TiO2/MXene-Assisted LDI-MS for Urine Metabolic Profiling in Urinary Disease

Cancer remains an intractable medical problem. Rapid diagnosis and identification of cancer are critical to differentiate it from nonmalignant diseases. High-throughput biofluid metabolic analysis has potential for cancer diagnosis. Nevertheless, the present metabolite analysis method does not meet the demand for high-throughput screening of diseases. Herein, a high-throughput, cost-effective, and noninvasive urine metabolic profiling method based on TiO₂/MXene-assisted laser desorption/ionization mass spectrometry (LDI-MS) is presented for the efficient screening of bladder cancer (BC) and nonmalignant urinary disease. Combined with machine learning, TiO₂/MXene-assisted LDI-MS enables high diagnostic accuracy (96.8%) for the classification of patient groups (including 47 BC and 46 ureteral calculus (UC) patients) from healthy controls (113 cases). In addition, BC patients can also be identified from noncancerous UC individuals with an accuracy of 88.3% in the independent test cohort. Furthermore, metabolite variations between BC and UC individuals are investigated based on relative quantification, and related pathways are also discussed. These results suggest that this method, based on urine metabolic patterns, provides a potential tool for rapidly distinguishing urinary diseases and it may pave the way for precision medicine.     

Real-time organic aerosol chemical speciation in the indoor environment using extractive electrospray ionization mass spectrometry

Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations.     

Estimation of power density in IMPATT using different materials

ABSTRACT

The RF output power dissipated per unit area is calculated using Runge-Kutta method for the high-moderate-moderate-high (n⁺-n-p-p⁺) doping profile of double drift region (DDR)-based impact avalanche transit time (IMPATT) diode by taking different substrate at Ka band. Those substrates are silicon, gallium arsenide, germanium, wurtzite gallium nitride, indium phosphide and 4H-silicon carbide. A comparative study regarding power dissipation ability by the IMPATT using different material is being presented thereby modelling the DDR IMPATT diode in a one-dimensional structure. The IMPATT based on 4H-SiC element has highest power density in the order of 10¹⁰ Wm^?2 and the Si-based counterpart has lowest power density of order 10⁶ Wm^?2 throughout the Ka band. So, 4H-SiC-based IMPATT should be preferable over others for the power density preference based application. This result will be helpful to estimate the power density of the IMPATT for any doping profile and to select the proper element for the optimum design of the IMPATT as far as power density is concerned in the Ka band. Also, we have focused on variation of power density with different junction temperatures and modelled the heat sink with analysis of thermal resistances.     

超宽带极窄脉冲设计与产生

超宽带(UWB)技术是以持续时间极短的脉冲作为传输载体进行数据通信的无线新技术。基于BJT雪崩特性,本文采用并行同时触发的工作方式,设计并产生了高重复速率的UWB脉冲电路发生器,极大地减少了时延,缩短了上升时间,提高了脉冲的幅度,并从等效电路法的观点分析计算了脉冲的特性参数,理论结果与实测结果具有较好的一致性。     

MPID─TOF质谱的快速时间分辨微弱信号测试系统

把瞬态记录仪Ｂｉｏｍａｔｉｏｎ８ｌ００与微型计算机ＩＢＭ─ｐＣ／ＸＴ联接建成了一个高速数据采集系统，本文介绍了系统的硬件接口设计及软件设计。在超声分子束条件下，把它应用于环氧乙烷（Ｃ＿２Ｈ＿４Ｏ）的多光子电离与离解飞行时间（ＭＰＩＤ─ＴＯＦ）质谱的实验研究中，并给出了实验结果；本系统在微观基元化学反应动力学实验研究中广泛适用于对时间分辨微弱信号的探测。     

测定环境中钚的新方法

提出了ＴＯＰＯ萃取，大面积有机相制原与平行板屏栅电离室α谱仪结合，测定草、土壤等环境中钚的新方法。土壤和草灰的化学回收率分别为７２％和９７％，最低探测限为４×１０＾－２Ｂｑ／ｋｇ。分析了Ｉ－ＡＥＡ和ＮＩＳＴ的标准物质，结果与标准值相符。操作程序简单、快速，适用于核事故应急分析和环境监测。     

铯原子激光共振电离

用Ｎｄ：ＹＡＧ及其泵浦的染料激光进行铯原子三步共振电离。求解了非饱和共振过程速率方程，计算出基态和激发态共振吸收截面，给出电离效率分别与激发电离速率以及作用时间的变化关系，得到饱和激发电离的流量条件和通量条件。     

Accurate Cross Sections for Microanalysis

To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane wave Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane wave theory is not appropriate for overvoltages less than 2.5 V.     

Accurate depth profiling through energy-dependent pulse height deficit compensation in gas ionization detectors

The impact of the pulse height deficit effect in gas ionization detectors on the accurate extraction of depth information from heavy ion elastic recoil detection spectra has been investigated. Thin GaN films and Ge_xSi_1−x/Si heterostructures have been analyzed with a 200 MeV ¹⁹⁷Au beam. Employing an empirical parameterisation of the pulse height deficit, a global energy calibration of the detector can be achieved. Energy spectra have been compared, calibrated with either a constant or a full energy-dependent compensation for the deficit. A constant compensation results in significant distortion of the extracted depth profile for heavier ions, whereas an energy-dependent compensation yields true concentration–depth profiles.