Spectroscopic study of carbaryl sorption on smectite from aqueous suspension

Sorption of carbaryl (1-naphthyl-N-methyl-carbamate) from aqueous suspension to smectite was studied using Fourier transform infrared (FTIR), high-performance liquid chromatography (HPLC) (for batch sorption), and quantum chemical methods. The amount of carbaryl sorbed was strongly dependent on the surface-charge density of the smectite with more sorption occurring on the two "low" surface-charge density smectites (SHCa-1 and SWy-2) compared to that of the high surface-charge SAz-1 smectite. In addition, the amount of carbaryl sorbed was strongly dependent on the nature of the exchangeable cation and followed the order of Ba approximately Cs approximately Ca > Mg approximately K > Na approximately Li for SWy-2. A similartrend was found for hectorite (SHCa-1) of Cs > Ba > Ca > K approximately Mg > Na approximately Li. Using the shift of the carbonyl stretching band as an indicator of the strength of interaction between carbaryl and the exchangeable cation, the observed order was Mg > Ca > Ba approximately K > Na > Cs. The position of the carbonyl stretching band shifted to lower wavenumbers with increasing ionic potential of the exchangeable cation. Density functional theory predicted a cation-induced lengthening of the C=O bond, resulting from the carbonyl group interacting directly with the exchangeable cation in support of the spectroscopic observations. Further evidence was provided by a concomitant shift in the opposite direction by several vibrational bands in the 1355-1375 cm(-1) region assigned to stretching bands of the carbamate N-Ccarbonyl and Oether-Ccarbonyl bonds. These data indicate that carbaryl sorption is due, in part, to site-specific interactions between the carbamate functional group and exchangeable cations, as evidenced by the FTIR data. However, these data suggest that hydrophobic interactions also contribute to the overall amount of carbaryl sorbed. For example, the FTIR data indicated thatthe weakest interaction occurred when Cs+ was the exchangeable cation. In contrast, the highest amount of carbaryl sorption was observed on Cs-exchanged smectite. Of all the cations studied, Cs has the lowest enthalpy of hydration. It is suggested that this low hydration energy provides the carbaryl with greater access to the hydrophobic regions of the siloxane surface.     

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)‐1‐benzyl‐6′‐chloro‐5‐(4‐fluorophenyl)‐7′‐methylspiro[1,2,3a,6a‐tetrahydropyrrolo[3,4‐c]pyrrole‐3,3′‐1H‐indole]‐2′,4,6‐trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo‐1, was found to enhance the effect of fluconazole with an EC₅₀ value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo‐1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo‐1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.     

Suppressive Fair Buffer Management Policy for Intermittently Connected Mobile Ad Hoc Networks

Wireless Personal Communications - We propose a suppressive fair buffer management policy for intermittently connected mobile ad-hoc networks. So far, several buffer management policies have been...     

Trend and variability of rainfall in two river basins in Sri Lanka: an analysis of meteorological data and farmers’ perceptions

Selected rainfall characteristics derived by analyzing observed rainfall data in two Sri Lankan river basins (Malwathu Oya and Kalu Ganga) were compared with the perceptions of farmers. The rainfall characteristics used for this analysis are trends, onset and cessation dates, length of the growing period, number of rainy days, and length of the dry spell. Farmers’ perceptions of changes in those characteristics were collected through household surveys. The majority of farmers in both river basins failed to recognize the long-term upward trend in annual rainfall. They also failed to describe the adaptation measures they were currently practising.     

Fabrication and characterization of uranium-thorium-zirconium hydrides

Two uranium-thorium-zirconium hydrides, (UTh₄Zr₁₀)H_1.9 and (U₄Th₂Zr₉)H_1.5, have been fabricated and characterized. Fabrication involved arc melting of the constituent pure metals to form homogenous alloys, followed by hydriding at elevated temperatures in a hydrogen gas environment. The compounds were characterized by X-ray powder diffractometry as well as scanning and transmission electron microscopy. These methods revealed a multi-phase mixture of δ-zirconium hydride (ZrH_1.6+x), thorium-zirconium hydride (ThZr₂H_7−x), and uranium metal. The elastic modulus was mapped across the microstructure using nanoscale dynamic stiffness mapping. The elastic modulus of ThZr₂H_7−x phase is found to be 172 GPa.     

Incorporating Environmental Value and Externality in Project Evaluation as a Sustainability Indicator to evaluate Bangladesh Water Development

A major difficulty of conventional cost benefit analysis is that it will allow choosing an alternative among others only on the criterion of economic efficiency: that the selected project or activity has been proven to produce economic benefits over costs for the period of the project. An analysis of this kind generally does not create a problem if the costs and benefits series are easy to quantify and clearly identifiable. However, almost all projects linked with the environment are clear exceptions to this category. Many environmental projects are facing a difficulty of evaluating the success based on economic efficiency due to two reasons: (a) environmental benefits are difficult to quantify and (b) environmental interactions that will cause severe externalities are difficult to predict. The main objective of this paper is to suggest a new method that can be used to overcome such difficulties in environmental projects. Data used in this analysis will demonstrate a practical approach to evaluate environmental projects. The evaluation proposed is different to traditional analysis in that it has been based on a large programme of primary research and has included efforts to achieve a consensus of all stakeholders, including those directly involved in project implementation.     

A comparison of wet-extracted coconut oils prepared under hot and cold conditions

Virgin coconut oil was prepared by four wet extraction methods which included hot extraction by boiling coconut milk, and three cold extraction methods by centrifugation, fermentation, and chilling followed by thawing of coconut milk. The chemical characteristics related to both saponifiable and unsaponifiable fractions of oils were evaluated. Quality parameters such as peroxide value, iodine value, saponification value, acid value, and moisture content of the four oils remain within the acceptable range for edible purposes. Hot conditions incorporate a richer phenolic profile, a higher α-tocopherol content, and a higher β-carotene content in coconut oil. Epimerization and hydrolysis of the phenolic compounds occur depending on the extraction conditions. The longest shelf-life of the coconut oil prepared under hot conditions may be due to the relatively lower contents of moisture, free acids, peroxides, and higher contents of phenolic compounds, α-tocopherol, and β-carotene in hot-extracted coconut oil. Contrary to popular belief, hot and wet extraction conditions may produce higher quality coconut oil compared to cold extraction conditions.     

A simple and rapid thyroxine radioimmunoassy (T4-RIA) in unextracted human serum; a comparison of T4-RIA and T4 displacement assay, T4(D), in normal and pathologic sera

A simple, rapid and accurate thyroxine radioimmunoassay (T4-RIA) in unextracted serum or plasma has been described, and for comparison T4 determinations have also been made by a T4(D) procedure using Abbott Tetrasorb kits. T4-RIA procedure basically involved denaturation of serum to dissociate T4-protein bond, and T4 released was allowed to react with [125I]T4-labeled T4 antiserum elicited by immunizing rabbits against bovine thyroglobulin. The displaced unbound [125I]T4 was rapidly taken up by an anionic resin sponge within 15 min and this sponge [125I]T4 uptake was linearly related to T4 present in standards or serum. The denaturation of serum effected by trichloroacetic acid-sodium hydroxide permitted virtually 100% T4 extraction recovery in normal, pregnancy, hypo- and hyperthyroid sera whereas 72.9-87.6% T4 recovery from normal serum (and with large individual differences) was noted with lower alcohols in T4(D) procedure. Cumbersome and/or tedious steps such as pre-extraction, centrifugation, time consuming bound and unbound hormone separation procedures, etc. are obviated in T4-RIA and the entire assay can be completed in the same tube in approximately an hour. These attributes along with increased sensitivity and specificity and the need for only microamounts of test sera (25-50 mul) in T4-RIA offer distinct advantages over T4(D) procedures, and in simplicity excel even other T4-RIAs. T4-RIA values in physiological and pathological states were highly correlated (r = 0.97) with T4(D) measurements and no differences between these two techniques were found. The reported discrepancies between T4-RIA and T4(D) measurements in human sera and some of the reasons for attributing these inconsistencies to probable methodological errors and variations are discussed.     

Effect of karawila (Momordica charantia) seed oil on synthesizing the alkyd resins based on soya bean (Glycine max) oil

Air drying long oil alkyd resins of 65% oil length were synthesized from a blend of soya bean (Glycine max) oil and karawila (Momordica charantia) seed oil. Different proportions of karawila seed oil (w/w% 10, 20, 30, 40 and 50) were blended with soya bean oil to examine the effect of karawila seed oil on the drying behavior of alkyds synthesized from soya bean oil. A sharp variation of viscosity is only observed for alkyd resins having more than 40% (w/w) of karawila seed oil. The polyesterification time was reduced and correspondingly the extent of polymerization was also reduced up to 30% (w/w). Significant variation in transesterification time was also observed for 30% (w/w). However, further increase in karawila seed oil above 40% (w/w) had only a marginal effect on the polyesterification reaction. The drying properties of the alkyd resins had been significantly improved with the increase of karawila seed oil up to 30% (w/w) but further increase in karawila seed oil resulted in poor drying characteristics. The film properties (drying time, hardness, adhesion, chemical resistance and gloss) of the alkyd resins were determined. The optimum film properties were recorded for the oil blend with 30% (w/w) karawila seed oil and 70% (w/w) soya bean oil.     

Studies on obesity. III. effect of triiodothyronine (T3) on thyroglobulin autoantibodies in euthyroid obese subjects

Effect of T3 therapy on tanned red cell agglutinating thyroglobulin (TRC-TG) antibodies in 10 obese subjects without apparent thyroid disease was investigated. Six other obese subjects without thyroid dysfunction and of approximately the same mean age who also had circulating TRC-TG antibodies served as control subjects and were untreated. In vitro thyroid tests (TSH, total and free T4) performed before T3 therapy, as well as clinical examination, showed thyroid function to be normal in all subjects, and there was no evidence of thyroiditis. TRC-TG antibodies were present in low to moderate titers of 40-1280 in control subjects as well as in subjects selected for T3 treatment. Therapy with T3 was started at 50 mug/day and gradually increased to a maximum of 250 mug/day, depending on clinical needs. T3-treated as well as untreated obese control subjects were all maintained on a high protein, low fat, low carbohydrate diet. Duration of T3 therapy varied from 2-8 mo, and in all but one T3-treated subject, TRC-TG antibodies completely disappeared. In the one exceptional case, TRC-TG antibody titer decreased from 1280 to 80 after 7 mo of therapy. In non-T3-treated obese control subjects, antibody titers remained at the same levels throughout the observation period, thereby indicating a lack of spontaneous regression of circulating immune response. Therapy with T3, by inhibiting TSH, may have caused regression of inapparent immunologic thyroid lesion, thus leading to the disappearance of circulating TRC antibodies; alternatively, T3 specifically may have accelerated catabolism of thyroid antibodies. The latter possibility is favored in the absence of clinical and laboratory evidence of thyroiditis in T3-treated subjects.