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Advances in microfluidic-based DNA methylation analysis

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Nanotechnology and precision Engineering 2024年第1期7卷 116-134页

作者： Jiwen Li Tiechuan Li Xuexin Duan state key laboratory of precision measuring technology and instruments Tianjin UniversityTianjin 300072China

DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientiﬁc research.Microﬂu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efﬁciency.In recent years,the use of novel microﬂuidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,weﬁrst focus on DNA methylation and its applications.Then,we discuss advanced microﬂuidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microﬂuidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microﬂuidic-based methods for DNA methylation analysis.

关键词： Microﬂuidic chip DNA methylation analysis Molecular analysis High throughput Low cost

Particle distributions in Lamb wave based acoustofluidics

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Nanotechnology and precision Engineering 2024年第2期7卷 60-68页

作者： Chuanchao Zhang Xian Chen Wei Wei Xuejiao Chen Quanning Li Xuexin Duan key laboratory of precision measuring technology and instruments College of Precision Instrument and Optoelectronics EngineeringTianjin UniversityTianjin300072China

Acoustic streaming enabled by a Lamb wave resonator(LWR)is efficient for particle trapping and enrichment in microfluidic channels.However,because Lamb waves combine the features of bulk acoustic waves and surface acoustic waves,the resulting acoustic streaming in the LWR occurs in multiple planes,and the particle flow behavior in this acoustofluidic system is largely unknown.Reported here are numerical simulations and laboratory experiments conducted to investigate the boundary conditions for particle motion inside a microvortex induced by an LWR.Upon dynamic capture,the particles’trajectories become orbital paths within an acoustic vortex.The suspended particles encounter two distinct acoustic phenomena,i.e.,the drag force resulting from acoustic streaming and the acoustic radiation force,which exert forces in various directions on the particles.When the acoustic radiation force and the fluid drag force are dominant for large and small particles in a mixed solution,respectively,the large particles reside within the vortex while the small particles remain at its periphery.Conversely,when the acoustic radiation force is dominant for both types of particles,the distribution pattern is reversed.

关键词： Acoustoﬂuidics Lamb wave resonator Particle manipulation Microvortex

Dynamic thermal modeling and parameter identification for a monolithic laser diode module

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Chinese Physics B 2013年第3期22卷 317-322页

作者：李金义杜振辉马艺闻徐可欣 state key laboratory of precision measuring technology and instruments Tianjin University

We improved the thermal equivalent-circuit model of the laser diode module（LDM） to evaluate its thermal dynamic properties and calculate the junction temperature of the laser diode with a high accuracy.The thermal parameters and the transient junction temperature of the LDM are modeled and obtained according to the temperature of the thermistor integrated in the module.Our improved thermal model is verified indirectly by monitoring the emission wavelength of the laser diode against gas absorption lines,and several thermal parameters are obtained with the temperature uncertainty of 0.01 K in the thermal dynamic process.

关键词： laser diode module,dynamic thermal modeling,thermal time constant,tunable diode laser absorption spectroscopy（TDLAS）

Linear group delay spectral interferometry for full-range precision absolute length metrology

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Photonics Research 2024年第2期12卷 313-320页

作者： JINDONG WANG JINGSHENG HUANG QIHUA LIU WEI DU FUMIN ZHANG TAO ZHU key laboratory of Optoelectronic technology&Systems(Ministry of Education) Chongqing UniversityChongqing 400044China state key laboratory of precision measuring technology&instruments Tianjin UniversityTianjin 300072China

The optical frequency comb serves as a powerful tool for distance measurement by integrating numerous stable optical modes into interferometric measurements,enabling unprecedented absolute measurement precision.Nonetheless,due to the periodicity of its pulse train,the comb suffers from measurement dead zones and ambiguities,thereby impeding its practical applications.Here,we present a linear group delay spectral interferometer for achieving precise full-range distance measurements.By employing a carefully designed linear group delay(LGD)device for phase modulation of the comb modes,interference can occur and be easily measured at any position.Our approach effectively eliminates the dead zones and ambiguities in comb-based ranging,without the need for cumbersome auxiliary scanning reference devices or reliance on complex high-repetition-rate combs or high-resolution spectrometers.We conducted length metrology experiments using a mode-locked comb referenced to a rubidium clock,achieving a large nonambiguity range up to 0.3 m,covering the entire measurement period.The maximum deviation compared to a laser interferometer was less than 1.5μm,and the minimum Allan deviation during long-term measurements reached 5.47 nm at a 500 s averaging time.The approach ensures high accuracy while maintaining a simple structure,without relying on complex external devices,thereby propelling the practical implementation of comb-based length metrology.

关键词： interferometer metrology delay

The Optical Characteristics of the Acousto-optic Tunable Filter with the Equivalent Point

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Chinese Journal of Lasers 2002年第2期11卷 55-60页

作者： XU Kexin NI Yong XUE Bin JIANG Chengzhi HU Xiaotang( state key laboratory of precision measuring technology and instruments, tianjin university, tianjin 300072, China) tianjin university State Key Laboratory of Precision Measuring Technology and Instruments 天津 300072

In this paper, the interaction curves of acoustic and optical waves in a non-collinear AOTF (acousto-optic tunable filter) cell under the parallel-tangent momentum matching condition are analyzed systematically. A new theory of equivalent point for AOTF design is put forward. The wavelength characteristics and the wavelength resolution of two diffraction beams with equivalent point design in AOTF are emphatically analyzed. The optical characteristics at δ = 0 (ideal case) and δ≠0 (real case) are also discussed. The advantages of the AOTF with equivalent point design include high wavelength resolution, more quantitative energy and larger incident angle aperture.

关键词： equivalent point momentum matching AOTF TeO2

Study on Calibration Methods of Structured Light Sensor

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Chinese Journal of Lasers 2002年第3期11卷 39-45页

作者： WANG Baoguang HE Zhonghai LIAO Yibai CHEN Lincai (state key laboratory of precision measuring technology and instruments, tianjin university, tianjin 300072, China) tianjin university State Key Laboratory of Precision Measuring Technology and Instruments 天津 300072

In this paper, advantages and disadvantages of existing calibration methods are presented. Based on the projective transformation which is the basic principle of a CCD camera, a new method of calibrating structured li... 详细信息

关键词： structured light sensor projective transformation calibration

Automatic Recognition Method for Optical measuring instruments Based on Machine Vision

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天津大学学报：英文版 2008年第3期14卷 202-207页

作者：宋乐林玉池郝立果 state key laboratory of precision measuring technology and instruments Tianjin University

Based on a comprehensive study of various algorithms, the automatic recognition of traditional ocular optical measuring instruments is realized. Taking a universal tools microscope(UTM) lens view image as an example, a 2-layer automatic recognition model for data reading is established after adopting a series of pre-processing algorithms. This model is an optimal combination of the correlation-based template matching method and a concurrent back propagation(BP) neural network. Multiple complementary feature extraction is used in generating the eigenvectors of the concurrent network. In order to improve fault-tolerance capacity, rotation invariant features based on Zernike moments are extracted from digit characters and a 4-dimensional group of the outline features is also obtained. Moreover, the operating time and reading accuracy can be adjusted dy-namically by setting the threshold value. The experimental result indicates that the newly developed algorithm has optimal recognition precision and working speed. The average reading ratio can achieve 97.23%. The recognition method can automatically obtain the results of optical measuring instruments rapidly and stably without modifying their original structure, which meets the application requirements.

关键词：机器视觉自动识别光学测量工具神经网络

Comparison Between MIR and NIR Spectroscopic Techniques for the Determination of Fat and Protein Contents in Milk

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Transactions of tianjin university 2007年第5期13卷 375-378页

作者：张学典常敏马真彭丹徐可欣 state key laboratory of precision measuring technology and instruments Tianjin University

To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the MIR range of 3 200-700 cm-1 and NIR range of 9 000-4 000 cm-1.The spectral features in the two regions were analyzed.The MIR spectra of milk were characteristic due to the MIR inherent molecular specificity,whereas the NIR spectra were relatively characterless due to the NIR low selectivity.Partial least squares(PLS)regression models for fat and protein were developed by using both MIR and NIR spectra.MIR data with no pretreatment gave better results than NIR data.The square correlation coefficient(R2)and the root mean square error of prediction(RMSEP)were 0.98 and 0.10 g/dL for fat and 0.97 and 0.11 g/dL for protein.With NIR techniques,satisfactory results were not obtained with raw data.However,NIR data after pretreatment gave similarly good results to the ones using MIR method.This paper indicates that either of the MIR and NIR spectral methods is reliable for the determination of the fat and protein contents.

关键词： MIR NIR 红外线光谱学牛奶脂肪蛋白质检测方法.

Effects of Parameters in Femtosecond Laser Micromachining on Ablation of Silicon

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Transactions of tianjin university 2009年第3期15卷 225-228页

作者：陈治傅星耿娜胡小唐 state key laboratory of precision measuring technology and instruments Tianjin University

A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.

关键词：激光微加工硅表面飞秒影响参数脉冲持续时间扫描电子显微镜原子力显微镜烧蚀阈值