The removal of Cr(VI) from aqueous solution by batch adsorption technique using different low-cost adsorbents was investigated. Adsorbents such as clarified sludge—a steel industry waste material, ...rice husk ash, activated alumina, fuller's earth, fly ash, saw dust and neem bark were used to determine the adsorption efficiency. The influence of pH, adsorbent type and concentration, initial Cr(VI) concentration and contact time on the selectivity and sensitivity of the removal process were investigated. Adsorption process was found to be highly pH dependent. The optimum pH range for adsorption of Cr(VI) was found to be between 2 and 3. Kinetics studies were performed to understand the mechanistic steps of the adsorption process and the rate kinetics for the adsorption of Cr(VI) was best fitted with the pseudo-2nd-order kinetic model. Langmuir and Freundlich adsorption isotherms were applicable to the adsorption process and their constants were evaluated. The thermodynamic equilibrium constant and the Gibbs free energy were determined for each system. The adsorption capacity (
q
max) calculated from Langmuir isotherm and the Gibbs free energy (Δ
G
o) value obtained for the different adsorbents showed that clarified sludge was the most effective among the selected adsorbents for the removal of Cr(VI) from aqueous solution. The adsorption efficiencies of rice husk ash and activated alumina were also equally comparable with that of clarified sludge.
The removal of Zn(II) from aqueous solution by different adsorbents was investigated. Clarified sludge (a steel industry waste material), rice husk ash, neem bark and a chemical adsorbent activated ...alumina were used for the adsorption studies. The influence of pH, contact time, initial metal concentration, adsorbent nature and concentration on the selectivity and sensitivity of the removal process was investigated. The adsorption of Zn(II) increased with increased concentration of the adsorbents and reached maximum uptake at 10
g/L and pH between 5 and 7. The equilibrium time was achieved after 1
h for clarified sludge, 3
h for rice husk ash and 4
h for activated alumina and neem bark, respectively. The adsorption process was found to follow a first-order rate mechanism and rate constant was evaluated at 30
°C. The rate constant was highest in case of clarified sludge (6.90
×
10
−2
min
−1) and the activated alumina gave the lowest value (1.86
×
10
−2
min
−1). Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated. The thermodynamic equilibrium constant and the Gibbs free energy were calculated for each system. The adsorption capacity (
q
max) calculated from Langmuir isotherm and the values of Gibbs free energy obtained showed that clarified sludge has the largest capacity and affinity for the removal of Zn(II) compared to the other adsorbents used in the study.
Sequence stratigraphy emphasizes facies relationships and stratal architecture within a chronological framework. Despite its wide use, sequence stratigraphy has yet to be included in any ...stratigraphic code or guide. This lack of standardization reflects the existence of competing approaches (or models) and confusing or even conflicting terminology. Standardization of sequence stratigraphy requires the definition of the fundamental model-independent concepts, units, bounding surfaces and workflow that outline the foundation of the method. A standardized scheme needs to be sufficiently broad to encompass all possible choices of approach, rather than being limited to a single approach or model.
A sequence stratigraphic framework includes genetic units that result from the interplay of accommodation and sedimentation (i.e., forced regressive, lowstand and highstand normal regressive, and transgressive), which are bounded by ‘sequence stratigraphic’ surfaces. Each genetic unit is defined by specific stratal stacking patterns and bounding surfaces, and consists of a tract of correlatable depositional systems (i.e., a ‘systems tract’). The mappability of systems tracts and sequence stratigraphic surfaces depends on depositional setting and the types of data available for analysis. It is this high degree of variability in the precise expression of sequence stratigraphic units and bounding surfaces that requires the adoption of a methodology that is sufficiently flexible that it can accommodate the range of likely expressions. The integration of outcrop, core, well-log and seismic data affords the optimal approach to the application of sequence stratigraphy. Missing insights from one set of data or another may limit the ‘resolution’ of the sequence stratigraphic interpretation.
A standardized workflow of sequence stratigraphic analysis requires the identification of all genetic units and bounding surfaces that can be delineated objectively, at the selected scale of observation, within a stratigraphic section. Construction of this model-independent framework of genetic units and bounding surfaces ensures the success of the sequence stratigraphic method. Beyond this, the interpreter may make model-dependent choices with respect to which set of sequence stratigraphic surfaces should be elevated in importance and be selected as sequence boundaries. In practice, the succession often dictates which set of surfaces are best expressed and hold the greatest utility at defining sequence boundaries and quasi-chronostratigraphic units. The nomenclature of systems tracts and sequence stratigraphic surfaces is also model-dependent to some extent, but a standard set of terms is recommended to facilitate communication between all practitioners.
Timely detection of pest infestation in agricultural crops plays a pivotal role in the planning and execution of pest management interventions. In this study, a ground measured electromagnetic ...spectrum through hyperspectral sensing (400–2500 nm) was conducted in healthy and aphid-infested mustard crops in different regions of the Bharatpur district of Rajasthan state, India. The ground measured hyperspectral reflectance and its derivatives during the mustard aphid infestation period were used to identify the sensitive spectral regions in the electromagnetic spectrum concerning Aphid Infestation Severity Grade (AISG) to discriminate Lipaphis-infested mustard crops from the healthy ones. Further Principal Component Analysis (PCA) and Partial Least Square Regression (PLSR) were utilized to identify specific spectral bands to differentiate the healthy from aphid-infested crops. The spectral regions of 493–497 nm (blue), 509–515 nm (green), 690–714 nm (red), 717–721 nm (red edge), and 752–756 nm (NIR) showed high correlation with AISG for reflectance, first and second order derivatives. Further analysis of the spectra using PCA and PLSR indicated that spectral bands of 679 nm, 746 nm, and 979 nm had high sensitivity for discriminating aphid-infested crops from the healthy ones. Average reflectance and various spectral indices such as ratio spectral index (RSI), difference spectral index (DSI), and normalized difference spectral index (NDSI) of identified spectral regions and absolute reflectance of identified specific spectral bands were used for predicting AISG. Several regression models, including PCR and PLSR, were examined to predict the AISG. PLSR was found to better predict infestation grade with RMSE of 0.66 and r2 0.71. Our outcomes counseled that hyperspectral reflectance data have the ability to detect aphid-infested severity in mustard.
Clarified sludge is a major waste generating during steel making process. In India and in most industrial countries, the use of clarified sludge as a road ballast and land filter has had a very long ...history. In present study, clarified sludge has been characterized and used for the removal of Cd(II) from aqueous solutions. The effect of pH, adsorbent dosage, adsorbate concentration, contact time and temperature on adsorption process was studied in batch experiments. Kinetics data were best described by pseudo-second order model. The effective diffusion co-efficient of Cd(II) is of the order of 10
−11 m
2/s. The maximum uptake was 36.23 mg/g. The adsorption data can be well described by Langmuir isotherm. The result of the equilibrium studies showed that the solution pH was the governing factor affecting the adsorption. Mass transfer analysis was also carried out for the adsorption process. The thermodynamic studies indicated that the adsorption was spontaneous and exothermic in nature. The sorption energy calculated from Dubinin–Radushkevich isotherm indicated that the adsorption process is chemical in nature. Desorption as well as the application studies were carried out considering the economic viewpoint of wastewater treatment plant operations.
The experimental runs measuring the effect of pH on the batch adsorption of metal solution containing 10 mg/L of Cd(II) at 30 °C.
The need for successful management of posterior urethral valves always captivates the minds of pediatric surgeons. Its success, however, depends on several factors ranging from prenatal preservation ...of upper tracts to postoperative pharmacological compliance. Regardless of measures available, some cases do not respond and progress to end stage. The management depends on several issues ranging from age and severity at presentation to long-term follow-up and prevention of secondary renal damage and managing valve bladder syndrome. This article is based on a consensus to the set of questionnaires, prepared by research section of Indian Association of Paediatric Surgeons and discussed by experienced pediatric surgeons based in different institutions in the country. Standard operating procedures for conducting a voiding cystourethrogram and cystoscopy were formulated. Age-wise contrast dosage was calculated for ready reference. Current evidence from literature was also reviewed and included to complete the topic.
ABSTRACT AstroSat is a multi-wavelength satellite launched on 2015 September 28. The CZT Imager of AstroSat on its very first day of operation detected a long duration gamma-ray burst (GRB), namely ...GRB 151006A. Using the off-axis imaging and spectral response of the instrument, we demonstrate that the CZT Imager can localize this GRB correctly to about a few degrees, and it can provide, in conjunction with Swift, spectral parameters similar to those obtained from Fermi/GBM. Hence, the CZT Imager would be a useful addition to the currently operating GRB instruments (Swift and Fermi). Specifically, we argue that the CZT Imager will be most useful for the short hard GRBs by providing localization for those detected by Fermi and spectral information for those detected only by Swift. We also provide preliminary results on a new exciting capability of this instrument: the CZT Imager is able to identify Compton scattered events thereby providing polarization information for bright GRBs. GRB 151006A, in spite of being relatively faint, shows hints of a polarization signal at 100-300 keV (though at a low significance level). We point out that the CZT Imager should provide significant time resolved polarization measurements for GRBs that have fluence three times higher than that of GRB 151006A. We estimate that the number of such bright GRBs detectable by the CZT Imager is five to six per year. The CZT Imager can also act as a good hard X-ray monitoring device for possible electromagnetic counterparts of gravitational wave events.
Complications of biliary-enteric anastomoses Kadaba, R S; Bowers, K A; Khorsandi, S ...
Annals of the Royal College of Surgeons of England,
03/2017, Letnik:
99, Številka:
3
Journal Article
Recenzirano
Odprti dostop
INTRODUCTION Biliary-enteric anastomoses are performed for a range of indications and may result in early and late complications. The aim of this study was to assess the risk factors and management ...of anastomotic leak and stricture following biliary-enteric anastomosis. METHODS A retrospective analysis of the medical records of patients who underwent biliary-enteric anastomoses in a tertiary referral centre between 2000 and 2010 was performed. RESULTS Four hundred and sixty-two biliary-enteric anastomoses were performed. Of these, 347 (75%) were performed for malignant disease. Roux-en-Y hepaticojejunostomy or choledocho-jejunostomy were performed in 440 (95%) patients. Perioperative 30-day mortality was 6.5% (n=30). Seventeen patients had early bile leaks (3.7%) and 17 had late strictures (3.7%) at a median of 12 months. On univariable logistic regression analysis, younger age was a significant risk factor for biliary anastomotic leak. However, on multivariable analysis only biliary reconstruction following biliary injury (odds ratio OR=6.84; p=0.002) and anastomosis above the biliary confluence (OR=4.62; p=0.03) were significant. Younger age and biliary reconstruction following injury appeared to be significant risk factors for biliary strictures but multivariable analysis showed that only younger age was significant. CONCLUSIONS Biliary-enteric anastomoses have a low incidence of early and late complications. Biliary reconstruction following injury and a high anastomosis (above the confluence) are significant risk factors for anastomotic leak. Younger patients are significantly more likely to develop an anastomotic stricture over the longer term.
Testing of groundwater used for drinking for arsenic has been undertaken more widely by state governments in several states of India in recent years with the support of UNICEF. Available data for ...five states are collated in this paper and this provides the most up-to-date picture of areas known to be affected by arsenic in groundwater in the Indian portion of the Ganges-Brahmaputra river basin. In West Bengal, water from 132,262 government installed handpumps in 8 districts has been tested and overall 25.5% of samples were found to contain arsenic at concentrations greater than 50 μ gL
−1
and 57.9% at concentrations greater than 10 μ gL
−1
. On the banks of the Brahmaputra in Assam, to date, samples from 5,729 government handpump sources in 22 districts have been tested for arsenic. Overall, samples from 6.3% of sources were found to contain arsenic at concentrations greater than 50 μ gL
−1
and 26.1% at concentrations greater than 10 μ gL
−1
. In Bihar, on the River Ganges upstream of West Bengal, 66,623 sources from 11 districts have been tested and water samples from 10.8% of sources were found to contain arsenic at concentrations greater than 50 μ gL
−1
and 28.9% at concentrations greater than 10 μ gL
−1
. Upstream of Bihar in Uttar Pradesh, home of the Taj Mahal, to date water samples from 20,126 government-installed handpump sources have been tested. As a result 2.4% of the samples tested were found to contain arsenic at concentrations greater than 50 μ gL
−1
and 21.5% at concentrations greater than 10 μ gL
−1
. Finally in one district of Jharkhand, lying on the Ganges alluvial plain between Bihar and West Bengal, 9,007 sources have been tested and water samples from 3.7% of sources were found to contain arsenic at concentrations greater than 50 μ gL
−1
and 7.5% at concentrations greater than 10 μ gL
−1
. State governments have adopted different sampling strategies and these are described in this paper. Testing is ongoing in several states and the complete picture is yet to emerge in some areas.
PDF
