bluuebunny/crossref_metadata_2025 huggingface dataset:
A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results
Authors: Weigel K. , Hoffmann L. , Günther G. , Khosrawi F. , Olschewski F. , Preusse P. , Spang R. , Stroh F. , Riese M.
Published: March 2012

Abstract. Remote sensing measurements from the Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF) during a flight on 29 July 2006 are presented. This flight is part of the AMMA-SCOUT-O3 measurement campaign, where CRISTA-NF was deployed on the high-flying research aircraft M55-Geophysica. The flight path was located over Italy and the Mediterranean Sea and crossed over the subtropical jet twice. Measurements of temperature, and the volume mixing ratios of water vapor (H2O), ozone (O3), nitric acid (HNO3) and peroxyacetyl nitrate (PAN) are available with a vertical resolution of up to 500 m between about 6 to 21 km altitude. CRISTA-NF observes these trace gases simultaneously and provides a quasi-2D view of the transition region between the troposphere and the stratosphere. The observation of these different trace gases allows to determine the origin of air masses in the stratosphere or troposphere. As expected, higher abundances are found where the main source of the trace gases is located: in the stratosphere for O3 and in the troposphere for H2O and PAN. Tracer-tracer correlations between O3 and PAN are used to identify mixed tropospheric and lowermost stratospheric air at the subtropical jet and around the thermal tropopause north of the jet. An intrusion of stratospheric air into the troposphere associated with the subtropical jet is found in the CRISTA-NF observations. The observations indicate that the intrusion is connected to a tropopause fold which is not resolved in the ECMWF analysis data. The intrusion was reproduced in a simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS). This work discusses the nature of the observed processes at the subtropical jet based on the CRISTA-NF observations and the CLaMS simulation.
A methodology for in-situ and remote sensing of microphysical and radiative properties of contrails as they evolve into cirrus
Authors: Jones H. M. , Haywood J. , Marenco F. , O'Sullivan D. , Meyer J. , Thorpe R. , Gallagher M. W. , Krämer M. , Bower K. N. , Rädel G. , Rap A. , Forster P. , Coe H.
Published: March 2012

Abstract. Contrails and especially their evolution into cirrus-like clouds are thought to have very important effects on local and global radiation budgets, though are generally not well represented in global climate models. Lack of contrail parameterisations is due to the limited availability of in situ contrail measurements which are difficult to obtain. Here we present a methodology for successful sampling and interpretation of contrail microphysical and radiative data using both in situ and remote sensing instrumentation on board the FAAM BAe146 UK research aircraft as part of the COntrails Spreading Into Cirrus (COSIC) study. Forecast models were utilised to determine flight regions suitable for contrail formation and sampling; regions that were both free of cloud but showed a high probability of occurrence of air mass being supersaturated with respect to ice. The FAAM research aircraft, fitted with cloud microphysics probes and remote sensing instruments, formed a distinctive spiral-shaped contrail in the predicted area by flying in an orbit over the same ground position as the wind advected the contrails to the east. Parts of these contrails were sampled during the completion of four orbits, with sampled contrail regions being between 7 and 30 min old. Lidar measurements were useful for in-flight determination of the location and spatial extent of the contrails, and also to report extinction values that agreed well with those calculated from the microphysical data. A shortwave spectrometer was also able to detect the contrails, though the signal was weak due to the dispersion and evaporation of the contrails. Post-flight the UK Met Office NAME III dispersion model was successfully used as a tool for modelling the dispersion of the persistent contrail; determining its location and age, and determining when there was interference from other measured other aircraft contrails or when cirrus encroached on the area later in the flight. The persistent contrails were found to consist of small (~10 μm) plate-like crystals where growth of ice crystals to larger sizes (~100 μm) was detected when higher water vapour levels were present. Using the cloud microphysics data, extinction co-efficient values were calculated and found to be 0.01–1 km−1. The contrails formed during the flight (referred to as B587) were found to have a visible lifetime of ~40 min, and limited water vapour supply was thought to have suppressed ice crystal growth.
Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine oxide particles in the coastal marine boundary layer
Authors: Murray B. J. , Haddrell A. E. , Peppe S. , Davies J. F. , Reid J. P. , O'Sullivan D. , Price H. C. , Kumar R. , Saunders R. W. , Plane J. M. C. , Umo N. S. , Wilson T. W.
Published: March 2012

Abstract. Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. There has been some debate over the chemical identity of these particles. Hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5 · H2O). In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH). On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass, but subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only ~6 %, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth factors observed in field experiments.
Effects of ice crystals on the FSSP measurements in mixed phase clouds
Authors: Febvre G. , Gayet J.-F. , Shcherbakov V. , Gourbeyre C. , Jourdan O.
Published: March 2012

Abstract. In this paper, we show that in mixed phase clouds FSSP-100 measurements may be contaminated by ice crystals, inducing wrong interpretation of particle size and subsequent bulk parameters. This contamination is generally revealed by a bimodal feature of the particle size distribution; in other words, in mixed phase clouds bimodal features could be an indication of the presence of ice particles. The combined measurements of the FSSP-100 and the Polar Nephelometer give a coherent description of the effect of the ice crystals on the FSSP-100 response. The FSSP-100 particle size distributions are characterized by a bimodal shape with a second mode peaked between 25 and 35 μm related to ice crystals. This feature is observed with the FSSP-100 at airspeed up to 200 m s−1 and with the FSSP-300 series. In order to assess the size calibration for clouds of ice crystals the response of the FSSP-100 probe has been numerically simulated using a light scattering model of randomly oriented hexagonal ice particles and assuming both smooth and rough crystal surfaces. The results suggest that the second mode measured between 25 μm and 35 μm, does not necessarily represent true size responses but likely corresponds to bigger aspherical ice particles. According to simulation results, the sizing understatement would be neglected in the rough case but would be major with the smooth case. Qualitatively, the Polar Nephelometer phase function suggests that the rough case is the more suitable to describe real crystals. Quantitatively, however, it is difficult to conclude. Previous cloud in situ measurements suggest that the FSSP-100 secondary mode, peaked in the range 25–35 μm, is likely to be due to the shattering of large ice crystals on the probe tips. This finding is supported by the rather good relationship between the concentration of particles larger than 20 μm (hypothesized to be ice shattered-fragments measured by the FSSP) and the concentration of (natural) ice particles larger than 100 μm (CPI data). The shattering efficiency is defined as the ratio of the measured ice shattered-fragments to the number of natural ice particles (with d>100 μm) impacting the probe leading edge. In the present study the shattering efficiency is evaluated to ~7%. It is found that about 400 ice fragments may result from the shattering of one equivalent irregular shaped ice crystal with a mean volume diameter of 310 μm. Obviously, these values could be strongly dependent on the inlet design, the airspeed and the robustness of ice crystals via the impact kinetic energy to surface energy ratio providing the particle breakup.
Systematic study of the impact of fresh water fluxes on the glacial carbon cycle
Authors: Bouttes N. , Roche D. M. , Paillard D.
Published: March 2012

Abstract. During glacial periods, atmospheric CO2 concentration increases and decreases by around 15 ppm. At the same time, the climate changes gradually in Antarctica. Such climate changes can be simulated in models when the AMOC (Atlantic Meridional Oceanic Circulation) is weakened by adding fresh water to the North Atlantic. The impact on the carbon cycle is less straightforward, and previous studies give opposite results. Because the models and the fresh water fluxes were different in these studies, it prevents any direct comparison and hinders finding whether the discrepancies arise from using different models or different fresh water fluxes. In this study we use the CLIMBER-2 coupled climate carbon model to explore the impact of different fresh water fluxes. In both preindustrial and glacial states, the addition of fresh water and the resulting slow-down of the AMOC lead to an uptake of carbon by the ocean and a release by the terrestrial biosphere. The duration, shape and amplitude of the fresh water flux all have an impact on the change of atmospheric CO2 because they modulate the change of the AMOC. The maximum CO2 change linearly depends on the time integral of the AMOC change. The different duration, amplitude, and shape of the fresh water flux cannot explain the opposite evolution of ocean and vegetation carbon inventory in different models. The different CO2 evolution thus depends on the AMOC response to the addition of fresh water and the resulting climatic change, which are both model dependent. In CLIMBER-2, the rise of CO2 recorded in ice cores during abrupt events can be simulated under glacial conditions, especially when the sinking of brines in the Southern Ocean is taken into account. The addition of fresh water in the Southern Hemisphere leads to a decline of CO2, contrary to the addition of fresh water in the Northern Hemisphere.
Simulations over South Asia using the Weather Research and Forecasting model with Chemistry (WRF-Chem): set-up and meteorological evaluation
Authors: Kumar R. , Naja M. , Pfister G. G. , Barth M. C. , Brasseur G. P.
Published: March 2012

Abstract. The configuration and evaluation of the meteorology is presented for simulations over the South Asian region using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Temperature, water vapor, dew point temperature, zonal and meridional wind components, precipitation and tropopause pressure are evaluated against radiosonde and satellite-borne (AIRS and TRMM) observations along with NCEP/NCAR reanalysis fields for the year 2008. Chemical fields, with focus on tropospheric ozone, are evaluated in a companion paper. The spatial and temporal variability in meteorological variables is well simulated by the model with temperature, dew point temperature and precipitation showing higher values during summer/monsoon and lower during winter. The index of agreement for all the parameters is estimated to be greater than 0.6 indicating that WRF-Chem is capable of simulating the variations around the observed mean. The mean bias (MB) and root mean square error (RMSE) in modeled temperature, water vapor and wind components show an increasing tendency with altitude. MB and RMSE values are within ±2 K and 1–4 K for temperature, 30% and 20–65% for water vapor and 1.6 m s−1 and 5.1 m s−1 for wind components. The spatio-temporal variability of precipitation is also reproduced reasonably well by the model but the model overestimates precipitation in summer and underestimates precipitation during other seasons. Such a behavior of modeled precipitation is in agreement with previous studies on South Asian monsoon. The comparison with radiosonde observations indicates a relatively better model performance for inland sites as compared to coastal and island sites. The MB and RMSE in tropopause pressure are estimated to be less than 25 hPa. Sensitivity simulations show that biases in meteorological simulations can introduce errors of ±(10–25%) in simulations of tropospheric ozone, CO and NOx. Nevertheless, a comparison of statistical metrics with benchmarks indicates that the model simulated meteorology is of sufficient quality for use in chemistry simulations.
ASAMgpu V1.0 – a moist fully compressible atmospheric model using graphics processing units (GPUs)
Authors: Horn S.
Published: March 2012

Abstract. In this work the three dimensional compressible moist atmospheric model ASAMgpu is presented. The calculations are done using graphics processing units (GPUs). To ensure platform independence OpenGL and GLSL are used, with that the model runs on any hardware supporting fragment shaders. The MPICH2 library enables interprocess communication allowing the usage of more than one GPU through domain decomposition. Time integration is done with an explicit three step Runge-Kutta scheme with a time-splitting algorithm for the acoustic waves. The results for four test cases are shown in this paper. A rising dry heat bubble, a cold bubble induced density flow, a rising moist heat bubble in a saturated environment, and a DYCOMS-II case.
On the factors influencing surface-layer energy closure and their seasonal variability over the semi-arid Loess Plateau of Northwest China
Authors: Xiao X. , Zuo H. C. , Yang Q. D. , Wang S. J. , Wang L. J. , Chen J. W. , Chen B. L. , Zhang B. D.
Published: March 2012

Abstract. The energy observed in the surface layer, when using eddy-covariance techniques to measure turbulent fluxes, is not balanced. Important progress has been made in recent years in identifying potential reasons for this lack of closure in the energy balance, but the problem is not yet resolved. In this paper, long-term data that include output of tower, radiation, surface turbulence flux and soil measurement collected from September 2006 to August 2010 in the Semi-Arid Climate Change and Environment Observatory, Lanzhou University, in the semi-arid Loess Plateau of Northwest China, were analysed, focusing on the seasonal characteristics of the surface energy and the factors that have impact on the energy balance closure (EBC). The analysis shows that (1) the long-term observations are successful; the interaction between the land and the atmosphere in semi-arid climates can be represented by the turbulent transport of energy. In addition, even though the residual is obvious, this suggests that the factors that impact the EBC are stable, and their seasonal variations are identical. The analysis also shows that (2) four factors have obvious impact on the EBC: the diverse schemes for surface soil heat flux, the flux contribution from the target source area, the low-frequency part of the turbulence spectra, and the strength of atmospheric turbulence motion. The impact of these four factors on the EBC are similar in all seasons. Lastly, the results indicate that (3) atmospheric turbulence intensity is a very important factor in terms of its impact on the EBC. The relative turbulence intensity, RIw, characterises the strength of atmospheric turbulence motion, and is found to exert a noticeable impact on the EBC; in all seasons, the EBC is increased when the relative turbulence intensity is enlarged.
Use of laser-scan technology to analyse topography and flow in a weir pool
Authors: Dresel P. E. , Hekmeijer P. , Dean J. F. , Harvey W. , Webb J. A. , Cook P.
Published: March 2012

Abstract. The development of laser-scan techniques provides opportunity for detailed terrain analysis in hydrologic studies. Ground based scans were used to model the ground elevation in the area of a stream gauge weir over an area of 240 m2 at a resolution of 0.05 m. The terrain model was used to assess the possibility of flow bypassing the weir and to calculate stream flow during filling of the weir pool, prior to flow through the weir notch. The mapped surface shows a subtle low-lying area at the south end of the structure where flow could bypass the weir. The flow calculations quantify low-flows that do not reach the weir notch during small rain events and flow at the beginning of larger events in the ephemeral stream.
Critical review of the application of SWAT in the upper Nile Basin countries
Authors: van Griensven A. , Ndomba P. , Yalew S. , Kilonzo F.
Published: March 2012

Abstract. The Soil and Water Assessment Tool (SWAT) is a hydrological simulation tool that is widely applied within the Nile basin. Up to date, more than 20 peer reviewed papers describe the use of SWAT for a variety of problems in the upper Nile basin countries, such as erosion modeling, land use modeling, climate change impact modeling and water resources management. The majority of the studies are clustered in the tropical highlands in Ethiopia and around Lake Victoria. The popularity of SWAT is attributed to the fact that the tool is freely available and that it is readily applicable through the development of Geographic Information System (GIS) based interfaces and its easy linkage to sensitivity, calibration and uncertainty analysis tools. The online and free availability of basic GIS data that are required for SWAT made its applicability more straight forward even in data scarce areas. However, the easy use of SWAT may not always lead to knowledgeable models. In this paper, we aim at critically reviewing the use of SWAT in the context of the modeling purpose and problem descriptions in the tropical highlands of the Nile Basin countries. A number of criteria are used to evaluate the model set-up, model performances, physical representation of the model parameters, and the correctness of the hydrological model balance. On the basis of performance indicators, the majority of the SWAT models were classified as giving satisfactory to very good results. Nevertheless, the hydrological mass balances as reported in several papers contained losses that might not be justified. Several papers also reported unrealistic parameter values. More worrying is that many papers lack this information. For this reason, it is difficult to give an overall positive evaluation to most of the reported SWAT models. An important gap is the lack of attention that is given to the vegetation and crop processes. None of the papers reported any adaptation to the crop parameters, or any crop related output such as leaf area index, biomass or crop yields. A proper simulation of the land cover is important for obtaining correct runoff generation, evapotranspiration and erosion computations. It is also found that a comparison of SWAT applications on the same or similar case study but by different research teams and/or model versions resulted in very different results. It is therefore recommended to try to find better methods to evaluate the representativeness of the distributed processes and parameters, especially when land use studies are envisaged or predictions of the future through environmental changes. The main recommendation is that more details on the model set-up, the parameters and outputs should be provided in the journal papers or supplementary materials in order to allow for a more stringent evaluation of these models.
Evaluation of real time and future global monitoring and forecasting systems at Mercator Océan
Authors: Lellouche J.-M. , Le Galloudec O. , Drévillon M. , Régnier C. , Greiner E. , Garric G. , Ferry N. , Desportes C. , Testut C.-E. , Bricaud C. , Bourdallé-Badie R. , Tranchant B. , Benkiran M. , Drillet Y. , Daudin A. , De Nicola C.
Published: March 2012

Abstract. Since December 2010, the global analysis and forecast of the MyOcean system consists in the Mercator Océan NEMO global 1/4° configuration with a 1/12° "zoom" over the Atlantic and Mediterranean Sea. The zoom open boundaries come from the global 1/4° at 20° S and 80° N. The data assimilation uses a reduced order Kalman filter with a 3-D multivariate modal decomposition of the forecast error. It includes an adaptative error and a localization algorithm. A 3D-Var scheme corrects for the slowly evolving large-scale biases in temperature and salinity. Altimeter data, satellite temperature and in situ temperature and salinity vertical profiles are jointly assimilated to estimate the initial conditions for the numerical ocean forecasting. This paper gives a description of the recent systems. The validation procedure is introduced and applied to the current and future systems. This paper shows how the validation impacts on the quality of the systems. It is shown how quality check (in situ, drifters) and data source (satellite temperature) impacts as much as the systems design (model physics and assimilation parameters). The validation demonstrates the accuracy of the MyOcean global products. Their quality is stable in time. The future systems under development still suffer from a drift. This could only be detected with a 5 yr hindcast of the systems. This emphasizes the need for continuous research efforts in the process of building future versions of MyOcean2 forecasting capacities.
Obstacles and benefits of the implementation of a reduced rank smoother with a high resolution model of the Atlantic ocean
Authors: Freychet N. , Cosme E. , Brasseur P. , Brankart J.-M. , Kpemlie E.
Published: March 2012

Abstract. Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Results show that the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical point of view. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the north-Brazil rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational centers systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network.
Combination Therapy with Focal Laser Photocoagulation and Intravitreal Ranibizumab for Polypoidal Choroidal Vasculopathy: a Case Series
Authors: Mitry Danny , Patra Sudeshna
Published: March 2012

Purpose.

The study aim is to describe the clinical outcomes of patients with polypoidal choroidal vasculopathy (PCV) treated with focal argon laser photocoagulation and ranibizumab combination therapy.

Methods.

This study is a retrospective case series of 6 patients (6 eyes) diagnosed with PCV who received combination therapy with argon laser photocoagulation and ranibizumab and have at least 12 months follow-up. Argon laser photocoagulation was applied directly to the polypoidal lesions as identified on indocyanine green angiography and followed by a course of intravitreal ranibizumab injections. The primary outcome measures were the mean change in logMAR visual acuity and the mean change in central macular thickness (CMT) at final follow-up.

Results.

The mean (SD) duration of follow-up was 1.09 (0.22) years. At the final follow-up the difference (95% confidence interval [CI]) in logMAR acuity was 0.48 (0.10-0.74) (p=0.01) and the difference (95% CI) in CMT was 207 μm (35-490) (p=0.02) on optical coherence tomography. The mean (SD) number of ranibizumab injections per eye was 4.83 (3.6). The mean (SD) number of laser treatments per eye was 1.16 (0.4).

Conclusions.

In this study, combination therapy with focal argon laser photocoagulation and intravitreal ranibizumab resulted in improved visual acuity and clinical outcomes for patients with PCV for up to 1 year.
Treatment of multilevel macular hemorrhage secondary to retinal arterial macroaneurysm with submacular tissue plasminogen activator
Authors: Sonmez Kenan , Ozturk Faruk , Ozcan Pehmen Y.
Published: March 2012

Purpose.

To evaluate the efficacy of pars plana vitrectomy (PPV) followed by internal limiting membrane (ILM) removal and injection of subretinal recombinant tissue plasminogen activator (rtPA)–assisted pneumatic displacement in eyes with massive multilevel macular hemorrhage caused by ruptured retinal arterial macroaneurysm (RAMA).

Methods.

Four eyes of 4 patients treated with PPV for recent (≤7 days) macular hemorrhage at both beneath the ILM and subretinal space involving the center of the fovea caused by RAMA were included in the study. In each case, following PPV, ILM removal, subretinal injection of rtPA (12.5 µg/0.1 mL), and fluid-air exchange with postoperative prone positioning was performed. Optical coherence tomography (OCT) examination was performed at the initial and the follow-up visits.

Results.

Duration of symptoms ranged from 3 to 7 days (average, 4.5±1.9 days). Preoperative visual acuity ranged from hand motions to 20/800. Follow-up ranged from 6 to 18 months (average, 13±5.2 months). The postoperative visual acuity improved in all eyes and ranged from 20/100 to 20/30 (mean, 20/50). At the final visit, OCT examination revealed well-preserved foveal structure in all eyes. Mild nuclear sclerosis developed in one eye.

Conclusions.

Pars plana vitrectomy followed by ILM removal and injection of subretinal rtPA-assisted pneumatic displacement appears to be effective in both improving visual acuity and preserving the foveal structure in eyes with recent massive multilevel macular hemorrhage secondary to RAMA.
Selectivity, Kinetics, and Efficiency of Reversible Anion Exchange with TcO4− in a Supertetrahedral Cationic Framework
Authors: Wang Shuao , Yu Ping , Purse Bryant A. , Orta Matthew J. , Diwu Juan , Casey William H. , Phillips Brian L. , Alekseev Evgeny V. , Depmeier Wulf , Hobbs David T. , Albrecht‐Schmitt Thomas E.
Published: March 2012

[ThB5O6(OH)6][BO(OH)2]·2.5H2O (Notre Dame Thorium Borate‐1, NDTB‐1) is an inorganic supertetrahedral cationic framework material that is derived from boric acid flux reactions. NDTB‐1 exhibits facile single crystal to single crystal anion exchange with a variety of common anions such as Cl−, Br−, NO3−, IO3−, ClO4−, MnO4−, and CrO42−. More importantly, NDTB‐1 is selective for the removal of TcO4− from nuclear waste streams even though there are large excesses of competing anions such as Cl−, NO3−, and NO2−. Competing anion exchange experiments and magic‐angle spinning (MAS)‐NMR spectroscopy of anion‐exchanged NDTB‐1 demonstrate that this unprecedented selectivity originates from the ability of NDTB‐1 to trap TcO4− within cavities, whereas others remain mobile within channels in the material. The exchange kinetics of TcO4− in NDTB‐1 are second‐order with the rate constant k2 of 0.059 s−1 M−1. The anion exchange capacity of NDTB‐1 for TcO4− is 162.2 mg g−1 (0.5421 mol mol−1) with a maximum distribution coefficient Kd of 1.0534 × 104 mL g−1. Finally, it is demonstrated that the exchange for TcO4− in NDTB‐1 is reversible. TcO4− trapped in NDTB‐1 can be exchanged out using higher‐charged anions with a similar size such as PO43− and SeO42−, and therefore the material can be easily recycled and reused.
Wearing Comfort of temperature‐adaptable textiles by dual‐phase coatings between phase‐change materials and silicon carbide particles
Authors: Park Youngmi , Kim Eunae
Published: March 2012

Two different thermally enhancing coating materials, namely, phase‐change materials (PCMs) and silicon carbide (SiC), which are both capable of managing heat storage, were coated directly onto breathable waterproof nylon, either alone or together. The comfort properties of 20 wt % PCM‐coated fabric (20PCM) and 20 wt % PCM/SiC dual‐coated fabric (SC–20PCM) were compared with those of a control in a human clothing environment (HCE) system and a wear trial test. The changes in the heat and moisture transfer were examined by measurement of the microclimate temperature (Tmi) and microclimate relative humidity (RHmi) of the coated fabrics with an HCE system. In addition, Tmi, RHmi, and subjective sensations in the wear trials were evaluated. With dry heat transfer in the HCE, the thermal insulation decreased in following order: SC–20PCM > 20PCM > Control. However, SiC could not function in the presence of simulated perspiration. The moisture‐buffering capacity in the outermost layer decreased when the fabrics were coated with 20PCM and SC–20PCM. In the wear trials, the subjects were unable to distinguish any difference in the thermal comfort between the garments, even though the Tmi of the SC–20PCM garments was 2.5°C higher than that of the control garments. Moreover, they did not report any significant differences in the humidity or comfort sensations between the test garments. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The effects of passive and active learning on student preference and performance in an undergraduate basic science course
Authors: Minhas Paras Singh , Ghosh Arundhati , Swanzy Leah
Published: March 2012

Active learning is based on self‐directed and autonomous teaching methods, whereas passive learning is grounded in instructor taught lectures. An animal physiology course was studied over a two‐year period (Year 1, n = 42 students; Year 2, n = 30 students) to determine the effects of student‐led seminar (andragogical) and lecture (pedagogical) teaching methods on students' retention of information and performance. For each year of the study, the course was divided into two time periods. The first half was dedicated to instructor‐led lectures, followed by a control survey in which the students rated the efficiency of pedagogical learning on a five‐point Likert scale from one (strongly disagree) to five (strongly agree). During the second period, students engaged in andragogical learning via peer‐led seminars. An experimental survey was then administered to students using the same scale as above to determine students' preferred teaching method. Raw examination scores and survey results from both halves of the course were statistically analyzed by ANOVA with Newman‐Keuls multiple comparison test. By the end of the study, student preference for peer‐led seminars increased [mean ± SD: (2.47 ± 0.94)/(4.03 ± 1.36), P < 0.04], and examination scores significantly increased [mean ± SD: (73.91% ± 13.18)/(85.77 ± 5.22), P < 0.001]. A majority of students (68.8%) preferred a method that contained peer‐led seminars and instructor‐led lectures. These results may indicate that integration of active and passive learning into undergraduate courses may have greater benefit in terms of student preference and performance than either method alone. Anat Sci Educ. © 2012 American Association of Anatomists.
Experimental evidence for improved neuroimaging interpretation using three‐dimensional graphic models
Authors: Ruisoto Pablo , Juanes Juan Antonio , Contador Israel , Mayoral Paula , Prats‐Galino Alberto
Published: March 2012

Three‐dimensional (3D) or volumetric visualization is a useful resource for learning about the anatomy of the human brain. However, the effectiveness of 3D spatial visualization has not yet been assessed systematically. This report analyzes whether 3D volumetric visualization helps learners to identify and locate subcortical structures more precisely than classical cross‐sectional images based on a two dimensional (2D) approach. Eighty participants were assigned to each experimental condition: 2D cross‐sectional visualization vs. 3D volumetric visualization. Both groups were matched for age, gender, visual‐spatial ability, and previous knowledge of neuroanatomy. Accuracy in identifying brain structures, execution time, and level of confidence in the response were taken as outcome measures. Moreover, interactive effects between the experimental conditions (2D vs. 3D) and factors such as level of competence (novice vs. expert), image modality (morphological and functional), and difficulty of the structures were analyzed. The percentage of correct answers (hit rate) and level of confidence in responses were significantly higher in the 3D visualization condition than in the 2D. In addition, the response time was significantly lower for the 3D visualization condition in comparison with the 2D. The interaction between the experimental condition (2D vs. 3D) and difficulty was significant, and the 3D condition facilitated the location of difficult images more than the 2D condition. 3D volumetric visualization helps to identify brain structures such as the hippocampus and amygdala, more accurately and rapidly than conventional 2D visualization. This paper discusses the implications of these results with regards to the learning process involved in neuroimaging interpretation. Anat Sci Educ. © 2012 American Association of Anatomists.
Gold Catalysis: One‐Pot Alkylideneoxazoline Synthesis/Alder‐Ene Reaction
Authors: Hashmi A. Stephen K. , Littmann Anna
Published: March 2012

Based on the gold‐catalyzed synthesis of methyleneoxazolines, a one‐pot combination with an Alder‐ene reaction was developed. For azodicarboxylates, good to very good yields (51–99 %) of the oxazolemethylhydrazinedicarboxylates were achieved with 3 mol % of the Gagosz catalyst, [Ph3PAuNTf3]. In a less‐selective reaction, 4‐phenyl‐3H‐1,2,4‐triazol‐3,5(4 H)‐dione gave lower yields (41–49 %) of the corresponding oxazolemethylphenyltriazolidinediones. Overall, five new bonds were formed. Tetracyanoethylene afforded a cyclobutane derivative through a [2+2] cycloaddition reaction at −40 °C, but only 45 % of the spiro compound was obtained. The less‐readily available KITPHOS ligands on gold gave even higher yields at lower catalyst loadings (2 mol %), but longer reaction times were required.
Chondrogenic phenotype of different cells encapsulated in κ‐carrageenan hydrogels for cartilage regeneration strategies
Authors: Popa Elena , Reis Rui , Gomes Manuela
Published: March 2012

Engineering articular cartilage substitutes using hydrogels with encapsulated cells is an approach that has received increasing attention in recent years. Hydrogels based on κ‐carrageenan (κC), a thermoreversible natural‐origin polymer, have been recently proposed as new cell/growth factor delivery vehicles for regenerative medicine. In this work, we report the potential of such hydrogels encapsulating either human‐adipose‐derived stem cells (hASCs), human nasal chondrocytes (hNCs), or a chondrocytic cell line (ATDC5) for cartilage regeneration strategies. The in vitro cellular behavior of the encapsulated cells within κC hydrogel was analyzed after different culturing periods using biochemical assays and histological and real‐time reverse‐transcription PCR analysis. The three types of cells encapsulated in κC hydrogels showed good cellular viability and proliferation up to 21 days of culture, and the cell‐laden hydrogels were positive for specific cartilage markers. In summary, the results demonstrate that hASCs embedded in κC hydrogels proliferate faster and exhibit higher expression levels of typical cartilage markers as compared with hNCs or ATDC5 cells. Based on these data, it is possible to conclude that κC hydrogel provides a good support for culture and differentiation of encapsulated cells and that hASCs may provide an advantageous alternative to primary chondrocytes, currently used in clinical treatments of cartilage defects/diseases.
Effects of embryonic hypoxia on lip formation
Authors: Nagaoka Ryosuke , Okuhara Shigeru , Sato Yutaka , Amagasa Teruo , Iseki Sachiko
Published: March 2012

The upper lip is formed by the fusion of facial processes, a process in which many genetic and environmental factors are involved. Embryonic hypoxia is induced by uterine anemia and the administration of vasoconstrictors during pregnancy. To define the relationship between hypoxia and upper lip formation, hypoxic conditions were created in a whole embryo culture system. Hypoxic embryos showed a high frequency of impaired fusion, reflecting failure in the growth of the lateral nasal process (LNP). In hypoxic embryos, cell proliferation activity in the LNP mesenchyme was decreased following downregulation of genes that are involved in lip formation. We also observed upregulation of vascular endothelial growth factor expression along with the induction of apoptosis in the LNP. These results suggest that embryonic hypoxia during lip formation induces apoptosis in physiologically hypoxic regions, hypoxia‐induced gene expression and downregulation of the genes involved in maxillofacial morphogenesis as immediate responses, followed by reduction of mesenchymal cell proliferation activity, resulting in insufficient growth of the facial processes. Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc.
Systematic review and meta-analysis of somatostatin analogues for the treatment of pancreatic fistula
Authors: Gans S L , van Westreenen H L , Kiewiet J J S , Rauws E A J , Gouma D J , Boermeester M A
Published: March 2012

Background

Somatostatin analogues are used for the treatment of pancreatic fistula, with the aim of achieving fistula closure or reduction of output.

Method

MEDLINE, Embase and Cochrane databases were searched systematically for relevant articles followed by hand-searching of reference lists. Data on patient recruitment, intervention and outcome were extracted and meta-analysis performed where reasonable.

Results

Seven randomized clinical trials met the inclusion criteria and included a total of 297 patients with fistulas of the gastrointestinal tract; of these, 102 patients had fistulas of pancreatic origin. Pooling of closure rates showed no significant difference between patients treated with somatostatin analogues compared with controls: odds ratio 1·52 (95 per cent confidence interval 0·88 to 2·61). Owing to inconsistent descriptions, pooling of results was not possible for other endpoints, such as time to fistula closure.

Conclusion

There is no solid evidence that somatostatin analogues result in a higher closure rate of pancreatic fistula compared with other treatments.
Endovascular embolization of a third jejunal artery aneurysm: Isolation technique using the amplatzer vascular plug 4
Authors: Rossi Umberto G. , Seitun Sara , Ferro Carlo
Published: March 2012

Aneurysm of the jejunal artery (JA) is very uncommon with few specific symptoms, but can be a lethal entity. When at risk to rupture, it must be treated expeditiously to avoid mortality. We report a case of a 76‐year‐old male patient that underwent contrast‐enhanced multi‐detector computed tomography (MDCT) which incidentally reveals a 12 mm saccular aneurysm of the third JA at the bifurcation of the first arcade. Patient underwent successful endovascular embolization using the isolation technique with the Amplatzer Vascular Plug 4. The patient's recovery was unremarkable and he was discharged on postoperative day 5. Follow‐up MDCT reveals total exclusion of the saccular aneurysm of the third jejunal artery with patency of the distal branches.© 2012 Wiley Periodicals, Inc.
Approximation of physicochemical properties of homologs using recurrent and related non‐recurrent relations
Authors: Zenkevich Igor G.
Published: March 2012

A number of updatings, both recurrent and non‐recurrent, can be suggested for recurrent relations A(n) = aA(n − 1) + b recently introduced into chemistry. Among them, the equation A(n) = a[A(n − 1) − A∞] + A∞, where A∞ denotes the limiting values of a physicochemical property at the number of carbon atoms in the molecule hypothetically tending to infinity, appears to be the most convenient and precise. The application of the new relations to evaluating the refractive indices, relative densities, and normal boiling points as examples is considered.

The problem of evaluating the limiting values of various physicochemical properties, discussed in chemistry for a long time, should be reconsidered as going beyond pure theory. The concept becomes very important for real evaluation of properties of organic compounds, A(n).

The application of recurrent relations simplifies the evaluation of the values of physicochemical properties of organic compounds. This problem seems to be the most important for low‐stability organic compounds, where only single homologs are properly characterized, whereas the experimentally determined properties for the most of them are lacking. Copyright © 2012 John Wiley & Sons, Ltd.
Limitations and caveats of magnetic cell labeling using transfection agent complexed iron oxide nanoparticles
Authors: Soenen Stefaan J. , De Smedt Stefaan C. , Braeckmans Kevin
Published: March 2012

Cell labeling with various types of nanomaterial, such as FDA‐approved iron oxide nanoparticles (IONPs) has become common practice in biomedical research. The low uptake of IONPs stimulates the use of transfection agents (TA), but the effect on stability of the IONPs and their cellular interactions has received minimal attention. In the present study, we evaluated the use of Lipofectamine as a commonly used TA and tested different ratios of TA and IONPs. While the TA–IONP complexes are stable in saline, at a high ratio of TA over IONP, substantial aggregation occurred in serum‐containing media. Even for the highest ratio, TA was unable to completely cover the IONPs, resulting in a net negative charge of all complexes. At high TA–IONP ratios, more complexes remained surface‐associated without internalization, resulting in cell death, while at lower TA–IONP ratios, complexes were more avidly taken up through fluid‐phase pinocytosis and clathrin‐mediated endocytosis. At later time points, the endocytosed complexes accumulated within the lysosomes and affected the appearance of lysosomal structures. The data indicate that TAs should be used with care as, depending on the ratio of TA and IONP, the complexes may aggregate, inducing cell death and preventing internalization. Copyright © 2012 John Wiley & Sons, Ltd.
Dual‐isotope 111In/177Lu SPECT imaging as a tool in molecular imaging tracer design
Authors: Hijnen Nicole M , de Vries Anke , Nicolay Klaas , Grüll Holger
Published: March 2012

The synthesis, design and subsequent pre‐clinical testing of new molecular imaging tracers are topic of extensive research in healthcare. Quantitative dual‐isotope SPECT imaging is proposed here as a tool in the design and validation of such tracers, as it can be used to quantify and compare the biodistribution of a specific ligand and its nonspecific control ligand, labeled with two different radionuclides, in the same animal. Since the biodistribution results are not blurred by experimental or physiological inter‐animal variations, this approach allows determination of the ligand's net targeting effect. However, dual‐isotope quantification is complicated by crosstalk between the two radionuclides used and the radionuclides should not influence the biodistribution of the tracer. Here, we developed a quantitative dual‐isotope SPECT protocol using combined 111Indium and 177Lutetium and tested this tool for a well‐known angiogenesis‐specific ligand (cRGD peptide) in comparison to a potential nonspecific control (cRAD peptide). Dual‐isotope SPECT imaging of the peptides showed a similar organ and tumor uptake to single‐isotope studies (cRGDfK–DOTA, 1.5 ± 0.8%ID cm−3; cRADfK–DOTA, 0.2 ± 0.1%ID cm−3), but with higher statistical relevance (p‐value 0.007, n = 8). This demonstrated that, for the same relevance, seven animals were required in case of a single‐isotope test design as compared with only three animals when a dual‐isotope test was used. Interchanging radionuclides did not influence the biodistribution of the peptides. Dual‐isotope SPECT after simultaneous injection of 111In and 177Lu‐labeled cRGD and cRAD was shown to be a valuable method for paired testing of the in vivo target specificity of ligands in molecular imaging tracer design. Copyright © 2012 John Wiley & Sons, Ltd.
Mn‐alginate gels as a novel system for controlled release of Mn2+ in manganese‐enhanced MRI
Authors: Mørch Ýrr A. , Sandvig Ioanna , Olsen Øystein , Donati Ivan , Thuen Marte , Skjåk‐Bræk Gudmund , Haraldseth Olav , Brekken Christian
Published: March 2012

The aim of the present study was to test alginate gels of different compositions as a system for controlled release of manganese ions (Mn2+) for application in manganese‐enhanced MRI (MEMRI), in order to circumvent the challenge of achieving optimal MRI resolution without resorting to high, potentially cytotoxic doses of Mn2+. Elemental analysis and stability studies of Mn‐alginate revealed marked differences in ion binding capacity, rendering Mn/Ba‐alginate gels with high guluronic acid content most stable. The findings were corroborated by corresponding differences in the release rate of Mn2+ from alginate beads in vitro using T1‐weighted MRI. Furthermore, intravitreal (ivit) injection of Mn‐alginate beads yielded significant enhancement of the rat retina and retinal ganglion cell (RGC) axons 24 h post‐injection. Subsequent compartmental modelling and simulation of ivit Mn2+ transport and concentration revealed that application of slow release contrast agents can achieve a significant reduction of ivit Mn2+ concentration compared with bolus injection. This is followed by a concomitant increase in the availability of ivit Mn2+ for uptake by RGC, corresponding to significantly increased time constants. Our results provide proof‐of‐concept for the applicability of Mn‐alginate gels as a system for controlled release of Mn2+ for optimized MEMRI application. Copyright © 2012 John Wiley & Sons, Ltd.