基于正交调制的激光测距系统和解模糊方法

提出一种基于正交调制的激光测距系统,该方案与传统的二次混频方法相比,提高了相位测量精度并简化了系统的硬件设计,针对距离测量过程中的距离模糊问题,提出了一种基于超定方程组的距离解模糊算法,避免了对最优解的搜索,最后使用2台K60激光测距仪和3台基于本方案的测距仪在精度为0.18 mm的国家标准基线上进行对比试验,结果显示,测距时间少于1.8 s,平均测量误差在2 mm以内,在60 m的量程内测距标准差在1 mm以内,验证了该方案相比较传统的方法具有更高的测量精度和速度。     

基于便携式近红外光谱仪的重金属离子定量分析研究

近红外光谱分析技术凭借分析速度快、样品预处理简单等特点,被广泛用于农业、医药、环境、石油化工等领域。为实现高效率的现场检测,便携式的近红外光谱仪越来越备受关注。由于近红外光谱分析技术能够对多组分同时进行测定,因此在该研究中使用便携式近红外光谱仪探索同时对稀溶液中多种重金属离子定量分析的可行性。使用胺基改性聚合淀粉富集水中的镍离子和铜离子,然后使用便携式近红外光谱仪直接采集胺基改性聚合淀粉的近红外漫反射光谱,再借助光谱预处理方法和偏最小二乘回归法建立模型,最后通过交叉验证和外部验证证明所建立模型的稳定性。结果表明,在其他干扰离子存在下,氨基改性聚合淀粉仍能分别以99.5%和99.8%高效率地富集稀溶液中的镍离子和铜离子。便携式光谱仪采集的近红外漫反射光谱分别经连续小波变换和多元散射校正结合卷积求导光谱预处理之后,使用偏最小二乘回归能够得到相关系数分别为0.981 9和0.965 4的稳健模型,实现了对稀溶液中镍离子和铜离子的同时测定,并且检测到的镍离子和铜离子的最低浓度均为3.0 mg·L-1。该方法不仅提高了近红外光谱分析技术的检测灵敏度,同时也表明了便携式近红外光谱仪对多种重金属离子同时定量分析的可行性,是一种拓宽近红外光谱分析技术的有益探索。     

Portable X-band system for solution state dynamic nuclear polarization

This paper concerns instrumental approaches to obtain large dynamic nuclear polarization (DNP) enhancements in a completely portable system. We show that at fields of 0.35 T under ambient conditions and at X-band frequencies, 1H enhancements of >100-fold can be achieved using nitroxide radical systems, which is near the theoretical maximum for 1H polarization using the Overhauser effect at this field. These large enhancements were obtained using a custom built microwave transmitter and a commercial TE102 X-band resonant cavity. The custom built microwave transmitter is compact, so when combined with a permanent magnet it is readily transportable. Our commercial X-band resonator was modified to be tunable over a range of approximately 9.5-10 GHz, giving added versatility to our fixed field portable DNP system. In addition, a field adjustable Halbach permanent magnet has also been employed as another means for matching the electron spin resonance condition. Both portable setups provide large signal enhancements and with improvements in design and engineering, greater than 100-fold 1H enhancements are feasible.     

便携式农药残留毒性快速测试仪--水果和蔬菜农药残留动力学速测方法

研制了一种新型的化学动力学测试仪器,适用于水果和蔬菜农药残留毒性的测试。阐述了根据农药的毒理学机制所进行的仪器设计原理,了满足设计要求的关键技术和测试方法,该仪器测定速度快,试剂费用低廉,其灵敏度的敌敌畏≤０．３ｍｇ／Ｌ,甲胺磷≤１．５ｍｇ／Ｌ。     

Screening of seized cocaine samples using electrophoresis microchips with integrated contactless conductivity detection

This study describes the development of a new analytical method for the separation and detection of cocaine (COC) and its adulterants, or cutting agents, using microchip electrophoresis (ME) devices coupled with capacitively coupled contactless conductivity detection (C⁴D). All the experiments were carried out using a glass commercial ME device containing two pairs of integrated sensing electrodes. The running buffer composed of 20 mmol/L amino‐2‐(hydroxymethyl) propane‐1,3‐diol and 10 mmol/L 3,4‐dimethoxycinnamic acid provided the best separation conditions for COC and its adulterants with baseline resolution (R > 1.6), separation efficiencies ranging from (2.9 ± 0.1) to (3.2 ± 0.2) × 10⁵ plates/m, and estimated LOD values between 40 and 150 μmol/L. The quantification of COC was successfully performed in four samples seized by the Brazilian Federal Police Department and all predicted values agree with values estimated by the reference method. Some other interfering species were detected in the seized samples during the screening procedure on ME–C⁴D devices. While lidocaine was detected in sample 3, the presence of levamisole was observed in samples 2 and 4. However, their concentrations were estimated to be below the LOQ. ME–C⁴D devices have proved to be quite efficient for the identification and quantification of COC with errors lower than 10% when compared to the data obtained by a reference method. The approach herein reported offers great potential to be used for on‐site COC screening in seized samples.     

The ChatterVox™ Portable Voice Amplifier: A Means to Vibration Dose Reduction?

By speaking loudly for extended periods, teachers are vulnerable to laryngeal and voice changes associated with vocal fold “vibration overdose.” Voice clinicians frequently recommend voice amplification ostensibly designed to reduce vibration dose and improve voice. However, there are few data regarding the degree of vocal loudness attenuation achieved by specific amplification devices. The purpose of this investigation was to examine the effectiveness of the ChatterVox™ Portable Voice Amplification System (Siemens Hearing Instruments) for reducing the sound pressure level (SPL) of a speaker's voice during a simulated classroom lecture. Ten participants were instructed to continuously read one of two phonetically balanced passages while amplified and unamplified. Voice intensity measurements were obtained at three inches from the mouth (i.e., mouth level) and at the back of a classroom in both amplified and unamplified conditions. When amplified with the ChatterVox™, speakers experienced an average decrease in vocal intensity at mouth-level of 6.03 dB SPL (p < 0.002). Furthermore, an average increase of 2.55 dB SPL (p < 0.038) at the back of the classroom was observed. Collectively, these results indicate that the ChatterVox™ amplification device reduced the speaker's vocal intensity level at the microphone, while it augmented the voice heard at the back of the classroom. By inference, this degree of vocal attenuation at mouth level should contribute to a desirable reduction in vibration dose, thus lowering the risk of vibration overdose.     

A Portable Fill‐and‐Flow Channel Biosensor with an Electrode to Predict the Effect of Interferences

A portable fill‐and‐flow channel biosensor with a “predictor electrode” is described. The predictor electrode, on the opposite channel wall and upstream of the detector electrode, allows direct evaluation of the current due to interfering species at the detector electrode. A model is developed which shows that the reaction at the upstream predictor electrode has no significant effect on the concentration distribution of the interfering species at the detector electrode. This enables a straightforward correction of the current at the detector electrode and a determination of the analyte concentration. The effect of interference from ascorbic acid in the detection of glucose in samples was efficiently removed by using such a concept. The recovery of glucose from samples containing ascorbic acid was 103% (s=12%, n=3). The approach was also applied to a biosensor for the determination of glucose in red wine samples containing polyphenolic interferents.     

Portable system for near-real time measurement of gaseous formaldehyde by means of parallel scrubber stopped-flow absorptiometry

Formaldehyde, HCHO, is one of the important causal agents of sick-building syndrome. It is also an important product of ambient air photochemistry. We report here a portable instrument capable of a 0.08 ppbv limit of detection (LOD) and a time resolution of 5 min that is useful for both indoor and ambient air applications. The detection is based on efficient gas collection and chromogenic reaction with 3-methyl-2-benzothiazolone hydrazone (MBTH) through a pair of alternately sampling small-bore porous-membrane tube diffusion scrubbers (DS). The chemistry is well established, requires no special reagent preparation or elevated reaction temperatures and permits the use of inexpensive light emitting diode (LED)-based detectors without need for long path cells. Stopped flow alternate sampling allows an HCHO collection performance, an order of magnitude better than any previous system with high throughput and high sensitivity. Results for indoor and ambient air analyses are presented.     

多种方法分析与评价乙酸乙酯合成实验中产物之纯度

采用气相色谱内标法、面积归一化法及NMR内标法3种方法对乙酸乙酯合成反应中的产物进行纯度分析.GC内标法可抵消由于操作条件的波动而带来的误差,只需内标物与待测组分在同样条件下出峰且分离度较好,定量精度高,测出的乙酸乙酯纯度最低;应用NMR内标法可同步完成纯度分析和结构鉴定,且无需引入校正因子,操作简便.     

A portable automated multianalyte biosensor

The array biosensor employs an array of capture molecules on a planar optical waveguide to interrogate multiple samples simultaneously for multiple targets. In assay development and demonstration studies published previously, we have quantified this biosensor's capability for rapid identification of a wide variety of targets in complex sample media. This paper describes the miniaturization and automation of the array biosensor for portability and on-site use. The fluidics have been redesigned and constructed with reliability and commercial production of disposable components in mind. To demonstrate the automated operation, simultaneous assays were automatically conducted on samples containing both ovalbumin and staphylococcal enterotoxin B. Results demonstrate the capability of the biosensor for detection and quantification.