A triphenyltin (TPT)-decomposing strain, Pseudomonas aeruginosa CGMCC 1.860, was screened out. It secreted an unknown TPT-decomposing factor into the medium, later shown to be pyochelin, even in the presence of 100 M iron. To our knowledge, this is the first report of organotin decomposition by pyochelin.Organotin compounds are ubiquitous in the environment and have a wide range of industrial and agricultural applications (7). However, they are toxic and harmful to a variety of nontarget organisms (see, e.g., references 10 and 16). Without a doubt, it is important to remove organotins from the environment.It has previously been reported that some microalgae were capable of degrading organotin, but their degradation rate was very low (14). Information on the bacterial degradation of organotin compounds is still severely limited (7, 9). This work investigated the decomposition of triphenyltin chloride (TPT) by microorganisms, and interestingly, pyochelin (PCH) [2-(2-o-hydroxy phenyl-2-thiazolin-4-yl)-3-methylthiazolidine-4-carboxylic acid], different from pyoverdine (PVD), was found as a new organotin-decomposing factor.Chemicals. TPT (95%), diphenyltin dichloride (DPT) (98%), and monophenyltin trichloride (MPT) (96%) were purchased from Aldrich Chemical Co.Seventeen strains belonging to Pseudomonas and Burkholderia genera, obtained from the China General Microbiological Culture Collection Center (Beijing, People's Republic of China), were used for screening for TPT-decomposing bacteria. The TPT decomposition activity was measured by monitoring the decrease of TPT concentrations and the increase of DPT and MPT levels using high-performance liquid chromatography (HPLC) as described previously (12). Shimadzu (Kyoto, Japan) HPLC equipment (LC-10AT VP ) with a UV-Vis detector and a reversed-phase column (Kromasil C 18 ) (250-by 4.6-mm internal diameter, 5 m) was used. The mobile phase consisted of methanol-acetate acid-water (60:10:30 [vol/vol/ vol]) containing 1 mM dithiothreitol. The flow rate was 0.75 ml/min, and the UV detection wavelength was 257 nm. Among all the strains, none of them were able to utilize TPT as a sole carbon source to support growth, but all of them were able to grow in the M9 medium with sodium succinate (4 g/liter) as a carbon source supplemented with 200 M TPT. Pseudomonas aeruginosa CGMCC 1.860, a fluorescent pseudomonad with the greatest ability to decompose TPT (data not shown), was chosen for the following experiments.The kinetics of TPT (200 M) decomposition by P. aeruginosa CGMCC 1.860 are shown in Fig. 1. TPT rapidly decomposed during log-phase growth and reduced to about 40% of the initial amount within 36 h, and it decreased slowly in the stationary phase (Fig. 1). The accumulation of DPT reached a maximal concentration of 50 M at 24 h and then slowly decreased. The concentration of MPT increased slowly during 96 h of incubation. This strain showed a decomposition ability similar to that of other Pseudomonas strains (7), and it had a relatively higher organotin-decomposing capacity...

During the formation of magnesium-organic frameworks, the coordination sphere of magnesium tends to be partially occupied by Ocontaining solvent molecules such as amides, which will dramatically decrease the symmetry of Mg-organic frameworks and thus lead to low stability. It is noted that up to now, most reported Mg-metal−organic frameworks (MOFs) (>80%) crystallize in the space groups whose symmetry is lower than that of a tetragonal system. In this work, we demonstrate that acetate (Ac) may act as modulator to eliminate the influence of amide solvent and improve the symmetry of Mg-organic frameworks. Two novel Mg-MOFs, namely, {were successfully designed, which crystallize in rhombohedral R-3 and tetragonal I4/mmm space groups, respectively. Four independent BTB ligands link three unique Mg cations and generate superlarge [Mg 21 BTB 17 ] nanocages, which interlock each other by strong π•••π stacking to give a two-fold interpenetrating architecture of SNNU-35. On the other hand, carboxylate and acetate groups chelate Mg atoms to form one-dimensional chains, which are extended by FDA to produce the rod-packing framework of SNNU-36. Two microporous Mg-MOFs both exhibit notable CO 2 and H 2 uptakes. H 3 BTB and H 2 FDA ligands both have emission features, and Mg ions usually can enhance the fluorescent intensity, which lead to a strong solid-state luminescence emission property of SNNU-35 and -36. Importantly, two Mg-MOFs both show fast and quantative sensing performance for nitrocompounds. Among three selected models of substrate, SNNU-35 and -36 can eliminate the interference of nitromethane (NM) and exhibit high sensitivity to nitrobenzene (NB) and o-nitrotoluene (2-NT) with large k sv values (>10 5 M −1 ). Especially, the fluorescence quenching efficiency of NB (5000 ppm) and 2-NT (8000 ppm) can reach 96.3% and 89.5% and 85.0% and 83.7% for SNNU-35 and -36, respectively. This work offers not only an effective route to improve the symmetry of magnesiumorganic frameworks but also two potential fluorescence sensors for nitroaromatic compounds.

Pyochelin (PCH), a kind of siderophore secreted by Pseudomonas aeruginosa, was recently found to have triphenyltin (TPT)-decomposing capacity. In this work, significant augmentation of TPT decomposition by ferripyochelin (FePCH), the chelating compound of PCH with iron, was demonstrated in Tris-HCl buffer (pH 8.0). The generation of hydroxyl radical (HO·) in the presence of FePCH was observed. Inhibition of HO· generation by adding catalase and HO· scavengers (methanol and dimethyl sulfoxide) decreased TPT decomposition, while an increase in HO· formation in the presence of H 2 O 2 enhanced its decomposition. Our findings indicated that HO· generated in the reaction system was responsible for the enhanced TPT decomposition by FePCH versus PCH. The existence of the TPT-pyochelin-iron ternary complex was demonstrated by electron spray ionization-mass spectrometry, tandem mass spectrometry, and 1 H nuclear magnetic resonance. On the basis of the above results, HO· produced in the presence of FePCH was deduced to be in close proximity to TPT and has more opportunity to attack the Sn-C bond, which resulted in the enhanced organotin decomposition. The information obtained may have considerable environmental significance.Triorganotin compounds, in particular triphenyltin (TPT), have been introduced into the aquatic environment in large quantities due to their extensive use as pesticides in agriculture and as antifouling agents in boat paints (11). As a highly toxic compound, TPT has caused harmful effects on a variety of nontarget organisms, such as mollusks and fish (2, 12), even at aqueous concentrations of a few nanograms per liter (2). Although organotins are banned in most developed countries, they are still being introduced into water and sediment around the world, causing an obvious health risk that has raised public interest in the removal of organotin in and from the environment (14). Microorganisms play a crucial role in organotin removal from the natural environment because of their surprising ability under evolution to degrade xenobiotics (26).Several strains have been isolated from the sediment or soil, and TPT degradation by these strains was investigated under pure culture conditions (13, 24). Although microbe-mediated dealkylation of organotin has been reported, information about details of the mechanism of microbial TPT degradation/ decomposition is still limited (13,14). Walts and Walsh (25) demonstrated that only a few kinds of organotins were substrates for bacterial organomercurial lyase. Most organotin compounds, such as tributyltin and triethyltin, were not substrates for lyase, and some even caused irreversible inhibition of enzymes. Inoue and coworkers (13, 14) have identified a kind of siderophore, pyoverdine (PVD), which was produced by Pseudomonas chlororaphis and was capable of decomposing triphenyltin and tributyltin. We recently showed that pyochelin (PCH), a siderophore secreted by Pseudomonas aeruginosa, could decompose triphenyltin, and its decomposition mechanism was proposed as che...

Acta Technologica Agriculturae 1/2016Dušan Páleš et al.The most effective way for determination of curves for practical use is to use a set of control points. These control points can be accompanied by other restriction for the curve, for example boundary conditions or conditions for curve continuity (Sederberg, 2012). When a smooth curve runs only through some control points, we refer to curve approximation. The B-spline curve is one of such approximation curves and is addressed in this contribution. A special case of the B-spline curve is the Bézier curve Rédl et al., 2014). The B-spline curve is applied to a set of control points in a space, which were obtained by measurement of real vehicle movement on a slope (Rédl, 2007(Rédl, , 2008. Data were processed into the resulting trajectory (Rédl, 2012;Rédl and Kučera, 2008). Except for this, the movement of the vehicle was simulated using motion equations (Rédl, 2003;Rédl and Kročko, 2007). B-spline basis functionsBézier basis functions known as Bernstein polynomials are used in a formula as a weighting function for parametric representation of the curve (Shene, 2014). B-spline basis functions are applied similarly, although they are more complicated. They have two different properties in comparison with Bézier basis functions and these are: 1) solitary curve is divided by knots, 2) basis functions are not nonzero on the whole area. Every B-spline basis function is nonzero only on several neighbouring subintervals and thereby it is changed only locally, so the change of one control point influences only the near region around it and not the whole curve.These numbers are called knots, the set U is called the knot vector, and the half-opened interval 〈u i , u i + 1 ) is the i-th knot span. Seeing that knots u i may be equal, some knot spans may not exist, thus they are zero. If the knot u i appears p times, hence u i = u i + 1 = ... = u i + p -1 , where p >1, u i is a multiple knot of multiplicity p, written as u i (p). If u i is only a solitary knot, it is also called a simple knot. If the knots are equally spaced, i.e. (u i + 1 -u i ) = constant, for every 0 ≤ i ≤ (m -1), the knot vector or knot sequence is said uniform, otherwise it is non-uniform.Knots can be considered as division points that subdivide the interval 〈u 0 , u m 〉 into knot spans. All B-spline basis functions are supposed to have their domain on 〈u 0 , u m 〉. We will use u 0 = 0 and u m = 1.To define B-spline basis functions, we need one more parameter k, which gives the degree of these basis functions. Recursive formula is defined as follows:This definition is usually referred to as the Cox-de Boor recursion formula. If the degree is zero, i.e. k = 0, these basis functions are all step functions that follows from Eq. (1). N i, 0 (u) = 1 is only in the i-th knot span 〈u i , u i + 1 ). For example, if we have four knots u 0 = 0, u 1 = 1, u 2 = 2 and u 3 = 3, knot spans 0, 1 and 2 are 〈0, 1), 〈1, 2) and 〈2, 3), and the basis functions of degree 0 are N 0, 0 (u) = 1 on interval 〈0, 1) Acta In this co...

Abstract-2, 6-bis (5,6-dipropyl-1,2,4-triazine-3-yl) pyridine (BDPTP) was synthesized with 2, 6 -dimethyl pyridine and ethyl butyrate as raw materials. And characterized by IR, 1HNMR and element analysis etc. The extraction performance of this kind of complexes for four kinds of cations, Cu(II), Cd(II), Pb(II), Ni(II) is studied in hydrochloric acid system. The results show that the extraction rate of cadmium chloride with BDPTP in dichloromethane can reach to 97.25%. It is meaningful to cadmium chloride wastewater treatment.