Mass detection algorithm based on support vector machine and relevance feedback

To improve the detection of mass with appearance that borders on the similarity between mass and density tissues in the breast,an support vector machine classifier based on typical features is designed to classify the region of interest(ROI).Furthermore,relevance feedback is introduced to improve the performance of support vector machines.A new mass detection scheme based on the support vector machine and the relevance feedback is proposed.Simulation experiments on mammograms illustrate that the novel support vector machine classifier based on typical features can improve the detection performance of the featureless classifier by 5%,while the introduction of relevance feedback can further improve the detection performance to about 90%.

Mass spectrometry detection of basic drugs in fast chiral analyses with vancomycin stationary phases

Current trends in chiral analysis of pharmaceutical drugs are focused on faster separations and higher separation efficiencies, Core-shell or superficially porous particles （SPP） based chiral stationary phases （CSPs） provide reduced analysis times while maintaining high column efficiencies and sensitivity. In this study, mobile phase conditions suitable for chiral analyses with electrospray ionization LC-MS were systematically investigated using vancomycin as a representative CSP. The performance of a 2.7 μm SPP based vancomycin CSP （SPP-V） 10 cm ×0.21 cm column was compared to that of a corresponding 5 μm fully porous particles based analogue column. The results demonstrated that the SPP-V column provides higher efficiencies, 2-5 time greater sensitivity and shorter analysis time for a set of 22 basic pharma- ceutical drugs. The SPP-V was successfully applied for the analysis of the degradation products of racemic citalopram whose enantiomers could be selectively identified by MS.

Detection of Optical Stability of chiral 2-Methylbutyric Acid in Gas Phase with Quadrupole-Quistor-Quadrupole Mass Spectrometer

Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are optically unstable in the process of self chemical ionization.

The“depict”strategy for discovering new compounds in complex matrices:Lycibarbarspermidines as a case

The comprehensive detection and identification of active ingredients in complex matrices is a crucial challenge.Liquid chromatography coupled with high-resolution mass spectrometry(LC-HRMS)is the most prominent analytical platform for the exploration of novel active compounds from complex matrices.However,the LC-HRMS-based analysis workflow suffers from several bottleneck issues,such as trace content of target compounds,limited acquisition for fragment information,and uncertainty in interpreting relevant MS2 spectra.Lycibarbarspermidines are vital antioxidant active ingredients in Lycii Fructus,while the reported structures are merely focused on dicaffeoylspermidines due to their low content.To comprehensively detect the new structures of lycibarbarspermidine derivatives,a“depict”strategy was developed in this study.First,potential new lycibarbarspermidine derivatives were designed according to the biosynthetic pathway,and a comprehensive database was established,which enlarged the coverage of lycibarbarspermidine derivatives.Second,the polarity-oriented sample preparation of potential new compounds increased the concentration of the target compounds.Third,the construction of the molecular network based on the fragmentation pathway of lycibarbarspermidine derivatives broadened the comprehensiveness of identification.Finally,the weak response signals were captured by data-dependent scanning(DDA)followed by parallel reaction monitoring(PRM),and the efficiency of acquiring MS2 fragment ions of target compounds was significantly improved.Based on the integrated strategy above,210 lycibarbarspermidine derivatives were detected and identified from Lycii Fructus,and in particular,170 potential new compounds were structurally characterized.The integrated strategy improved the sensitivity of detection and the coverage of low-response components,and it is expected to be a promising pipeline for discovering new compounds.

Development of 2D computer program to determine geometry of rock mass blocks

Due to various geological processes such as tectonic activities fractures might be created in rock mass body which causes creation of blocks with different shapes and sizes in the rock body. Exact understand- ing of these blocks geometry is an essential issue concerned in different domains of rock engineering such as support system of underground spaces built in jointed rock masses, design of blasting pattern, optimi- zation of fragmentation, determination of cube blocks in quarry mines, blocks stability, etc. The aim of this paper is to develop a computer program to determine geometry of rock mass blocks in two dimen- sional spaces. In this article, the eometrv of iointed rock mass is programmed in MATLABTM.

Simultaneous separation and determination of four main isoflavonoids in Astragali Radix by an isocratic LC/ESI-MS method

A simple, reliable and rapid isocratic liquid chromatography(LC)-mass spectrometric detection(MS) coupled with electrospray ionization(ESI) method for simultaneous separation and determination of calycosin-7-O-β-D-glucoside, ononin, calycosin and formonometin in Astragali Radix was developed. After the samples were extracted with ethanol, the optimum separation conditions for these analytes were achieved using water and acetonitrile(70:30, v/v) containing 0.2%(v/v) acetic acid as a mobile phase and a 2.0 mm×150 mm Hypersil-Keystone C18 column. Selective ion monitoring(SIM) mode and [M+H]+ ions at m/z 447, 431, 285 and 269 were used for quantitative analysis of four main active components above mentioned. The calibration curves were linear in the range of 0.4-175.0 μg/mL for calycosin-7-O-β-D-glucoside, 0.2-146.0 μg/m L for ononin, 0.4-210.0 μg/mL for calycosin and 0.5-217.0 μg/mL for formonetion, respectively. The limits of quantification(LOQ) and detection(LOD) were 0.4 μg/mL and 0.08 μg/m L for calycosin-7-O-β-D-glucoside, 0.2 μg/mL and 0.06 μg/m L for ononin, 0.4 μg/mL and 0.1 μg/mL for calycosin, 0.5 μg/m L and 0.1 μg/m L formonetion, respectively. The standard recoveries were in the range of 96.5%-104.7%. The developed method has successfully been used for the determination of four main flavonoids in Astragali Radix from various sources and can be used for identification, differentiation and quality evaluation of Astragali Radix.

Separation and identification of moxifloxacin impurities in drug substance by high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform ion cyclotron resonance mass spectrometry

In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry （HPLC-UV/FrICRMS） method was described for the investigation of impurity profile in moxifloxacin （MOX） drug substance and chemical reference substance. Ten impurities were detected by HPLC-UV, while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules. In addition, to our knowledge, five impurities were founded for the first time in MOX drug substance.

Cantilever with immobilized antibody for liver cancer biomarker detection

A novel cantilever array-based bio-sensor was batch-fabricated with IC compatible MEMS technology for precise liver cancer bio-marker detection. A micro-cavity was designed in the free end of the cantilever for local antibody-immobilization, thus the adsorption of the cancer biomarker takes place only in the local region of the cantilever instead of the whole lever, and the effect of adsorption-induced k variation can be dramatically reduced. These structural features offer several advantages： high sensitivity, high throughput, high mass detection accuracy, and a portable system. In addition, an analytical model has been established to eliminate the effect of the adsorption-induced lever stiffness change and has been applied to the precise mass detection of the cancer biomarker AFP; the experimentally detected AFP antigen mass by the sensor （7.6 pg/mL） is quite close to the calculated one （5.5 pg/mL）, two orders of magnitude better than those of the fully antibody-immobilized cantilever sensor. These approaches can promote real applications of the cantilever sensors in cancer diagnosis.

Nontargeted identification of peptides and disinfection byproducts in water

A broad range of organic compounds are known to exist in drinking water sources and serve as precursors of disinfection byproducts（DBPs）.Epidemiological findings of an association of increased risk of bladder cancer with the consumption of chlorinated water has resulted in health concerns about DBPs.Peptides are thought to be an important category of DBP precursors in water.However,little is known about the actual presence of peptides and their DBPs in drinking water because of their high sample complexity and low concentrations.To address this challenge and identify peptides and non-chlorinated/chlorinated peptide DBPs from large sets of organic compounds in water,we developed a novel high throughput analysis strategy,which integrated multiple solid phase extraction（SPE）,high performance liquid chromatography（HPLC）separation,and non-target identification using precursor ion exclusion（PIE）high resolution mass spectrometry（MS）.After MS analysis,structures of candidate compounds,particularly peptides,were obtained by searching against the Human Metabolome Database（HMDB）.Using this strategy,we successfully detected 625 peptides（out of 17,205 putative compounds）and 617 peptides（out of 13,297）respectively in source and finished water samples.The source and finished water samples had 501 peptides and amino acids in common.The remaining 116 peptides and amino acids were unique to the finished water.From a subset of 30 putative compounds for which standards were available,25 were confirmed using HPLC-MS analysis.By analyzing the peptides identified in source and finished water,we successfully confirmed three disinfection reaction pathways that convert peptides into toxic DBPs.