Adsorption behavior of benzenesulfonic acid by novel weakly basic anion exchange resins

Two novel weakly basic anion exchange resins(SZ-1 and SZ-2) were prepared via the reaction of macroporous chloromethylated polystyrene-divinylbenzene(Cl-PS-DVB) beads with dicyclohexylamine and piperidine, respectively. The physicochemical structures of the resulting resins were characterized using Fourier Transform Infrared Spectroscopy and pore size distribution analysis. The adsorption behavior of SZ-1 and SZ-2 for benzenesulfonic acid(BA) was evaluated, and the common commercial weakly basic anion exchanger D301 was also employed for comparison purpose. Adsorption isotherms and influence of solution p H, temperature and coexisting competitive inorganic salts(Na2SO4and Na Cl) on adsorption behavior were investigated and the optimum desorption agent was obtained.Adsorption isotherms of BA were found to be well represented by the Langmuir model.Thermodynamic parameters involving ΔH, ΔG and ΔS were also calculated and the results indicate that adsorption is an exothermic and spontaneous process. Enhanced selectivity of BA sorption over sulfate on the two novel resins was observed by comparison with the commercial anion exchanger D301. The fact that the tested resins loaded with BA can be efficiently regenerated by Na Cl solution indicates the reversible sorption process. From a mechanistic viewpoint, this observation clearly suggests that electrostatic interaction is the predominant adsorption mechanism. Furthermore, results of column tests show that SZ-1possesses a better adsorption property than D301, which reinforces the feasibility of SZ-1for potential industrial application.     

Incidental detection of premature centromere separation in amniocytes associated with a mild form of Roberts syndrome

Premature centromere separation (PCS) was detected in amniocytes after an amniocentesis was done because of markedly elevated maternal serum alpha-fetoprotein values in a healthy primiparous young woman. PCS has been associated with the Roberts-SC phocomelia syndrome (RS). By 23 weeks' gestation, ultrasonic evaluations did not reveal abnormal fetal development. The pregnancy continued and a male infant was born with mild manifestations of RS. PCS was confirmed in cord blood lymphocytes. This case illustrates that PCS, when detected in amniotic fluid cell cultures, requires a thorough evaluation.     

Acid azo dye degradation by free and immobilized horseradish peroxidase (HRP) catalyzed process

Acid azo (Acid Black 10 BX) dye removal by plant based peroxidase catalyzed reaction was investigated. Horseradish peroxidase (HRP) was extracted from horseradish roots and its performance was evaluated in both free and immobilized form. HRP showed its ability to degrade the dye in aqueous phase. Studies are further carried out to understand the process parameters such as aqueous phase pH, H2O2 dose, dye and enzyme concentrations during enzyme-mediated dye degradation process. Experimental data revealed that dye (substrate) concentration, aqueous phase pH, enzyme and H2O2 dose play a significant role on the overall enzyme-mediated reaction. Acrylamide gel immobilized HRP showed effective performance compared to free HRP and alginate entrapped HRP. Alginate entrapped HRP showed inferior performance over the free enzyme due to the consequence of non-availability of the enzyme to the dye molecule due to polymeric immobilization. Standard plating studies performed with Pseudomonas putida showed enhanced degradation of HRP catalyzed dye compared to control.     

Assessment of the nested grid model estimates for driving regional visibility models in the southwestern United States

The Nested Grid Model (NGM) is a primitive-equation meteorological model that is routinely exercised over North America for forecasting purposes by the National Meteorological Center. While prognostic meteorological models are being increasingly used to drive air quality models, their use in conducting annual simulations requires significant resources. NGM estimates of wind fields and other meteorological variables provide an attractive alternative since they are typically archived and readily available for an entire year. Preliminary evaluation of NGM winds during the summer of 1992 for application to the region surrounding the Grand Canyon National Park showed serious shortcomings. The NGM winds along the borders between California, Arizona and Mexico tend to be northwesterly with a speed of about 6 m/sec, while the observed flow is predominantly southerly at about 2-5 m/sec. The mesoscale effect of a thermal low pressure area over the highly heated Southern California and western Arizona deserts does not appear to be represented by the NGM because of its coarse resolution and the use of sparse observations in that region. Tracer simulations and statistical evaluation against special high resolution observations of winds in the southwest United States clearly demonstrate the northwest bias in NGM winds and its adverse effect on predictions of an air quality model. The "enhanced" NGM winds, in which selected wind observations are incorporated in the NGM winds using a diagnostic meteorological model provide additional confirmation on the primary cause of the northwest bias. This study has demonstrated that in situations where limited resources prevent the use of prognostic meteorological models, previously archived coarse resolution wind fields in which additional observations are incorporated to correct known biases provide an attractive option.     

Cadmium-induced toxicity reversal by zinc in Ceratophyllum demersum L. (a free floating aquatic macrophyte) together with exogenous supplements of amino- and organic acids

This paper analyzes the detoxification mechanisms adopted by amino- and organic acids to alleviate Cd toxicity. In addition, with our published data on Zn–Cd interactions, the influence of Zn (200 μM) supplements on the detoxification mechanisms of amino- and organic acids have also been studied. The experimental studies on metal uptake, lipid peroxidation levels, estimation of reduced and oxidized glutathione levels as well as γ-glutamylcysteine synthetase activity in amino acid supplemented Cd treatments indicated glutathione-mediated detoxification system, which was also enhanced by Zn (200 μM) supplements. However Zn did not aid in glutathione synthesis, but maintained the ratio of reduced and oxidized forms. The supplementation of organic acids to Cd treatments indicated detoxification through the mechanism of chelation. Zn seemed to be less influential on organic acids-mediated detoxification mechanism as compared to amino acid mediated detoxification system.     

SWAT‐LUT: A Desktop Graphical User Interface for Updating Land Use in SWAT

Long‐term simulations of agricultural watersheds have often been done assuming constant land use over time, but this is not a realistic assumption for many agricultural regions. This paper presents the soil and water assessment tool (SWAT)‐Landuse Update Tool (LUT), a standalone, user‐friendly desktop‐based tool for updating land use in the SWAT model that allows users to process multi‐year land use data. SWAT‐LUT is compatible with several SWAT model interfaces, provides users with several options to easily prepare and incorporate land use changes (LUCs) over a simulation period, and allows users to incorporate past or emerging land use categories. Incorporation of LUCs is expected to provide realistic model parameterization and scenario simulations. SWAT‐LUT is a public domain interface written in Python programming language. Two applications at the Fort Cobb Reservoir Experimental Watershed located in Oklahoma and pertinent results are provided to demonstrate its use. Incorporating LUCs related to implementation of recommended conservation practices over the years reduced discharge, evapotranspiration, sediment, total nitrogen, and total phosphorus loads by 59%, 9%, 68%, 53%, and 88%, respectively. The user’s manual is included in this article as Supporting Information. The SWAT‐LUT executable file and an example SWAT project with three land use rasters and the user’s manual are available at the United States Department of Agriculture‐Agricultural Research Service Grazinglands Research Laboratory website under Software. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

Spatial patterns of off-the-system traffic crashes in Miami–Dade County,Florida, during 2005–2010

Objective: The objective of this study is to analyze the spatial distribution of the vehicles involved in crashes in Miami–Dade County. In addition, we analyzed the role of time of day, day of the week, seasonality, drivers’ age in the distribution of traffic crashes.

Method: Off-the-system crash data acquired from the Florida Department of Transportation during 2005–2010 were divided into subcategories according to the risk factors age, time of day, day of the week, and travel season. Various spatial statistics methods, including nearest neighbor analysis, Getis-Ord hot spot analysis, and kernel density analysis revealed substantial spatial variations, depending on the subcategory in question.

Results: Downtown Miami and South Beach showed up consistently as hotspots of traffic crashes in all subcategories except fatal crashes. However, fatal crashes were concentrated in residential areas in inland areas.

Conclusion: This understanding of patterns can help the county target high-risk areas and help to reduce crash fatalities to create a safer environment for motorists and pedestrians.