substrate (3). The cladding layers were 1.5 µm thick Al0.85Ga0.15As0.07Sb0.93. The nominally undoped Al0.3Ga0.7As0.02Sb0.98 waveguide layer with a total thickness of about 800 nm contained four 12.5 nm-wide In0.23Ga0.77As0.1Sb0.9 quantum wells centered in the waveguide and spaced 40 nm apart. The compressive strain in the quantum wells was about 1.45%. We fabricated 3 and 4 µm ridges by inductively coupled plasma reactive ion etching using a thin layer of silicon nitride as a dry etch mask; the etching depth was 1.65 µm with smooth sidewalls. We used SiNx to electronically isolate the active region. Windows were plasma etched in the dielectric above the ridges for electrical contact. Both n-side (Ti/PtAu) and p-side (Pd/Ge/Au/Pt/Au) metal contacts were e-beam deposited then alloyed for 1 min at 260 oC. Before facet coating, laser bars were cleaved to a 2 mm cavity length. Ar plasma was used to clean the laser facets. The back facet was high reflectivity (HR) coated with two pairs of Al2O3/Si. We estimate a coating reflectivity of 95%. The front facet was anti-reflection (AR) coated using a single layer of Al2O3 for a facet reflectivity of 4%. In both cases, Y2O3 was used as an adhesion layer. Finally, the lasers were cleaved into chips and mounted junction-side up using Au10Sn90 solder on an Au-coated C-mount copper block. 3. Device performance and analysis

We report single spatial mode diode lasers operating near 2.05 μm with room-temperature continuous-wave output power exceeding 100 mW. At 20°C, threshold currents were near 25 mA (320 A/cm2).

本文从我国现有的化学品检测方法标准与欧盟REACH注册要求的数据和测试信息比较人手,通过与REACH注册主要采用的OECD化学品测试方法比对,分析了我国应对REACH的检测方法体系的现状和存在的问题,并对今后的检测方法标准研究工作提出建议.

Methods of GC-MS(SIM) and GC-MS/MS were applied to simultaneous determination of 6 diuretics in tea drinks with microwave assisted derivatization.The sample was extracted with ethyl acetate and purified on Florisil SPE column.Under the microwave-heating condition,the time of derivatization with CH3I,acetone and K2CO3 was shortened to 8 min.It was found that values of intraday and interday RSD′s(n=6) of the method were less than 10%.Values of detection limit(3S/N) and lower limit of determination(10S/N) by GC-MS/MS was far lower than those obtained by GC-MS(SIM).The method of GC-MS/MS was applied to the analysis of samples of tea drinks,giving values of recovery in the range of 65.1%-108.5%.

The adsorption performance of MWCNTs to four benzodiazepines including diazepam, estazolam, alprazolam and triazolam was examined. Four drugs can be adsorbed rapidly and quantitatively oil MWCNTs in the static adsorption experiment, and the adsorption equilibrium was obtained within 10 unit. The adsorptive capacities of MWCNTs increase with increasing concentration of these drugs. In original drugs concentration, the adsorptive capacities of MWCNTs to four drugs were greater. The adsorptive capacity was 7.95, 7.88, 7.99 and 7.73 mg/g, respectively. The effects of experimental temperature were studied at 295 K, 303 K and 313 K. The adsorptive capacities of MWCNTs increased while temperature dropped. The data were simulated by Freundlich and Langmuir equations. The Langmuir equation accorded with the static adsorption characteristic of the compounds. The data from the dynamic adsorption experiment showed that the adsorption capacity and the extraction recoveries of four drugs on MWCNTs were satisfactory. The extraction recoveries of four drugs were more than 90%. The results indicated that MWCNTs could be used as a solid phase sorbents for the determination of benzodiazepines residues.

A large volume injection-gas chromatography-mass spectrometry(LVI-GC-MS) method for the determination of 205 pesticide residues in spinach,cabbage,apple,rice and bean samples was developed.Pesticides were determined by GC-MS under the selective-ion monitoring(SIM) mode and identified by their retention times and characteristic ions.This method is equivalent to the Japanese Standard Method in terms of detecting levels and purifying effects.Over 95% of the compounds have mean recoveries of 80%-120%,and the RSD(n=7) is less than 10%.

A typical set up used to perform lifetime tests of packaged, fiber pigtailed semiconductor lasers is described, as well as tests performed on a set of four pump lasers. It was found that two lasers failed after 3200 and 6100 hours under device specified bias conditions at elevated temperatures. Failure analysis of the lasers indicates imperfections and carbon contamination of the laser metallization, possibly from improperly cleaned photo resist. SEM imaging of the front facet of one of the lasers, although of poor quality due to the optical fiber charging effects, shows evidence of catastrophic damage at the facet. More stringent manufacturing controls with 100% visual inspection of laser chips are needed to prevent imperfect lasers from proceeding to packaging and ending up in space applications, where failure can result in the loss of a space flight mission.

We compare photonic crystal lasers with other microcavities for future switching and spectroscopy systems. High speed and efficiency along with massive lithographic integration makes these lasers particularly interesting for optical switching and signal processing.

An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

Efficient mid-IR interband cascade (IC) lasers have been developed based on III-V semiconductor materials with lasing emission covering a wavelength range from 2.7 to 5.6 microns. These IC lasers reuse injected electrons in cascade stages for photon generation with high quantum efficiency to achieve high output powers. Also, IC lasers have a low threshold current density with a very efficient use of applied voltage, resulting in reduced power consumption. Single-mode distributed feedback lasers have been made, and integrated into aircraft and balloon instruments which made atmospheric measurements of CH 4 and HCl. In this work, the characteristics of IC lasers and their recent developments are reviewed.

A method for the analysis of chloramphenicol in cosmetic by gas chromatography(GC)/mass spectrometry(MS)(negative chemical ionization)(NCI) was studied.The optimum conditions are as follows: using acetic ether as an extractant and BSTFA+TMCS(99+1) as derivative reagents,chloramphenicol was derived at 70 ℃ for 60 min,and then determined by GC/MS(NCI).The detection limit is 10 μg/kg,and the linear range is from 0.5 to 500 ng/mL.The recoveries are 94.4%～95.7% and the relative standard deviations are 0.23%～1.3%.The method is simple and rapid,and the samples can be finished the analysis within 3 h.The method has been applied to the determination of chloramphenicol in cosmetics.

A new method was developed for the rapid screening and confirmation analysis of barbital, amobarbital and phenobarbital residues in pork by gas chromatography-tandem mass spectrometry (GC/MS/MS) with ion trap MSD. The residual barbiturates in pork were extracted by ultrasonic extraction, cleaned up on a multiwalled carbon nanotubes (MWCNTs) packed solid phase extraction (SPE) cartridge and applied acetone-ethyl acetate (3:7, v/v) mixture as eluting solvent and derivatized with CH3I under microwave irradiation. The methylated barbiturates were separated on a TR-5MS capillary column and detected with an ion trap mass detector. Electron impact ion source (EI) operating MS/MS mode was adopted for identification and external standard method was employed for quantification. One precursor ion m/z 169 was selected for analysis of barbital and amobarbital and m/z 232 was selected for phenobarbital. The product ions were obtained under 1.0 V excitation voltage. Good linearities (linear coefficient R > 0.99) were obtained at the range of 0.5-50 microg kg(-1). Limit of detection (LOD) of barbital was 0.2 microg kg(-1) and that of amobarbital and phenobarbital were both 0.1 microg kg(-1) (S/N > or = 3). Limit of quantification (LOQ) was 0.5 microg kg(-1) for three barbiturates (S/N > or = 10). Satisfying recoveries ranging from 75% to 96% of the three barbiturates spiked in pork were obtained, with relative standard deviations (R.S.D.) in the range of 2.1-7.8%.

A method was developed for the simultaneous determining of Clenbuterol,Salbutamol,Terbutaline and Fenoterol residues in pork tissues using gas chromatography-mass spectrometry(GC-MS).The homogenized samples were enzyme digested by β-glucuronidase enzyme,and extracted with ammonium acetate.Further cleanup was performed on a MCX cartridge and the purified drugs were derivatized with Sylon BFT [N,Obis(trimethylsilyl) trifluoroacetamide(BSTFA)-trimethylchlorosilane(TMCS),99+1].The selected ion monitoring(SIM) method was used for detection,and the monitored ions were m/z 86,187,212,and 262 for Clenbuterol,m/z 86,350,369,and 440 for Salbutamol,m/z 86,336,356,and 357 for Terbutaline,and m/z 236,322,356,and 412 for Fenoterol,respectively.Quantitation ions were selected at m/z 86 for Clenbuterol,m/z 369 for Salbutamol,m/z 356 for Terbutaline,and m/z 322 for Fenoterol.The limits of detection were 0.5 μg/kg for Clenbuterol and Salbutamol,5 μg/kg for Terbutaline and Fenoterol.The correlation coefficients were better than 0.99 for the calibration curves for the drugs.The linear range is(0.5-)200 μg/kg for Clenbuterol and Salbutamol,5-200 μg/kg for Terbutaline and Fenoterol.The recoveries were 68%-128%,with relative standard deviations of 3%-17%.

Continuous-wave operation of a mid-infrared (similar to 3.3 mu m) interband cascade laser has been demonstrated at temperatures up to 264 K. The laser has also been operated continuously with a thermoelectric cooler near 260 K for more than 1900 h without observable degradation.

A method was developed for the simultaneous determination of chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) residues in animal tissues using gas chromatography/mass spectrometry (GC/MS) with chemical ionization source in negative mode. The homogenized samples were extracted with ethyl acetate and the extracts were partitioned with n-hexane to remove lipids. Further cleanup was performed on a florisil cartridge and the purified samples were derivatized with Sylon BFT [N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA)-trimethylchlorosilane (TMCS), 99: 1, v/v] in toluene. Meta-nitrochloramphenicol (m-CAP) was used as the internal standard for the determination. Selected ion monitoring (SIM) was used for detection, ions were chosen, respectively, for the monitoring at m/z 432, 466, 468, 470 for m-CAP, m/z 376, 378, 466, 468 for CAP, m/z 409, 411, 499, 501 for TAP, and m/z 339, 341, 429, 431 for FF. Quantitative ions were selected at m/z 466 for CAP and m-CAP, at m/z 339 for FF and at m/z 409 for TAP. The detection limits were 0.03 microg/kg for CAP, 0.2 microg/kg for FF and TAP. The correlation coefficients were above 0.99 for the calibration curves of the medicines. The linear ranges were 0.1 - 8.0 microg/kg for CAP and 0.2 - 4.0 microg/kg for FF and TAP. The reproducibilities of the compounds within a batch were 5.5%, 10.4%, and 8.8% for CAP, FF, and TAP respectively, while the corresponding values between the batches were 7.4%, 20.7%, and 19.1%. The recoveries were 80.0% - 111.5%, and the relative standard deviations were 1.2% - 15.4%. The method is applicable for detection of the residues in animal derived food, such as pork, poultry and aquatic products.

The figure depicts a proposed semiconductor laser, based on In(As)Sb quantum dots on a (001) InP substrate, that would operate in the wavelength range between 1.8 and 2.3 m. InSb and InAsSb are the smallest-bandgap conventional III-V semiconductor materials, and the present proposal is an attempt to exploit the small bandgaps by using InSb and InAsSb nanostructures as midinfrared emitters. The most closely related prior III-V semiconductor lasers are based, variously, on strained InGaAs quantum wells and InAs quantum dots on InP substrates. The emission wavelengths of these prior devices are limited to about 2.1 m because of critical quantum-well thickness limitations for these lattice mismatched material systems. The major obstacle to realizing the proposed laser is the difficulty of fabricating InSb quantum dots in sufficient density on an InP substrate. This difficulty arises partly because of the weakness of the bond between In and Sb and partly because of the high temperature needed to crack metalorganic precursor compounds during the vapor-phase epitaxy used to grow quantum dots: The mobility of the weakly bound In at the high growth temperature is so high that In adatoms migrate easily on the growth surface, resulting in the formation of large InSb islands at a density, usually less than 5 x 10(exp 9) cm(exp -2), that is too low for laser operation. The mobility of the In adatoms could be reduced by introducing As atoms to the growth surface because the In-As bond is about 30 percent stronger than is the In-Sb bond. The fabrication of the proposed laser would include a recently demonstrated process that involves the use of alternative supplies of precursors to separate group-III and group-V species to establish local non-equilibrium process conditions, so that In(As)Sb quantum dots assemble themselves on a (001) InP substrate at a density as high as 4 x 10(exp 10) cm(exp -2). Room-temperature photoluminescence spectra of quantum dots formed by this process indicate that they emit at wavelengths from 1.7 to 2.3 microns.

A solid-phase extraction (SPE)/GC–MS method using multiwalled carbon nanotubes (MWCNTs) was developed for the determination of four benzodiazepine residues including diazepam, estazolam, alprazolam and triazolam in pork. The analytes were extracted by ultrasonic assistant extraction using acetonitrile, concentrated and purified by MWCNTs packed cartridge, and determined by GC–MS. Ultrasonic extraction conditions, which included temperature, time, power, and solvent volume, were optimized. Comparative studies showed that MWCNTs were superior to C18 for the adsorption of drugs. Parameters influencing SPE efficiency, such as sample amounts, variety and volume of the eluent, were also optimized. Electron ionization (EI) operating in time program-selected ion monitoring mode (SIM) was used for GC–MS identification. The analytes were quantified with external standard calibration curve method. Lower limit of detection and quantification was obtained by the new method. Linear calibration curves were obtained in the concentration range from 10ng/mL to 500ng/mL for diazepam and from 20ng/mL to 1000ng/mL for estazolam, alprazolam and triazolam with calibration coefficients of 0.99 and above. The average recoveries for the four benzodiazepines spiked in pork were 75% to 104% and their relative standard deviations were between 1.3% and 10%. The limits of detection were 2μg/kg for diazepam and 5μg/kg for estazolam, alprazolam and triazolam in pork, respectively.

A new method was developed for the rapid extraction and unequivocal determination of barbital, amobarbital and phenobarbital residues in pork. The isolation of the analytes from pork samples was accomplished by utilizing an accelerated solvent extractor ASE 300. The procedure was automatically carried out in series for fat removing and extraction, respectively with n-hexane and acetonitrile pressurized constantly at 10.3 MPa for 30 min. After evaporation, the extracts were cleaned up on a C(18) solid phase extraction (SPE) cartridge and the barbiturates were eluted with hexane-ethyl acetate (7:3), evaporated on a rotary evaporator and derivatized with CH(3)I. The methylated barbiturates were separated on a HP-5MS capillary column and detected with a mass detector. Electron impact ion source (EI) operating in time program-selected ion monitoring mode (SIM) was used for identification and external standard method was used for quantification. Good linearity was obtained in the range from 0.5 microg/kg to 25 microg/kg. Average recoveries of the three barbiturates spiked in pork ranged from 84.0% to 103.0%, with relative standard deviations from 1.6% to 12%. The limit of detection (LOD) was 0.5 microg/kg for the three barbiturates (S/N>or=3). The quantification limit (LOQ) was 1 microg/kg for the three barbiturates (S/N>or=10).