Novel adsorbent based on silkworm chrysalides for removal of heavy metals from wastewaters

In this contribution, maximum capacity for adsorption of Pb(2+), Ni(2+), and Cu(2+) by silkworm chrysalides (SC) was determined. The raw silkworm chrysalides (SC(r)) and chrysalides after acidic washing (SC(w)) were used. Chitin (CT), extracted from SC, and chitosan (CS), with 85% deacetylation, were employed as reference samples. Adsorption tests showed that all the studied adsorbents exhibited excellent performance in removal of metals. The choice of a more appropriate adsorbent is related to its efficiency for removal of a specific metal. The studied materials presented different intensities for metal adsorption as follows: (i) Ni(2+)>Cu(2+)>Pb(2+) for SC(r); (ii) Pb(2+)>Cu(2+)>Ni(2+) for SC(w); (iii) Ni(2+)>Cu(2+)>Pb(2+) for CT; and (iv) Cu(2+)>Pb(2+)>Ni(2+) for CS. Metal adsorption onto SC(r) and CS was analyzed by Freundlich and Langmuir isotherm equations. Adsorption values for CS-Pb and SC(r)-Ni were provided by the Freundlich model, while the adsorption values for CS-Cu, CS-Ni, SC(r)-Pb, and SC(r)-Cu were provided by the Langmuir model. The studied adsorbents are suitable for use in treatment of wastewater. From the economic point of view, the use of SC(r) as an adsorbent of heavy metals (mainly Ni(2+)) on the large industrial scale would be more appropriate.     

Determination of diclofenac in pharmaceutical preparations by diffuse reflectance photometry

A quantitative analytical method for the determination of diclofenac in pharmaceutical preparations by diffuse reflectance in the visible region of the spectrum is presented. The color reaction is done directly in the measuring cell immediately after mixing, using small volumes of the analyte solution, of the reagent and of the buffer solutions. All reflectance measurements were carried out in a home made reflectometer equipped with a red LED as light source and a LDR as detector. The calibration curves were constructed from 1.0 to 18 mg mL⁻¹ (about 3.0 × 10⁻³ to 5.5 × 10⁻² mol L⁻¹) of sodium diclofenac or of potassium diclofenac in the analytical solution, with typical correlation coefficients equal to 0.999. The detection limit was estimated to be about 0.7 mg mL⁻¹ (2 × 10⁻³ mol L⁻¹). The method was applied to determine diclofenac in solid and liquid pharmaceutical preparations. The R.S.D. varied from 2% to 4% depending of the sample. The results were compared with those obtained with the HPLC procedure recommended by the United States Pharmacopoeia using the statistical Student's t-test procedure.     

Intrinsic acidity of dimethylhalonium ions: evidence for hyperconjugation in dimethylhalonium ylides in the gas phase

The intrinsic acidity of dimethylhalonium ions has been determined, both by theoretical methods and by gas-phase reactions of the isolated ions with pyridine bases. The calculated geometry of the dimethylhalonium ions shows a bent structure with the C-X-C angle decreasing in the order Cl > Br > I. Thermochemical calculations for the reaction of the dimethylhalonium ions with pyridine, 2,6-dimethylpyridine, and 2,6-di-tert-butylpyridine indicate that proton transfer, with the formation of the dimethylhalonium ylide is endothermic, whereas methyl transfer, with formation of methylhalide, is exothermic. The endothermicities for proton transfer are, nevertheless, dependent on the steric hindrance of the base. The bulkier the bases, the less endothermic the proton-transfer reaction is. Experimental gas-phase reactions support the calculations, showing that methyl transfer is the major reaction of dimethylchloronium and dimethyliodonium with pyridine, whereas proton transfer, as well as single electron transfer, is observed for the bulkier bases. The calculations also indicate that acidity increases in the order chloronium > bromonium > iodonium. NBO calculations predict that hyperconjugation with the sigma carbon-halogen orbital plays a role in stabilizing the halonium ylide species in the gas phase.     

Master integrals for double real radiation emission in heavy-to-light quark decay

We evaluate analytically the master integrals for double real radiation emission in the \(b \rightarrow u W^*\) decay, where b and u are a massive and massless quark, respectively, while \(W^{*}\) is an off-shell charged weak boson. Since the W boson can subsequently decay in a lepton anti-neutrino pair, the results of the present paper constitute a further step toward a fully analytic computation of differential distributions for the semileptonic decay of a b quark at NNLO in QCD. The latter partonic process plays a crucial role in the study of inclusive semileptonic charmless decays of B mesons. Our results are expressed in terms of multiple polylogarithms of maximum weight four.     

Shock Fluctuations for the Hammersley Process

We consider the Hammersley interacting particle system starting from a shock initial profile with densities \(\rho ,\lambda \in {\mathbb R}\) (\( \rho < \lambda \)). The microscopic shock is taken as the position of a second-class particle initially at the origin, and the main results are: (i) a central limit theorem for the shock; (ii) the variance of the shock equals \(2[\lambda \rho (\lambda - \rho )]^{-1}t + O(t^{2/3})\). By using the same method of proof, we also prove similar results for first-class particles.     

Introduction to Topological Phases and Electronic Interactions in (2+1) Dimensions

A brief introduction to topological phases is provided, considering several two-band Hamiltonians in one and two dimensions. Relevant concepts of the topological insulator theory, such as: Berry phase, Chern number, and the quantum adiabatic theorem, are reviewed in a basic framework, which is meant to be accessible to non-specialists. We discuss the Kitaev chain, SSH, and BHZ models. The role of the electromagnetic interaction in the topological insulator theory is addressed in the light of the pseudo-quantum electrodynamics (PQED). The well-known parity anomaly for massless Dirac particle is reviewed in terms of the Chern number. Within the continuum limit, a half-quantized Hall conductivity is obtained. Thereafter, by considering the lattice regularization of the Dirac theory, we show how one may obtain the well-known quantum Hall conductivity for a single Dirac cone. The renormalization of the electron energy spectrum, for both small and large coupling regime, is derived. In particular, it is shown that massless Dirac particles may, only in the strong correlated limit, break either chiral or parity symmetries. For graphene, this implies the generation of Landau-like energy levels and the quantum valley Hall effect.     

A liquid chromatography‐atmospheric pressure photoionization tandem mass spectrometric (LC‐APPI‐MS/MS) method for the determination of triterpenoids in medicinal plant extracts

An analytical method using liquid chromatography‐atmospheric pressure photoionization tandem mass spectrometry with toluene as a dopant was developed for the determination of triterpenes in medicinal plant extracts. The 12 compounds determined have been shown to exhibit biological activity, such as gastroprotective, hepatoprotective, anti‐inflammatory, antiviral and anti‐tumor effects. The parameters of the atmospheric pressure photoionization interface were optimized to obtain the highest possible sensitivity for all of the compounds. The limits of detection and quantification ranged from 0.4 to 157.9 µg l^?1 and 1.3 to 526.4 µg l^?1, respectively. The method was validated and applied to extracts of five medicinal plants species (Mansoa alliacea (Lam.) A.H.Gentry, Bauhinia variegata var variegata, Bauhinia variegata var alboflava, Cecropia obtuse Trécul and Cecropia palmate Willd) from the Amazonian region. The concentrations of the six triterpenes quantified in the samples ranged from 0.424 mg kg^?1 for ursolic acid to 371.96 mg kg^?1 for β‐amyrin, which were quantified by using the standard addition method (n = 3). Copyright © 2016 John Wiley & Sons, Ltd.     

Measuring void fraction and velocity fields of a stepped spillway for skimming flow using non-intrusive methods

Stepped spillways have higher energy dissipation than smoother hydraulic structures used to divert flood discharges. The inception point related to air entrainment is, however, located further upstream causing an undesired bulking of the flow depth. For large discharge rates and for straight stepped spillways, the skimming flow regime may be assumed two dimensional; this is an attractive feature for the application of non-intrusive flow visualization techniques because these methods measure the flow characteristics in the vicinity of the sidewalls which are likely to correlate with the flow at the centre of the flume. This paper tests the hypothesis that such techniques can be used to measure the flow inside the flume. The hypothesis is tested against measurements taken with an intrusive probe. Void fraction contour lines and velocity fields are obtained in 12 different stepped spillway configurations using the image processing procedure and the bubble image velocimetry, respectively. The void fraction and velocity results are overall consistent with the probe measurements. The velocity fields show a persistent underestimation of the probe measurements which can at least be partially explained by sidewall effects and possible probe’s overestimation.     

Syntheses, structural and spectroscopic characterization of novel zinc(II)-bis(trithiocarbimato) complexes and bis(N-methylsulfonyldithiocarbimate)-sulfide

Four zinc(II)-bis(trithiocarbimato) complexes with the general formula A₂[Zn(RSO₂NCS₃)₂] [A = Ph₄P⁺: R = CH₃ (1), 4-CH₃C₆H₄ (2); A = Bu₄N⁺: R = CH₃ (3), 4-CH₃C₆H₄ (4)] were obtained by the reaction of sulfur with the correspondent zinc(II)-bis(dithiocarbimato) complexes. Additionally, the compound (Ph₄P)₂[(CH₃SO₂NCS₂)₂S)] (5) was prepared from the potassium methylsulfonildithiocarbimate by oxidation with iodine. The compounds were characterized by elemental analyses and IR, ¹H NMR and ¹³C NMR spectroscopies. The compounds 4 and 5 were also characterized by X-ray diffraction techniques. The compound 4 crystallizes in the centrosymmetric space group C2/c of the monoclinic system. The Zn(II) is in a distorted tetrahedral environment (ZnS₄) in compound 4, and differ from the coordination mode observed in compound 1, which involves one sulfur and one nitrogen atom of each trithiocarbimate ligand. Compound 5 is the first example of a compound containing a bis(N-alkylsulfonyldithiocarbimate)-sulfide dianion and crystallises in the non-centrosymmetric space group P4₁2₁2 of the tetragonal system.     

Poly[di‐μ‐aqua‐[μ6‐N‐(4‐bromophenylsulfonyl)dithiocarbimato]dipotassium] and poly[di‐μ‐aqua‐[μ4‐N‐(4‐iodophenylsulfonyl)dithiocarbimato]dipotassium]

The rigid organic linkers N‐(4‐bromophenylsulfonyl)dithiocarbimate(2−) and N‐(4‐iodophenylsulfonyl)dithiocarbimate(2−) crystallize with two potassium cations and two water molecules in their asymmetric units, forming the title coordination polymers, [K₂(C₇H₄BrNO₂S₃)(H₂O)₂]_n and [K₂(C₇H₄INO₂S₃)(H₂O)₂]_n. The anions and the water molecules link the potassium cations into broad two‐dimensional networks, which are further linked by K...halide interactions.