Thin-layer chromatographic separation of aldrin,dieldrin, γ-hexachlorocyclohexane,malathion, ethyl-parathion,pentachlorophenol, and of chlordane,dieldrin, γ-hexachlorocyclohexane,malathion, ethyl-parathion,and pentachlorophenol from each other

A thin-layer chromatographic method is reported for the separation of aldrin (or chlordane), dieldrin, γ-hexachlorocyclohexane, malathion, ethyl-parathion, and pentachlorophenol from each other. The procedure, however, does not separate aldrin and chlordane from each other although it does separate either pesticide from the other components. The method employs alumina plates with n-hexane:xylene:benzene:toluene:cyclohexane:methyl cyclohexane (50:50:50:50:50:50:) as developing solvent.     

Thin-layer chromatographic separation of dicrotophos,ethion (or phorate), fensulfothion,oxydemeton-methyl,phosmet, phospholan,and trichlorfon from each other

A thin-layer chromatography method is reported for the separation of dicrotophos, ethion (or phorate), fensulfothion, oxydemeton-methyl, phosmet, phospholan, and trichlorfon. The procedure involves the use of commercially prepared silica gel 1B Baker-flex plates and developing with 2,2,4-trimethylpentane:methyl cyclohexane:n-hexyl alcohol:acetone (18:9:9:9). The pesticides are located by spraying with ammoniacal silver nitrate solution in acetone follwed by exposure to longwave UV light. The method does not separate ethion and phorate from each other. A method is also reported for the thin-layer chromatographic separation of ethion from phorate in the presence of the other six pesticides using solvent system 2,2,4-trimethylpentane:n-hexane:chloroform (18:18:12) on silica gel 1B Baker-flex plates.     

Synthesis, crystal structure analysis, and pharmacological characterization of desmethoxy-sila-venlafaxine, a derivative of the serotonin/noradrenaline reuptake inhibitor sila-venlafaxine

rac-Desmethoxy-sila-venlafaxine (rac-3) is a derivative of the noradrenaline-selective serotonin/noradrenaline reuptake inhibitor rac-sila-venlafaxine (rac-1b), a silicon analogue of the serotonin-selective serotonin/noradrenaline reuptake inhibitor rac-venlafaxine (rac-1a) (rac-1a, rac-1-[2-(dimethylamino)-1-(4-methoxyphenyl)ethyl]cyclohexan-1-ol; rac-1b, rac-1-[2-(dimethylamino)-1-(4-methoxyphenyl)ethyl]-1-silacyclohexan-1-ol). The synthesis and crystal structure analyses of rac-3 and rac-3 · HCl are reported, and the pharmacological properties of rac-1a, rac-1b, rac-2 (a sila-venlafaxine derivative with a silacyclopentanol skeleton instead of a silacyclohexanol framework), and rac-3 are compared (comparison of the pharmacological selectivity profiles with respect to serotonin, noradrenaline, and dopamine reuptake inhibition).     

A study on the stability,chirality, and theoretical spectra of the heterofullerenes C69X (X = N,P, As,B, Si,Ge)

There are two chiral and three achiral C₆₉X isomers possible. The achiral structures belong to the C_S group of symmetry while the chiral ones possess no symmetry elements. The stability of all five C₆₉X heterofullerenes for each of the X heteroatoms (X = N, P, As, B, Si, Ge) was determined at the (U)B3LYP/6-31G¹ level. The isomer population in an equilibrium mixture varies with the heteroatom type: the highest content of the chiral isomers was predicted for boron (92%) and nitrogen (47% plus 48%), while for the other heteroatoms studied the achiral isomers significantly dominate. For the chiral structures, four different sinister-rectus chirality measures, ^SRCM: pure geometrical, labeled, mass, and charge, were calculated by our CHIMEA program. We found that the labeled and mass chirality measures calculated for the two types of chiral isomers did correlate with each other. For each chiral C₆₉X molecule, spectroscopic VCD, IR, Raman, and NMR characteristics are discussed and demonstrated for their possible use for future identification and distinction of the isomers.     

Determination of serotonin and bufotenin as their dansyl derivatives.

A method is described which permits the determination of serotonin and bufotenin in the same tissue sample. It comprises the following steps: (a) tissue extraction with acetone-0.1 M hydrochloric acid (19:1); (b) reaction of the tissue extract with dansyl (Dns) chloride; (c) pre-separation of O-Dns-bufotenin from O,N-bis-Dns-serotonin and other Dns-amides on a small silica gel column (this step is dispensable if only serotonin or bufotonin is being determined); (d) TLC separation of O-Dns-bufotenin and O,N-bis-Dns-serotonin from other Dns derivatives; (e) quantitative evaluation of the separated compounds by fluorimetry for O-Dns-bufotenin and by fluorimetry or mass spectrometry for the serotonin derivative. The photometer response is linear within the range 0.1-300 nmole. With the mass spectrometric method, 2 pmole of O,N-bis-Dns-serotonin could be determined with a standard deivation of +/-9%. The recovery of the amines from tissue was better than 85%. Reserpine treatment of toads caused a concomitant decrease in serotonin and bufotenin in the brain, but not in the skin of the animals. Repletion of bufotenin in the brain occurs at a higher rate than the repletion of the serotonin pool.     

Thin-layer chromatographic separation of serotonin from epinephrine and norepinephrine

A thin-layer chromatographic procedure is reported for the separation of serotonin from epinephrine and norepinephrine. The method involves the use of ethylenediaminetetraacetic acid-impregnated silica gel G plates and n-butanol-ethanol-acetic acid-water (8:2:1:3) as developer. Serotonin is well separated from both epinephrine and norepinephrine. Epinephrine and norepinephrine overlapped slightly but were both detectable. The procedure is thus applicable to the separation of all three biogenic amines in spite of the absence of an absolutely clear separation of epinephrine from norepinephrine.     

(5R,7R)-5-Methylheptadecan-7-ol: a novel sex pheromone component produced by a female lichen moth, Miltochrista calamina, in the family Arctiidae

A methyl-branched heptadecanol was found in the pheromone gland extract of a female lichen moth, Miltochrista calamina (Arctiidae, Lithosiinae). GC-MS analyses of the alcohol and a hydrocarbon derived from it by subsequent treatments with methanesulfonyl chloride and LiAlD₄ in microscale reactions indicated 5-methylheptadecan-7-ol (1) as one possible structure. The four stereoisomers of 1 in a ratio of 4:4:1:1 were prepared from (S)-β-citronellol with 60% ee, and were separated by a combination of achiral and chiral HPLC columns. The absolute configuration of each isomer was determined by the comparison with the chromatographic behaviors of other samples synthesized by a different scheme, which applied the Jacobsen hydrolytic kinetic resolution of racemic 1,2-epoxydodecane to fix the configuration of the 7-hydroxy group. Only the (5R,7R)-isomer attracted male moths; thus, we concluded that M. calamina females secrete (5R,7R)-1 as a sex pheromone, indicating a new chemical class of lepidopteran female sex pheromones.     

Madey's theorems for free-electron devices,spontaneous emission,and applications

Two theorems due to Madey occupy a central position in free-electron laser physics: one relates the gain to the derivative of the spontaneous emission line shape and the other one relates it to the derivative of the electron energy spread in stimulated emission. We use quantum mechanical perturbation thoery of first order in the radiation field to give a general derivation of the theorems based on(a) the hermiticity of the electronfield interaction,(b) the applicability of lowest order perturbation theory, and(c) the assumption that the emitted photon have a sufficiently low energy. Assumption(b) restricts the validity of the theorems to the small-signal weak-field regime,(c) to the small recoil regime where the gain is classical. We use scalar quantum electrodynamics in the Furry picture in order to keep effects which are nonlinear in the undulator field, e.g. higher harmonic emission. We consider a fairly general one-dimensional (i.e. not having transverse variations) monochromatic undulator field (magnetic or optical undulator, linear or circular polarization, possible presence of a diffractive medium). An appendix considers nonmonochromatic fields. We derive explicit results for the linearly polarized and the helical undulator allowing for an arbitrary orientation of the undulator axis, the electron beam and the emitted radiation with respect to each other. In particular, we discuss the case of Gaussian modes where the applicability of the first theorem has been questioned. It turns out that the theorem is applicable provided that spontaneous emission into the Gaussian mode in question is considered (more generally, into whatever mode is of interest for the gain).     

Application of structural analogs of dimercaptosuccinic acid-functionalized silica nanoparticles (DMSA-[silica]) to adsorption of mercury, cadmium, and lead

In order to gain additional insight into mercury selectivity with nano-sized DMSA-[silica], we investigated a series of ligands related to DMSA, these are: monomercaptosuccinic acid; MMSA, 2-mercapto-4-methyl-5-thiazoleacetic acid; MCT, ortho-thiosalicylic acid; o-TSA and para-thiosalicylic acid; p-TSA. The MMSA chelate is structurally similar to DMSA except that it has only one thiol group. The chelates o-TSA and p-TSA each have one thiol and one carboxylic acid group. MCT includes neutral S and N atoms in close proximity to the thiolate binding site. MCT, o-TSA and p-TSA resemble each other in having equal numbers of carboxylic acid and thiol groups and formation of amide bonds with the linker on silica is expected to eliminate the carboxylate binding sites, making thiolates the only binding sites for Hg(II), Cd(II), and Pb(II) metals ions in the nano-sized; MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica]. Each of the nano-sized MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica], show a higher preference for Hg(II) over Cd(II) and Pb(II) compared to the same free chelates in solution, respectively. In addition, there are differences in the level of metal ion chelation for each functionalized silica nanoparticle. These differences in the degree of metal chelation for each functionalized silica nanoparticles surface are explained by the difference in thiolate/carboxylate ratio upon attachment to the surface and on steric reasons based on the orientation of the thiol groups on the surface. When attached via amide bond formation, the thiolate site in o-TSA-[silica] will face towards the silica surface, while for p-TSA-[silica], the thiolate site is expected to be pointed outwards and away from the silica surface. In comparing MMSA-[silica] to DMSA-[silica], the thiolate/carboxylate ratio decreases from 2/1 in DMSA-[silica] to 1/1 in MMSA-[silica] (assuming attachment via one amide bond in each case). This effect of increasing the ratio of thiolate to carboxylate upon attachment to the surface is believed to play a role in the selectivity enhancement towards Hg(II) over Cd(II) and Pb(II).     

Topological systematization of layered coordination compounds of Cu, Ag, Zn, and Cd

The topological analysis and systematization of basis lattices in 1972 coordination compounds of Cu, Ag, Cd, and Zn containing organic ligands and layered complex groups (both isolated and interlaced with each other) are carried out by the TOPOS structural topological program package. The structures considered are most frequently based on the square (sql) or hexagonal (hcb) Shubnikov lattice (38.6 and 18.7%, respectively). The increased specificity of the sql and hcb lattices is due to specific features of coordination of the lattices facilitating their mutual penetration. Two types of interlacing of the layered groups (parallel and inclined) are revealed, and the former predominates.     

Variation of melatonin and serotonin content in rat pineal gland with sex and oestrous phase difference determined by high-performance liquid chromatography with fluorimetric detection

Simultaneous determination of melatonin and serotonin in rat pineal gland is described using reversed-phase high-performance liquid chromatography with fluorimetric detection. These indoles were analysed isocratically within 15 min. In this work, veratric acid (3,4-dimethoxybenzoic acid), which has fluorescence characteristics (lambda ex = 290 nm, lambda em = 350 nm) around the wavelength of native fluorescence of melatonin (lambda ex = 285 nm, lambda em = 345 nm), was used as an internal standard. This method was applied to the determination of melatonin and serotonin in male and female rat pineal gland. No significant differences between the two groups were observed in the pineal melatonin and serotonin contents. The pineal melatonin and serotonin contents were compared with the oestrous and the di-oestrous phases of female rats. They were not widely different from each other.     

Neurotransmitter sampling and storage for capillary electrophoresis analysis

Quantitative analysis of signaling molecules from single cells and cellular materials requires careful validation of the analytical methods. Strategies have been investigated that enable single neurons and neuronal tissues to be stored before being assayed for many low-weight, biologically active molecules, such as serotonin, dopamine, and citrulline. Both metacerebral cell and pedal ganglia homogenates isolated from Pleurobranchaea californica have been studied by capillary electrophoresis with two complimentary laser-induced fluorescence detection methods. For homogenized ganglia samples, several cellular analytes (such as arginine and citrulline) are unaffected by standing at room temperature for days. Many other analytes in the biological matrix, including the catecholamines and indolamines, degrade by 20% within 10 h at room temperature. Rapidly freezing samples or preserving them with ascorbic acid preserves more than 80% of the dopamine and about 70% of the serotonin even after five days. In addition, serotonin and dopamine remain completely stable for at least five days by combining the ascorbic acid preservation and freezing at –20 °C. The timing of preservation is critical in maintaining the original composition of the biological samples. Using our optimum storage protocol of freezing the sample within 2 h after isolation, we can store frozen homogenate ganglia samples for more than four weeks before assay while still obtaining losses less than 10% of the original serotonin and dopamine. The nanoliter-volume single cell samples, however, must be analyzed within 4 h to obtain losses of less than 10% for serotonin related metabolites. Received: 23 August 2000 / Revised: 2 November 2000 / Accepted: 7 November 2000     

Extraction of metal ions by N-phenyl-, N-methyl-, and N-unsubstituted hydroxamic acid resins

Procedures are described for preparing macroreticular chelating resins with hydroxamic acid or N-methylhydroxamic acid functional groups. The chelating properties of the resins are compared with each other and with an N-phenylhydroxamic acid resin reported earlier. The extraction of 19 metal ions was studied as a function of pH for the N-methylhydroxamic acid resin. Several analytical applications of this resin have been demonstrated including the purification of chemical reagents, concentration of trace metal ions, and chromatographic separation of metal-ion mixtures.     

The determination of trace amounts of zirconium,hafnium, thorium and cerium in silicate rocks

A method is described for the determination of traces of zirconium, hafnium, cerium and thorium in rocks. After the sample has been opened up, these elements are separated from the major component elements by extraction from 10 N nitric acid with a 40% solution of tri-n-butyl phosphate, cerium being oxidised with bro-mate. After back-extraction the elements are separated from each other and from other extracted elements by cation exchange. Zirconium is determined photometrically with quinalizarin sulphonic acid which gives about twice the sensitivity of alizarin red S. Thorium is determined photometrically with thorin, and cerium by utilizing its bleaching action on iron(II) phenanthroline. Hf is determined spectro-graphically.     

Molecular dynamics simulation studies suggests unconventional roles of non-secretary laccases from enteropathogenic gut bacteria and Cryptococcus neoformans serotype D

Laccase in Cryptococcus neoformans is covalently linked to the carbohydrate moiety of the cell wall, which allows it to get access to the different substrates for catalyzing their oxidation and therefore plays a vital role in the virulence. The laccase gene (3.0 kb) from C. neoformans serotype D was amplified, cloned and sequenced for protein modeling, docking and simulation studies. The three dimensional homology models of laccase protein from C. neoformans and other pathogenic gut bacteria were docked with selected biomolecules like prostaglandins (PG), membrane phospholipids, neurotransmitters (serotonin) using GOLD software. The GOLDscore values of laccase from C. neoformans docked with prostaglandinH₂ (59.76), prostaglandinG₂ (59.45), prostaglandinE₂ (60.99), phosphatidylinositol (54.95), phosphatidylcholine (46.26), phosphatidylserine (55.26), arachidonic acid (53.08) and serotonin (46.22) were similar to the laccase from enteropathogenic bacteria but showed a better binding affinity as compared to that of the non-pathogenic bacteria (e.g. Bacillus safensis, Bacillus pumilus and Bacillus subtilis). The RMSD of MD simulation study done for 25 ns using laccase protein from C. neoformans complexed with phosphatidylcholine was found to be highly stable, followed by the laccase-PGE₂ and laccase-serotonin complexes. Furthermore, the binding free energy results were found to support the docking and MD simulation results. The present study implies that few candidate ligands can be intermediate substrate in the catalysis of microbial laccases, which can further play some crucial role in the cell signaling and pathogenesis of enteropathogenic gut micro flora and C. neoformans.     

Increasing the Efficacy of Seproxetine as an Antidepressant Using Charge–Transfer Complexes

The charge transfer interactions between the seproxetine (SRX) donor and π-electron acceptors [picric acid (PA), dinitrobenzene (DNB), p-nitrobenzoic acid (p-NBA), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), and 7,7′,8,8′-tetracyanoquinodi methane (TCNQ)] were studied in a liquid medium, and the solid form was isolated and characterized. The spectrophotometric analysis confirmed that the charge–transfer interactions between the electrons of the donor and acceptors were 1:1 (SRX: π-acceptor). To study the comparative interactions between SRX and the other π-electron acceptors, molecular docking calculations were performed between SRX and the charge transfer (CT) complexes against three receptors (serotonin, dopamine, and TrkB kinase receptor). According to molecular docking, the CT complex [(SRX)(TCNQ)] binds with all three receptors more efficiently than SRX alone, and [(SRX)(TCNQ)]-dopamine (CTcD) has the highest binding energy value. The results of AutoDock Vina revealed that the molecular dynamics simulation of the 100 ns run revealed that both the SRX-dopamine and CTcD complexes had a stable conformation; however, the CTcD complex was more stable. The optimized structure of the CT complexes was obtained using density functional theory (B-3LYP/6-311G++) and was compared.     

Comparison of restricted, unrestricted, inverse, and dual kinetic balances for four-component relativistic calculations

Various kinetic balances for constructing appropriate basis sets in four-component relativistic calculations are examined in great detail. These include the well-known restricted (RKB) and unrestricted (UKB) kinetic balances, the less-known dual kinetic balance (DKB) as well as the unknown inverse kinetic balance (IKB). The RKB and IKB are complementary to each other: The former is good for positive-energy states, whereas the latter good for negative-energy states. The DKB combines the good of both RKB and IKB and even provides full variational safety. However, such an advantage is largely offset by its complicated nature. The UKB does not offer any particular advantages as well. Overall, the RKB is the simplest ansatz. Although the negative-energy states by a finite RKB basis are in error of O(c ⁰), there is no objection to using them as intermediates for a sum-over-states formulation of perturbation theory, provided that the magnetic balance is also incorporated in the case of magnetic properties. In particular, the RKB is also an essential ingredient for formulating two-component relativistic theories, while all the others are simply incompatible. As such, the RKB should be regarded as the cornerstone of relativistic electronic structure calculations.     

Substituted propanes: VI. The vibrational spectra and conformations of 1,3-dichloro-, 1,3-bromochloro-, 1,3-dibromo- and 1,3-diiodo-propane

The infrared and Raman spectra of 1,3-dichloro-, 1,3-bromochloro-, 1,3-dibromo- and 1,3-diiodopropane were recorded as liquids and in the crystalline state at low temperatures. Crystals of 1,3-dibromo- and 1,3-diiodopropane formed under ca. 20 kbar pressure at ambient temperature were studied by infrared technique.No evidence was found for the GG₁ conformer (parallel C-halogen bonds), but the other three staggered conformers (GG, AA, and AG) (four for 1,3-bromo-chloropropane) were observed in the liquid. In all the stable low temperature crystals the GG conformers were present, at high pressure 1,3-dibromopropane crystallized in GG and 1,3-diiodopropane in the AA conformation. The C-halogen stretching vibrations have been interpreted in detail. A complete list of fundamentals have been proposed for the GG conformers in each compound, for 1,3-diiodopropane the additional AA fundamentals have been assigned whereas some AG bands were interpreted for each compound.     

Aluminum,gallium and indium chelates of salicylidene-o-aminophenol

Conditions necessary to determine spectrophotometrically the composition of the chelates of aluminum, gillium, and indium with salicylidene-o-aminophenol have been determined. Under these conditions, in each case a chelate containing a 2 : 1 ratio of salicylidene-o-aminophenol to metal is formed.     

Synthesis, crystal structure, and vibrational spectra of MVO(SO4)2 (M = Rb, Cs, or Tl)

A series of MVO(SO₄)₂ vanadium complexes, where M = Rb, Cs, or Tl, were prepared, and their crystal structures and physicochemical properties studied. The rubidium and thallium compounds of this series were found to be isostructural to each other and to crystallize, like KVO(SO₄)₂ and NH₄VO(SO₄)₂, in orthorhombic system (space group P2₁2₁2₁, No. 19, Z = 4) with the unit cell parameters a = 4.9735(2) Å, b=8.7894(4) Å, c = 16.6968(8) Å, V = 729.88 ų (Rb); and a = 4.9636(1) Å, b = 8.7399(2) Å, c = 16.8598(4) Å, V = 731.39 ų (Tl). The cesium compound was found to crystallize in monoclinic system (space group P2₁/a, No. 14-2, Z = 4): a = 10.0968(6) Å, b = 8.9131(4) Å, c = 9.8675(5) Å, β = 114.640(2)°, V = 807.16 ų. The MVO(SO₄)₂ crystal structure is built of VO₆ octahedra, which are linked into layers by bridging SO₄ groups. At the apex of each VO₆ octahedron, there is a short V-O terminal bond having a length of 1.54(1) Å (Rb), 1.57(2) Å (Tl), and 1.52(4) Å (Cs).