Fluorescence properties of a novel side-chain polymer based on polyamic acid

The p-π conjugated polyamic acid (PAA) had been synthesized through 1,4-diaminoanthraquinone (DAAQ) and pyromellitic dianhydride (PMDA) under microwave irradiation. The graft PAAs were obtained by toluene-2,4-diisocyanate (TDI) derivatives having different straight-chain alkyl. The resulted graft polymers had good dissolution capabilities, film-forming capabilities and strong fluorescence. We investigated some factors influencing fluorescence performance on graft PAA and found that with increasing chain length of the straight-chain alkyl or increasing graft degree, the fluorescence intensity and quantum efficiency will be enhanced markedly.     

Synthesis, characterization, photophysics and electroluminescence based on a series of pyran-containing emitters

Four unsymmetric as well as symmetric carbazole or oxadiazole modified pyran-containing compounds have been synthesized and characterized. These compounds are 4-(dicyanomethylene)-2-methyl-6-(4-(carbazolo-9-yl)phenyl)-4H-pyran (10), 4-(dicyanomethylene)-2,6-bis(4-(carbazolo-9-yl)phenyl)-4H-pyran (11), 4-(dicyanomethylene)-2-methyl-6-(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl)-4H-pyran (12), and 4-(dicyanomethylene)-2,6-bis(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl-4H-pyran (13). Photoluminescent measurements indicated that their maximal emissions can be tuned from 543 to 590 nm in acetone solution. Electroluminescent studies based on these compounds as dopants resulted in greenish yellow light emission. It was found that the device based on the bis-condensed symmetric compound (11) with the configuration of indium tin oxide / Copper (II) phthalocyanine (5 nm) / N,N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine (40 nm) / compound (11) : tris-(8-quinolinolato)aluminium (Alq₃) (1%) (30 nm) / 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (5 nm) / Alq₃ (40 nm) / Mg : Ag (9 : 1) (200 nm) / Ag (80 nm) has achieved the highest luminance (6869 cd/m²) and efficiency (1.32 lm/W and 2.52 cd/A) among the four emitters.     

Rare-earth coordination polymer micro/nanomaterials: Preparation,properties and applications

Rare-earth coordination polymers (RECPs), as a family member of coordination polymers (CPs), have been prepared and studied widely. Thanks to their characteristic properties and functions, RECPs have already been used in various application fields ranging from catalysis to drug delivery. In recent years, CPs with tunable morphologies and sizes have drawn increasing interest and attractive attention. This review presents the recent research progress of RECP micro/nanomaterials, and emphasizes the preparation, properties and broad applications of these fascinating materials.     

Thin film metallic glasses in optoelectronic,magnetic, and electronic applications: A recent update

Thin film metallic glass (TFMG) is a new class of metallic thin film with unique characteristics, including smooth surface, absence of grain boundaries, second-order glass transition, annealing-induced amorphization, soft magnetic properties, and high thermal stability. Hence, with these properties, TFMGs are found very useful and promising in many areas, ranging from structural, biomedical to electrical components. This review provides an update on future challenges and opportunities associated with the further development of TFMG.     

Synthesis and red electrophosphorescence of a novel cyclometalated iridium complex in polymer light-emitting diodes

The preparation and characterization of a new cyclometalated iridium complex with 2-(1-naphthalene) pyridine ligand were reported. An electrophosphorescent device was fabricated by using this new iridium complex as guest and poly-(cyano-paraphenylene) as host. Red electrophosphorescence was observed with an emission peak at approximately 600 nm. An external quantum efficiency of 1.3% was achieved in this electrophosphorescent polymer light-emitting devices.     

Synthesis, properties, and applications of iron nanoparticles

Iron, the most ubiquitous of the transition metals and the fourth most plentiful element in the Earth's crust, is the structural backbone of our modern infrastructure. It is therefore ironic that as a nanoparticle, iron has been somewhat neglected in favor of its own oxides, as well as other metals such as cobalt, nickel, gold, and platinum. This is unfortunate, but understandable. Iron's reactivity is important in macroscopic applications (particularly rusting), but is a dominant concern at the nanoscale. Finely divided iron has long been known to be pyrophoric, which is a major reason that iron nanoparticles have not been more fully studied to date. This extreme reactivity has traditionally made iron nanoparticles difficult to study and inconvenient for practical applications. Iron however has a great deal to offer at the nanoscale, including very potent magnetic and catalytic properties. Recent work has begun to take advantage of iron's potential, and work in this field appears to be blossoming.     

Synthesis,properties and applications of titanium aluminides

Attractive elevated-temperature properties and low density make the titanium aluminides very interesting for both engine and airframe applications, particularly in the aerospace industry. The challenge to the materials scientist is to maintain these characteristics while building-in “forgiveness”. The basic phase diagram and crystal structure of both the Ti₃Al and TiAl phases are reviewed, followed by a consideration of chemistry-processing-microstructure-deformation/fracture-mechanical property relationships in monolithic material. Conventional and innovative synthesis methods are presented, including use of hydrogen as a temporary alloying element. Composite concepts as a method to enhance not only “forgiveness” but also elevated-temperature behaviour are discussed. Environmental effects are evaluated prior to consideration of present and projected applications of both monolithic and composite material. It is concluded that while the titanium aluminides in monolithic form can be used now in non-demanding applications, much further research and development is required before this material class can be used in critical applications, especially in composite concepts. On leave from Ben Gurion University of the Negev, Beer Sheva, Israel.     

聚酰亚胺基偶氮聚合物的合成及热光性能的研究

4,4'-二胺基二苯醚(4,4'-ODA),4,4'-(六氟异丙基)-苯二酸酐(6FDA)和分散红1(DR1)合成了可制作光波导器件的聚酰亚胺基偶氮聚合物;采用示差扫描量(DSC)、热失重分析(TGA)等方法对该聚合物的热稳定性进行了表征.示差扫描量热和热失重分析结果显示,该聚合物的玻璃化转变温度(Tg)为223℃,5%的热失重温度为282℃,表明具有非常好的热稳定性.测定了材料在复合光和577nm单波长光照射下该的折射率(n)和热光系数(dn/dT);通过热光系数的测量,计算了聚合物的介电常数(ε)、介电热光系数(dε/dT)、体积热膨胀系数β和(dβ/dT)值.制得的聚合物材料在复合光下的热光系数(dn/dT)值为(-2.1464～-3.8857)×10-4/℃,体积热膨胀系数变化率(dβ/dT)为(2.13～7.44)×10-7/℃;在577nm单波长光照射下的热光系数(dn/dT)值为-3.8445×10-4/℃,体积热膨胀系数变化率(dβ/dT)为7.81×10-7/℃,表明该聚合物在低驱动功率的新型数字热光开关、光通信器件等领域具有潜在的应用前景.     

Novel hypolipidemic conjugates of fatty acid and bile acid with lysine for linkage

Novel fatty acid–bile acid conjugates (1a–1k) were designed and synthesized by coupling of the fatty acids to the 3-OH of bile acids using lysine for linkage. In the conjugates, the 24-COOH of the bile acids was kept intact to preserve liver-specific recognition. The ability of the newly synthesized conjugates (at 100?mg/kg dosage) to reduce total cholesterol (TC) and triglyceride (TG) levels in mice fed with high-fat diet (HFD) was evaluated. Conjugates of stearic acid with cholic acid and palmitic acid with ursodeoxycholic acid (at dosages of 50, 100, and 200?mg/kg) were further evaluated to determine their ability to reduce aspartate aminotransferase (AST), alanine aminotransferase (ALT), TC, and TG levels in mice fed with HFD. All conjugates showed potent hypolipidemic activity. Further investigation revealed that compounds 1c and 1?g not only dose-dependently reduced serum levels of TC and TG, but also inhibited the elevation of serum AST and ALT levels in mice fed with HFD. Thus, compounds 1c and 1?g are promising hypolipidemic agents with hepatocyte protective effects against HFD-induced liver damage.     

Sonochemical synthesis of Fe-doped Cu3Se2 nanoparticles: Correlation of the strain and electrical properties for optoelectronics applications

This research presents the effect of different concentrations of iron (Fe) as dopants on the physical properties of the copper selenide (Cu₃Se₂) nanoparticle (NPs). The physical properties of the Cu₃Se₂ NPs were investigated using structural, morphological, and optical analysis. The results revealed that the Fe concentrations change the crystallite size (from ∼8 to 44 nm) and strain (from ∼0.0007 to 0.0030). Fe-doped Cu₃Se₂ NPs showed a higher optical energy band gap in comparison to the un-doped sample (1.80 eV). The films prepared by green binder (ethyl cellulose) indicated that the sample with minimum Fe concentration presents the highest carrier concentration (9.56e+18 cm⁻³) and lowest ideality factor (2.02) amounts. The electrical study shows space charge limited current (SCLC) mechanism in Fe-doped Cu₃Se₂ NPs that is not observed in un-doped sample. Using this mechanism, the highest carrier mobility (16.22 cm⁺²V⁻¹s⁻¹) obtained for sample with the lowest amount of Fe concentrations.     

Recent advances in germanium nanocrystals: Synthesis,optical properties and applications

Germanium nanocrystals (Ge NCs) have recently attracted renewed scientific interest as environmentally friendlier alternatives to classical II–VI and IV–VI QDs containing toxic elements such as Hg, Cd and Pb. Importantly, Ge NCs are nontoxic, biocompatible, and electrochemically stable. An essential requirement is the ability to prepare Ge NCs with narrow size distributions and well characterized surface chemistry, as these define many of their photophysical properties. However, a thorough discussion on these criteria has not been achieved to date. Here, size, surface control, and mechanisms for light emission in Ge NCs are discussed and their exciting recent applications are highlighted. The beneficial properties of Ge NCs suggest that this material can improve the performance of numerous devices like solar cells, photodetectors, and lithium ion batteries.     

Morphology and photophysical properties of polymer thin films dispersed with dye nanoparticle

We prepared nanoparticles of an organic dye, acridine orange (AO), dispersed in poly(methacrylic acid) (PMA) films by spin-coating the solution of the two components. The surface of the AO/PMA films became bumpier with increasing AO concentration (c_AO). The absorption and fluorescence spectra of AO/PMA films exhibited a marked dependence on c_AO at low c_AO (c_AO < 2.1 × 10^− 1 mol kg^− 1), and were independent of c_AO at high c_AO (c_AO > 2.1 × 10^− 1 mol kg^− 1). The peak shift of fluorescence spectra with changing c_AO was as large as ∼ 100 nm.     

Electronic structure and optical properties in ZnO:M(Co, Cd): Effect of band-gap variation

ZnO doped with some transitions metals (ZnO:M) has several significant potential application. ZnO:Co is proposed to be used in advanced spintronic devices due to its high Curie temperature and large magnetic moments per transition metal. ZnO:Cd has potential applications in short-wavelength optoelectronic devices. This work focuses on an ab-initio study of the electronic and optical properties of ZnO:M doped with Co, and Cd. Theoretical calculations have been done with different computational codes, using the density functional theory (DFT) at the GGA and GGA+U level. The latter introduces a Hubbard term correction in the “d” levels of the Zn and Co. We used different supercells in order to have different realistic dilution levels which can be achieved in experiments. Doping effects on the features of the optical absorption are also studied and analysed in this work.     

Monodisperse ceria nanospheres: Synthesis,characterization, optical properties,and applications in wastewater treatment

Monodisperse ceria nanospheres have been synthesized by a facile solvothermal method, and their morphology and microstructures have been revealed by a combination of X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and N₂ adsorption. It is demonstrated that the as-synthesized powders are highly uniform CeO₂ in spherical shape with cubic fluorite structure. HRTEM and XRD studies show that each ceria nanosphere is composed of dozens of nanocrystals with the average size of 8.5 nm. The direct optical band gap of the ceria nanospheres estimated from the ultraviolet–visible absorption spectrum is 2.7 eV, which is evidently red-shifted with respect to the bulk material (E_g = 3.19 eV); the reduced band gap could be resulted from the high concentration of grain boundaries and defects present in the ceria nanospheres. In addition, the ceria nanospheres exhibit a strong blue luminescence at 504 nm and a broad orange luminescence centered at 645 nm. As a result of the large specific surface area, ceria nanospheres are revealed to be an excellent sorbent for the removal of poisonous pollutants present in water, such as chromium ions and rhodamine B. The removal efficiency of chromium ions is as high as ∼94%.     

富勒烯(C60)-苯乙烯-丙烯酸三元共聚物的合成及其润滑性能

通过自由基聚合,合成了一种新型纳米级富勒烯-苯乙烯-丙烯酸三元共聚物,该聚合物易溶于碱性水、甲醇、四氢呋喃等溶剂。采用FTIR、UV-240等进行结构表征。TEM分析表明其在水溶液中形貌为理想的球形,平均粒径约为36nm。四球机试验测试结果表明,一定浓度的该富勒烯共聚物可有效增强抗磨能力。对其磨斑表面采用电子扫描显微镜分析,结果表明,磨痕变浅,磨斑减小,有效地降低了磨损。     

Synthesis, characterization and antimicrobial activity of conjugates based on fluoroquinolon-type antibiotics and gelatin

Different fluoroquinolon-type antibiotics were conjugated to gelatin with the aim to synthesize biomacromolecules with antimicrobial properties. The covalent linkage of the antibiotic was performed by a radical process involving the residues in the side chains of gelatin able to undergo oxidative modifications. The conjugation of antibiotic moieties onto the protein structure was confirmed by FT-IR, UV–Vis, fluorescence, and calorimetric analyses. Biocompatibility tests were performed on human bone marrow mesenchymal stromal cells and the antibacterial properties of bioactive polymers were investigated by appropriate tests against Klebsiella pneumoniae and Escherichia coli. With regard to the tests conducted in the presence of E. coli, a minimum inhibitory concentration (MIC) ranging from 0.05 to 0.40 μg mL^?1 was recorded, while in the presence of K. pneumoniae this concentration varies from 0.10 to 1.60 μg mL^?1. In all the conjugates, the drug moieties retain their biological activity and the MIC values are lower than the resistance parameters of fluoroquinolon-type antibiotics versus Enterobacteriacae. The collected data suggest a broad range of applications, from biomedical to pharmaceutical and food science for all conjugates.     

复合酸掺杂聚苯胺电极膜的制备及其电化学性能的研究

采用了恒电压法在不同的电解液中分别制备出硫酸(H2SO4)和复合酸(SSA+H2SO4)掺杂的聚苯胺(PAn)电极膜.通过循环伏安法(CV)、电化学阻抗谱(EIS)和塔菲尔曲线(TAF),对H2SO4和复合酸掺杂聚苯胺电极膜的电化学稳定性、导电性以及耐腐蚀性进行了研究与表征.结果表明,复合酸掺杂的PAn电极膜具有较好的电化学稳定性、导电性以及较强的耐腐蚀性,更能满足实际应用的要求.     

Synthesis,electron transport properties of transition metal nitrides and applications

To understand the electron transport properties of transition metal nitrides (MN), electronic structure relationship between metal and corresponding nitrides is important. In binary nitrides, when nitrogen atoms occupy interstitial sites of metal lattice, volume expansion started initially without changing structure of metal lattice. Above certain concentration of nitrogen into interstitial sites of lattice, the system starts stabilizing its energy to minimum that in turn changes to another crystal structure. The chemical bonding in MN is due to the mixing of d-orbitals of M and p-orbitals of N. This is confirmed theoretically and experimentally such as X-ray photoelectron spectroscopy. The Fermi energy is generally lowered by the introduction of vacancies. However, reports on the particle size effect in the electrical resistivity of nitrides are scanty. One reason is that the role of the particle size in resistivity is difficult to determine because there is a need to understand N concentration. It poses a challenge to the synthesis of nanostructured transition metal nitrides. The transition metal binary nitrides show unusual electron transport, optical and magnetic properties as compared to their metal counterparts. Electronic properties of all transition metal nitrides known till date are discussed. Different ways of synthesis of nitrides and their applications are mentioned.