[Ammonia volatilization under different nitrogen and water treatments of tomato-watermelon rotation system in solar greenhouse in Losses Plateau, China].

To understand the characteristics of ammonia volatilization in Losses Plateau, an experiment was conducted in a typical solar greenhouse involving four treatments. Intermittent ventilation chamber method was used to measure NH volatilization over the period of tomato-watermelon rotation. The results showed that nitrogen transformation was rapid in solar greenhouse system.

[Effects of nitrogen fertilizer application on carbon dioxide emissions from soils with different inorganic carbon contents.].

The application of nitrogen (N) fertilizer results in decreases of soil pH, but its effects on CO emission from soils with different inorganic carbon contents remain unclear. An closed-jar incubation experiment was conducted to examine the effects of N fertilizer and nitrification inhibitor (DCD) on soil pH and CO emissions from three soil types with different contents of soil inorganic carbon (SIC), including paddy soil (PS), lime concretion black soil (CS), and eum-orthic anthrosols (AS). There were three treatments for each soil type, including control (N), 0.

Rising time restoration for nuclear pulse using a mathematic model.

The rising time of a nuclear pulse is slowed before being digitized because of the effect of distributed capacitance and resistance. This results in the waveform distortion of a shaped pulse. In this study, the effect of distributed capacitance and resistance is equivalent to the result of RC network.

Study on Heavy Metal Detection in Soil with Improved EDXRF.

Due to the low precision and accuracy of trace heavy metals detection wiith traditional energy dispersive X-ray fluorescence (EDXRF) system, an improved EDXRF system is proposed. In order to reduce the influence of reflected rays, the sample is irradiated with the incident X-rays vertically, and the detector is placed in parallel with the sample’s section. The sample is connected with detector through collimator.

[Study on the High Speed and Precision Gaussian Function Fitting Algorithm for Nuclear Single Spectral Peak].

In nuclear spectrum, Gaussian function least square fitting is a commonly used method. Usually the method has high precision, but it is very much sensitive to noise, which causes that the residual vector is larger near the peak in the Gaussian function. To solve the problem, Gaussian function least square fitting was deduced particularly, and the causes are analyzed.

[Effects of long-term different fertilizations on biomass and nutrient content of maize root].

Taking two long-term local field trials at the south edge of the Loess Plateau, which were found in 1990 and 2003, respectively, as test subjects, the effects of different fertilization practices on the maize root biomass and nutrient content were investigated in this paper. Maize roots in the 0-20 cm top soil post-maize harvest from the different fertilization practices were collected by hand in October 2011. The results showed that compared with control without fertilization and N, NK, or PK treatments, the NP, NPK, fertilizers plus manure (M1NPK and M2NPK) or plus straw return (SNPK) treatments significantly increased the dry mass of maize root.

[The study of baseline estimated in digital XRF analyzer].

For the digital X-ray fluorescence analyzer, the voltage of the instability baseline will directly affect the performance of the instrument, resulting in decreased energy resolution. In order to solve this problem, Kalman filtering algorithm was used for pulse signal baseline estimate in the digital X-ray fluorescence. Whether using the classic Kalman filter, or the simplified sage-husa, or the improved sage-husa, their baseline filtering effects were all poor.

[Decomposition of different plant litters in Loess Plateau of Northwest China].

Taking the litters of species Hippophae rhamnoides, Medicago sativa, Populus simonii, Robinia pseudoacaci, Salix psammophila, and Stipa bungeana in the Loess Plateau of Northeast China as test objects, and by using mesh bags, this paper studied the dynamic changes of the litters mass, carbon, and nitrogen during decomposition after buried in the field in semiarid region. The litters buried were from one, two, or three of the plant species, and mixed thoroughly with equal proportion of masses. During decomposition, the mass loss rate, total carbon and nitrogen release rates, and total soluble carbon and nitrogen contents of different litters were higher at the early than at the later decomposition stage.

[Methods of detector response function establishment in X-ray fluorescence spectra analysis].

During the measurement and analysis process of X-ray fluorescence spectra, it is very helpful to improve the analyze speed, accuracy and automaticity of X-ray fluorescence spectra analysis by establishing detector response function(DRF), which represents the shape of full energy peak and can provide former basic data for subsequent X-ray analysis technique. For the theory and model of semiconductor DRF in X-ray energy spectrum measurements, methods of three typical detector response function model establishment, key parameters of full energy peak standard deviation and Fano factor calculation, etc. are discussed, and meanwhile, the summarization and contrast of existing studies are shown in this paper.

[Effects of combined application of maize- and horsebean straws on the straws decomposition and soil nutrient contents].

A laboratory incubation experiment was conducted to study the straw decomposition and soil nutrient contents after single and combined applications of maize- and horsebean straws. With the single application of maize straw, the mineralization rates of the straw and soil organic C were lower, and the immobilization of soil mineral N sustained longest. Combined application of maize- and horsebean straws promoted the mineralization of the straws organic C and soil immobilized N.

[Contents and biodegradation of soluble organic carbon in different plant residues from the Loess Plateau].

Soluble organic carbon (SOC) in plant residues extracted by water or different extractants is an active component, and has important roles in carbon and nitrogen biogeochemical process in soil ecosystem. Reestablishing the vegetation on the Loess Plateau is changing the types and amounts of the plant residues into soil ecosystem. Therefore, our objective was to evaluate the contents and biodegradation of SOC of residues of different species from this region.

[Soluble organic carbon in plant litters on Loess Plateau: content and biodegradability].

The litters of eight plant species from the Loess Plateau were cut into pieces with 2 mm and 1 cm in size, and extracted with distilled water and 0.01 mol x L(-1) CaCl2 to determine the soluble organic carbon (SOC) content. In the meantime, a 7-day indoor incubation test was conducted at (25 +/- 3) degrees C to investigate their biodegradability.

[Effects of fertilization on carbon/nitrogen ratio of maize straw and its minereffects of fertilization on carbon/nitrogen ratio of maize straw and its mineralization in soil.alization in soil].

Maize straws were collected from different treatments of two long-term fertilization studies, their carbon (C)/nitrogen (N) ratios were determined, and their C and N mineralization rates in soil were compared in an aerobic incubation test. The results showed that comparing with no fertilization, applying chemical fertilizers (NPK) or chemical fertilizers plus manure (MNPK) increased the N content and decreased the C/N ratio of maize straw. The amounts of mineralized and immobilized C and N of the straws from different fertilization treatments differed with incubation time.

Nonlinear Dynamics and Chaos of Microcantilever-Based TM-AFMs with Squeeze Film Damping Effects.

In Atomic force microscope (AFM) examination of a vibrating microcantilever, the nonlinear tip-sample interaction would greatly influence the dynamics of the cantilever. In this paper, the nonlinear dynamics and chaos of a tip-sample dynamic system being run in the tapping mode (TM) were investigated by considering the effects of hydrodynamic loading and squeeze film damping. The microcantilever was modeled as a spring-mass-damping system and the interaction between the tip and the sample was described by the Lennard-Jones (LJ) potential.

[Effects of long-term fertilization and fallowing on soil nitrogen mineralization and exogenous NO3(-) -N transformation].

Soil samples were collected from a 17-year fertilization experiment site in southern Loess Plateau to study the effects of different fertilizations and fallowing on the characteristics of soil nitrogen mineralization, and the transformation of exogenous NO3(-) -N in sterilized and non-sterilized soil samples. The results showed that a combined application of manure and chemical NPK and long-term fallowing increased the contents of soil organic matter, total N, and mineralized N, as well as the N mineralization rate significantly, compared with the control. Applying chemical NPK increased soil inorganic N content, but had less effects on the contents of soil organic matter, total N and mineralized N, as well as the N mineralization rate.

[Adsorption characteristics of soluble organic carbon and nitrogen in two cultivated soils].

In this paper, soluble organic carbon (SOC) and nitrogen (SON) were extracted from manure, and their adsorption characteristics in Argosols and Anthrosols in Guanzhong region of Shaanxi Province were investigated. The results showed that the adsorption of SON and SOC in the two soils could be fitted by initial mass isotherm model, and the adsorbed amounts of SON and SOC had a significant linear relationship with the initial concentrations of SON and SOC added into soils. The partition coefficient, m of the initial mass isotherm model, indicated that Argosols had a higher adsorbility than Anthrosols.

[Studies on triterpenoids from Potentilla chinensis].

Objective: To investigate the chemical constituents of Potentilla chinensis.

Method: Silica gel column chromatography and Sephadex LH - 20 gel column chromatography were employed for the isolation and purfication. The structures were identified on the basis of spectral data and chemical evidence.

[Study on chemical constituents of Potentilla chinensis Ser].

Five compounds (I - V) were isolated from Potentilla chinensis Ser. On the basis of spectral data and chemical evidence. I - V were identified as 2alpha-hydroxyoleanolic acid (I), 2alpha-hydroxyursolic acid (II), 5, 7, 4'-trihydroxyflavone (IIl), beta-sitosterol (IV), daucostarine (V).