evidence of progression by serial increasing M-spike values were excluded.. We assigned the pattern of M-spike values over time into two groups according to stability. To eliminate the test-to-test variability, we defined stable disease as lack of more than 20% difference from lowest M-spike, and fluctuating disease if the difference exceeds 20%. The time-to-treatment (TTT) was then measured from the first positive SPEP to the time of treatment and was censored at the date of last follow-up for pts who did not have anti-myeloma treatment with death as competing risk. The effect of M-spike pattern on TTT, treating as binary outcome, was also evaluated using logistic regression analysis. Univariate analysis of TTT was performed using Gray's method. All tests were two-sided and p-value ≤ 0.05 were considered statistically significant.Results: A total of 565 pts were studied, 193 with a fluctuating pattern and 372 with a stable pattern. Median age at first positive SPEP was 76 years old (range: 38-101), 271 (48%) of them were male; 427 (75%) were Caucasian and 123 (22%) African American. Baseline creatinine was 1.17 mg/dl (range 0.5-11.2 SD 0.94). Baseline albumin was 3.97 g/dl (range 1.6-5.2 SD 0.47), 336 pts (59%) were IgG, 75 (13%) IgA, and 142 (25%) had IgM M-spike; 326 (58%) pts had Kappa light chain and 239 (42%) had Lambda. Autoimmune diseases were more common in the stable disease pattern (17% vs. 10% p=0.028), the most frequent one was Rheumatoid arthritis in 33 pts (6%). Furthermore, baseline albumin was statistically higher in pts in the stable cohort (4.04 vs. 3.85g/dl, p=<0.0001). Median follow up was 46.9 months (range: 3.2-120.9). Logistic regression: the odds ratio (OR) of having progression to treatment for fluctuation group was 4.5 (95% CI: 1.37-14.18, p= 0.013) in comparison to stable group. Time-to-event analysis: pts with fluctuating M-spike had higher chance of needing therapy (Hazard Ratio: 3.73, 95% CI: 1.19-11.66, p=0.024) than stable group. Cumulative incidence of needing treatment is shown in Figure-1.Conclusion: The dynamic pattern of M-spike seen here with fluctuating values over time (over time is two words) was significantly predictive of progression to MM in pts with a precursor disease state. These findings may reflect a different nature of tumor vs. immune system balance and possible impaired immunity in these pts which may have implications for future clinical trials that evaluate the efficacy of anti-myeloma immunotherapeutics. Furthermore, our finding suggest that fluctuations in M-spike levels may be factored into risk models that predict the progression to MM among pts with precursor clones. Larger studies are warranted to further study this concept. [Display omitted] DisclosuresMalek: Medpacto Inc.: Research Funding; Janssen: Other: Advisory board ; Takeda: Honoraria; Cumberland Inc.: Research Funding; Amgen: Honoraria; BMS: Honoraria, Research Funding; Bluespark Inc.: Research Funding; Sanofi: Other: Advisory Board.

Anopheles Kdr mutation threatens the operational effectiveness of malaria vector control strategy in the health district of Ngaoundere, savannah area in north Cameroon

Malaria prevention in Cameroon mainly relies on insecticide treated bet nets mass use. Its success depends on vectors sensitivity to insecticides used and population’s involvement. This study aimed at determining the operational effectiveness of treated net nets and find ways to improve the vector control strategy in Ngaoundere and Tchabal. Knowledge, attitudes and practices of populations toward malaria were assess. The susceptibility of local populations of Anopheles gambiae to deltamethrin and permethrin, the effect of synergist (PBO) and mosquito treated nets efficacy were determined using WHO protocols. Mosquitoes were genotyped for kdr L1014 mutations using Hot Oligonucleotide Ligation Assay. Mosquito displayed insecticide resistance with variable knockdown and mortality rates. Synergist (PBO) increased mortality but not enough to break their resistance. We found 78.33% and 93.33% Kdr resistant allele and in Tchabba and Ngaoundere respectively. New mosquito nets generation with PBO should be combined with other control methods to curb resistance.

Side-chain modification of collagen-targeting peptide prevents dye aggregation for improved molecular imaging of arthritic joints

Near-infrared (NIR) dye-peptide conjugates are widely used for tissue-targeted molecular fluorescence imaging of pathophysiologic conditions. However, the significant contribution of both dye and peptide to the net mass of these bioconjugates implies that small changes in either component could alter their photophysical and biological properties. Here, we synthesized and conjugated a type I collagen targeted peptide, RRANAALKAGELYKCILY, to either a hydrophobic (LS1000) or hydrophilic (LS1006) NIR fluorescent dye. Spectroscopic analysis revealed rapid self-assembly of both LS1000 and LS1006 in aqueous media to form stable dimeric/H aggregates, regardless of the free dye's solubility in water. We discovered that replacing the cysteine residue in LS1000 and LS1006 with acetamidomethyl cysteine to afford LS1001 and LS1107, respectively, disrupted the peptide's self-assembly and activated the previously quenched dye's fluorescence in aqueous conditions. These results highlight the dominant role of the octadecapeptide, but not the dye molecules, in controlling the photophysical properties of these conjugates by likely sequestering or extruding the hydrophobic or hydrophilic dyes, respectively. Application of the compounds for imaging collagen-rich tissue in an animal model of inflammatory arthritis showed enhanced uptake of all four conjugates, which retained high collagen-binding affinity, in inflamed joints. Moreover, LS1001 and LS1107 improved the arthritic joint-to-background contrast, suggesting that reduced aggregation enhanced the clearance of these compounds from non-target tissues. Our results highlight a peptide-driven strategy to alter the aggregation states of molecular probes in aqueous solutions, irrespective of the water-solubilizing properties of the dye molecules. The interplay between the monomeric and aggregated forms of the conjugates using simple thiol-modifiers lends this peptide-driven approach to diverse applications, including the effective imaging of inflammatory arthritis joints.

Performance analysis of a solar still driven by a packed bed thermal storage tank during off-sunshine period

During cloudy or rainy days, when sunlight is absent, a solar still cannot operate in its natural mode. In such circumstances, the still can be run using energy stored in thermal storage systems during sunshine hours. This work presents an analytical investigation of such a scenario in which a packed bed sensible thermal storage tank is used to provide the input energy for desalination via a double basin solar still during off sunshine season. Closed form solutions are derived for the temperature profile in storage tank, and of temperatures in both upper and lower basins of the still. Using these solutions, a closed form solution is obtained for the net mass of distillate produced until the cessation of operation. Parametric studies reveal that the present system can produce appreciable quantity of pure water that remains unchanged with any variation in mass of water in ether basin of the double basin still, mw1, mw2. The net distillate increases linearly with an increase in the initial tank excess temperature,θ0. Further, the analysis tells that there is optimum mass flow rate of the working fluid that delivers heat from storage tank to the still,m˙athat maximizes net distillate production. The reason of existence of such an optimum mass flow rate is discussed in detail. For the values considered, it is seen that a storage tank of 1 m3 vol, at an initial temperature of 50 °C above ambient, can produce 11.69 kg of potable water, yielding a thermal efficiency of about 68%. This work is a first ever investigation of the viability of a packed bed thermal storage tank for operating a solar still, and can serve as a guiding study for further, more comprehensive research work in this direction.

The Potential of Digital Data Collection Tools for Long-lasting Insecticide-Treated Net Mass Campaigns in Nigeria: Formative Study.

BackgroundNigeria has the world’s largest malaria burden, accounting for 27% of the world’s malaria cases and 23% of malaria mortality globally. This formative study describes the operational process of the mass distribution of long-lasting insecticide-treated nets (LLINs) during a campaign program in Nigeria.ObjectiveThis study aims to assess whether and how digital data collection and management tools can change current practices and help resolve major implementation issues.MethodsQualitative data on the technical features and operational processes of paper-based and information and communication technology (ICT)–based systems in the Edo and Kwara states from June 2 to 30, 2017, were collected on the basis of documented operation manuals, field observations, and informant interviews. During the LLIN campaign in Edo State, we recruited 6 local government area focal persons and monitors and documented daily review meetings during household mobilization (9 days) and net distribution (5 days) to understand the major program implementation issues associated with the following three aspects: logistic issues, technical issues, and demand creation. Each issue was categorized according to the expected degree (low, mid, and high) of change by the ICT system.ResultsThe net campaign started with microplanning and training, followed by a month-long implementation process, which included household mobilization, net movement, net distribution, and end process monitoring. The ICT system can improve management and oversight issues related to data reporting and processes through user-centered interface design, built-in data quality control logic flow or algorithms, and workflow automation. These often require more than 50% of staff time and effort in the current paper-based practice. Compared with the current paper-based system, the real-time system is expected to reduce the time to payment compensation for health workers by about 20 days and produce summary campaign statistics for at least 20 to 30 days.ConclusionsThe ICT system can facilitate the measurement of population coverage beyond program coverage during an LLIN campaign with greater data reliability and timeliness, which are often compromised due to the limited workforce capacity in a paper-based system.

Estimating the Importance of Hydrologic Conditions on Nutrient Retention and Plant Richness in a Wetlaculture Mesocosm Experiment in a Former Lake Erie Basin Swamp

The western basin of Lake Erie, the shallowest of the Laurentian Great Lakes in North America, is now plagued by harmful algal blooms annually due to nutrient discharges primarily from its basin. Water quality was impacted so significantly by toxic cyanobacteria in 2014 that the city of Toledo’s water supply was shut off, affecting hundreds of thousands of residents. A new agricultural land management approach, ‘wetlaculture (=wetland + agriculture)’, has a goal of reducing the need for fertilizer applications while preventing fluxes of nutrients to downstream aquatic ecosystems. A wetlaculture mesocosm experiment was set up on agricultural land near Defiance, Ohio, on the northwestern edge of the former ‘Great Black Swamp’. The mesocosms were randomly assigned to four hydrologic treatments involving two water depths (no standing water and ~10-cm of standing water) and two hydraulic loading rates (10 and 30 cm week−1). Nearby agricultural ditch water was pumped to provide weekly hydraulic loading rates to the mesocosms. During the two-year period, the net mass retention of phosphorus from the water was estimated to have averaged 1.0 g P m−2 in the wetland mesocosms with a higher hydraulic loading rate, while the highest estimated net nitrogen mass retention (average 22 g N m−2) was shown in the wetland mesocosms with 10 cm of standing water and higher hydraulic loading rate. Our finding suggests that hydrologic conditions, especially water level, contribute directly and indirectly to nutrient retention, partially through the quick response of the wetland vegetation community. This study provides valuable information for scaling up to restore significant areas of wetlaculture/wetlands in the former Great Black Swamp, strategically focused on reducing the nutrient loading to western Lake Erie from the Maumee River Basin.

Satellite and ground based estimates for ice surface velocities in the part of central Dronning Maud Land, East Antarctica: Implications for ice flux calculations

The ice sheet and glaciers of Antarctica and Greenland represent the largest sources of freshwater on planet Earth. The understanding and quantification of their dynamic properties such as albedo, precipitation, ice mass movement, and ice elevation changes are critical for the improved climate and mass balance models. The present study utilizes space-borne optical and synthetic aperture radar (SAR) imagery to measure the ice surface velocity at high spatial resolution for a part of the central Dronning Maud Land (cDML), East Antarctica. The datasets from Landsat-8 and Sentinel-1 SAR satellite are used for ice stream velocity estimation using feature-offset tracking and differential interferometric SAR (DInSAR) methods. The derived velocity products are validated with ground based stakes network at annual time scale. The fundamental ice flow laws are used to estimate the ice outflux or discharge for selected ice stream drainage basins of cDML at fluxgate locations. The ice stream basin has been delineated using combination of elevation, slope and continental scale velocity maps. The ice influx for study area is estimated using ECMWF fifth generation reanalysis (ERA5) and Regional Atmospheric Climate Model (RACMO) v2.3 model outputs. The estimated influx and outflux are in the ranges of 0.18–4.167 Gt/y and 0.201 to 1.278 Gt/y respectively, indicating net positive mass balance for the selected area.

Flow Characteristics and Novel Applications of Synthetic Jets: A Review

Abstract Synthetic jets, often abbreviated as “SJs” or “Synjets,” are a type of zero net mass flux (ZNMF) jets, which have gained popularity due to their ability to transfer momentum without transferring mass. This property distinguishes SJs from their counterpart traditional continuous jets. Over a stretch of time, SJs have been employed extensively in applications such as active flow control, impingement heat transfer, and miniature electronics cooling. However, researchers are now slowly extending the frontiers of SJ research and making efforts to utilize excellent properties of SJs in novel applications such as autonomous underwater vehicles (AUVs), marine systems, and bio-inspired propulsion systems. This paper strives to identify the gaps in the current research and the areas that have remained unexplored yet. The article begins with a brief discussion of the origin of SJs, i.e., “acoustic streaming.” Resulting segments talk about the formation criteria and the recent works employing various configurations of orifices and cavities. The paper discusses the critical concepts such as jet impact factor, volumetric efficiency, and propulsive efficiency of synthetic jets. It is followed by introduction of novel flow control systems employing SJs such as gurney flaps, bumps, and electro-active synthetic jets. Finally, the most innovative applications of SJs such as AUVs, unmanned air vehicles, and jetting cavities are also brought out. Pulsatile jet flows found in jellyfish, cephalopod, squid, and salp have been discussed in great detail. The exhaustive discussion on future prospects strives to not only provide the reader with the comprehensive insights into SJs, but also to motivate future researchers to overcome the gaps identified in this paper.

Rapid recovery by fat- and muscle-depleted Blackpoll Warblers following trans-oceanic migration is driven by time-minimization

Abstract Nonstop endurance flights are a defining characteristic of many long-distance migratory birds, but subsequent recovery phases are not typically distinguished from fueling phases (collectively “stopovers”), despite endurance flights inducing marked physiological changes including flight muscle atrophy and gastrointestinal tract reductions. Here, we hypothesize that recovery requires unique behavioral adaptations, leading to departures from the predictions of optimal migration theory for time-minimizing migrants. We predict that recovering birds will (1) select (moist) food-rich habitats on arrival; (2) have slow initial fueling rates due to decreased gastrointestinal capacity; (3) show a negative correlation between stopover duration and arrival condition instead of a negative correlation with fuel deposition rate (FDR); (4) stopover longer than required to store energy reserves for subsequent flights; and (5) show evidence of rebuilding flight muscles. To test these predictions, we studied Blackpoll Warblers (Setophaga striata) in northern Colombia following trans-oceanic flights &amp;gt;2,250 km. Birds selected dry seasonal habitats, despite the proximity of moist forests, and among 1,227 captured individuals, 14–21% were emaciated and 88% had atrophied flight muscles. We recaptured 74 individuals, revealing net positive mass gains and, contrary to prediction (2), no evidence for slow initial recovery rates. Contrary to prediction (3), stopover duration was only weakly correlated with arrival condition and birds with high FDR (4.9% lean body mass day–1) had shorter durations (3 days) relative to birds with slower rates (7 days): both groups accumulated sufficient fuel to reach nonbreeding (over-wintering) grounds 500–1,000 km away. Mass increases were largely attributable to fat deposition but some birds improved flight muscle condition (31.9%), consistent with prediction (5). Together these results reveal a strong selection for time-minimization in the decisions made by Blackpoll Warblers following trans-oceanic flights, likely mediated through advantages to early arrival on nonbreeding grounds, contrary to our hypothesis of recovery imposing unique selection pressures.

A low-boom and low-drag design method for supersonic aircraft and its applications on airfoils

Sonic boom reduction has been an urgent need for the development of future supersonic transport, because of the heavy damage of noise pollution. This paper provides a novel concept for supersonic aircraft to reduce the sonic boom and drag coefficient, wherein a suction slot near the leading edge and an injection slot near the trailing edge on the airfoil suction surface are opened. To make sure of a zero net mass flux flow control, the mass flow sucked in near the leading edge is equal to the mass flow injected near the trailing edge. The diamond and NACA0008 airfoils are adopted as the baseline airfoil to verify the capability of the proposed design method. The effects of the suction and injection location, the suction and injection slot size, the mass flow rate and the attack angle on the ground boom signature and drag coefficient are studied in detail. The results show that the optimized airfoils with the suction and injection have benefits in both sonic boom reduction and wave drag reduction. And the reduction of the sonic boom intensity is more sensitive to the injection near the trailing edge than the suction near the leading edge. From the viewpoint of aerodynamics, opening the suction and injection slots will have no adverse effect on the aerodynamic performances of the supersonic aircraft and even increase the lift-drag ratio under some circumstances. For energy saving, the suction and injection slots can be selectively opened, which are opened when the supersonic aircraft flies over the city but are closed when the aircraft flies over the sea.

Mass balance and hydrological modeling of the Hardangerjøkulen ice cap in south-central Norway

Abstract. A detailed, physically based, one dimensional column snowpack model (Crocus) has been incorporated into the hydrological model, Weather Research and Forecasting (WRF)-Hydro, to allow for direct surface mass balance simulation of glaciers and subsequent modeling of meltwater discharge from glaciers. The new system (WRF-Hydro/Glacier) is only activated over a priori designated glacier areas. This glacier area is initialized with observed glacier thickness and assumed to be pure ice (with corresponding ice density). This allows for melting of the glacier to continue after all accumulated snow has melted. Furthermore, the simulation of surface albedo over the glacier is more realistic, as surface albedo is represented by snow, where there is accumulated snow, and glacier ice, when all accumulated snow is melted. To evaluate the WRF-Hydro/Glacier system over a glacier in southern Norway, WRF atmospheric model simulations were downscaled to 1 km grid spacing. This provided meteorological forcing data to the WRF-Hydro/Glacier system at 100 m grid spacing for surface and streamflow simulation. Evaluation of the WRF downscaling showed a good comparison with in situ meteorological observations for most of the simulation period. The WRF-Hydro/Glacier system reproduced the glacier surface winter/summer and net mass balance, snow depth, surface albedo and glacier runoff well compared to observations. The improved estimation of albedo has an appreciable impact on the discharge from the glacier during frequent precipitation periods. We have shown that the integrated snowpack system allows for improved glacier surface mass balance studies and hydrological studies.

The Role of Discrete Capillary Rings in Mass Transfer From the Surface of a Drying Capillary Porous Medium

The mass exchange between the surface of a model capillary porous medium and the adjacent gas-side boundary layer is studied in the limiting condition of isothermal, slow drying. In order to quantify the role and significance of liquid films in the mass exchange process, three-dimensional pore network Monte Carlo simulations are carried out systematically in the presence and absence of discrete capillary rings. The pore network simulations performed with capillary rings show a noticeable delay in transition from the capillary-supported regime to the diffusion-controlled regime. These simulation results differ significantly from the predictions of classical pore network models without liquid films, and they appear to be more consistent with the experiments conducted with real porous systems. As compared to classical pore network models, the pore network model with rings seems to predict favorably the spatiotemporal evolution of wet and dry patches at the medium surface as well as of their relative contributions to the net mass exchange rate. This is apparent when the analytical solution of the commonly used Schlünder’s model is examined against the numerical simulations conducted using classical and ring pore network models.

Net particulate matter removal ability and efficiency of ten plant species in Beijing

Particulate matter (PM) removal is a major component of ecosystem services provided by urban green infrastructure. The annual PM removal service of plant species has generally been determined based on net PM removal ability. However, little is known about the leaf surface area normalized net PM mass removal abilities and efficiencies of different species. Net PM removal ability is the PM removed from the atmosphere by leaf surface during a period. We evaluated the net PM removal abilities and efficiencies of ten species based on quantitative leaf surface PM 1 day after and 21 days after a rainfall event. Net PM removal ability differed between plant species during the study period, and the net PM removal abilities were strongly correlated with the leaf surface PM 21 days after the rainfall, and this relationship weakened with the decrease of PM diameter. Plant species had significantly different net PM removal efficiencies except for large PM, and net PM removal efficiency was lower for coniferous trees and higher for species with high self-cleaning ability during our study period. Species differed in net PM removal ability and efficiency, and there were greater differences in the net removal ability of fine and coarse PM compared with large PM; therefore, care should be taken when species are selected for fine and coarse PM mitigation.

Physical implications of massless objects

Normal massless objects have no mass but do have energy, and they always move at the speed of light. This article proposes another way to construct massless objects theoretically by combining normal mass and negative mass of equal magnitudes. Such objects have zero net mass, qualifying as massless, and can be used to investigate the behaviors of general massless objects. Particularly, two kinds of such proposed massless objects, neutral and electrically charged, are studied under the influences of gravity and electric fields. By excluding the factor of mass, it is discovered that the motion of electrically charged massless objects is counterintuitive. The physical implications of the motion of massless objects are analyzed in detail within the framework of classical physics. Some surprising results arise from these analyses, and possible explanations of these dilemmas lead to the possibility of a new relationship between electric charge and mass.