Photochromic behavior of a bisthienylethene bearing Cu(I)-1,10-phenanthroline complexes

A novel diarylethene having a 1,10-phenanthroline unit at each end of the molecule has been synthesized. Among the metal ions, it formed a stable complex with Cu(I) ions in acetonitrile. Rational structures of the Cu(I) complexes of the colorless and the photo-generated blue form have been given by PM3 semiempirical molecular orbital calculations to be 2:2 cyclic complexes for both isomers, with the complex of the open form belonging to the C₂ symmetry group while the complex of the closed form belongs to the D₂ symmetry group. Although the ring-closing quantum yield for free diarylethene in acetonitrile was 0.75, that for the complex was 0.026, due to the long distance of the bond-forming carbon atoms in the rigid (open form)₂-Cu(I)₂ complex.     

High-Performance Photodetector and Angular-Dependent Random Lasing from Long-Chain Organic Diammonium Sandwiched 2D Hybrid Perovskite Non-Linear Optical Single Crystal

3D organic-inorganic metal halide perovskites are excellent materials for optoelectronic applications due to their exceptional properties, solution processability, and cost-effectiveness. However, the lack of environmental stability highly restricts them from practical applications. Herein, a stable centimeter-long 2D hybrid perovskite (N-MPDA)[PbBr₄] single crystal using divalent N1-methylpropane-1,3-diammonium (N-MPDA) cation as an organic spacer, is reported. The as-grown single crystal exhibits stable optoelectronic performance, low threshold random lasing, and multi-photon luminescence/multi-harmonic generation. A photoconductive device fabricated using (N-MPDA)[PbBr₄] single crystal exhibits an excellent photoresponsivity (≈124 AW⁻¹ at 405 nm) that is ≈4 orders of magnitudes higher than that of monovalent organic spacer-assisted 2D perovskites, such as (BA)₂PbBr₄ and (PEA)₂PbBr₄, and large specific detectivity (≈10¹² Jones). As an optical gain media, the (N-MPDA)[PbBr₄] single crystal exhibits a low threshold random lasing (≈6.5 µJ cm⁻²) with angular dependent narrow linewidth (≈0.1 nm) and high-quality factor (Q ≈ 2673). Based on these results, the outstanding optoelectronic merits of (N-MPDA)[PbBr₄] single crystal will offer a high-performance device and act as a dynamic material to construct stable future electronics and optoelectronic-based applications.     

Ion exchanger resins,I. Anion exchangers with tertiary amine groups on poly(acrylonitrile-co-divinylbenzene) networks

Macroporous copolymers of poly(acrylonitrile-co-divinylbenzene) were synthesized in the presence of 2-ethyl-1-hexanol (2EH) and toluene as diluents. The copolymers were characterized by acrylonitrile content and from morphological point of view. Samples with a minimum content of homopolymer were transformed into weak base anion exchangers by the aminolysis-hydrolysis reaction of the nitrile groups with N,N-dialkylaminoalkylamines. The reactions were investigated by the exchange capacity variation and IR-spectral analysis. It was emphasized that the reactivity of asymmetrical diamines depends on the nucleophilicity of the primary amine group.     

Template and template-free preparation of one-dimensional metallic nanostructures

In this article, we have studied and developed two approaches for organizing metallic nanoparticles into one-dimensional assemblies. The first uses DNA as a ‘template’ and allows the preparation of various silver nanostructures (‘beads-on-a-string’ or rod-like wires). The conductance of such nanostructures was demonstrated by employing a powerful technique, Electrostatic Force Microscopy (EFM). This technique gave us ‘contactless’ information about the electrical properties of silver nanostructures, aligned on a SiO₂/Si surface. Additionally, I–V characteristics of a single silver nanowire crossing two microelectrodes were recorded. The nanowire resistivity was estimated at 1.46 × 10⁻⁷ Ω m (at 300 K), which is one order of magnitude higher than that of bulk silver (1.6 × 10⁻⁸ Ω m). The second approach is a ‘template-free’ one, and exploits the binding ability of l-arginine, which favours the self-assembling of capped gold nanoparticles into gold nanochains. The results suggest that gold nanochains were formed due to dipole–dipole interaction between adjacent nanoparticles, which fuse together through an oriented attachment mechanism. Atomic force microscopy, TEM, UV–vis spectroscopy and X-ray diffraction were used to characterize the morphological, optical and structural properties of these metallic nanostructures.     

Investigation of carbon nanofibers as support for bioactive substances

In this paper we have studied the adsorption properties of various bio-active systems onto the surface of carbon nanofibers (CNF) synthesized by chemical vapor deposition (CVD). Amino acids (alanine, aspartic acid, glutamic acid) and glucose oxidase (GOx) were adsorbed on CNF and the results were compared with those obtained when activated carbon (AC) was used as support. CNF and AC properties (hydrophilic or hydrophobic properties) were characterized by the pH value, the concentration of acidic/basic sites and by naphthalene adsorption. CNF with immobilized GOx was additionally investigated as a highly sensitive glucose biosensor. An amperometric method was used in an original manner to detect the changes in the specific activity of GOx, immobilized longer time on CNF. The method demonstrates that not the whole enzyme adsorbed onto CNF can catalyze the oxidation of glucose from the solution.     

Green solvents for green technologies

In many industrial processes, large quantities of volatile and flammable organic solvents are used in various reaction systems and separation steps defining a major part of the environmental and economic performance of a process. Accordingly, a growing area of research in the development of green technologies is devoted to designing new, environment‐friendly and tunable solvents the use of which would meet both technological and economic demands. Among proposed solvents, room temperature ionic liquids, supercritical and subcritical fluids and solvents from natural and renewable sources stand out as the most promising approaches for current solvent innovation. A brief overview of up‐to‐date knowledge regarding these solvents is presented herein, with special emphasis on their properties, applications and further perspectives as truly green industrial solvents. © 2015 Society of Chemical Industry     

Behaviour of regenerated polyethylene,recovered from worn out packaging,to artificial ageing and under natural climate conditions

This paper presents the efficiency of styrenated phenol and dian (bisphenol A) stabilizers in high density polyethylene regenerated from worn out packaging samples, by following up the regenerates' behaviour under artificial ageing as well as in natural climate conditions. The efficiency of the stabilizers was assessed by following up the characteristic physical-mechanical modifications and the formation of carbonyl groups in the stabilized, regenerated polyethylene samples, as compared with the primary polyethylene and the unstabilized regenerated samples.     

The Development Process of the Metropolitan Region of Sao Paulo: Contradictory and Accelerated-SP Brazil-Social and Environmental Aspects

This paper addresses the contradictions that can be seen within the process of economic and urban growth experienced by developing countries. Sao Paulo synthesizes these contradictions and is an example of how far people can go on environmental destruction when associated with social inequity.     

Research and partnership in studies of sugarcane using molecular markers: a scientometric approach

In this study, we applied scientometric methods and performed a science mapping analysis to investigate and describe the application of molecular markers in genetic studies for sugarcane. We analyzed 344 papers retrieved from Web of Science Thomson Reuters database, considering the time frame from 1974 to 2017, allowing the analysis of the produced scientific knowledge, temporal trends and research partnership in the subject. To our knowledge, a scientometric evaluation of the use of molecular markers for genetic studies in sugarcane has not yet been reported. Our main finding shows that dominant markers are more commonly used than co-dominant markers, and that when co-dominant markers are applied, most of the retrieved information is underexploited, due to lack of knowledge for the use of dosage information. Our results also show that despite the development of high-throughput sequencing technologies, for sugarcane only 13.33% of the studies reported the use of more than 1000 markers. We also found connectivity among researchers and institutions publishing worldwide, but only few authors represented a bridge between different research groups. Thus, the international research partnership is still low. Our findings show dominance in country publication. Six countries (India, Brazil, USA, Australia, China, and France) were responsible for 80% of the published papers and received most citations. We suggest special reinforcement in building international partnership, since collaborations occur mostly within countries. International collaboration can improve research performance and eventually lead to a better exploitation and more development of knowledge for sugarcane.