光导纤维光谱法——Ⅲ.光波导吸光光度分析

本文介绍了利用光波导原理制成的长光程毛细吸收管的原理,仪器装置及其在分光光度分析中的应用。讨论了光在几种不同类型的长光程毛细吸收管中的传播方式以及对测定灵敏度的影响。探讨了在全反射型长光程毛细吸收管中引起透过光谱的形变和工作曲线弯曲的原因,给出了长光程毛细吸收管吸光光度法中吸光度的理论计算式。

Determination of Chromium and Zinc in Soil by Microwave Digestion and Flame Atomic Absorption Spectrometry

[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by combined flame atomic absorption spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-0.8 mg/L for Cr and 0-0.8 mg/L for Zn, the detection limits of Cr and Zn was 0.0025 mg/L and 0.002 3 mg/L, respectively. Recoveries of 102.4%-103.2% for Cr and 97.7%-98.3% for Zn were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of Cr and Zn in soil samples.

矿物的颜色

中国画常有的颜色主要是花青、藤黄、胭脂、朱砂、赭石、石青、石绿等，前3种是植物颜色，后4种是矿物颜色，因为植物颜色在空气中不稳定，易变色；而矿物颜色稳定，千年不变色。如绿色的孔雀石，褐红色的赤铁矿等都可作为天然颜料。那么矿物的颜色是怎样形成的呢?

Conditions of synthesis for PpIX

The characteristics of ALA absorption spectra under different conditions are studied with spectrometers. The results indicate that the wavelength of ALA,corresponding to the strongest absorption peak, is 282 nm under different conditions. The content of PplX synthesized is in direct proportion to the density of Jurkat cells. The most suitable culture time is 8 hours in order to synthesize more PplX. FCS has a block effect on the synthesis of PpIX.

Hermiticity of Hamiltonian Matrix using the Fourier Basis Sets in Bond-Bond-Angle and Radau Coordinates

In quantum calculations a transformed Hamiltonian is often used to avoid singularities in a certain basis set or to reduce computation time. We demonstrate for the Fourier basis set that the Hamiltonian can not be arbitrarily transformed. Otherwise, the Hamiltonian matrix becomes non-hermitian, which may lead to numerical problems. Methods for cor- rectly constructing the Hamiltonian operators are discussed. Specific examples involving the Fourier basis functions for a triatomic molecular Hamiltonian （J=0） in bond-bond angle and Radau coordinates are presented. For illustration, absorption spectra are calculated for the OC10 molecule using the time-dependent wavepacket method. Numerical results indicate that the non-hermiticity of the Hamiltonian matrix may also result from integration errors. The conclusion drawn here is generally useful for quantum calculation using basis expansion method using quadrature scheme.

Research on the sensitivity for the coal mine gas concentration detection by laser spectrum absorption

Because of the former gas chemistry examination method defects, tunable diode laser absorption spectrum technology （TDLAS） was used. It used an isolated absorption spectrum of the gas molecule to measure the gas absorption spectrum in order to distinguish the gas conveniently. The second harmonic （20 was measured in this system. Due to the fact which the harmonious signal is proportional to the concentration of the absorption gas, the gas concentration may be obtained through examining harmonious signal. The theoretical analysis and the experimental result indicate that under the same level of pressure, survey with the signal-to-noise ratio（SNR） of 2fsignal increases the accuracy by one order of magnitude and may reach 10 ^-3 and the sensitivity may reach the 10^-6 level compared to that of direct absorption. 5% methane density and a 30 cm absorption cell were used in the experiment. It has several advantages including high sensitivity, best resolution, and faster response and so on. The gas concentration monitoring of coal mine may be accomplished.

An all optical fiber gas sensor of NH3 and CO based on based on the spectral absorption and harmonic detection

An all optical fiber gas sensor is presented to detect the concentration of NH3 and CO. Based on the spectral absorption, The wideband light source is used to reflect two narrowband spectra by fiber grating of different duty. and piezoelectric ceramics to obtain narrowband output light. The high sensitivity detection can be measured from the second harmonic signal. The two narrowband spectra are corresponding to the absorption spectra of NH3 and CO. Concentration detection are realized by the detection of variety of light intensity. Sensitivity is proved and cost is reduced.

Aroma Properties of Selected Local Spices of Akwa Ibom State of Nigeria

Some famous local spices were selected to determine their potentials in terms of their aroma and utilization. They included Tea Bush （Ocimum basilicum）, Guinea Black Pepper （Piper guineense）, African Pepper （Xylopia aethiopica）, Alden Tree （Tetrapleura tetraptera） and the African Meg Nut or Onion Tree （Blighia unijugata）. Essential oils were extracted from the samples and used for aroma absorption test in a uv-visible spectrometer V2.03. The intensity of aroma was indicated at some peak values of absorption at particular wavelengths. The compounds responsible for the aroma at this peak values were identified by matching their wavelengths with those of known compounds at similar wavelengths of absorption. Thus, a compound such as Quinoline that has hot strong aroma and little bleaching effect was proved to be present in Guinea black pepper ;at the wavelength of 313.0 nm. Benzene with hot strong aroma and flammable effect was also indicated in this spice at the wavelength of 253.0 rim. Proximate analysis carried out showed that these spices have high nutritive values. Some of them such as Guinea black pepper, African Nutmeg and Ethiopian （African） pepper had high ether extract of 20.01, 25.97 and 31.25 respectively, and could be regarded as oil seeds, they contain much of essential oils.

Spectral Absorption Gas Sensor Based on Anti-Resonant Reflecting Optical Waveguide

An air-silica microstructure optical fiber based on the anti-resonant reflecting optical waveguide （ARROW） principle was used to develop a spectral absorption gas sensor. The ARROW fiber has an air core and an air cladding layer. An ARROW fiber with a length of 725mm was used to construct a sensing system to detect acetylene gas. The gas was injected into the fiber from one end of the fiber. The transmission spectra were collected using an optical spectrum analyzer. The results indicate that the system can detect the gas of different concentrations and has the good system linearity. The response time of the system is about 200 s.

A switchable dual-wavelength erbium-doped fiber laser based on saturable absorber and active optical fiber ring filter

A dual-wavelength erbium-doped fiber laser(EDFL) with outstanding stability is presented. In the fiber laser system, two nested active optical fiber ring filters are configured to improve the comb spectrum performance, a saturable absorber is employed to form a gain grating for both filtering and frequency stabilizing, two cascaded fiber Bragg gratings(FBGs) are utilized to achieve dual-wavelength output, and a variable attenuator is arranged to adjust output power. Experimental results illustrate that the peak wavelength drift is less than 3 pm, and a good linear relationship between output power and pump power is realized.

Water Vapor Detection System Based on Scanning Spectra

Scanning the absorption spectral line of water vapor through wavelength around 1368.597nm is successfully used to measure the value of micro-moisture content. The synchronous superposition average of original signal algorithm based on labview is innovated and applied to detecting weak spectrum absorption signal instead of low pass filter. Two data processing methods are used to get the concentration of water vapor in ppm： one is a general formula method which has newly deduced a general formula to calculate the concentration of gas with temperature and beam intensity ratio when the pressure is equal to or greater than 1 atm; the other is engineering calibration method which is proved to have high resolution and accuracy with the fitted curve of beam intensity ratio and concentration in ppm when the temperature changes form 258K to 305K and the pressure ranges from 1 atm to 5 atm.

High-permittivity Sb_(2)S_(3) single-crystal nanorods as a brand-new choice for electromagnetic wave absorption

The application of antimony sulfide(Sb_(2)S_(3))has been limited mainly to the energy storage and photoelectric conversion fields.However,in this work,the application of Sb_(2)S_(3) is extended to the field of electromagnetic(EM)wave absorption for the first time.High-permittivity Sb_(2)S_(3) singlecrystal nanorods were prepared successfully and exhibited excellent performance,with a low reflection loss of -65.9 dB(13.0 GHz,3.8 mm)and an ultra-wide effective absorption bandwidth of 9.5 GHz(8.5-18.0 GHz,4.1 mm).After excluding the general absorption mechanisms,including conductive losses,interfacial polarization,and dipole polarization,the distinctive single-crystal volume polarization affected by shape anisotropy was proposed.This work not only meets the challenge of a single-component dielectric material design but also introduces a new concept for construction of efficient dielectric EM wave absorption material.