ALBERT

Description: An ultrasonic enhanced salt-containing hydrodistillation (UESHD) method for separating essential oil from lavender ( Lavandula angustifolia ) flowers was investigated using response surface methodology (RSM). The experimental data obtained from a 27-run experiment were fitted to a second-order polynomial equation. The optimal conditions were determined by the 3D response surface and the contour plots derived from the models. The efficiency of UESHD and conventional hydrodistillation (HD) was compared. The extraction yield of UESHD was two-fold higher than that of HD. In addition, GC-MS results indicated some differences in composition and content between the two essential oils from UESHD and HD. An ultrasonic enhanced salt-containing hydro-distillation (UESHD) method was developed to separate lavender essential oil. The extraction yield of the oil was optimized by statistical software, the separation conditions by the Box-Behnken design. UESHD enabled a more than two-fold yield of essential oil than conventional hydrodistillation.

Description: The 1,1,1,2-tetrafluoroethane (HFC-134a), an important alternative to CFC-12 in accordance with the Montreal Protocol on Substances that Deplete the Ozone Layer, is a high Global Warming Potential (GWP) greenhouse gas. Here we evaluate variations in global and regional HFC-134a emissions and emission trends, from 1995 to 2010, at a relatively high spatial and temporal (3.75° in longitude × 2.5° in latitude and 8-day) resolution, using surface HFC-134a measurements. Our results show a progressive increase of global HFC-134a emissions from 19 ± 2 Gg/yr in 1995 to 167 ± 5 Gg/yr in 2010, with both a slowdown in developed countries and a 20 %/yr increase in China since 2005. A seasonal cycle is also seen since 2002, which becomes enhanced over time, with larger values during the boreal summer.

Description: We discuss results of a superposed epoch analysis of dipolarization fronts, rapid (δt 〈 30 s), high-amplitude (δBz 〉 10 nT) increases in the northward magnetic field component, observed during six Time History of Events and Macroscale Interactions during Substorms (THEMIS) conjunction events. All six fronts propagated earthward; time delays at multiple probes were used to determine their propagation velocity. We define typical magnetic and electric field and plasma parameter variations during dipolarization front crossings and estimate their characteristic gradient scales. The study reveals (1) a rapid 50% decrease in plasma density and ion pressure, (2) a factor of 2–3 increase in high-energy (30–200 keV) electron flux and electron temperature, and (3) transient enhancements of ∼5 mV/m in duskward and earthward electric field components. Gradient scales of magnetic field, plasma density, and particle flux were found to be comparable to the ion thermal gyroradius. Current densities associated with the Bz increase are, on average, 20 nA/m2, 5–7 times larger than the current density in the cross-tail current sheet. Because j · E 〉 0, the dipolarization fronts are kinetic-scale dissipative regions with Joule heating rates of 10% of the total bursty bulk flow energy.

Description: An online coupled regional climate-chemistry model called RegCCMS is used to investigate the interactions between anthropogenic aerosols and the East Asian summer monsoon (EASM) over East Asia. The simulation results show that the mean aerosol loading and optical depth over the region are 17.87 mg/m 2 and 0.25, respectively. Sulfate and black carbon (BC) account for approximately 61.2 % and 7.8 % of the total aerosols, respectively. The regional mean radiative forcing (RF) is approximately −3.64, −0.55 and +0.88 W/m 2 at the TOA for the total aerosol effect, the total aerosol direct effect, and the BC direct effect, respectively. The surface direct RF of BC accounts for approximately 31 % of the total RF of all aerosols. Because of the total aerosol effect, both the energy budgets and air temperature are considerably reduced in the region with high aerosol loadings, leading to decreases in the land-ocean air temperature gradient in summer. The total column absorbed solar radiation (TCASR) and surface air temperature (SAT) decrease by 8.4 W/m 2 and 0.31 K, respectively. This cooling effect weakens horizontal and vertical atmospheric circulations over East Asia. The wind speed at 850 hPa decreases by 0.18 m/s, and the precipitation decreases by 0.29 mm/d. The small responses of solar radiation, air temperature and atmospheric circulations to the BC warming effect are opposite to those of the total aerosol effect. The BC-induced enhancement of atmospheric circulation can increase local floods in South China, while droughts in North China may worsen in response to the BC semi-direct effect. The total aerosol effect is much more significant than the BC direct effect. The East Asian summer monsoon becomes weaker due to the total aerosol effect. However, this weakness could be partially offset by the BC warming effect. Sensitivity analyses further indicate that the influence of aerosols on the EASM might be more substantial in years when the southerlies or southwesterlies at 850 hPa are weak compared with years when the winds are strong. Changes in the EASM can induce variations in the distribution and magnitude of aerosols. Aerosols in the lower troposphere over the region can increase by 3.07 and 1.04 µg/m 3 due to the total aerosol effect and the BC warming effect, respectively.

Description: [1]  On 12 October 2011 the two ARTEMIS probes, in lunar orbit ~9 R E north of the neutral sheet, sequentially observed a tailward-moving, expanding plasmoid. Their observations reveal a multi-layered plasma sheet composed of tailward-flowing hot plasma within the plasmoid surrounded by earthward-flowing, less energetic plasma. Prior observations of similar earthward flows ahead of or behind plasmoids have been interpreted as earthward outflow from a continuously active distant-tail neutral line (DNL) opposite an approaching plasmoid. No evidence of active DNL reconnection was observed by the probes, however, as they traversed the plasmoid's leading and trailing edges, penetrating to above its core. We suggest an alternate interpretation: compression of ambient plasma by the tailward-moving plasmoid proper propels the plasma lobeward and earthward, i.e., above and below the plasmoid proper. Using the propagation velocity obtained from timing analysis, we estimate the average plasmoid proper size in its propagation direction to be 9 R E and its expansion rate to be ~7 R E /min at the observation locations. This observation of plasmoid expansion made at the plasmoid boundary is interpreted as plasmoid growth in both the X GSM and the Z GSM directions due to near-Earth-neutral-line (NENL) reconnection on closed plasma sheet field lines. The velocity inside the plasmoid proper was found to be non-uniform; the core likely moves as fast as 500 km/s, yet the outer layers move more slowly (and reverse direction). The absence of lobe reconnection, in particular on the earthward side, suggests that plasmoid formation and expulsion both result from closed plasma sheet field-line reconnection.

Description: Calculating the cyclone pressure drop, Δ p c , at a high inlet solid concentration, C s,in , is important for the design and operation of circulating fluidized bed boilers. Three typical Δ p c models that consider the effect of C s,in were selected and assessed. Compared with experimental results, it was found that only the model developed by Chen and Shi can correctly predict the variation trend of Δ p c with C s,in at high values of C s,in , but the predicted values are much greater than the measured values. It is suggested that the dissipative loss of swirling dynamic pressure should be excluded from the total dissipative loss of gas dynamic energy when the pressure tap is closely installed to the outlet and the swirl exponent could be assumed to be null for high C s,in conditions. A set of equations modified from the original C-S model is given. Compared with the experimental data obtained from the present study and some data from literature, the improved C-S model can predict Δ p c at high C s,in well. In addition, it was found that the correction of pressure tap position is more obvious than the correction of swirl exponent. Validation of the model to calculate cyclone pressure drop under a condition of high inlet solid concentration was conducted. Three models were selected and assessed. It was found that only the model of Chen and Shi could correctly predict the variation trend, however, with a remarkable overprediction. Suggestions are given for improvement under high inlet solid concentration.

Description: We study the force balance surrounding the arrival of dipolarization fronts within bursty bulk flows near substorm onset by comparing curvature force densities and total pressure gradient force densities ahead of and behind the fronts using three inner Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes separated along the Xgsm and the Zgsm directions. Curvature force density estimates are obtained by field line modeling utilizing the Z separation of the probes and the self-similar structure of the front over short distances. A dipolarization front is a boundary between the energetic particle population in the flow burst magnetic flux bundle and the ambient colder plasma ahead of the front. Force density imbalance is found ahead of and behind the front. Ahead of the front, decrease in tailward pressure gradient force results in earthward flow acceleration. Behind the dipolarization front, even though the radius of field line curvature increases, the curvature force density increases even further, mostly due to the increase in the magnetic field magnitude. Thus, plasma acceleration at and immediately after the dipolarization front can be explained by the resultant increased curvature force density.

Description: Our understanding of the global budget of atmospheric hydrogen (H2) contains large uncertainties. An atmospheric Bayesian inversion of H2 sources and sinks is presented for the period 1991–2004, based on a two networks of flask measurement stations. The types of fluxes and the spatial scales potentially resolvable by the inversion are first estimated from an analysis of the correlations of errors between the different processes and regions emitting or absorbing H2. Then, the estimated budget of H2 and its uncertainties is presented and discussed, for five groups of fluxes and three groups of large regions, in terms of mean fluxes, seasonal and interannual variations, and long-term trends. One main focus of the study is the improvement of the estimate of H2 soil uptake, which is the largest sink of H2. Various sensitivity tests are performed defining an ensemble of more than 20 inversions. We show that inferring a robust estimate of the H2 soil uptake requires to prescribe the prior magnitude of some other sources and sinks with a small uncertainty. Doing so an estimate of the H2 soil uptake of −62 ± 3 Tg y−1 is inferred for the period 1991–2004 (the uncertainty is the residual error after inversion). The inferred soil H2 sink presents a negative long-term trend that is qualitatively consistent with a bottom-up process-based model.

Description: [1]  Although distant-tail plasmoids are perceived to extend across most of the magnetotail (~40 R E ), recent studies in the near-Earth region (X 〉 -30 R E ) have revealed that near-Earth reconnection (where plasmoids originate) is likely localized and takes place preferentially on the dusk side. This discrepancy in plasmoid azimuthal extent suggests that a plasmoid may grow as it moves from near Earth to the distant tail. Comprehensive multi-point, mid-tail plasmoid observations can be used to test this hypothesis. Between October 2010 and July 2011 the ARTEMIS spacecraft (P1 and P2) at the Earth-Moon Lagrange points (mid-tail, X ~ -45 to -65R E ) provided simultaneous two-point observations across the magnetotail for 4 days every lunar month, with a large range of spacecraft separations (0.1 to 25R E ). We find that plasmoids near lunar orbit, like other near-Earth reconnection-related phenomena, occur preferentially on the dusk side of the magnetotail. Two-point ARTEMIS observations reveal that the typical plasmoid azimuthal size in our dataset is about 5 to 10 R E , much smaller than expected from previous distant-tail observations. Plasmoids with an azimuthal size greater than 9 R E also exist, but only at geomagnetic activity levels higher (AE peak  〉 400nT) than typically found in our dataset (median AE peak  ~ 230 nT for our plasmoid dataset, median AE ~ 100 nT during the entire period of ARTEMIS magnetotail observations). We conclude that plasmoids during small to moderate substorms (AE peak  〈 400nT) do not grow beyond ~10 R E until they have moved tailward of ~ -45 to -65 R E . Plasmoids during large substorms (AE peak  〉 400nT), however, either grow beyond ~10 R E before they reach lunar distance or initially extend across a large portion of the magnetotail.

Description: Polyelectrolyte-enhanced ultrafiltration was investigated for rhenium(VII) recovery from aqueous solutions by using polyquaternium-6 (PQ6) as a complexing agent. The effects of the operating parameters on the permeate flux ( J ) and the rhenium rejection coefficient ( R ) were studied. In the process of concentration, J declines slowly and R is about 1. The concentrated solution was used for the decomplexation. It takes 10 min to achieve the decomplexation equilibrium at a chloride ion concentration of 100 mg L –1 . The decomplexation percentage reaches 45.6 %. In the diafiltration process, rhenium is extracted effectively, and the purification of the regenerated PQ6 is satisfactory. The regenerated PQ6 was used to bind rhenium(VII). The binding capacity of the regenerated PQ6 is close to that of fresh PQ6. Polyelectrolyte-enhanced ultrafiltration was originally used to achieve the recovery of rhenium from aqueous solutions with the help of polyquaternium-6. The effects of various operating parameters on the permeate flux and the rhenium rejection coefficient were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of the regenerated polymer was carried out.