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This paper investigates the attenuation and directional spreading of large amplitude waves traveling through pancake ice. Directional spectral density is analyzed from in situ wave buoy data collected during a 3‐day storm event in October 2015 in the Beaufort Sea. Two proxy metrics for wave amplitude obtained from energy density spectra, namely, spectral amplitude and significant wave height, are used to track the waves as they propagate along transects through the array of buoys in the predominantly pancake ice field. Two types of wave buoys are used in the analysis and compared, exhibiting significant differences in the wave energy density and directionality estimates. Although exponential decay is observed predominantly, one of the two buoy types indicates a potential positive correlation between wave energy density and the occurrence of linear wave decay, as opposed to exponential decay, in accord with recent observations in the Antarctic marginal ice zone. Factors affecting the validity of this observation are discussed. An empirical power law with exponent 2.2 is also found to hold between the exponential attenuation coefficient and wave frequency. The directional content of the wave spectrum appears to decrease consistently along the wave transects, confirming that wave energy is being dissipated by the pancake ice as opposed to being scattered by ice cakes. Ocean waves in the Arctic Ocean are becoming increasingly energetic as a result of the retreating sea ice caused by climate change. Very little is known of the physical processes governing the interactions between ocean waves in sea ice, however, mainly due to the lack of field data measuring the underlying physics. Here we analyze a data set acquired by a collection of wave measuring devices in the Beaufort Sea over a 3‐day period in October 2015, as part of a large experimental program funded by the the U.S. Office of Naval Research. This period coincided with a storm event with waves up to 5 m high. We analyzed the attenuation of such large waves as well as smaller amplitude waves due to the sea ice cover, which mainly consisted of pancake ice. We found that large waves as well as long waves attenuate much more slowly than small waves and short waves. In particular, the more energetic the waves the more likely they are to decay linearly, as opposed to exponentially, with distance, which is in agreement with a similar observation made in the Southern Ocean in 2012. Possible processes causing this effect are discussed in the paper. In situ data of a large wave event propagating through pancake ice are analyzed for attenuation and directional spreadingWave decay through O(10 km)‐long transects is predominantly exponential with attenuation rate related to frequency according to a power lawObserved directional narrowing of the wave spectrum is caused by wave dissipation from pancake ice

This study presents Arctic sea ice drift fields measured by shipboard marine X‐band radar (MR). The measurements are based on the maximum cross correlation between two sequential MR backscatter images separated ∼1 min in time, a method that is commonly used to estimate sea ice drift from satellite products. The advantage of MR is that images in close temporal proximity are readily available. A typical MR antenna rotation period is ∼1–2 s, whereas satellite revisit times can be on the order of days. The technique is applied to ∼4 weeks of measurements taken from R/V Sikuliaqin the Beaufort Sea in the fall of 2015. The resulting sea ice velocity fields have ∼500 m and up to ∼5 min resolution, covering a maximum range of ∼4 km. The MR velocity fields are validated using the GPS‐tracked motion of Surface Wave Instrument Float with Tracking (SWIFT) drifters, wave buoys, and R/V Sikuliaqduring ice stations. The comparison between MR and reference sea ice drift measurements yields root‐mean‐square errors from 0.8 to 5.6 cm s−1. The MR sea ice velocity fields near the ice edge reveal strong horizontal gradients and peak speeds > 1 m s−1. The observed submesoscale sea ice drift processes include an eddy with ∼6 km diameter and vorticities <–2 (normalized by the Coriolis frequency) as well as converging and diverging flow with normalized divergences <–2 and >1, respectively. The sea ice drift speed correlates only weakly with the wind speed (r2= 0.34), which presents a challenge to conventional wisdom. Marine X‐band radar data are processed to yield sub‐km scale sea ice velocity fieldsRoot‐mean‐square errors between radar and reference sea ice drift measurements are ∼1–6 cm s^–1Contrary to conventional wisdom, sea ice drift and wind speed are only weakly correlated (r^2 = 0.34) near the ice edge

Analysis of field measurements of ocean surface wave activity in the marginal ice zone, from campaigns in the Arctic and Antarctic and over a range of different ice conditions, shows the wave attenuation rate with respect to distance has a power law dependence on the frequency with order between two and four. With this backdrop, the attenuation‐frequency power law dependencies given by three dispersion relation models are obtained under the assumptions of weak attenuation, negligible deviation of the wave number from the open water wave number, and thin ice. It is found that two of the models (both implemented in WAVEWATCH III®), predict attenuation rates that are far more sensitive to frequency than indicated by the measurements. An alternative method is proposed to derive dispersion relation models, based on energy loss mechanisms. The method is used to generate example models that predict power law dependencies that are comparable with the field measurements. An analysis of the measured wave attenuation shows a power law dependence on frequency with an exponent between two and fourWe show how to connect various dispersion equation models with a given power law, under the assumption of weak attenuation by a thin layerWe show how energy loss mechanisms are connected to dispersion equations and power laws

Quantitative structure activity relationship (QSAR) studies of selective COX-2 inhibitors of commercial interest (drugs in market and on clinical trials) were performed. The COX-2 inhibitory activity (pIC50-logIC50) of these twelve compounds was correlated with nineteen descriptors including steric, electronic and constitutional parameters. pIC50 activity showed high positive correlation with both volume and HOMO (Highest occupied molecular orbital). A Biparametric model was developed that included both these descriptors. The predictive capability (q2 0.66) of this equation was satisfactory. So it can be used to design newer templates or modify existing templates. Volume is an important parameter for the selective COX-2 inhibitory activity, because the secondary pocket in the active site of this enzyme is bigger than the active site of COX-1 enzyme (by 17). HOMO is a measure of the nucleophilicity of the molecule and a molecule with high HOMO energy is ready to donate its electrons and thus is more reactive than molecule with low values. Binding studies were performed between the COX-2 enzyme and these molecules. The inhibitory activity increased with decrease in binding energy (or interaction energy) between the compounds with the COX-2 enzyme (with a correlation coefficient -0.65). Calculated Log BBB (Blood Brain barrier), Log P (octonol water partition) and HBD (hydrogen bond donor) values were in the acceptable range (i.e., BBB -1 to 0.3; LogP 0 to 5; HBD < 5).

The winter advance of the sea ice edge in the Bellingshausen Sea is frequently interrupted by periods of rapid retreat lasting a few days. The frequency and duration of such events strongly controls the location of the late winter sea ice edge in this sector of the Antarctic. We examine the dynamics and thermodynamics of a retreat event that occurred in May 2001 using data from a drifting buoy array together with diagnostics from a kinematic/thermodynamic ice growth model and a high‐resolution (11 km) regional coupled ocean‐ice model. During the retreat event, the ice edge retreated by 250 km over 13 days in response to strong and persistent northerly winds associated with a quasi‐stationary low‐pressure system. Ice motion in the outer part of the pack was convergent and correlated strongly with local wind forcing. By contrast, in the region closer to the coast, ice motion was less well correlated with wind forcing. Model diagnostics indicate that ice thickening resulting from convergence in the outer pack was largely balanced by basal melting. In the outer pack, ice was in a state close to free drift while, closer to the coast, internal ice stresses became significant. The ocean‐ice model simulated the characteristics of the retreat event realistically, giving us confidence in the ability of such models to reproduce ice conditions in this sector.

Cycloaddition of an azomethine ylide, generated in situ from isatins (IV) and sarcosine (V), with the dipolarophile (III) yields the dispiropyrrolidines (VI) in good yields.