Spontaneous copolymerization of N-(2-hydroxyethyl)ethyleneimine with maleic anhydride

Summary The copolymerization of N-(2-hydroxyethyl)ethyleneimine, (HEEI) as nucleophilic monomer and maleic anhydride (MA) as electrophilic monomer in the absence of initiator in acetonitrile was investigated. Copolymers were characterized by IR, ¹H-NMR and ¹³C-NMR spectroscopy. The copolymer composition depends on the monomer ratio in the feed, determined by ¹H-NMR spectroscopy. The presence of MA bridges between copolymer chains was established by spectroscopic analysis. At lower temperature the yield and molecular weight of copolymers decrease as well as the MA unit content in the copolymer.     

An improved electrokinetic method to consolidate porous materials

Consolidation is considered one of the major restoration treatments applied on cultural heritage. This kind of treatment is focused on to preserve the external weathered layers of stone reducing their degradation caused by external alteration agents (mainly water and soluble salts). However the consolidation using commercial products have some limitations, such as: (1) low penetrability; (2) no chemical and mineralogical affinity with the material to treat and (3) release of toxic compounds (VOCs), during the solvent evaporation. In the last years, a new consolidation method based on electrokinetic techniques was developed. This method allows filling some pores by the precipitation of an inorganic compound. As a result the method allows increasing the penetration depth of current consolidation treatments. However, this method needs to be improved since: (1) no special care is taking in controlling the pH of the solutions in contact with the porous material, which can damage it and (2) it is difficult to determine in which area the consolidation takes place. In this study an electrokinetic consolidation method, which has two steps between which the current is reversed, is proposed to solve all of these problems. The results show that the proposed treatment achieves better results in terms of penetrability and durability of current consolidation treatments, and moreover prevent that the treated material to be exposed to extreme pH values.     

Silver Atomic Quantum Clusters of Three Atoms for Cancer Therapy: Targeting Chromatin Compaction to Increase the Therapeutic Index of Chemotherapy

Nanomaterials with very low atomicity deserve consideration as potential pharmacological agents owing to their very small size and to their properties that can be precisely tuned with minor modifications to their size. Here, it is shown that silver clusters of three atoms (Ag₃‐AQCs)—developed by an ad hoc method—augment chromatin accessibility. This effect only occurs during DNA replication. Coadministration of Ag₃‐AQCs increases the cytotoxic effect of DNA‐acting drugs on human lung carcinoma cells. In mice with orthotopic lung tumors, the coadministration of Ag₃‐AQCs increases the amount of cisplatin (CDDP) bound to the tumor DNA by fivefold without modifying CDDP levels in normal tissues. As a result, CDDP coadministered with Ag₃‐AQCs more strongly reduces the tumor burden. Evidence of the significance of targeting chromatin compaction to increase the therapeutic index of chemotherapy is now provided.     

Optimal Designs for Random Blocks Model Using Corrected Criteria

Many industrial experiments involve random factors. The random blocks model defines a covariance structure in the data, thus generalized least square estimators of the parameters are used, and their covariance matrix is usually computed using the inverse of the generalized least square estimators information matrix. Many optimality criteria are based on this approximation of the covariance matrix. However, this approach underestimates the true covariance matrix of the parameters, and thus, the optimality criteria should be corrected in order to pay attention to the actual covariance. The bias in the estimation of the covariance matrix is negligible (or even null) for many models, and for this reason in those cases, it has no sense to deal with the corrected criteria because of the complexity of the calculations involved. But for some models, the correction does have importance, and thus, the modified criteria should be considered when designing; otherwise, the practitioner may risk to deal with poor designs. Some analytical results are presented for simpler models, and optimal designs taking into account the corrected variance will be computed and compared with those using the traditional approach for more complex models, showing that the loss in efficiency may be very important when the correction for the covariance matrix is ignored. Copyright © 2015 John Wiley & Sons, Ltd.     

Copolymerization via zwitterion

Summary Copolymers of 2-methyl-2-oxazoline and phtalic anhydride without initiator were prepared at 60°C in DMF, CH₃CN and in bulk. The copolymers were statistical rich in 2-methyl-2-oxazoline and the -COCH₃ groups are partially hydrolized. The composition and the degree of hydrolysis of the copolymers were determined by ¹H-NMR. ¹³C-NMR proved that the hydrolisis did not occur during the polymerization process. A scheme of copolymerization via zwitterion is presented.     

Water‐insoluble polymers with ability to remove metal ions

Crosslinked poly[3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonium hydroxide‐co‐2‐acrylamido glycolic acid [P(MAAPDSA‐co‐AGCO)] was synthesized by radical polymerization and tested as an adsorbent under competitive and noncompetitive conditions for Cu(II), Cd(II), Hg(II), Zn(II), Pb(II), and Cr(III) by batch and column equilibrium procedures. The resin–metal ion equilibrium was achieved before 1 h. The resin showed a maximum retention capacity value for Hg(II) at pH 2 of 1.084 meq/g. The recovery of the resin was investigated at 20°C under different concentrations of HNO₃ and HClO₄. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3679–3685, 2004     

Simazine Fenton’s oxidation in a continuous reactor

The removal of the herbicide simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) in aqueous phase has been carried out continuously by means of Fenton’s reagent (Fe(II)+H₂O₂). The influence of the main operating parameters, Fe(II) concentration (5.0×10⁻⁵ to 4.0×10⁻⁴ M), pH (2–6) and temperature (10–30 °C) has been studied. Based on HPLC analysis, the main route of simazine removal has been proposed to be the dechlorination reaction to generate 2-hydroxy-4,6-bis(ethylamino)-s-triazine. Nevertheless the dealkylated first intermediate of the herbicide was also identified by chromatography techniques. By means of a pseudoempirical model based on the classic Fenton’s chemistry and the mass balances for a continuos perfectly mixed reactor, the theoretical evolution profiles of the species involved in the process have been calculated.     

Retention properties of efficient adsorbent to silver(I)

The binding capability of crosslinked poly(acrylic acid‐co‐2‐acrylamide‐2‐methyl‐1‐propane sulfonic acid) for silver(I) ions by the batch equilibrium method is investigated. The effects of the pH, temperature, time of contact, and resin–metal ion molar ratio on the retention ability are studied. The retention for silver(I) increases from 21.7% at pH 1 to 94.6% at pH 5. The adsorption capacity at pH 5 is 1.18 meq/g dry resin. The maximum load capacity at the optimum pH is determined. In order to recover the resin, elution runs in acid and basic media are carried out. The best eluent is 4M HNO₃ (84.9%). Moreover, retention–elution cycles are performed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1501–1506, 2002     

Metal‐ion‐retention properties of the poly(2‐acrylamido‐2‐methyl‐1‐propanosulfonic acid‐co‐4‐vinyl pyridine) resin

The water‐insoluble resin poly(2‐acrylamido‐2‐methyl‐1‐propanosulfonic acid‐co‐4‐vinyl pyridine), through a radical polymerization solution, was synthesized with ammonium persulfate as an initiator and N,N‐methylene bisacrylamide as a crosslinking reagent. The metal‐ion‐retention properties were studied by batch and column equilibrium procedures for the following metal ions: Hg(II), Cu(II), Cd(II), Zn(II), Pb(II), and Cr(III). These properties were investigated under competitive and noncompetitive conditions. The effects of the pH, maximum retention capacity, and regeneration capacity were studied. The resin showed a high retention ability for Hg(II) ions at pH 2.0. The retention of Hg(II) ions from a mixture of ions was greater than 90%. The resin showed a high selectivity for Hg(II) with respect to other metal ions. The Hg(II)‐loaded resin was able to be recovered with 4M HClO₄. The retention capacity was kept after four cycles of adsorption and desorption. The retention properties for Hg(II) were very similar with the batch and column methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3556–3562, 2003