Optical spin generated by a soliton pulse in an add–drop filter for optoelectronic and spintronic use

A new concept of an optical spin generation using bright and dark soliton conversion behaviors within a modified optical add–drop filter known as PANDA ring resonator is proposed. The orthogonal solitons can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the dark and bright soliton pair corresponding to the left-hand and right-hand rotating solitons (photons) can be generated. When a soliton is absorbed by an object, an angular momentum of either +? or ?? is imparted to the object, in which two possible spin states known as optoelectronic(soliton) spins are exhibited. Furthermore, an array of soliton spins, i.e. particles can be generated and detected by the proposed system, which can be used to form large scale spin generation.     

Reverse flow injection spectrophotometric determination of iron(III) using norfloxacin

A reversed flow injection colorimetric procedure for determining iron(III) at the μg level was proposed. It is based on the reaction between iron(III) with norfloxacin (NRF) in 0.07 mol l⁻¹ ammonium sulfate solution, resulting in an intense yellow complex with a suitable absorption at 435 nm. Optimum conditions for determining iron(III) were investigated by univariate method. The method involved injection of a 150 μl of 0.04% w/v colorimetric reagent solution into a merged streams of sample and/or standard solution containing iron(III) and 0.07 mol l⁻¹ ammonium sulfate in sulfuric acid (pH 3.5) solution which was then passed through a single bead string reactor. Subsequently the absorbance as peak height was monitored at 435 nm. Beer's law obeyed over the range of 0.2–1.4 μg ml⁻¹ iron(III). The method has been applied to the determination of total iron in water samples digested with HNO₃–H₂O₂ (1:9 v/v). Detection limit (3σ) was 0.01 μg ml⁻¹ the sample through of 86 h⁻¹ and the coefficient of variation of 1.77% (n=12) for 1 μg ml⁻¹ Fe(III) were achieved with the recovery of the spiked Fe(III) of 92.6–99.8%.     

Characterisation of an extract and fractions of Azadirachta indica flower on cholesterol lowering property and intestinal motility

Azadirachta indica has long been used in traditional medicine. This study focused on isolation and characterisation of active ingredients in the extract, its fractions (NF-EA, NF-AQ, NF-G) and its effect on the cholesterol absorption activity. The NF-EA fraction was identified by marker compounds by LC-ESI-QTOF/MS. Cholesterol absorption activity was performed by measuring the solubility and size of cholesterol micelles. The intestinal motility was also examined by isolated rat’s ileum to test the contraction. The extract and its fractions consist of flavonoids and phenolic compounds, like quercetin, kaempferol and myricetin. We found that A. indica extract and NF-EA increase cholesterol micelles size, while the extract, NF-AQ, myricetin and quercetin, reduced the solubility of cholesterol in micelles. The extract and quercetin inhibited the contraction induced by KCl up to 29 and 18%, respectively, and also decreased CaCl₂-induced contraction. This finding is in support to traditional uses of A. indica as cholesterol-lowering agents and regulator of gastrointestinal motility.     

New approach to single-particle time-correlation function theory: Application to intramolecular dephasing in the condensed phase

A new approach to solve the linewidth expression of infrared line shape based on the Kim-Wilson single-particle time-correlation function theory is presented. A projection-operator technique coupled with an explicit series-expansion method is used to reduce the unusual operator exp[1(1 - P)Lt] in the damping function to the usual operator exp(i L⁰t). This approach is applied to a study of a temperature dependence of the width and shift of the infrared line shape for intramolecular dephasing of a polyatomic molecule in the condensed phase.     

An experimental investigation of P–N diode electrical characteristics by soft X-ray annealing method

We present new experimental results for the electrical behaviors of P–N junction diodes irradiated by X-rays. The current–voltage (I–V) characteristics of the P–N junction diodes were measured at room temperature. The reverse and forward current before and after irradiation can be explained relative to the following parameters: carrier generation lifetime (τ_g), ideality factor (n), series resistance (R_s), and sheet resistance (ρ). After irradiation at 40 and 55 keV, a small increment in the diode leakage current was seen, while at 70 keV of exposure, the leakage current was slightly decreased. On the other hand, the forward current was dramatically increased by about three orders of magnitude. In addition, the series resistance of the diodes was confirmed to be positively modified by the use of the soft X-ray annealing method.     

Antiferroelectric–ferroelectric phase transition in lead zinc niobate modified lead zirconate ceramics: crystal studies, microstructure, thermal and electrical properties

The combination of antiferroelectric PbZrO₃ (PZ) and relaxor ferroelectric Pb(Zn_1/3Nb_2/3)O₃ was prepared via the columbite precursor method. The basic characterizations were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), linear thermal expansion, differential scanning calorimetry (DSC) techniques, dielectric spectroscopy, and hysteresis measurement. The XRD result indicated that the solid solubility limit of the (1−x)PZ–xPZN system was about x=0.40. The crystal structure of (1−x)PZ–xPZN transformed from orthorhombic to rhombohedral symmetry when the concentration of PZN was increased. A ferroelectric intermediate phase began to appear between the paraelectric and antiferroelectric phases of pure PZ, with increasing PZN content. In addition, the temperature range of the ferroelectric phase increased with increasing PZN concentration. The morphotropic phase boundary (MPB) in this system was located close to the composition, x=0.20.     

Melamine-mediated self-assembly of a Cu(II)–methylmalonate complex assisted by π+–π+ and anti-electrostatic H-bonding interactions

A Cu(II)-methylmalonate complex, (C₃H₇N₆)₄[Cu(II)(C₄H₄O₄)₂](H₂O)₄Cl₂ (1) (where C₃H₇N₆ = protonated melamine, C₄H₄O₄ = methylmalonic acid), has been synthesized from aqueous media and its crystal structure was determined by single-crystal X-ray diffraction. The anionic Cu(II)-methylmalonate complex mediated formation of interesting supramolecular assemblies in the solid state by means of ionic interactions with protonated melamine. Moreover, other forces such as antielectrostatic H-bonding and π⁺–π⁺ interactions also play a crucial role in defining the final 3-D architecture of 1. An interesting stacking among protonated melamine molecules is studied by DFT calculations. Lattice water molecules and chlorides form various hydrogen bonds to take part in the self-assembly processes.     

Binding affinity of a small molecule to an amorphous polymer in a solvent. Part 2: preferential binding to local sites on a surface

Crystallization, a separation and purification process, is commonly used to produce a wide range of materials in various industries, and it usually begins with heterogeneous nucleation on a foreign surface in industrial practice and most other circumstances. Recent studies show that amorphous polymeric substrates are useful in controlling crystallization and selectively producing pharmaceutical polymorphs. In our previous publication, we investigated the possible correlation of the binding affinity of one molecule to key binding sites (local binding), and the possibility of using this binding affinity to guide the selection of polymers promoting heterogeneous nucleation. The studied systems were aspirin binding to four nonporous cross-linked polymers in ethanol-water 38 v% mixture. Cross-linked with divinylbenzene (DVB), these polymers were poly(4-acryloylmorpholine) (PAM), poly(2-carboxyethyl acrylate) (PCEA), poly(4-hydroxylbutyl acrylate) (PHBA), and polystyrene (PS). We discovered that the trend of the magnitudes of the average free energies of binding to the best sites is very similar to that of heterogeneous nucleation activities. This Article aims to investigate whether or not local binding to key sites is the important variable to describe heterogeneous nucleation as opposed to the overall/average binding affinity of molecules to a surface, and to investigate the possibility of using the overall binding affinity to guide the selection of polymers. We used the polymer surfaces generated from our previous study to calculate the overall binding affinity of aspirin molecules to the surface as measured by the preferential interaction coefficients of aspirin (1 m) to these polymers. We discovered that the trend of the average preferential interaction coefficients does not correlate as well to that of heterogeneous nucleation activities as the free energies of binding to the best sites. We also computed the average numbers of aspirin molecules associated with the areas of the surfaces' best binding sites and found that they correlate better to heterogeneous nucleation activities than the average preferential interaction coefficients. These results further support that local binding is indicative of heterogeneous nucleation. Moreover, we found a weak trend of the distance order parameters of the aspirin molecules to be similar that of heterogeneous nucleation activities. Our results from the two-part study suggest the importance of local binding to heterogeneous nucleation as well as the possibility of using the binding affinity to the local area (the free energy of binding to the best site and the number of nucleating molecules associated with the area of the best binding site) and the distance order parameters to guide the selection of polymers.     

Fluorene‐rich high performance polyesters: Synthesis and characterization of 9,9‐fluorenylidene and 2,7‐fluorenylene‐based polyesters with excellent optical property

Polyesters PEs containing high content of fluorene units in their backbones were synthesized from 9,9‐diarene‐substituted fluorene diols ( 1 ) and fluorene‐based diacid chlorides ( 2 ) by high temperature polycondensation at 185 °C in diphenyl ether. The molecular weights of the polyesters PE1‐PE5 were in a range of M_w 25,000–165,000. The polyesters displayed their high thermostability: the glass transition temperatures (T_g) by differential scanning calorimetry analysis ranged from 109 to 217 °C, while the 10% weight loss temperatures (T_d10) measured by thermogravimetric analysis were over 400 °C in nitrogen and 395 °C in air. The polyesters had good solubility in most common organic solvents such as chloroform and toluene and gave tough, transparent and flexible cast films. The transmittance of the films was over 80% in the wavelength range from 450 to 700 nm in any PEs . The PEs exhibited high refractive index values around 1.65, while they had very low degree of birefringence. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2549–2556, 2008     

光量子随机数发生器

设计制作了基于单光子量子随机性的二进制随机数发生器,通过50/50光分束器的光子流被其后的单光子探测器记录下光子路径,经高速电路和计算机数据采集系统转换为二进制随机数流,目前实验中随机数采集速率达100 Kbit/s,本文采用延迟符合计数法来克服探测器暗计数的影响.使暗计数对随机数序列的影响下降了2到3个数量级,最后应用的三种随机性测试表明所采数据随机性良好.