Dry Column Research Articles

Using a case‐study approach to improve the Madden–Julian oscillation in the Hadley Centre model

In its default configuration, the Hadley Centre climate model (GA2.0) simulates roughly one‐half the observed level of Madden–Julian oscillation activity, with MJO events often lasting fewer than 7 days.We use initialized, climate‐resolution hindcasts to examine the sensitivity of the GA2.0 MJO to a range of changes in subgrid parametrizations and model configurations. All 22 changes are tested for two cases during the Years of Tropical Convection. Improved skill comes only from (i) disabling vertical momentum transport by convection and (ii) increasing mixing entrainment and detrainment for deep and mid‐level convection. These changes are subsequently tested in a further 14 hindcast cases; only (ii) consistently improves MJO skill, from 12 to 22 days. In a 20 year integration, (ii) produces near‐observed levels of MJO activity but propagation through the Maritime Continent remains weak.With default settings, GA2.0 produces precipitation too readily, even in anomalously dry columns. Implementing (ii) decreases the efficiency of convection, permitting instability to build during the suppressed MJO phase and producing a more favourable environment for the active phase. The distribution of daily rain rates is more consistent with satellite data; default entrainment produces 6–12 mm day−1 too frequently. These results are consistent with recent studies showing that greater sensitivity of convection to moisture improves the representation of the MJO.

Multiple pixel-scale soil water retention curves quantified by neutron radiography

The soil water retention function is needed for modeling multiphase flow in porous media. Traditional techniques for measuring the soil water retention function, such as the hanging water column or pressure cell methods, yield average water retention data which have to be modeled using inverse procedures to extract relevant point parameters. In this study, we have developed a technique for directly measuring multiple point (pixel-scale) water retention curves for a repacked sand material using 2-D neutron radiography. Neutron radiographic images were obtained under quasi-equilibrium conditions at nine imposed basal matric potentials during monotonic drying of Flint sand at the High Flux Isotope Reactor (HFIR) Cold Guide (CG) 1D beamline at Oak Ridge National Laboratory. All of the images were normalized with respect to an image of the oven dry sand column. Volumetric water contents were computed on a pixel by pixel basis using an empirical calibration equation after taking into account beam hardening and geometric corrections. Corresponding matric potentials were calculated from the imposed basal matric potential and pixel elevations. Volumetric water content and matric potential data pairs corresponding to 120 selected pixels were used to construct 120 point water retention curves. Each curve was fitted to the Brooks and Corey equation using segmented non-linear regression in SAS. A 98.5% convergence rate was achieved resulting in 115 estimates of the four Brooks and Corey parameters. A single Brooks and Corey point water retention function was constructed for Flint sand using the median values of these parameter estimates. This curve corresponded closely with the point Brooks and Corey function inversely extracted from the average water retention data using TrueCell. Forward numerical simulations performed using HYDRUS 1-D showed that the cumulative outflows predicted using the point Brooks and Corey functions from both the direct (neutron radiography) and inverse (TrueCell) methods were in good agreement with independent measurements of cumulative outflow determined with a transducer. Our results indicate that neutron radiography can be used to quantify the point water retention curve of homogeneous mineral particles. Further research will be needed to extend this approach to more heterogeneous porous media.

Application of thin layer and column chromatography in monitoring the synthesis of α- tocopheryl-lysine ester

Vitamin E comprises of two families of compounds, tocopherols and tocotrienols. It is well known for its antioxidant activity, but recently special attention is paid to the use of vitamin E and its derivatives in the prevention and the treatment of cancer. Various derivatives of vitamin E are synthesized, which exhibit antiproliferative activity. It has been shown that the α-tocopherol ester with the amino acid lysine exhibits improved antiproliferative activity on MCF-7 breast cancer cell line as compared to commercially available preparations. The first stage was the synthesis of α-tocopherol ester with di-Cbz-lysine. Synthesis of ester was monitored by thin layer chromatography (mobile phase: n-hexane-ethyl acetate 3: 1,2 v/v) and the purification of product was done by dry flash column chromatography and by preparative plate chromatography (mobile phase: n-hexane-ethyl acetate 3: 1,2 v/v). In the second stage, Cbz protecting groups were removed by catalytic hydrogenation. The final product α- tocopheryl-lysine ester was detected by TLC (mobile phase: dichloromethane-methanolammonia 9 : 0,9 : 0,1 v/v).

Ossified ligamentum longitudinale anterius in adult human dry vertebrae.

The ligamentum longitudinale anterius is a broad and strong band of fibrous tissue that runs along the anterior surfaces of the bodies of the vertebrae. The study was undertaken to evaluate the incidence of ossified ligamentum longitudinale anterius in adult dry human vertebra. This study was carried out on 95 sets of dry human vertebral columns irrespective of age and sex at Mayo Institute of Medical Sciences- Barabanki,-UP, Melaka Manipal Medical College-Manipal University and Department of Anatomy, KMCT Medical College, Manassery- Calicut, India. All the sets of vertebral columns were macroscopically inspected for the ossified ligamentum longitudinale anterius. It was observed that out of 95 sets of vertebral columns, 27 (28.42%) vertebral columns showed ossification. Out of 27 vertebral columns, 17 (17.89%) vertebral columns showed segmental type of ossification, 2 (2.11%) vertebral columns showed continuous type of ossification and 8 (8.42%) vertebral columns showed mixed type of ossification at different vertebral level. Such type of ossification will affect the biomechanics of the spine and may result in stiff neck, low back pain, dysphagia, odynophagia, compression of the brachial plexus, aphonia, immobility or mucosal thickening of larynx. Hence, knowledge of such abnormalities should be kept in mind to minimise serious complications in any surgical intervention or investigative procedures in the region.

Probabilistic design of dry deep mixing using an observational approach

The evaluation of material parameters for design should consider the spatial variability of measured parameters, the extent and type of tests, and the type and size of the current mechanical system. This is stated in Eurocode 7; however, there is very little guidance as to how this is to be done in practice. The strength and deformation properties of dry deep mixing columns are subject to high variability, and it is difficult to estimate these parameters in advance. Owing to this high variability, probabilistic analyses are considered useful for the design and quality assessment decision procedure. This paper presents a procedure, based on probabilistic analysis, which is a combination of design by calculation and the observational method. The procedure renders the possibility to update acceptance criteria based on measurements during construction, and the methodology rewards the development of the mixing process and increased testing.

Mobilization and transport of organic compounds from reservoir rock and caprock in geological carbon sequestration sites

Supercritical CO2 (scCO2) is a good solvent for organic compounds such as benzene, toluene, ethyl-benzene, and xylene (BTEX), phenols, and polycyclic aromatic hydrocarbons (PAHs). Monitoring results from geological carbon sequestration (GCS) field tests have shown that organic compounds are mobilized following CO2 injection. Such results have raised concerns regarding the potential for groundwater contamination by toxic organic compounds mobilized during GCS. Knowledge of the mobilization mechanism of organic compounds and their transport and fate in the subsurface is essential for assessing risks associated with GCS. Extraction tests using scCO2 and methylene chloride (CH2Cl2) were conducted to study the mobilization of volatile organic compounds (VOCs, including BTEX), the PAH naphthalene, and n-alkanes by scCO2 from representative reservoir rock and caprock obtained from depleted oil reservoirs and coal from an enhanced coal-bed methane recovery site. Results showed that the extent of mobilization for the organic compounds was a function of the source rock. In fate and transport sand column experiments, moisture content was found to have an important influence on the transport of the organic compounds. In dry sand columns the majority of the compounds were retained in the column except benzene and toluene. In wet sand columns the mobility of the BTEX was much higher than that of naphthalene. Based upon the results determined for the reservoir rock, caprock, and coal samples studied here, the risk to aquifers from contamination by organic compounds appears to be relatively low; however, further work is necessary to fully evaluate the risks.

Antibacterial Activity of Methanolic Extracts, Decoction and Isolated Triterpene Products from Different Parts of Birch, Betula pendula, Roth

Five methanolic extracts obtained from different parts of birch, Betula pendula, Roth. (external and internal bark, flowers, leaves and buds), were evaluated for their antibacterial activity in this study. Triterpene compounds, betulin, betulinic acid, oleanolic acid and lupeol, were isolated from the external parts of birch bark using the method of dry column chromatography (DCC) as well as preparative thin layer chromatography (TLC). These compounds were also investigated for their antibacterial activity. Taking into account that decoction is the most commonly used pharmaceutical form of herbal drug, decoctions made from external bark, leaf, flower and bud were investigated for their antibacterial activity. Antibacterial screening, against selected Gram-positive bacteria, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538P and Gram-negative bacteria, Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027 was carried out. The methods of diffusion and dilution were used for this investigation according to European Pharmacopoea, 1996. The most prominent antibacterial activity showed oleanolic acid against bacterial species Staphylococcus aureus, expressed as minimal inhibitory concentration (MIC): 1.25% and Bacillus subtilis MIC: 0.625%. Escherichia coli showed resistance on all investigated samples.

Quantification of methane emission rates from coal mine ventilation shafts using airborne remote sensing data

Abstract. The quantification of emissions of the greenhouse gas methane is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. Our current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as landfills or fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of the greenhouse gases carbon dioxide and methane is the optical remote sensing instrument MAMAP (Methane airborne MAPper), operated from aircraft. After a recent instrument modification, retrievals of the column-averaged dry air mole fractions for methane XCH4 (or for carbon dioxide XCO2) derived from MAMAP data have a precision of about 0.4% or better and thus can be used to infer emission rate estimates using an optimal estimation inverse Gaussian plume model or a simple integral approach. CH4 emissions from two coal mine ventilation shafts in western Germany surveyed during the AIRMETH 2011 measurement campaign are used as examples to demonstrate and assess the value of MAMAP data for quantifying CH4 from point sources. While the knowledge of the wind is an important input parameter in the retrieval of emissions from point sources and is generally extracted from models, additional information from a turbulence probe operated on-board the same aircraft was utilised to enhance the quality of the emission estimates. Although flight patterns were optimised for remote sensing measurements, data from an in situ analyser for CH4 were found to be in good agreement with retrieved dry columns of CH4 from MAMAP and could be used to investigate and refine underlying assumptions for the inversion procedures. With respect to the total emissions of the mine at the time of the overflight, the inferred emission rate of 50.4 kt CH4 yr−1 has a difference of less than 1% compared to officially reported values by the mine operators, while the uncertainty, which reflects variability of the sources and conditions as well as random and systematic errors, is about ±13.5%.

Study on remote sensing of carbon dioxide column concentration in the atmosphere by direct-sun infrared absorption spectroscopy

The concentration of carbon dioxide in the atmosphere has been increasing continuously. This is a big concern with respect to the environment and climate changes and so on. A kind of ground-based low-resolution remote sensing system and a real-time spectral inversion method are presented for the real-time remote sensing column concentration of carbon dioxide. Based on continuous observation of this system in Hefei, the total atmospheric transmittance is real-timely obtained from the solar absorption spectrum. The column concentrations of carbon dioxide and oxygen are inversed from total atmospheric transmittance by line-by-line nonlinear least squares spectral inversion algorithm. The column concentration of oxygen is used as internal standard function to obtain the column average volume mixing ratio of carbon dioxide in total dry air column, and the precision is better than 3%.The average volume mixing ratio of carbon dioxide in dry-air column, from 12: 00 to 15:00 on September 25, 2012, is compared with observation results by Japanese greenhouse-gases satellite over the site in this period, showing that the relative deviation is less than 1%. Obviously, it is an effective way to measure greenhouse gases concentration with high precision and accuracy.

State of the art in strength development of soil–cement columns

The in situ deep mixing technique has been established as an effective means to effect columnar inclusions into soft clay to enhance bearing capacity and reduce settlement. In this paper, the factors governing strength development in soil–cement columns are presented. The clay-water/cement ratio, wc/C is the prime parameter for consideration in a laboratory mix design. The generalised strength equation is developed for various curing times and combinations of clay-water content, cement content and ash content. It helps minimise the number of trials required to arrive at the quantity of cement to be admixed. For low-strength soil–cement columns (laboratory 28 day strength less than 1500 kPa), the field strength, quf, made up from both dry and wet mixing methods is higher than 0·6 times the laboratory strength, qul. The quf/qul ratios for the wet mixing columns are generally higher than those for the dry mixing columns. This higher strength ratio is due to the dissipation of the excess water in the column (consolidation) caused by the field stress. A fast installation rate has been shown to provide high quality for low-strength columns.

Estimation of Hydrodynamic Parameters in Spinning Cone Column Using Computational Fluid Dynamics

Spinning cone column (SCC) is a gas–liquid contacting device which is utilized in the food processing industries, and is useful in areas that require tolerance to the presence of solids and low-thermal impact of processing. The geometrical complexity, rotational parts, and different flow regimes inside SCC columns make modeling and simulation of these columns complicated, for which computational fluid dynamics (CFD) is used here. This work contains presenting the results of hydrodynamic parameters, including dry and two-phase pressure drops and flooding predictions in a pilot scale SCC. For expressing turbulence in gas and liquid phases, the standard $${k{-}\varepsilon }$$ model and the zero equation model were utilized, respectively. For predicting flooding points, the dimensionless number Fr LG is used, when it is equal to 1 or more, flooding is occurred in the column. CFD results shows that increasing the rotating speed and also air flow rate at specific liquid flows would cause the pressure drop to increase at both states of dry and two-phase columns, which corresponds to the experimental data. This simulation results can be utilized for prediction of the industrial applications of SCC, including estimation of the pressure drop parameters, flooding, column efficiency and also designing the diameters of SCC column.

Rapid, clean and efficient one-pot synthesis of thiopyrano[2,3-b]quinolines via domino Michael addition/cyclization reactions

Rapid and efficient one-pot synthesis of thiopyrano[2,3-b]quinolines is described from the reaction of 3-formyl-quinoline-2-thiones with acrylonitrile using economical organic base Et3N at room temperature. The reaction proceeded smoothly via domino Michael addition/cyclization reactions and did not require dry solvent, inert atmosphere and column chromatography purifications.

Evaluation of Pakgen 99mTc generators loaded with indigenous fission 99Mo

Abstract Fission produced 99Mo/99mTc generators, called Pakgen, have been manufactured at the PINSTECH generator production facility since 2000 for nuclear medicine applications in Pakistan. These generators were loaded with fission 99Mo imported from NTP South Africa. Recently production of fission 99Mo has begun in the Molybdenum-99 Production Facility at PINSTECH. Prior to use in the clinic, eight sets of generators were produced, 23 GBq and 74 GBq at time of calibration, and they were subjected to various quality control procedures recommended in the pharmacopoeia to assess their performance. The elution profile, volume, activity, pH, radionuclidic, chemical, radiochemical and biological purity, and expiry time of the eluates were examined. Labeling efficiency tests were also carried out with a number of the more widely used in vivo radiopharmaceutical kits like DTPA, MDP and MIBI. Performance of 99mTc generators loaded with locally produced and imported fission 99Mo was comparable, and the users of Pakgen generators were fully satisfied. The effect of a wet vs. a dry column on 99mTc yields of generators loaded with low and high activity was also studied for the first time.

Total Carbon Column Observing Network (TCCON) activities at Izaña, Tenerife

The Total Carbon Column Observing Network (TCCON) is a global network of ground-based Fourier Transform InfraRed spectrometers (FTIR). We present the first results obtained in the framework of TCCON at the Izana Station. We find a strong correlation between the retrieved O2 column amounts and the dry pressure column obtained from a high precision barometer. This documents the good quality of the Izana TCCON measurements. We show the retrieved annual cycles (from 05 May, 2009 to 06 June, 2010) of CO2 and we compare to simultaneously performed in-situ measurements.

Energy Dissipation in Nearly Saturated Poroviscoelastic Soil Columns during Quasi-Static Compressional Excitations

AbstractThis paper presents a theoretical investigation on the energy dissipation in a nearly saturated poroviscoelastic soil column under quasi-static compressional excitations. Different components of the energy dissipation are evaluated and compared. The magnitude of fluid- induced energy dissipation is primarily a function of a normalized excitation frequency Ω. For small values of Ω, a drained soil column is fully relaxed and essentially behaves as a dry column with negligible pore pressure. For such a soil column, fluid-induced energy dissipation is negligible, and the total damping ratio of the column is essentially the same as that of the solid skeleton. For very high values of Ω, a drained soil column is fully loaded and the excitation-generated pore pressure decreases as the fluid becomes more compressible. For such a soil column, the fluid pressure gradient only exists in a thin boundary layer near the drainage boundary, where drainage occurs and fluid induces energy dissipation, whereas the re...

Antimicrobial Activity of Essential Oils againstStreptococcus mutansand their Antiproliferative Effects

This study aimed to evaluate the activity of essential oils (EOs) against Streptococcus mutans biofilm by chemically characterizing their fractions responsible for biological and antiproliferative activity. Twenty EO were obtained by hydrodistillation and submitted to the antimicrobial assay (minimum inhibitory (MIC) and bactericidal (MBC) concentrations) against S. mutans UA159. Thin-layer chromatography and gas chromatography/mass spectrometry were used for phytochemical analyses. EOs were selected according to predetermined criteria and fractionated using dry column; the resulting fractions were assessed by MIC and MBC, selected as active fractions, and evaluated against S. mutans biofilm. Biofilms formed were examined using scanning electron microscopy. Selected EOs and their selected active fractions were evaluated for their antiproliferative activity against keratinocytes and seven human tumor cell lines. MIC and MBC values obtained for EO and their active fractions showed strong antimicrobial activity. Chemical analyses mainly showed the presence of terpenes. The selected active fractions inhibited S. mutans biofilm formation (P < 0.05) did not affect glycolytic pH drop and were inactive against keratinocytes, normal cell line. In conclusion, EO showed activity at low concentrations, and their selected active fractions were also effective against biofilm formed by S. mutans and human tumor cell lines.

The Australian methane budget: Interpreting surface and train-borne measurements using a chemistry transport model

[1] We investigate the Australian methane budget from 2005–2008 using the GEOS-Chem 3D chemistry transport model, focusing on the relative contribution of emissions from different sectors and the influence of long-range transport. To evaluate the model, we use in situ surface measurements of methane, methane dry air column average (XCH4) from ground-based Fourier transform spectrometers (FTSs), and train-borne surface concentration measurements from an in situ FTS along the north–south continental transect. We use gravity anomaly data from Gravity Recovery and Climate Experiment to describe the spatial and temporal distribution of wetland emissions and scale it to a prior emission estimate, which better describes observed atmospheric methane variability at tropical latitudes. The clean air sites of Cape Ferguson and Cape Grim are the least affected by local emissions, while Wollongong, located in the populated southeast with regional coal mining, samples the most locally polluted air masses (2.5% of the total air mass versus <1% at other sites). Averaged annually, the largest single source above background of methane at Darwin is long-range transport, mainly from Southeast Asia, accounting for ∼25% of the change in surface concentration above background. At Cape Ferguson and Cape Grim, emissions from ruminant animals are the largest source of methane above background, at approximately 20% and 30%, respectively, of the surface concentration. At Wollongong, emissions from coal mining are the largest source above background representing 60% of the surface concentration. The train data provide an effective way of observing transitions between urban, desert, and tropical landscapes.

MAMAP – a new spectrometer system for column-averaged methane and carbon dioxide observations from aircraft: retrieval algorithm and first inversions for point source emission rates

Abstract. MAMAP is an airborne passive remote sensing instrument designed to measure the dry columns of methane (CH4) and carbon dioxide (CO2). The MAMAP instrument comprises two optical grating spectrometers: the first observing in the short wave infrared band (SWIR) at 1590–1690 nm to measure CO2 and CH4 absorptions, and the second in the near infrared (NIR) at 757–768 nm to measure O2 absorptions for reference/normalisation purposes. MAMAP can be operated in both nadir and zenith geometry during the flight. Mounted on an aeroplane, MAMAP surveys areas on regional to local scales with a ground pixel resolution of approximately 29 m × 33 m for a typical aircraft altitude of 1250 m and a velocity of 200 km h−1. The retrieval precision of the measured column relative to background is typically &amp;amp;lesssim;1% (1σ). MAMAP measurements are valuable to close the gap between satellite data, having global coverage but with a rather coarse resolution, on the one hand, and highly accurate in situ measurements with sparse coverage on the other hand. In July 2007, test flights were performed over two coal-fired power plants operated by Vattenfall Europe Generation AG: Jänschwalde (27.4 Mt CO2 yr−1) and Schwarze Pumpe (11.9 Mt CO2 yr−1), about 100 km southeast of Berlin, Germany. By using two different inversion approaches, one based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data, and another using a simple Gaussian integral method, the emission rates can be determined and compared with emissions reported by Vattenfall Europe. An extensive error analysis for the retrieval's dry column results (XCO2 and XCH4) and for the two inversion methods has been performed. Both methods – the Gaussian plume model fit and the Gaussian integral method – are capable of deriving estimates for strong point source emission rates that are within ±10% of the reported values, given appropriate flight patterns and detailed knowledge of wind conditions.

Chemical Composition and Antibacterial Activity of Origanum majorana L. Essential Oil from the Venezuelan Andes

Origanum majorana L. (Lamiaceae) is a plant that is used in gastronomy and natural medicine. The plant material used in this study was collected at San Isidro de Apartaderos, Mérida State. A yield of 0.6% of essential oil was obtained by hydro-distillation using a Clevenger trap. The main constituents found were: cis-sabinene hydrate (30.2%), terpinen-4-ol (28.8%), γ-terpinene (7.2%), α-terpineol (6.9%), trans-sabinene hydrate (4.4%), linalyl acetate (3.8%), and α-terpinene (3.6%). The essential oil was also fractionated over a silica gel dry column. Two main fractions were isolated, the first containing 67.6% of cis-sabinene hydrate and the second 72.8% of terpinen-4-ol. The antibacterial activity of the oil was determined using the agar diffusion method and it was found that it was active against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Klebsiella pneumoniae. Antibacterial activity of the fractions obtained by dry column chromatography was also tested. It was found that the fraction rich in cis-sabinene hydrate was more active than the one rich in terpinen-4-ol. It was concluded that in the essential oil of Origanum majorana, cis-sabinene hydrate is the more important compound responsible for inhibition of bacterial growth.

Removal of AsV by FeIII-Loaded XAD7 Impregnated Resin Containing Di(2-ethylhexyl) Phosphoric Acid (DEHPA): Equilibrium, Kinetic, and Thermodynamic Modeling Studies

In this paper, we studied the feasibility of using FeIII-loaded Amberlite XAD7 impregnated resin containing di(2-ethylhexyl) phosphoric acid (DEHPA) as adsorbents for the removal of AsV from aqueous solution. The XAD7-DEHPA resins are obtained by the dry method (DM) and column method (CM) of impregnation, respectively. Equilibrium, kinetic, and thermodynamic studies are carried out to study the adsorption performance of both types of Fe-XAD7-DEHPA resins for the removal process of AsV from aqueous solution. The effects of initial AsV concentration, contact time, and temperature of the solution on the adsorption were studied. The Langmuir and Dubinin–Kaganer–Radushkevich (DKR) isotherm models fit the equilibrium data better than Freundlich and Temkin isotherm models, which are used to describe the adsorption of AsV onto Fe-XAD7-DEHPA resins. The pseudosecond-order model is suitable for describing the adsorption kinetics for AsV removal from aqueous solutions onto Fe-XAD7-DEHPA resins. Thermodynamic paramet...