Fe(II) Spin Crossover/Polymer Hybrid Materials: Investigation of the SCO Behavior via Temperature-Dependent Raman Spectroscopy,Physicochemical Characterization and Migration Release Study

Polymeric composites constitute an appealing class of materials with applications in various fields. Spin crossover (SCO) coordination complexes are switchable materials with potential use in data storage and sensors. Their incorporation into polymers can be considered an effective method for their wider practical application. In this study, Fe(II) SCO/polylactic acid hybrid polymeric composites have been prepared by film casting. The mononuclear coordination complex [Fe{N(CN)₂}₂(abpt)₂] was incorporated into polylactic acid. The morphological, structural and thermoanalytical characterization of the composite films were performed via scanning electron microscopy (SEM), attenuated total reflectance (ATR/FTIR), Raman spectroscopy and differential scanning calorimetry (DSC). In addition, the migration release study (MRS) of the SCO compound from the polymeric matrix into the food simulant 50% v/v water/ethanol solution was also examined via UV/Vis absorption. Of particular interest was the investigation of the SCO behavior of the coordination complex after its incorporation into the polymer matrix; it was accomplished by temperature-dependent micro-Raman spectroscopy. The described attempt could be considered a preparatory step toward the development of SCO-based temperature sensors integrated into food packaging materials.     

Monte Carlo simulations of a coarse grained model for an athermal all-polystyrene nanocomposite system

The structure of a polystyrene matrix filled with tightly cross-linked polystyrene nanoparticles, forming an athermal nanocomposite system, is investigated by means of a Monte Carlo sampling formalism. The polymer chains are represented as random walks and the system is described through a coarse grained Hamiltonian. This approach is related to self-consistent-field theory but does not invoke a saddle point approximation and is suitable for treating large three-dimensional systems. The local structure of the polymer matrix in the vicinity of the nanoparticles is found to be different in many ways from that of the corresponding bulk, both at the segment and the chain level. The local polymer density profile near to the particle displays a maximum and the bonds develop considerable orientation parallel to the nanoparticle surface. The depletion layer thickness is also analyzed. The chains orient with their longest dimension parallel to the surface of the particles. Their intrinsic shape, as characterized by spans and principal moments of inertia, is found to be a strong function of position relative to the interface. The dispersion of many nanoparticles in the polymeric matrix leads to extension of the chains when their size is similar to the radius of the dispersed particles.     

The interaction of water vapors with H3PO4 imbibed electrolyte based on PBI/polysulfone copolymer blends

The interaction of steam with phosphoric acid imbibed electrolyte composed of PBI/PPy(50)coPSF 50/50 polymer blend and its effect on fuel cell performance was studied regarding its permeability through and its chemical interaction with the membrane. It was found that steam is the only gas that permeates the membrane with a permeability coefficient 1.1 × 10⁻¹⁴ mol cm cm⁻² s⁻¹ Pa⁻¹ at 150 °C. This is attributed either to the high solubility of water in phosphoric acid or to the chemical interaction with pyrophosphoric acid_. The latter was demonstrated by carrying out TGA experiments under various water vapor partial pressures. Water reacts with pyrophosphoric acid in order to maintain the equilibrium concentration of phosphoric acid at high level, thus improving proton conductivity and fuel cell performance. In addition it is shown that excess water dissolves in the membrane thus maintaining the “membrane/acid” system at high hydration level. This depends both on temperature and steam partial pressure. Although in the present study it is shown that steam plays a significant role in the performance of the high temperature Polymer electrolyte membrane (PEM) fuel cell, nevertheless its feed with humidified gases is not necessary, due to the back transport of the water produced at the cathode.     

内蒙古地区天然植物沙棘果中黄色素的提取工艺及性质研究

以内蒙古地区沙棘果实为原料，研究了提取黄色素的工艺条件，同时对该色素的性质进行了初步探讨。结果表明，以95％的乙醇溶液作浸提剂，提取的黄色素浓度最高，工艺流程简单易行，且无毒，无污染。对提取的黄色素进行的性质试验表明，沙棘黄色素对光、热具有较好的稳定性，适用于酸性或弱碱性的食品中，葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。     

种植沙生植物--沙棘改善内蒙古地区生态环境

结合内蒙古地区现状，对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明，沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质，并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施，是贫瘠的不毛之地发展经济、增加收入的经济树种。另外．种植沙棘的技术简便，容易掌握，投资少，见效快。     

Solid-Phase Synthesis of a Monofunctional trans-a(2)Pt(II) Complex Tethered to a Single-Stranded Oligonucleotide

Cross-linking ability is possible with the oligonucleotide-tethered, monofunctional trans-Pt(II) complex shown. It was synthesized by a novel solid-phase approach comprising conjugation of immobilized tetrathymidylic acid with a trans-a(2)Pt(II) building unit, ammonolysis, and transformation of the resulting complex (R=1-N-cyclohexylmethylthyminate) into the chloro derivative (R=Cl). a=NH(2)CH(3), T=thymine.     

Quantitative surface enhanced Raman scattering measurements at the early stage of active agent release processes

The surface enhanced Raman scattering spectroscopy (SERS) is introduced as a new method to probe the initial release of active agents from controlled delivery systems. As a model system, mitoxantrone‐loaded polypropylene specimens immersed in water have been utilized. Surface enhanced resonance Raman scattering (SERRS) measurements allowed the quantitative delineation of the initial drug release profile. SERRS was also compared in early stage release processes with UV–vis absorption often used in traditional quantitative analysis via HPLC, a common technique for controlled release evaluation. More and above the high selectivity of the Raman Effect, SERS has been proved as a highly sensitive method to quantitatively monitor the initial release of the medicine even at the very early stage of the delivery process; UV–vis absorbance was unable to respond accordingly. Copyright © 2012 John Wiley & Sons, Ltd.