Efficient removal of hexavalent chromium and lead from aqueous solutions by s‐triazine containing nanoporous polyamide

s‐Triazine containing dicarboxylic acid was synthesized. Then, it was reacted with 1,3‐phenylenediamine in molten tetrabutylammonium bromide to formed soluble aromatic polyamide with good yield and moderate inherent viscosity of 0.35 dL g^?1. The solubility and flexibility of polyamides are low. So, we used ether group such as di(4‐aminephenyl) ether in building polyamide. The structure of monomer and polymer was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and proton nuclear magnetic resonance techniques. Thermogravimetric analysis was used to evaluate the thermal properties of synthesized polyamide, and their results show that this polymer had a good thermal stability. The surface morphology of s‐triazine containing polyamide was studied by field emission‐scanning electron microscopy and transmission electron microscopy, and the results show that it has a porous morphology and moderate Brunauer–Emmett–Teller specific surface (367 m² g^?1). It was further investigated for Pb (II) and Cr(VI) ion removal by optimizing the parameters including pH and contact time. The maximum uptakes of Pb(II) and Cr(VI) at pH 5.0 and pH 4.0 are 57% and 76%, respectively. Also, sorption kinetics of this polymer was investigated. Copyright © 2017 John Wiley & Sons, Ltd.     

Conducting hydrogels based on semi‐interpenetrating networks of polyaniline in poly(acrylamide‐co‐itaconic acid) matrix: synthesis and characterization

In this work, acrylamide/itaconic acid copolymeric hydrogels are prepared by free radical polymerization initiated by redox initiators of potassium persulfate and N ,N ,N ′,N ′‐tetramethyl ethylene diamine; N ,N ′methylene bisacrylamide was employed as a crosslinking agent. Aniline monomer was absorbed in the network of poly(acrylamide‐co‐itaconic acid) P(AAm‐co‐IA) hydrogel and followed by gamma radiation induced polymerization at room temperature. The novel semi‐interpenetrating network was comprised of linear polyaniline immersed in P(AAm‐co‐IA) matrix. Electrical conductivity of the hydrogels was measured using four‐probe technique. The conductivities for the prepared hydrogels are found to increase from 5.5 × 10^?7 S cm^?1 for P(AAm‐co‐IA) alone to 4.4 × 10^?3 S cm^?1 for semi‐interpenetrating polymer network P(AAm‐co‐IA)/polyaniline. Thus, a new composite hydrogel with good conductive properties also displaying enhanced mechanical strength and pH sensitivity was prepared. Copyright © 2017 John Wiley & Sons, Ltd.     

Step‐Growth Polymerizing Systems of General Type “AfiBgi”: Calculating the Radius of Gyration and the g‐Curve Using Generating Functions and Recurrences

Step‐growth polymerized systems of general type “AfiBgi” are considered. One or more of the monomer species carries at least three reactive groups and thus can act as a branching point in a polymeric molecule. An algorithmic method is presented to calculate the topology‐averaged square radius of gyration, R ²[s ], of the molecules in the class of s‐mers. The degree of polymerization, s , may run through its full range. In addition to R ²[s ], the shrinking factor, g [s ], is calculated. The method uses integer arithmetic, generating functions, and computer algebra.

     

Poly(HEMA-co-AA) microparticles for removal of aluminum: The reason for Alzheimer's

Aluminum is one of the most toxic metals causing a variety of neurologic diseases, especially Alzheimer's disease. It is impossible to avoid contact with aluminum because of its existence in food to medications. Therefore, removal of aluminum from the blood or wastewater is urgently important. The cost-effective and easy-to-prepare adsorbents are needed to get efficient aluminum removal. For that purpose, the poly(2-hydroxyethylmethacrylate-co-acrylic acid), poly(HEMA-co-AA), microparticles was synthesized to remove aluminum in a very short interaction time. The achievement of the desired polymeric structure was confirmed via Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM), etc. Additionally, particle features such as swelling ratio, size, and surface area were determined. The microparticles synthesized in this study have been determined with very good adsorption capacity even in small aluminum concentrations.     

Synthesis,electrolyte properties and solar cell performance of hyperbranched poly(aryl-ether-urea)s

Hyperbranched poly(aryl-ether-urea)s with phenyl, N,N-dimethylamino ethyl and polyethylene oxide end-groups linked through urethane group – HBPEU-1, HBPEU-2 and HBPEU-3 respectively – were synthesized from an AB₂-type blocked isocyanate monomer and characterized by FT-IR, ¹H-NMR, SEC-MALLS, TGA and DSC techniques. The molecular weight of the polymers were found to be ranged from 4.9 × 10³ ? 1.96 × 10⁴ g/mol. The TGA results showed that the polymers decompose between 175°C – 220°C. In the DSC curves, HBPEU-1 and HBPEU-3 showed T_g at 160°C and 53°C respectively, whereas HBPEU-2 did not showed clear T_g. All the three polymers were converted into polymer electrolytes by doping with LiI/I₂. The doped polymers showed remarkably high ionic conductivity, up to 222 – 277 times compared to the un-doped polymers and the highest conductivity was observed with doped HBPEU-2. The TiO₂ based dye-sensitized solar cells (DSSCs) were fabricated using the doped polymer electrolytes and their performance was tested; HBPEU-2 showed good performance by yielding energy conversion efficiency (η) of 4.5%.     

Effects of covalent modification by 4‐hydroxy‐2‐nonenal on the noncovalent oligomerization of ubiquitin

When lipid membranes containing ω‐6 polyunsaturated fatty acyl chains are subjected to oxidative stress, one of the reaction products is 4‐hydroxy‐2‐nonenal (HNE)—a chemically reactive short chain alkenal that can covalently modify proteins. The ubiquitin proteasome system is involved in the clearing of proteins modified by oxidation products such as HNE, but the chemical structure, stability and function of ubiquitin may be impaired by HNE modification. To evaluate this possibility, the susceptibility of ubiquitin to modification by HNE has been characterized over a range of concentrations where ubiquitin forms non‐covalent oligomers. Results indicate that HNE modifies ubiquitin at only two of the many possible sites, and that HNE modification at these two sites alters the ubiquitin oligomerization equilibrium. These results suggest that any role ubiquitin may have in clearing proteins damaged by oxidative stress may itself be impaired by oxidative lipid degradation products. Copyright © 2016 John Wiley & Sons, Ltd.     

Rasagiline-encapsulated chitosan-coated PLGA nanoparticles targeted to the brain in the treatment of parkinson's disease

The aim of this study was to investigate the brain targeting potential of rasagiline-encapsulated chitosan-coated PLGA nanoparticles (RSG-CS-PLGA-NPs) delivered intranasally into the brain. Chitosan-coated PLGA nanoparticles (RSG-CS-PLGA-NPs) were developed through double emulsification-solvent evaporation technique. RSG-CS-PLGA-NPs were characterized for particle size, zeta potential, size distribution, encapsulation efficiency, and in vitro drug release. The mean particle size, polydispersity index, and encapsulation efficiency were found to be 122.38?±?3.64, 0.212?±?0.009, and 75.83?±?3.76, respectively. High-performance liquid chromatography–mass spectroscopy and mass spectroscopy study showed a significantly high mucoadhesive potential of RSG-CS-PLGA-NPs and least for conventional and homogenized nanoformulation. Pharmacokinetic results of RSG-CS-PLGA-NPs in Wistar rat brain and plasma showed a significantly high (**p?<?0.005) AUC_0-24 and amplified C_max over intravenous treatment group. Finally, the investigation demonstrated that intranasal delivery of mucoadhesive nanocarrier showed significant enhancement of bioavailability in brain, after administration of the RSG-CS-PLGA-NPs which could be a substantial achievement of direct nose to brain targeting in Parkinson’s disease therapy and related brain disorders.     

Parsing disease‐relevant protein modifications from epiphenomena: perspective on the structural basis of SOD1‐mediated ALS

Conformational change and modification of proteins are involved in many cellular functions. However, they can also have adverse effects that are implicated in numerous diseases. How structural change promotes disease is generally not well‐understood. This perspective illustrates how mass spectrometry (MS), followed by toxicological and epidemiological validation, can discover disease‐relevant structural changes and therapeutic strategies. We (with our collaborators) set out to characterize the structural and toxic consequences of disease‐associated mutations and post‐translational modifications (PTMs) of the cytosolic antioxidant protein Cu/Zn‐superoxide dismutase (SOD1). Previous genetic studies discovered >180 different mutations in the SOD1 gene that caused familial (inherited) amyotrophic lateral sclerosis (fALS). Using hydrogen–deuterium exchange with mass spectrometry, we determined that diverse disease‐associated SOD1 mutations cause a common structural defect – perturbation of the SOD1 electrostatic loop. X‐ray crystallographic studies had demonstrated that this leads to protein aggregation through a specific interaction between the electrostatic loop and an exposed beta‐barrel edge strand. Using epidemiology methods, we then determined that decreased SOD1 stability and increased protein aggregation are powerful risk factors for fALS progression, with a combined hazard ratio > 300 (for comparison, a lifetime of smoking is associated with a hazard ratio of ~15 for lung cancer). The resulting structural model of fALS etiology supported the hypothesis that some sporadic ALS (sALS, ~80% of ALS is not associated with a gene defect) could be caused by post‐translational protein modification of wild‐type SOD1. We developed immunocapture antibodies and high sensitivity top‐down MS methods and characterized PTMs of wild‐type SOD1 using human tissue samples. Using global hydrogen–deuterium exchange, X‐ray crystallography and neurotoxicology, we then characterized toxic and protective subsets of SOD1 PTMs. To cap this perspective, we present proof‐of‐concept that post‐translational modification can cause disease. We show that numerous mutations (N➔D; Q➔E), which result in the same chemical structure as the PTM deamidation, cause multiple diseases. Copyright © 2017 John Wiley & Sons, Ltd.     

达布定理和比较定理思想在中值定理类问题中的运用

微分达布定理表明区间内的导函数具有介值性,这使得我们在考虑一些数学分析问题时,往往可以不需要最高阶导函数的连续性.而在微分方程理论中,比较定理的思想对于解的估计非常重要.本文利用比较定理的思想将中值定理类问题转化为微分方程解的估计问题,对于在数学分析的学习中提高学生的认识和兴趣很有意义.