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In this study, the idea of sample-specific metabolites library with retention neighbor was presented for better identification and quantitation of metabolites. Compared with universal libraries, the established library was found to have significantly improved match indices (similarity, reverse, and probability), indicating better identification of metabolites. For quantitative metabolic profiling of temperature treated tobacco samples, the established method integrated and aligned 175 metabolites with no missing value, better than the widely used metabolomics software including XCMS Online, MetaboliteDetector, SpectConnect, and ChromaTOF. Partial least squares discriminant analysis models were also used for quantitative evaluation and the established method produced better values of model parameters than the compared software, indicating a better model was established using the present method.

Technological standard is an important scientific basis for marine and airborne gravity surveys. In accordance with the lack of the present specifications to reflect the trend of the times for marine and airborne gravity surveys,a detail analysis and research is made on key targets, such as the density of surveying line layout, survey accuracy, space resolution, zero drift and dynamic repeatability of air-sea gravimeter,etc. An evaluation system of survey accuracy targets including root mean square of errors(RMS),systematic error and mean error for marine and airborne gravity surveys is suggested. And an evaluation system of stability targets including calibration accuracy of scale value, total month zero drift, RMS of nonlinear month drift and limited deviation of nonlinear month drift is proposed. The methods of testing and evaluating the above technological targets are introduced. And some key mathematic models about reduction of observed values for marine gravity survey,Eötvös correction for airborne gravimetry,platform tilt correction and evaluation of survey accuracy for air-sea-borne gravimetry are analyzed and modified. The obtained conclusions provide useful theoretical support for the revision of existing specifications for future civil-military inosculation of marine and airborne gravity surveys.

Centred on the support requirement of flying track control for a long range spacecraft, a detail research is made on the computation of external disturbing gravity field, the survey accuracy of gravity anomaly on the earth' surface and the program of surveying line layout for marine gravity survey. Firstly, the solution expression of navigation error for a long range spacecraft is analyzed and modified, and the influence of the earth's gravity field on flying track of spacecraft is evaluated. Then with a given limited quota of biased error of spacecraft drop point, the accuracy requirement for calculating the external disturbing gravity field is discussed and researched. Secondly, the data truncation error and the propagated data error are studied and estimated, and the quotas of survey resolution and computation accuracy for gravity anomaly on the earth' surface are determined. Finally, based on the above quotas, a corresponding program of surveying line layout for marine gravity survey is proposed. A numerical test has been made to prove the reasonableness and validity of the suggested program.

Triple-frequency global navigation satellite systems allow the introduction of additional linear observation combinations. We define two geometry-free phase combinations and one geometry-free pseudorange minus phase linear combination to detect and correct cycle slip in real time. At first, the optimal BDS (BeiDou System) triple-frequency geometry-free phase combinations are selected for cycle slip detection. Then, a detailed analysis of the cycle slip detection is performed by examining whether some special cycle slip groups cannot be discovered by the selected combinations. Since there still remain some cycle slip groups undetectable by the two geometry-free phase combinations, we add a pseudorange minus phase linear combination which is linearly independent with these two phase combinations, to be sure that all the cycle slips can be detected. After that, an effective decorrelation search based on LAMBDA and least squares minimum principle is applied to calculate and determine the cycle slips. The method has been tested on triple-frequency undifferenced BDS data coming from a benign observation environment. Results show that the proposed method is able to detect and repair all the small cycle slips in the three carriers.

The existing triple-frequency cycle-slip detection method usually can not detect and repair the cycle-slip correctly in the ionospheric activity phase or when the magnetic storm happening. To solve the problem, the triple-frequency TurboEdit method for weakening the ionospheric error is advanced based on the dual-frequency TurboEdit method. Both the triple-frequency geometry-free and ionospheric-free combination and second-order time-difference phase geometry-free combination in this algorithm can whittle the influence of ionospheric error effectively. And then, the triple-frequency data is used to validate this algorithm, the experiment results show that this method can weaken the ionospheric error and realize the no-difference dynamicreal-time cycle-slip detection and correction under ionospheric activity phase.

In order to evade the ill-posedness of downward continuation for airborne gravity data using traditional inverse Poisson integral, in a recent published article,a practical downward continuation method of airborne gravity data was used for the sea surveying areas using the differential conception in navigation and location for reference, in which the continuation corrections are calculated using ultra-high-degree geopotential model. In this paper, we continue using the same idea and develop the method to the application for land surveying areas. It suggests that terrain Information can be used to improve the calculated accuracy of continuation correction from geopotential model. The differential of local topographic corrections on flying height and corresponding ground point is added to the continuation correction from geopotential model, and it makes up the total continuation correction. It is ultimately realized to continue airborne gravity measurements to the ground in full frequency extension. EGM2008 geopotential model, ground gravity data and digital elevation model in high resolution are used as a case study to prove the efficiency of the new method.

A detailed analysis is made on the different former and existing formulae of Eötvös corrections for airborne gravimetry in view of the inconsistency of their uses by many scholars at home and abroad. A numeral comparison between the different formulae is accomplished. The problems from the use of approximate formulae by our country's scholars are pointed out. And the necessity of using rigorous formulae is emphasized.

Plant flavonoids are very important secondary metabolites for insect and virus control of their host plant and are potent nutrients for humans. To be able to understand the bioavailability and functions of plant flavonoids, it is necessary to reveal their exact chemical structures. Liquid chromatography with tandem mass spectrometry is a powerful approach for structural elucidation of metabolites. In this report, a two-step precursor ion scanning based liquid chromatography with tandem mass spectrometry method was developed for the structural elucidation of plant flavonoids. The established method consists of the two-step precursor ions scanning for possible flavonoids extraction, MS(2) fragment spectra acquisition and comparison with an online database, liquid chromatography retention rules correction, and commercial standards verification. The developed method was used for the structure elucidation of flavonoids in flowers and leaves of tobacco (Nicotiana tabacum), and 17 flavonoids were identified in the tobacco variety Yunyan 97. Nine of the 17 identified flavonoids were considered to be found in tobacco flowers or/and leaves for the first time based on the available references. This method was proved to be very effective and can be used for the identification of flavonoids in other plants.

A hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was established for the simultaneous determination of maleic hydrazide (MH) and its two glucosides in tobacco leaves. Ultrasonic assisted extraction of MH and its glucosides was performed using acetonitrile-methyl tert-butyl ether-water (7:10:13, volume ratio). The extraction solution was then centrifuged, and the subnatant was transferred for solvent replacement using acetonitrile. The extract in acetonitrile was then analyzed using HILIC-MS/MS. Method validation was performed, and the linear ranges for MH and MH-O-β -D-glucoside were 5-150 mg/kg with correlation coefficients (r2) greater than 0.9971 for matrix-matched calibration curves. Limits of detection for MH and MH-O-β -D-glucoside were 0.5 mg/kg and 0.3 mg/kg, and limits of quantification were 1.0 mg/kg and 0.8 mg/kg, respectively. The recoveries were in the range of 83.1%-112.3% at three spiked levels (10, 40, 80 mg/kg), with intra-day repeatability of 2.7% and 3.8%, inter-day repeatability of 8.3% and 7.1% at 40 mg/kg. The established method was used for the study of MH metabolism in tobacco leaves. By the 28th day after MH spraying, the content of MH in tobacco leaves had decreased by 80.8%, of which only 7.6% transformed to MH-glucosides. The disposition of the remainder needs to be studied.

Tobacco alkaloids (e.g., nicotine) and their metabolized tobacco-specific nitrosamines (TSNAs) are very important compounds for tobacco quality and safety. A simple and specific liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of eight tobacco alkaloids and their related four TSNAs in tobacco leaves. The milled tobacco was extracted using 0.1 mol/L ammonium acetate solution and purified using methanol. Mass spectrometry parameters including declustering potential and collision energy were optimized to ensure that both the TSNAs and the tobacco alkaloids have suitable responses. Recoveries for accuracy were in the range of 80.2-105.2%. Intra-day and inter-day repeatability were in the range of 1.7-12.1% and 6.4-18.7%, respectively. Limit of detection and limit of quantitation were estimated in the range of 6 ng/g-45 μg/g and 24 ng/g-90 μg/g, respectively. The established method was applied to investigate the distribution of tobacco alkaloids and TSNAs in four kinds of tobacco. The result showed that the burley and the flue-cured have the highest (0.00047%) and the lowest (0.000024%) percentage of transformation from alkaloids to TSNAs, respectively. Thus, this method can be used for a wide range of samples.

To study changing characteristics of chlorophyll SPAD value in leaves during their developments and the difference of agronomic traits and economic traits in different flue-cured tobacco cultivars,field experiment was conducted to investigate chlorophyll content in leaves of flue-cured tobacco with four cultivars (K326,HD,NC82,Liaoyan13) by SPAD-502 chlorophyll meter,periodically.The results showed that changing characteristics of both chlorophyll SPAD value and relative variance rate involved not only the cultivars,but also the leaf positions.

Polystyrene/Poly(Ethyl acrylate-n-Butyl acrylate) (PS/P(EA-nBA) latex interpenetrating polymer networks (LIPNs) were synthesized by a two stage emulsion polymerisation technique. The effects of fillers and PMMA/P(EA-EMA) LIPN on damping of the LIPNs have been investigated. The results indicate that inorganic fillers produce increases in tan δ values and broaden the damping temperature range. Among the fillers, mica has shown good result on damping properties. Blending of PS/(EA-nBA) LIPN with PMMA/P(EA-EMA) LIPN produces similar results as the inorganic fillers. Damping materials whose tan 8 values exceed 0.5 over 82°C temperature range between -21.3 and 60.7 has been obtained.

In order to eliminate the inconsistency of the existing data from multi-satellite missions, we propose a new method for optimal combination of altimeter data. In our data management system, the crossover adjustment is modified to two-step processing based on the a posteriori compensation theory of error; i.e., the crossover adjustment of condition equations is made in the first step, and the filtering and prediction of adjustment corrections done along each single pass in the second step. Using the new approach can simplify greatly the computational procedure of crossover adjustment, and the stability and reliability of its solution can be expected. The new method can be used for both local and global crossover adjustment problems. Finally, a practical altimeter dataset from Geosat, ERS-1, ERS-2, and TOPEX/POSEIDON (T/P) is used as a case study to prove the efficiency of the integrated data processing method.