Polyepoxysuccinic acid with hyper-branched structure as an environmentally friendly scale inhibitor and its scale inhibition mechanism

In order to improve the scale inhibition efficiency of existing polyepoxysuccinic acid (PESA) and to study the impact of their molecular structure on scale inhibition efficiency, a series of PESA with linear and hyper-branched structure have been designed and synthesized through co-polymerization reaction with glycidyl and epoxy succinate. The scale inhibition behavior of PESA with linear and hyper-branched structure against CaCO₃ and CaSO₄ scales was evaluated using static scale inhibition method, and their ability to retard deposition of CaCO₃ was also examined. The experimental results showed that, for CaCO₃ and CaSO₄, the PESA with hyper-branched structure provides a scale inhibiting efficiency as high as 95.9% and 94.3%, respectively, at an inhibitor concentration of 15?mg/L. In addition, the processes of crystal nucleation, growth and crystal morphology have been analyzed. The experimental results show that the PESA with hyper-branched structure not only prolongs the induction period of CaCO₃ crystal nucleation, but also reduces the number of crystal nuclei and changes the size and morphology of the CaCO₃ crystal. Moreover, the FTIR, SEM and XRD analyses showed that the PESA with hyper-branched structure can induce the irregularity of growing CaCO₃ crystal, destroy the formation of crystals and change the polymorphs of calcium scale crystal. This conclusion indicates that the prepared PESA with hyper-branched structure has great potential for applying in the treatment of industrial water.     

pH Resistant Ratiometric Measurement of Nicotinamide Adenine Dinucleotide Levels by Time-resolved Fluorescence Spectroscopy

Circular permutation fluorescent protein is a novel method to construct biosensors. The ratio of two excitation channels is employed to quantitatively calibrate the level of analysts. SoNar is one of them, which can be used to monitor cellular NADH/NAD⁺ levels. However, the 490 nm excitation channel of these biosensors is sensitive to pH environments, which is negative in real applications. In this work, we demonstrated that the fractional intensity ratio extracted from time-resolved fluorescence spectroscopy could be used to quantify NADH levels with one excitation (420 nm) and one emission channels. The 420-nm excitation channel was pH resistant. Comparing to average lifetime, the fractional intensity ratio had a 3.2-fold dynamic range, which was much wider than average lifetimes.     

Bis­(tetra­phenyl­phospho­nium) (μ‐tetra­thio­tungstenio‐κ4S,S′:S′′:S′′′)­bis­[(cyano‐κC)­cuprate](2–) aceto­nitrile solvate monohydrate

The reaction of CuCN and KCN with (NH₄)₂[WS₄] followed by cation exchange with PPh₄Br produced the title compound, (C₂₄H₂₀P)₂[Cu₂WS₄(CN)₂]·CH₃CN·H₂O or (PPh₄)₂[(NC)Cu(μ‐S)₂W(μ‐S)₂Cu(CN)]·MeCN·H₂O. In the structure of the dianion, [(NC)Cu(μ‐S)₂W(μ‐S)₂Cu(CN)]²⁻, the WS₄ moiety acts as a bidentate ligand that binds two CuCN groups, thus forming a slightly bent WCu₂ core with approximate D_2d symmetry. The W—Cu distances are in the range 2.6463 (6)–2.6545 (6) Å.     

A facile route to vinyl- and arylphosphonates by vinyl and aryl radical trapping with (MeO)3P

The generation of vinyl or aryl radicals under classical, thermal AIBN/n-Bu(3)SnH conditions at 80 degrees C in the presence of an excess of (MeO)(3)P gives rise to the corresponding vinyl- or arylphosphonates in good yields. This approach complements the photochemical reactions of the same systems previously used. Reactions with the individual stereoisomers of MeCH=CHMeBr (thermal AIBN/n-Bu(3)SnH conditions) afford a radical-equilibrated 96/4 E/Z ratio of vinylphosphonates. Substitution of (TMS)(3)SiH for n-Bu(3)SnH yields an approximately 1/1 ratio of separable E and Z vinylphosphonate diastereomers.     

Z‐bpy,a New C2‐Symmetric Bipyridine Ligand and Its Application in Enantioselective Copper(I)‐Catalyzed Cyclopropanation of Olefins

A rigid C₂‐symmetric chiral bipyridine ligand Z‐bpy with a triptycene‐like backbone was designed and synthesized from simple chemicals in a scalable route. Using this new ligand, copper(I) catalyzed cyclopropanation of styrenes with commercial ethyl diazoacetate produced various corresponding cyclopropanes in high yields, diastereoselectivity and enantioselectivity up to 97% ee.     

Analysis of sialic acid levels in Chinese intravenous immunoglobulins by high‐performance liquid chromatography with fluorescence detection

Intravenous immunoglobulin (IVIg) is increasingly used for the treatment of autoimmune and systemic inflammatory diseases with both licensed and off‐label indications. Recent studies indicated that IVIg‐mediated immunomodulation and anti‐inflammation are closely associated with the IgG sialylation, especially with IgG crystallizable fragment (Fc) sialylation. The sialic acid levels of the IgG molecules and Fc fragments in 12 IVIg preparations from six Chinese manufacturers were evaluated. The Fc fragments were derived from the papain digestion of IVIg, followed by affinity and size exclusion chromatography. The sialic acid levels in Fc fragments and IVIg preparations were determined by high‐performance liquid chromatography with fluorescence detection, after the sialic acid residues were released from the proteins. The results showed that the sialic acid levels in Chinese IVIg preparations ranged from 0.875 (mol/mol IgG) to 1.085 (mol/mol IgG), and the sialic acid levels in Fc fragments were from 0.321 (mol/mol Fc) to 0.361 (mol/mol Fc). Furthermore, the sialic acid levels of IVIg preparations and Fc fragments from different Chinese manufactures were significantly different. These findings will contribute to an increased understanding of Chinese IVIg preparations and the relationship between the sialic acid levels in IVIg preparations and their clinical efficacy in future clinical studies.     

Regulating PdC3/PtC3···thiophene interaction by small molecule doping (AgOTf,CuBr, CuI,CuBr2, PdCl2)

Structural Chemistry - The influences of small molecule doping on PdC3/PtC3···thiophene interaction have been investigated by atoms in molecules (AIM) theory, electron location...