Effect of^3B Group in Rings on Special Dispersion of B2O3-SiO2-ZrO2-Ta2O5-Na2O System Glass

Borosilicate glasses,with x B2O3-（60-x）SiO2-8ZrO2-8Ta2O5-24Na2O（7≤x≤59 mol%）composition,were fabricated by melt-quenching technique.NMR,UV-Vis,Raman and IR spectroscopic studies were utilized to investigate the structure of fabricated glasses.The NMR spectrum was deconvoluted into five Gaussian bands,assigned to ^4B（0B,4Si）,^4B（1B,3Si）,^4B（2B,2Si）,^3B（rings）and ^3B（loose）,to get their quantitative information.The relative dispersion deviation？P（g,F） was attributed to the relative quantity of ^3B（rings）but not all ^3B groups,and B2O3 existed mainly as[BO3]in rings firstly,and then as[BO3]in loose condition.The UV-Vis spectra revealed that the quantity of non-bridging oxygen increased firstly and then decreased with increasing concentration of B2O3.Acting as complementary techniques,Raman and IR measurements revealed that four-coordinated boron and silica mainly existed as ^4B-O-B,and Si-O-Si in Q^2,respectively,as chain structure but not framework structure,and[B？4]units prefered connections with borate rather than with silicate entities of the glass network in these studied glasses.In addition,the conclusion also certified that ^3B in＂loose＂condition located in lower wavenumbers between 1 200-1 600 cm^-1 in Raman spectra.

A single-cell encapsulation method based on a microfluidic multi-step droplet splitting system

Single cell analysis is of great significance to understand the physiological activity of organisms.Microfluidic droplet is an ideal analytical platform for single-cell analysis. We developed a microfluidic droplet splitting system integrated with a flow-focusing structure and multi-step splitting structures to form 8-line droplets and encapsulate single cells in the droplets. Droplet generation frequency reached1021 Hz with the aqueous phase flow rate of 1 m L/min and the oil phase flow rate of 15 mL /min. Relative standard deviation of the droplet size was less than 5% in a single channel, while less than 6% in all the8 channels. The system was used for encapsulating human whole blood cells. A single-cell encapsulation efficiency of 31% was obtained with the blood cell concentration of 2.5 ？ 104cells/mL, and the multicellular droplet percentage was only 1.3%. The multi-step droplet splitting system for single cell encapsulation featured simple structure and high throughput.

Development of a portable mid-infrared methane detection device

Based on direct absorption spectroscopy(DAS), a portable methane(CH_4) detection device was implemented. The device mainly includes a dual-channel non-dispersive infrared sensor(integrated with an infrared light source, light path and pyroelectric detector), a driving circuit of the sensor, an ARM11 embedded Win CE system, and a Lab VIEW-based data-processing platform. Experiments were carried out with prepared CH_4 samples to investigate the sensing performance. The relative detection error is less than 9.14% within the measuring range of 0—7×10^(-2). For a CH_4 sample with concentration of 0(i.e., pure nitrogen), the measured concentration fluctuation range is-1.2×10^(-5)—+2×10^(-5). An Allan deviation analysis on the gas sample with concentration of 0 indicates that the 1σ limit of detection(LoD) of the device is 4.8×10^(-6) with an average time of 1 s. Experiments were performed on three CH_4 samples with different concentrations to test the response time, which is validated to be less than 20 s. Due to the small size of the ARM11 embedded system and the powerful data processing capability of the Lab VIEW platform, the proposed portable and miniaturized CH_4 sensor shows a good application prospect in mining operations and some other industrial fields.