Preparation of a novel self-assembling nonlinear optical (NLO) polymer film

A novel self-assembling crosslinking second harmonic generation nonlinear optical (SHG/NLO) film with high SHG coefficient (2×10-7 e.s,u.by IR dichroism) was prepared by morecular design and "in-situ poling and sol-gel process".The content of the NLO chromophore (S)-(-)-1-(4)-mtrophenyl-2-pyrrolidinemethanol (NPP) is as high as 50 mol% since NPP molecules probably disperse in the film at a molecular level The film is rigid,uni form and transparent.This designed clathrate supermolecular structure was poved by IR,atomic force microseopv (AFM) and differential scanning calorimetry (DSC) detection.The title film exhibits a long-term temporal stability with 95% of the initial value of SHG coefficient maintained even after 20 d at 65℃(by UV spectroscopy)     

Quantitative millimetre wavelength spectrometry at pressures approaching atmospheric: II. Determination of oxygen at atmospheric pressure

A millimetre wavelength (MMW) Fabry-Perot cavity spectrometer described in earlier work has been applied to the measurement of oxygen absorption at 60 GHz and atmospheric pressure in a gas matrix of nitrogen. The spectrometer has also been modified such that the MMW source is stabilised by a sub-harmonic microwave signal transmitted by an infrared carrier on a single mode telecommunications fibre optic. This is a step towards developing an instrument comprising minimal electronic components that can perform MMW spectrometry remotely. Oxygen determinations were achieved by monitoring the change in the quality factor (Q) of a resonant Fabry-Perot cavity due to the presence of an absorbing sample. The MMW absorption of the sample was determined by incrementing the frequency modulation (FM) deviation of the source frequency scanning the cavity resonance profile. The response curve of absorption signal versus fraction of oxygen in nitrogen was found to be linear throughout the working range of 1-100% O₂ (v/v) in N₂ with a slope of (1.407±0.007)×10⁻⁴ m⁻¹ (% O₂)⁻¹. The detection limit (3× standard deviation of the background) was found to be ∼0.8% (v/v). The MMW technique employed is advantageous since, unlike common MMW techniques, there is no vacuum requirement. Application of this method, to the monitoring of oxygen in gas mixtures of practical importance, is proposed. Values of the oxygen spectral absorption coefficients of lines between 55 and 60 GHz were measured at reduced pressure and found to be within ±2% of previous literature values. A pressure correction coefficient for O₂ absorption at 60 GHz in the 45-121 kPa range was obtained and found to be (1.354±0.014)×10⁻⁴ m⁻¹ kPa⁻¹.     

Use of NIRS technology with a remote reflectance fibre-optic probe for predicting major components in bee pollen

In the present work, we study the use of near infra-red spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe for determination of the major components in bee pollen. The method allows immediate control of the bee pollen without prior sample treatment or destruction through direct application of the fibre-optic probe to the sample.The regression method employed was modified partial least squares (MPLS). The calibration results obtained using 45 samples of bee pollen allowed the measurement of protein, moisture, ash, reducing sugars, and pH with multiple correlation coefficients (RSQ) and prediction corrected standard errors (SEPC) of 0.91, 0.56% for protein, of 0.78 and 0.49% for moisture; 0.92 and 0.049% for ash; 0.81 and 1.32 g of glucose/100 g of bee pollen; 0.84 and 0.15 for pH, respectively.The prediction capacity of the pattern was checked by applying it to samples of unknown pollen in external validation.     

固定化酶不对称合成（S）＋—（＋）—布洛芬的研究

能够不对称水解布洛芬乙酯的酵母菌Ｔ１５８固定化在壳聚糖珠中，固定化酵母菌的活力回收达６０％，最适温度为４５℃，半衰期为７５ｄ以上。     

Determination of organochlorine pesticides by gas chromatography with solid-phase microextraction

Summary A study of different extraction techniques for the determination of a selected group of organochlorine compounds in surface waters is presented. Comparison of liquid-liquid extraction (LLE) with solid-phase extraction (SPE) and solid-phase microextraction (SPME) with fibers of different polarity shows that SPME with a recently commercialised fiber of polydimethylsiloxane divinylbenzene allows these compounds to be determined in surface waters with good extraction efficiencies. Extraction time, effect of temperature, ionic strength and pH were optimised, allowing quantification in agricultural effluents in the range 1.0–60 ng·L⁻¹.     

锗的市场结构变化与光纤通信

介绍了锗在光纤通信中的作用，分析了世界光纤市场的变化及其对锗的市场结构的影响，预测近期国内锗的市场结构不会有大的变化。     

Voltammetric Determination of Antibacterial Nitro‐Compounds at Activated Carbon Fibre Microelectrodes

The electrochemical behavior of the nitrofuran antibiotics nitrofurantoin (NFA) and nitrofurazone (NFZ), as well as the related nitroimidazole drug, metronidazole (MNZ) at electrochemically activated carbon fibre microelectrodes (CFMEs) is reported. These nitrofurans have been widely used in the form of feed additives for the treatment of gastrointestinal infections in cattle, pigs and poultry. Electrochemical activation of CFMEs by repetitive square‐wave (SW) voltammetric scans between 0.0 and +2.6 V, produced an unexpected high cathodic response from these compounds. This is attributed to the increase of the carbon fibre surface area due to its fracture and the appearance of deep fissures along the main fibre axis. Penetration of the nitroderivative compounds into the micro‐channels of the activated fibres was profited to develop a sensitive and selective method for NFA based on stripping SW voltammetry. The metabolite of NFA, 1‐aminohydantoin (AHD), did not exhibit cathodic response in the potential range between ?0.9 and +0.1 V. However, AHD gave a SW oxidation signal at activated CFMEs, with a potential of +0.95 V, which did not appear at non‐activated microelectrodes. Based on this finding, the simultaneous determination of NFA and AHD was performed by amperometry using two activated CFMEs in a parallel configuration connected to a multichannel detector. This methodology was also used to carry out degradation studies of NFA in acidic and basic media under photodegradation or thermal degradation conditions.     

PET导电纤维的制取及研究

以过氧化二苯甲酰为引发剂,使丙烯睛在涤沦(PET)纤维上接枝共聚。接枝纤维在含铜化合物,含硫还原剂溶液中反应,制备PET导电纤维。讨论了影响接枝共聚的各种因素,选择出最佳聚合条件。对该纤维的导电成份和结构以及性能进行了研究。     

The crystallinity of polyaryl ether ether ketone

Measurement of the degree of crystallinity of the polymer matrix in a composite is complicated by the presence of the reinforcing additive. This is particularly the case in APC-2 in which as much as 70% can be carbon fibre. A First Law procedure, developed for determining the degree of crystallinity of PEEK, which involves direct measurement of the enthalpy changes associated with melting, crystallization and heat capacity changes, has found to be an effective method for the determination of the crystallinity of the PEEK matrix. The procedure has been applied to carbon fibre and glass fibre PEEK composites.     

Experimental and numerical investigation of aramid fibre reinforced laminates subjected to low velocity impact

The low velocity impact performance of domestic aramid fibre reinforced laminates is investigated experimentally and numerically. Laminates with different thicknesses are impacted by drop-weight test machine under different impact energies. The time histories of impact force are recorded and ultrasonic C-scan technology is used to inspect the internal damage of the laminates. Numerical simulation is conducted using finite element method (FEM), taking into account both intralaminar and interlaminar damage. The intralaminar damage model is based on the continuum damage mechanics (CDM) approach, which consists of the strain-based Hashin failure criteria and the exponential damage evolution law, and considers the nonlinear shear behaviour of the material. The interlaminar damage is simulated by interface elements with cohesive zone model. The numerical results show good agreements with the experiments, thus verifying the validity of the presented numerical model.