Closure Experiment Research Articles

Precise three dimensions reconstruction closure experiment and a new apparent compliance model for self-propped fractures

Fracture compliance, an essential indicator of fracture deformation, is also a key parameter for post-fracturing network diagnosis and inversion. However, current research lacks detailed experimental studies to acquire this vital parameter of fracture compliance, and the influence of fracture roughness and rock Young’s modulus on fracture compliance remains unclear, leading to a deficiency in models for the evolution of fracture compliance. Therefore, based on 3D reconstruction technology of fracture surfaces, an experiment was designed to observe the deformation of self-propped fractures, obtaining experimental data on fracture deformation. Utilizing this data, a new apparent compliance model for fractures was proposed. The results indicate that closure pressure is the decisive factor affecting the apparent compliance of fractures, regardless of their roughness. The influence of fracture roughness and rock Young’s modulus on apparent compliance shifts under varying closure pressures. At lower closure pressures, apparent compliance is primarily governed by fracture roughness—the greater the roughness, the higher the compliance. At higher closure pressures, the apparent compliance are mainly controlled by the rock’s Young’s modulus—the higher the modulus, the lower the compliance. This phenomenon is attributed to the elastic-plastic damage cycle during the compressive deformation of fractures.

Quantifying the Atmospheric Water Balance Closure over Mainland China Using Ground-Based, Satellite, and Reanalysis Datasets

Quantifying the atmospheric water balance is critical for the study of hydrological processes in significant regions. This study quantified atmospheric water balance closure at 205 stations in mainland China on a monthly timescale from 2009 to 2018 using datasets from ground- and satellite-based observations and reanalysis data. The closure performances were firstly quantified using the mean and root mean square (RMS) of the residuals, and the possible influencing factors were explored, as well as the influence of different water balance components (WBCs) using different datasets. In the closure experiment using ERA5, the mean and residuals were 6.26 and 12.39 mm/month, respectively, on average, which indicated a closure uncertainty of 12.8%. Using ERA5 analysis as a reference, the closure experiment using different combinations revealed average mean residuals of 8.73, 11.50, and 15.89 mm/month, indicating a precipitation closure uncertainty of 22.0, 23.7, and 24.4% for the ground- and satellite-based observations and reanalysis data, respectively. Two possible influencing factors, station latitude and the climatic zone in which the station is located, were shown to be related to closure performance. Finally, the analysis of the impact from different WBCs showed that precipitation tended to have the most significant impact, which may have been due to larger observation uncertainties. Generally, the atmospheric water balance in mainland China can be closed using datasets from different observational techniques.

Distributions and Direct Radiative Effects of Different Aerosol Types in North China

Different aerosol types exhibit distinct radiative effects in different regions, attributed to their unique optical characteristics and regional distributions. This study focuses on North China, which is impacted by both natural and anthropogenic aerosols with high concentrations and a variety of aerosol types. While many studies on aerosol direct radiative effects have been conducted in this region, the majority have focused on a specific type of aerosol or overall aerosol, leaving limited research on the direct radiative effects and contributions of different aerosol types. In this study, we use CALIPSO satellite data from 2011 to 2020 to investigate concentrations and distributions of different aerosol types. The results reveal that dust, polluted dust, polluted continental/smoke, and elevated smoke are the dominant aerosol types in North China. Based on the radiative closure experiment, we systematically calculate the radiative effects of different aerosol types and their corresponding contributions to the energy budget by combining satellite data with the Fu–Liou radiative transfer model. The annual average net aerosol direct radiative effect (ADRE) of North China is −6.1 and −13.43 W m−2 at the TOA and surface, respectively, causing a net warming effect of 7.33 W m−2 in the atmosphere. For each main aerosol type, dust contributes 93% to the shortwave ADRE in the western dust source region, while polluted dust mainly contributes 31% and 45% of the total ADRE, in Northwest China and North China Plain, respectively. Anthropogenic pollutant aerosols account for 58% of the total ADRE in Northeast China. This study holds great significance in elucidating the dominant aerosol types and their concentrations in North China, comprehending the impacts of different aerosol types on the local energy balance.

Validating HONO as an Intermediate Tracer of the External Cycling of Reactive Nitrogen in the Background Atmosphere.

In the urban atmosphere, nitrogen oxide (NOx═NO + NO2)-related reactions dominate the formation of nitrous acid (HONO). Here, we validated an external cycling route of HONO and NOx, i.e., formation of HONO resulting from precursors other than NOx, in the background atmosphere. A chemical budget closure experiment of HONO and NOx was conducted at a background site on the Tibetan Plateau and provided direct evidence of the external cycling. An external daytime HONO source of 100 pptv h-1 was determined. Both soil emissions and photolysis of nitrate on ambient surfaces constituted likely candidate mechanisms characterizing this external source. The external source dominated the chemical production of NOx with HONO as an intermediate tracer. The OH production was doubled as a result of the external cycling. A high HONO/NOx ratio (0.31 ± 0.06) during the daytime was deduced as a sufficient condition for the external cycling. Literature review suggested the prevalence of high HONO/NOx ratios in various background environments, e.g., polar regions, pristine mountains, and forests. Our analysis validates the prevalence of external cycling in general background atmosphere and highlights the promotional role of external cycling regarding the atmospheric oxidative capacity.

Numerical investigation of unpropped fracture closure process in shale based on 3D simulation of fracture surface

Unpropped fractures constitute a major part of the fracture network in shale after hydraulic fracturing, and their closure process under in situ stress has a significant effect on the well production. In this study, a 3D simulation method based on core experiments and reverse engineering technology was established to simulate the unpropped fracture surface. A contact and deformation model of rock with a rough boundary and normal stress was constructed to investigate the closure process. The plastic characteristics of shale were taken into account through the embedment of the Drucker–Prager yield criterion. An unpropped fracture closure experiment was conducted for validating the model, and the influence of stress state, mechanical properties, fracture roughness and slippage degree on the closure process was analyzed. Numerical results demonstrate that an unpropped fracture with greater roughness and slippage degree possesses more flow regions and a larger residual width under a low stress state, which decreases rapidly as the normal stress rises because of the small contact area. Young's modulus is considered to have a positive effect on resisting fracture closure and maintaining effective flow regions under a high stress state. For the shale of the deep Longmaxi formation in south Sichuan, China, the simulation results indicate that the unpropped fractures always retain a residual width greater than 0.7 mm under a closure stress of 60 MPa, which is suitable for flow passages of oil and gas in shale. Methods for moderating the closure process were also analyzed. The numerical simulations provide insights on the unpropped fracture closure process under in situ stress, which will be helpful for fracturing design and production prediction of shale wells.

Wildfire smoke, Arctic haze, and aerosol effects on mixed-phase and cirrus clouds over the North Pole region during MOSAiC: an introduction

Abstract. An advanced multiwavelength polarization Raman lidar was operated aboard the icebreaker Polarstern during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition to continuously monitor aerosol and cloud layers in the central Arctic up to 30 km height. The expedition lasted from September 2019 to October 2020 and measurements were mostly taken between 85 and 88.5∘ N. The lidar was integrated into a complex remote-sensing infrastructure aboard the Polarstern. In this article, novel lidar techniques, innovative concepts to study aerosol–cloud interaction in the Arctic, and unique MOSAiC findings will be presented. The highlight of the lidar measurements was the detection of a 10 km deep wildfire smoke layer over the North Pole region between 7–8 km and 17–18 km height with an aerosol optical thickness (AOT) at 532 nm of around 0.1 (in October–November 2019) and 0.05 from December to March. The dual-wavelength Raman lidar technique allowed us to unambiguously identify smoke as the dominating aerosol type in the aerosol layer in the upper troposphere and lower stratosphere (UTLS). An additional contribution to the 532 nm AOT by volcanic sulfate aerosol (Raikoke eruption) was estimated to always be lower than 15 %. The optical and microphysical properties of the UTLS smoke layer are presented in an accompanying paper (Ohneiser et al., 2021). This smoke event offered the unique opportunity to study the influence of organic aerosol particles (serving as ice-nucleating particles, INPs) on cirrus formation in the upper troposphere. An example of a closure study is presented to explain our concept of investigating aerosol–cloud interaction in this field. The smoke particles were obviously able to control the evolution of the cirrus system and caused low ice crystal number concentration. After the discussion of two typical Arctic haze events, we present a case study of the evolution of a long-lasting mixed-phase cloud layer embedded in Arctic haze in the free troposphere. The recently introduced dual-field-of-view polarization lidar technique was applied, for the first time, to mixed-phase cloud observations in order to determine the microphysical properties of the water droplets. The mixed-phase cloud closure experiment (based on combined lidar and radar observations) indicated that the observed aerosol levels controlled the number concentrations of nucleated droplets and ice crystals.

All‐Sky Aerosol Direct Radiative Effects at the ARM SGP Site

AbstractAll‐sky aerosol direct radiative effect (DRE) was estimated for the first time at the Atmospheric Radiation Measurement Southern Great Plains site using multiyear ground‐based observations. The NASA Langley Fu‐Liou radiation model was employed. Observed inputs for the radiation model include aerosol and cloud vertical extinction profile from Raman lidar; spectral aerosol optical depth, single‐scattering albedo, and asymmetry factor from Aerosol Robotic Network; cloud water content profiles from radars; temperature and water vapor profiles from radiosondes; and surface shortwave spectral albedo from radiometers. A cloudy‐sky radiative closure experiment was performed. The relative mean differences between modeled and observed surface downwelling shortwave total fluxes were 6% (7%) for transparent (opaque) cloudy‐skies. The estimated annual mean all‐sky aerosol DRE is −2.130.54 W m−2 at the top of atmosphere (TOA) and −5.950.87 W m−2 at the surface, compared to −3.000.58 W m−2 and −6.851.00 W m−2, respectively, under clear‐sky conditions. The seasonal cycle of all‐sky aerosol DRE is similar to that of the clear‐sky, except with secondary influences of the clouds: The cloud radiative effect is strongest (most negative) in the spring, which reduces the all‐sky aerosol DRE. The relative uncertainties in all‐sky aerosol DRE due to measurement errors are generally comparable to those in clear‐sky conditions except for the aerosol single‐scattering albedo. The TOA all‐sky aerosol DRE relative uncertainty due to aerosol single‐scattering albedo uncertainty is larger than that in clear‐sky, leading to a larger total relative uncertainty. The measurement errors in cloud properties have small effects on the all‐sky aerosol DRE.

Hyperspectral optical absorption closure experiment in complex coastal waters

AbstractAccurate measurements of absorption data are required for the development and validation of inversion algorithms for upcoming hyperspectral ocean color imaging sensors, such as the NASA Phytoplankton, Aerosol, Cloud, and ocean Ecosystem mission. This study aims to provide uncertainty estimates associated with leading approaches to measure hyperspectral absorption coefficients in complex coastal waters. Absorption spectra were collected at 12 different stations, all located in the Indian River Lagoon, Florida, USA, between 09 January 2017 and 13 January 2017. Measurements included spectral absorption coefficients in the visible range (400–700 nm) associated with dissolved, aCDOM, total particulate, ap, and total nonwater, anw, fractions, and were made both in situ and from discrete samples. Discrete sample approaches included dual‐beam spectrophotometer, liquid waveguide capillary cell, point‐source integrating cavity absorption meter (PSICAM) for dissolved matter absorption samples, and quantitative filter technique ICAM measurements and the dual‐beam spectrophotometer with center‐mounted integrating sphere filter pad technique, while the Turner Designs ICAM, and WET Labs AC‐s, and AC‐9 instruments were used to determine absorption coefficients in situ. The Gershun approach, determining absorption from measurement of the irradiance quartet with respect to depth was also assessed in situ. Measurement uncertainties and relative accuracies were quantified for each of these approaches. Results showed generally strong agreements between different discrete sample methods, with average percent absolute error %δabs < 7% for aCDOM and < 9% for ap. In situ approaches showed higher variability and reduced accuracy. For anw, %δabs deviation relative to PSICAM data was on average 12% to 20%. Results help identify remaining technological gaps and need for improvements in the different absorption measurement approaches.

Characterization of submicron aerosols over the Yellow Sea measured onboard the Gisang 1 research vessel in the spring of 2018 and 2019

The physico-chemical properties of submicron aerosols were measured in the spring of 2018 and 2019 over the Yellow Sea onboard the Gisang 1 research vessel. Aerosol number concentrations in 2019 were slightly higher than those in 2018, and the mean number concentrations of particles larger than 10 nm and cloud condensation nuclei (CCN) at 0.6% supersaturation (S) in spring 2019 were 7312 ± 3807 cm−3 and 4816 ± 1692 cm−3, respectively. Aerosol concentrations in June were lower than those in April and May, which was considered to be due to the East Asian summer monsoon. Aerosol number concentrations and size distributions were significantly influenced by meteorological conditions, such as wind and relative humidity. Aitken and accumulation mode particles dominated the aerosol number size distributions over the Yellow Sea. A distinct new particle formation (NPF) and growth event was observed, the spatial extent of which was estimated to cover at least 200 km × 400 km of the Yellow Sea. The general characteristics of NPF and growth over the Yellow Sea were similar to those in rural areas. Aerosol number concentrations below 1000 cm−3 were recorded on extremely clean days. A CCN closure experiment conducted using previous measurement data showed good results, indicating that CCN concentrations can be estimated with good accuracy, and the hygroscopicity over the Yellow Sea was similar to that of aged continental aerosols.

Aerosol Direct Radiative Effects at the ARM SGP and TWP Sites: Clear Skies

AbstractThe clear‐sky aerosol direct radiative effect (DRE) was estimated at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) and Tropical Western Pacific (TWP) sites. The NASA Langley Fu‐Liou radiation model was used with observed inputs including aerosol vertical extinction profile from the Raman lidar; spectral aerosol optical depth (AOD), single‐scattering albedo and asymmetry factor from Aerosol Robotic Network; temperature and water vapor profiles from radiosondes; and surface shortwave (SW) spectral albedo from radiometers. A radiative closure experiment was conducted for clear‐sky conditions. The mean differences of modeled and observed surface downwelling SW total fluxes were 1 W m−2 at SGP and 2 W m−2 at TWP, which are within observational uncertainty. At SGP, the estimated annual mean clear‐sky aerosol DRE is −3.00 W m−2 at the top of atmosphere (TOA) and −6.85 W m−2 at the surface. The strongest aerosol DRE of −4.81 (−10.77) W m−2 at the TOA (surface) are in the summer when AODs are largest. The weakest aerosol DRE of −1.28 (−2.77) W m−2 at the TOA (surface) are in November–January when AODs and single‐scattering albedos are lowest. At TWP, the annual mean clear‐sky DRE is −2.82 W m−2 at the TOA and −10.34 W m−2 at the surface. The strongest aerosol DRE of −5.95 (−22.20) W m−2 at the TOA (surface) are in November (October) due to the biomass burning season’s peak. The weakest aerosol DRE of −0.96 (−4.16) W m−2 at the TOA (surface) are in March (April) when AODs are smallest.

Dynamics Modeling and Simulation of a Net Closing Mechanism for Tether-Net Capture

Tether-net is a promising active debris removal technique, and a closing mechanism can ensure the reliable wrapping of space debris by using tether-net. This study focuses on the dynamics model of the split closing mechanism and the sliding joint between thread and ring. First, a new kind of closing mechanism is proposed, which drives the closing thread to close the net mouth through the split masses, and the mass-spring-damper method is used to model tether-net. Thereafter, for the first time, the model of thread-ring sliding joint is proposed based on the mass-spring-damper method, which can be used to simulate the closing process of tether-net. Finally, one-edge closure experiment of the net is carried out and the experimental results are compared with the simulation results, and the closing process of the tether-net is simulated by using the thread-ring sliding joint. Results reveal that the thread-ring sliding joint can be used to simulate the relative slip between the thread and the ring, and the tether-net can wrap the target reliably in a short time by using the split closing system. The split closing mechanism can make it possible for the tether-net to close successfully, whether it starts to work before or after the net contacts with the target.

How do people use Frankfurt Mainkai riverfront during a road closure experiment? A snapshot of public space usage during the coronavirus lockdown in May 2020

ABSTRACT In a one-year long experiment, the City of Frankfurt has limited the vehicular access to an 800 m stretch of its Mainkai riverfront as part of its plans to improve quality of life and support green mobility. With pre-intervention data collected in July 2019, this article presents the first results on how pedestrians, cyclists and other user-groups have been using this open public space in May 2020, i.e. post road closure and during the coronavirus restrictions. Based on pedestrian counts and behavioural observations, the authors report on a changed pedestrian mobility, spatial distribution and different stationary activities such as playing, sitting and socializing. The results show an increased peak hour frequency among cyclists (+45%) and pedestrians (+20%) on Mainkai street, along with more vulnerable user groups including including children cycling independently (+1150%) and people with restricted mobility (+25%). The study underlines related initiatives world-wide that pedestrianization acts as a catalyst for safer and healthier urban environments. Particularly, under the impression of an ongoing coronavirus pandemic, the study suggests that (temporary) road closure to cars is a key element in qualifying public space that attracts different user-groups and caters to an increased need to become physically active and engage socially while keeping distancing rules.

Aerosol optical properties in the Arctic: The role of aerosol chemistry and dust composition in a closure experiment between Lidar and tethered balloon vertical profiles

A closure experiment was conducted over Svalbard by comparing Lidar measurements and optical aerosol properties calculated from aerosol vertical profiles measured using a tethered balloon. Arctic Haze was present together with Icelandic dust. Chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. Moreover, scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDS) data were at disposal showing the presence of several mineralogical phases (i.e., sheet silicates, gypsum, quartz, rutile, hematite).The closure experiment was set up by calculating the backscattering coefficients from tethered balloon data and comparing them with the corresponding lidar profiles. This was preformed in three subsequent steps aimed at determining the importance of a complete aerosol speciation: (i) a simple, columnar refractive index was obtained by the closest Aerosol Robotic Network (AERONET) station, (ii) the role of water-soluble components, elemental carbon and organic matter (EC/OM) was addressed, (iii) the dust composition was included.When considering the AERONET data, or only the ionic water-soluble components and the EC/OM fraction, results showed an underestimation of the backscattering lidar signal up to 76, 53 and 45% (355, 532 and 1064 nm). Instead, when the dust contribution was included, the underestimation disappeared and the vertically-averaged, backscattering coefficients (1.45 ± 0.30, 0.69 ± 0.15 and 0.34 ± 0.08 Mm−1 sr−1, at 355, 532 and 1064 nm) were found in keeping with the lidar ones (1.60 ± 0.22, 0.75 ± 0.16 and 0.31 ± 0.08 Mm−1 sr−1). Final results were characterized by low RMSE (0.36, 0.08 and 0.04 Mm−1 sr−1) and a high linear correlation (R2 of 0.992, 0.992 and 0.994) with slopes close to one (1.368, 0.931 and 0.977, respectively). This work highlighted the importance of all the aerosol components and of the synergy between single particle and bulk chemical analysis for the optical property characterization in the Arctic.

Lidar/radar approach to quantify the dust impact on ice nucleation in mid and high level clouds

We present the first attempt of a closure experiment regarding the relationship between ice nucleating particle concentration (INPC) and ice crystal number concentration (ICNC), solely based on active remote sensing. The approach combines aerosol and cloud observations with polarization lidar, Doppler lidar, and cloud radar. Several field campaigns were conducted on the island of Cyprus in the Eastern Mediterranean from 2015-2018 to study heterogeneous ice formation in altocumulus and cirrus layers embedded in Saharan dust. A case study observed on 10 April 2017 is discussed in this contribution.

Characterization of submicron aerosols and CCN over the Yellow Sea measured onboard the Gisang 1 research vessel using the positive matrix factorization analysis method

Aerosol size distributions and cloud condensation nuclei (CCN) number concentrations were measured in spring 2017 over the Yellow Sea on board the research vessel Gisang 1. The average number concentration of particles larger than 10 nm and CCN at 0.65% supersaturation (S) were 7622 ± 4038 cm−3 and 4821 ± 1763 cm−3, respectively. Characteristics of aerosol size distribution data were analyzed using a positive matrix factorization (PMF) method. It was found that only 6 Factors could explain the aerosol size distribution reasonably well. Factors 1 and 2 indicated nucleation mode particles, Factor 3 indicated Aitken mode particles, and Factors 4, 5, and 6 indicated accumulation mode particles. The concentrations of nucleation and Aitken mode particles showed a clear wind direction dependence; high under westerly winds due to the high concentrations of particles and precursor gases in eastern China. Meanwhile, the concentration of larger particles and CCN showed no significant wind direction dependence. Aerosol size distribution was also significantly influenced by meteorology. Small particles were predominant during clear days. In contrast during mist or fog days, the aerosol size distribution shifted to larger sizes. A CCN closure experiment was conducted using results of the PMF analysis. The assumption of internally mixed particles led to overestimation of predicted CCN concentrations but agreement was significantly better when externally mixed particles were considered. The logarithmic curve fit of NCCN(S) = 4825 ∗ log S + 4933 was found to very well explain measured CCN concentrations at a few S over the Yellow Sea, and therefore is recommended as input CCN spectral data for numerical models that explicitly treat CCN activation.

Measuring the detector-observed impact of optical blurring due to aerosols in a laboratory cloud chamber

Deleterious effects of the atmosphere on remotely acquired images includes absorption and scattering of light by aerosol particulates, which not only attenuates the signal but can potentially cause blurring due to forward-scattered light accepted by the imaging system. Proposed aerosol scattering models (e.g., Ishimaru) provide a method for simulating the contrast and spatial detail expected when imaging through atmospheres with significant aerosol optical depth. This work explores closure between modulation transfer functions (MTFs) obtained from directly measured images and MTFs calculated from theory using measured cloud properties. The closure experiments are performed in a laboratory cloud chamber in which cloud droplet number density and size distribution are directly measured. Images of a binary knife-edge target were taken with an optical detector on the other side of a water cloud generated through reduction of pressure in the humidified chamber. The key results of this closure experiment are: the theoretical expression for the aerosol MTF is likely overly simplistic and does not account for broad particle size distributions. The significance of optical blurring from light scattering by aerosol particles depends sensitively on the properties of both the particles and the imaging system.

Mechanical Alteration Associated With Chemotherapeutic Resistance of Breast Cancer Cells.

BackgroundThe mechanical deformability of cancer cells has attracted particular attention as an emerging biomarker for the prediction of anti-cancer drug sensitivity. Nevertheless, it has not been possible to establish a general rubric for the identification of drug susceptibility in breast cancer cells from a mechanical perspective. In the present study, we investigated the mechanical alteration associated with resistance to adjuvant therapy in breast cancer cells.MethodsWe performed an ‘atomic force microscopy (AFM)-based nanomechanical study’ on ‘drug-sensitive (MCF-7)’ and ‘drug-resistant (MCF-7/ADR)’ breast cancer cells. We also conducted cell viability tests to evaluate the difference in doxorubicin responsiveness between two breast cancer cell lines. We carried out a wound closure experiment to investigate the motility changes associated with chemotherapeutic resistance. To elucidate the changes in molecular alteration that accompany chemotherapeutic resistance, we investigated the expression of vinculin and integrin-linked kinase-1–which are proteins involved in substrate adhesion and the actin cytoskeleton–using Western blotting analysis.ResultsA MTT assay confirmed that the dose-dependent efficacy of doxorubicin was reduced in MCF-7/ADR cells compared to that in MCF-7 cells. The wound assay revealed enhanced two-dimensional motility in the MCF-7/ADR cells. The AFM mechanical assay showed evidence that the drug-resistant breast cancer cells exhibited a significant decrease in mechanical deformability compared to their drug-sensitive counterparts. The mechanical alteration in the MCF-7/ADR cells was accompanied by upregulated vinculin expression.ConclusionsThe obtained results manifestly showed that the altered mechanical signatures–including mechanical deformability and motility–were closely related with drug resistance in the breast cancer cells. We believe that this investigation has improved our understanding of the chemotherapeutic susceptibility of breast cancer cells.

Growth rates of fine aerosol particles at a site near Beijing in June 2013

Growth of fine aerosol particles is investigated during the Aerosol–CCN–Cloud Closure Experiment campaign in June 2013 at an urban site near Beijing. Analyses show a high frequency (∼ 50%) of fine aerosol particle growth events, and show that the growth rates range from 2.1 to 6.5 nm h−1 with a mean value of ∼ 5.1 nm h−1. A review of previous studies indicates that at least four mechanisms can affect the growth of fine aerosol particles: vapor condensation, intramodal coagulation, extramodal coagulation, and multi-phase chemical reaction. At the initial stage of fine aerosol particle growth, condensational growth usually plays a major role and coagulation efficiency generally increases with particle sizes. An overview of previous studies shows higher growth rates over megacity, urban and boreal forest regions than over rural and oceanic regions. This is most likely due to the higher condensational vapor, which can cause strong condensational growth of fine aerosol particles. Associated with these multiple factors of influence, there are large uncertainties for the aerosol particle growth rates, even at the same location.

Stromal vascular fraction shows robust wound healing through high chemotactic and epithelialization property

BackgroundAlthough human stromal vascular fraction (SVF) has been regarded as an attractive stem cell source, its therapeutic mechanism in wound healing has not been fully elucidated. AimsIn this study, we investigated the molecular characteristics and therapeutic property of SVF for wound healing. MethodsMicroarray data showed that SVF cells are enriched with a higher level of wound healing or epithelium development–related genes and micro RNA. ResultsQuantitative polymerase chain reaction (PCR) and reverse transcriptase PCR results revealed that the epithelialization growth factor, epidermal growth factor (EGF), chemokines, stromal cell–derived factor (SDF-1 or CXCL12), neutrophil-activating protein-2 (NAP-2 or CXCL7), chemokine receptors (CXCR1, CCR2 and CCR3) and wound healing genes were up-regulated in SVF compared with those in adipose-derived mesenchymal stem cells (ASCs). An in vitro scratch wound closure experiment demonstrated that co-culture with SVF substantially accelerated the wound closure of fibroblasts. Wounds in nude mice were created by skin excisions followed by injections of SVF with Pluronic hydrogel. SVF implantation highly accelerated wound closure and increased cellularity and re-epithelialization. In addition, the transplanted SVF exhibited high engraftment rates in the wound area, suggesting direct benefits for cutaneous closure. ConclusionsTaken together, these data suggest that SVF possesses high therapeutic capability for wound healing via the secretion of epithelialization and chemotactic growth factors and enhanced engraftment properties.

Absorption correction and phase function shape effects on the closure of apparent optical properties.

We present a closure experiment between new inherent optical properties (IOPs: absorption a, scattering b, backscattering b_b) and apparent optical properties (AOPs: remote-sensing reflectance R_rs, irradiance reflectance R, and anisotropic factor at nadir Q_n) data of Ionian and Adriatic seawaters, from very clear to turbid waters, ranging across one order of magnitude in R_rs. The internal consistency of the IOP-AOP matchups was investigated though radiative transfer closure. Using the in situ IOPs, we predicted the AOPs with the commercial radiative transfer solver Hydrolight. Closure was limited by two unresolved issues, one regarding processing of in situ data and the other related to radiative transfer modeling. First, different correction methods of the absorption data measured by the Wetlabs ac-s produced high variations in simulated reflectances, reaching 40% for the highest reflectances in our dataset. Second, the lack of detailed volume scattering function measurements forces us to adopt analytical functions that are consistent with a given particle backscattering ratio. The analytical phase functions named Fournier-Forand and two-term Kopelevich presented reasonable angular shapes with respect to measurements at a few backward angles. Between these phase functions, induced changes were within 4% for R_rs, within 11% for R, and within 10% for Q_n. Additionally, closure of Q_n was generally not successful considering radiometric uncertainties. Simulated Q_n overestimated low values and underestimated high values, especially at 665 nm, where Hydrolight was unable to predict measured Q_n values greater than 6 sr. The physical nature of Q_n makes this mismatch almost independent of the measured IOPs, thus precluding Q_n tuning by varying the former. The non-closure of Q_n might be caused by an inaccurate phase function and, to a lesser extent, by the modeling of the incoming radiance. For the future, this remains the task of accurate absorption and phase function measurements, especially at red wavelengths.