Binding of hexacyanoferrate(II) by aliphatic amines in aqueous solution

The stability of hexacyanoferrate(II)-amine(methylamine, ethylenediamine, diethylenetriamine and tetraethylenepentamine) was determined potentiometrically. Species Fe(CN)₆(A)H _j ^(j–4) (A=amine) are formed in all the systems investigated, with j=1...n+2 (n=number of aminogroups). Some other complexes Fe(CN)₆(A)_iH_j (with i>1) were also found. The stability of these complexes is fairly high: the full protonated amine species, show for the reaction Fe(CN)₆ ^4- + H_nAⁿ⁺ = Fe(CN)₆(A)H_n ^(n-4) an equilibrium constant given by logK=0.686+2.10n. Factors affecting the stability are discussed in comparison with similar systems, together with the importance of interferences.     

NMR and potentiometric determination of the high pK values and protonation sequence of dipyridino-hexaaza-28-crown-8 and its interactions with selenate,sulfate and nitrate ions in aqueous solution

The aqueous protonation and anion-binding SeO ₂ ^–/4 SO _2– ⁴ , and NO _– ³ ) constants of the macrocyclic polyamine ligand, dipyridino-hexaaza-28-crown-8(L), were measured in 0.1M KCl using a potentiometric titration technique. The protonation sequence of the aza groups of L was studied in D₂O from the chemical shifts of the nonlabile protons so as to find the charge distribution geometry as a function of pD. The study indicates that in 0.1M KC1 fully protonated L forms stable l: 1 complexes with SeO _2– ⁴ (logK=3.68) and SO _2– ⁴ (logK=3.55), but not with NO _– ³ (logK < l.5). All of the amine pK values were above 6.3, thus allowing the use of the protonated form of this ligand over a wide pH range.     

Complexes of tri- and tetra-protonated forms of 1,4,8,12-tetraazacyclopentadecane with chloride,nitrate, iodate,and sulfate ions in aqueous media: I. Formation constants,thermodynamic properties,and bonding mechanisms

Complexation stoichiometries and formation constants of tri- and tetra-protonated forms of 1,4,8,12-tetraazacyclopentadecane with NO ₃ ^– , Cl^–, IO ₃ ^– and SO ₄ ^2– ions are determined by pH potentiometric and¹³C NMR spectrometric measurements. Estimates of H and S are obtained from the values of the temperature dependent formation constants and acid dissociation constants. All four anions form only 1 : 1 complexes with the triprotonated amine species. NO ₃ ^– and Cl^– form 1 : 1 complexes only with the tetraprotonated amine, while IO ₃ ^– and SO ₄ ^2– form both 1 : 1 and 2 : 1 complexes. The complexation behavior is interpreted in terms of solvation and internal hydrogen bonding interactions.     

Silver Nanoparticles in Polyacrylamide and Hyperbranched Polyamine Matrix

Silver nanoparticles have been prepared in a polyacrylamide (PA) matrix, as well as in the presence of a hyperbranched polyamine/polyacrylamide combined system (HB‐PA) by using a reductive technique. The stability of colloidal solution of silver nanoparticles is higher (5 months) in combined matrix compared to PA alone (4 months). The prepared silver nanoparticles were characterized by different spectroscopic and analytical techniques such as FTIR, UV‐visible, X‐ray diffraction, TEM etc. TEM and XRD studies confirmed the formation of well‐dispersed nanoparticles with an average size of 9.91 nm and 8.5 nm for PA and HB‐PA matrices, respectively. The antibacterial activity of silver nanoparticles in both the matrices was tested against Bacillus Subtilis bacteria by using the diffusion disc technique. The result shows that the antibacterial activity of the active agent, Ag(0) is a little higher in the case of HB‐PA system. The dielectric constant of the matrices decreases with an increase in frequency, but the values increase with an increase of concentration of silver nanoparticles in PA matrix.     

Comparison of Two Rhodamine-Polyamine Polystyrene Solid-phase Fluorescence Sensors for Hg(II) Detection Based on Theoretical Calculation

Two novel rhodamine-based polystyrene solid-phase fluorescence sensors PS-PA-I and PS-PA-II with different lengths of polyamines were synthesized for Hg(II) determination. The detection mechanism involving the Hg(II) chelation-induced spirocycle open of rhodamine was proposed with the aid of theoretical calculation. The stronger N-Hg bond and the longer polyamine chain in PS-PA-II led to a better selectivity, much higher and more quickly fluorescence response to Hg(II).     

Applying Text Analytics for Studying Research Trends in Dependability

The dependability of systems and networks has been the target of research for many years now. In the 1970s, what is now known as the top conference on dependability—The IEEE/IFIP International Conference on Dependable Systems and Networks (DSN)—emerged gathering international researchers and sparking the interest of the scientific community. Although it started in niche systems, nowadays dependability is viewed as highly important in most computer systems. The goal of this work is to analyze the research published in the proceedings of well-established dependability conferences (i.e., DSN, International Symposium on Software Reliability Engineering (ISSRE), International Symposium on Reliable Distributed Systems (SRDS), European Dependable Computing Conference (EDCC), Latin-American Symposium on Dependable Computing (LADC), Pacific Rim International Symposium on Dependable Computing (PRDC)), while using Natural Language Processing (NLP) and namely the Latent Dirichlet Allocation (LDA) algorithm to identify active, collapsing, ephemeral, and new lines of research in the dependability field. Results show a strong emphasis on terms, like ‘security’, despite the general focus of the conferences in dependability and new trends that are related with ’machine learning’ and ‘blockchain’. We used the PRDC conference as a use case, which showed similarity with the overall set of conferences, although we also found specific terms, like ‘cyber-physical’, being popular at PRDC and not in the overall dataset.     

两个多胺铜配合物的合成，晶体结构以及DNA切割活性

本文以配体N,N′-二(3-氨丙基)-4-甲氧基苄胺(amba)与4,4′-联吡啶,铜盐反应合成了两种多胺Cu(Ⅱ)配合物[Cu(amba)Cl2](1)和[Cu(4,4′-bipy)(amba)(ClO4)]ClO4(2),通过红外光谱、质谱和X-射线单晶衍射对其结构进行了表征。利用紫外吸收光谱、分子荧光,电化学以及粘度试验研究了配合物与小牛胸腺DNA(CT-DNA)的相互作用方式。通过紫外吸收光谱得到配合物1和2与DNA的结合常数Kb分别为1.3×104 mol-1.L和1.7×104 mol-1.L,荧光光谱得到配合物1和2的荧光淬灭常数分别为1.04×103mol-1.L和1.81×103 mol-1.L,表明了配合物1和2与CT-DNA结合方式均为静电模式。凝胶电泳实验的结果表明配合物对pBR322 DNA的切割均为水解切割。     

Synthesis, Characterization and Inclusion Properties of an Iron(II) Polyimine Complex Derived from 2,6-Diacetylpyridine and an Aliphatic Polyamine

A novel multibinding species has been obtained by attaching four aliphatic polyamine chains to an iron(II)-polyimine centre, derived from 2,6-diacetylpyridine. Molecular simulations for the complex corroborate the evidence from 1H NMR spectroscopy of a symmetric structure, with the four polyamines displaying a tetrahedral arrangement around the metal centre. The protonated polyamine complex interacts with hexacyanoferrate(II) ions, leading to an inclusion compound which has been characterized based on vibrational and Mössbauer spectroscopy, and on cyclic voltammetry.     

The value of competitive information in forecasting FMCG retail product sales and the variable selection problem

Sales forecasting at the UPC level is important for retailers to manage inventory. In this paper, we propose more effective methods to forecast retail UPC sales by incorporating competitive information including prices and promotions. The impact of these competitive marketing activities on the sales of the focal product has been extensively documented. However, competitive information has been surprisingly overlooked by previous studies in forecasting UPC sales, probably because of the problem of too many competitive explanatory variables. That is, each FMCG product category typically contains a large number of UPCs and is consequently associated with a large number of competitive explanatory variables. Under such a circumstance, time series models can easily become over-fitted and thus generate poor forecasting results.     

Electrospray Mass Spectrometry Study on Polynuclear Pd(II) and Ni (II) Complexes of 3, 6, 9, 16, 19, 22‐Hexaazatricyclo [22. 2.2.211,14] triaconta‐11, 13, 24, 26 (1), 27, 29‐Hexaene

Polynuclear Pd(II) and Ni(II) complexes of macrocyclic polyamine 3,6,9,16,19,22‐hexaazatricyclo[22.2.2.2^11,14]‐triaconta 11,13,24,26(l),27,29‐hexaene (L) in solution were investigated by electrospray ionization mass spectrometry (ESIMS). For methanol solution of complexes M₂LX₄ (M = Pd(II) and Ni(II), X= Cl and I), two main clusters of peaks were observed which can be assigned to [M₂LX₃]⁺ and [M₂LX₂]²⁺. When Pd₂LCl₄ was treated with 2 or 4 mol of AgNO₃, it gave rise formation of Pd₂LCl₂ (NO₃)₂ · H₂O and [Pd₂L(H₂O)_m(NO₃)_n]^(4‐n)+, respectively. ESMS spectra show that the dissociation of the former in the ionization process gave peaks of [Pd₂LCl₂]²⁺ and [(Pd₂LCl₂)NO₃]⁺, while dissociation of the later gave the peaks of [Pd₂L(CH₃CO₂)₂]²⁺ and [Pd₂L(CH₃CO₂)₂](NO₃) ⁺ in the presence of acetic acid. Similar species were observed for Pd₂LI₄ when treated with 4 mol of AgNO₃. When [Pd₂L · (H₂O)_m(NO₃)_n]^(4‐n)+ reacted with 2 mol of oxalate anions at 40°C, [Pd₄L₂(C₂O₄)₂(NO₃)₂]²⁺ and [Pd₄L₂(C₂O₄)₂ (NO₃)]³⁺ were detected. This implies the formation of square‐planar molecular box Pd₄L₂(C₂O₄)₂(NO₃)₄ in which C₂O₄^? may act as bridging ligands as confirmed by crystal structure analysis. The dissociation form and the stability of complex cations in gaseous state are also discussed. This work provides an excellent example of the usefulness of ESIMS in the identification of metal complexes in solution.