高效液相色谱-串联质谱法测定粮谷中9种氨基甲酸酯类农药残留

本研究采用了高效液相色谱-串联质谱联用(HPLC-MS/MS)技术,建立了高灵敏度的同时检测粮谷中9种氨基甲酸酯类农药残留量的方法。样品经乙腈提取,中性氧化铝填充柱净化,然后采用HPLC-ESI( )-MS/MS测定。对液-质分离条件和样品前处理条件进行了优化。9种氨基甲酸酯类农药在0.1~100μg/L范围内线性良好,相关系数为0.9986~0.9998。在0.001~0.05mg/kg浓度范围内,平均加标回收率在73.40%~102.01%之间;相对标准偏差为1.25%~9.94%。该方法简便、快速、灵敏、净化效果好。可同时满足进、出口粮谷中多种氨基甲酸酯类农药残留量的检验工作需要。     

The role of physicochemical interactions and FLO genes expression in the immobilization of industrially important yeasts by adhesion

One of the industrially important qualities of yeast is their ability to provide the cell-cell and cell-support interactions. This feature of yeast is responsible for technologically significant phenomena such as flocculation (brewing) and yeast biofilm formation (immobilization to supports), whereas these phenomena are time, environment, and strain dependent. Therefore, the goal of this work was to verify the possibility to predict and subsequently select yeast strains capable to colonize solid supports by using physicochemical adhesion models. Three different industrial yeast strains (Saccharomyces cerevisiae) were tested for their adhesion onto spent grain particles in the continuous gas-lift reactor. The cell adhesion energies were calculated, based on physicochemical characteristics of surfaces involved, according to three adhesion models (DLVO theory, thermodynamic approach, and extended DLVO theory). The role of physicochemical surface properties in the cell-cell and cell-support interactions was evaluated by comparing the computed predictions with experimental results. The best agreement between forecast and observation of the yeast adhesion to spent grains was achieved with the extended DLVO (XDLVO) theory, the most complex adhesion model applied in this study. Despite its relative comprehensiveness, the XDLVO theory does not take into account specific biochemical interactions. Consequently, additional understanding of the yeast adhesion mechanism was obtained by means of quantifying the expression of selected FLO genes. The presented approach provides tools to select the appropriately adhesive yeast strains and match them with solid supports of convenient surface properties in order to design immobilized biocatalysts exploitable in biotechnological processes.     

钨—镍—铁系重合金中粘结相的定量测定

通过对９３Ｗ－Ｎｉ－Ｆｅ－Ｃｏ（Ｍｎ）合金中粘结相和钨颗粒化学及电化学性质的研究，提出了一种定量提取Ｗ－Ｎｉ－Ｆｅ系重合金中粘结相的电解液，建立了定量测定其粘结相和钨颗粒组成及含量的方法。     

Spray-dried calcined clays in water filtration columns used for chromium removal

 Well-rounded grains are normally used as filtration media, because the spherical shape seems to be most suitable to get rapid and efficient removal operations. In this sense, the direct use of natural clays as filtration media is problematic, due to the plate-type shape of the particles. In this work, rounded grains of two natural clays processed by spray-drying are tested as filtration media. The settling regime of the grains in a filtration column was determined and the chromium removal from water was also tested. Sieved fractions now used (355–1680 μm) show settling behavior according to the transition regime. Preliminary results of chromium removal by the selected 355–420 μm sieved fraction bed show interesting capabilities for the Cr³⁺ species, while chromate (VI) retention is extremely low. Received: 12 January 1998 Accepted: 2 April 1998     

Preparation and characterization of AgSt/AgC1 composite grains

AgSt/AgC1 composite gains were prepared by adding chloride ions to a mixed solvent in which silver stearate （AgSt） grains were dispersed under the condition of controlled pH value and characterized by SEM, XRD, UV and DSC. The results showed that AgSt/AgC1 composite grains were composed of plateqike AgSt grains with small face-centered cubic AgC1 particles formed on the surface of AgSt. UV spectra displayed a red shift of absorption for AgSt/AgC1 relative to pure AgSt or AgC1. DSC showed a new thermal phase transition of AgSt/AgC1 grains.     

Element concentrations of dry-grind corn-processing streams

The dry-grind corn process is one of two technologies used to convert corn into ethanol. In his process, all kernel components are processed through several sequential steps, including fermentation. Only one coproduct (distillers’ dried grains with solubles [DDGS]) is available for marketing. DDGS provide income to offset costs of processing; issues that affect marketing have implications in the economic viability of dry-grind plants. Two issues relate to elements in DDGS: high concentrations and excessive variation. Data on element concentrations in dry-grind processing streams could be helpful in addressing these concerns. The objective of this study was to determine element concentrations in primary process streams from dry-grind plants. Samples of corn, ground corn, beer, wet grains, syrup, and DDGS were obtained from nine dry-grind plants, and element concentrations were determinined. The concentrations of most elements in corn were not different among processing plants and were similar to published data. However, for the processing streams, there were differences in several element concentrations among processing plants. The concentrations of most elements in beer were about three times those of corn, due to the disappearance of starch during fermentation. Syrup had the highest element concentrations. Variations in element contents of DDGS and parent streams were due to processing conditions and not corn. Appropriate processing of thin stillage (the parent stream of syrup) could reduce the element content of DDGS.     

Effect of germ and fiber removal on production of ethanol from corn

Ethanol fermentations were conducted using both whole corn, and corn with 100% of the germ, and a portion (∼74%) of the fiber removed. Ethanol production increased 11% in the germ and fiber-removed corn vs the whole corn. The protein content of distiller's dried grains and solubles increased from 30 to 36%, and phosphate levels were 60% lower in corn with germ and fiber removed vs whole corn. Removal of germ and fiber prior to fermentation allows higher starch loading and results in increased ethanol production. The integration of germ and fiber removal in the dry-grind ethanol industry could increase capacity and add valuable coproducts, resulting in increased productivity and profits.     

Amino-Acid Composition of Protein Fractions from Fermented Feed

The possibility of preparing feed from wheat straw via fermentation by cellulolytic enzymes from the fungusTrichoderma harzianumis demonstrated. The water- and salt-soluble fractions of the fermented feed contain the largest quantity of essential amino acids (22.93%). The predominant essential amino acids are lysine, leucine, methionine, and threonine. The total essential amino acids in the water- and salt-soluble fractions represent 31.44% of the total amount of protein in the fermented feed     

Numerical study of growth competition between twin grains during directional solidification by using multi-phase field method

A multi-phase field model is established to simulate the growth competition and evolution behavior between seaweed and columnar dendrites during directional solidification.According to the effects of surface tension and interfacial energy,we quantitatively analyze the influences of factors such as inclination angles,pulling velocity,and anisotropic strength on twin growth.The results demonstrate that the pulling velocity and anisotropic strength have an important influence on the morphology and evolution of the seaweed and dendritic growth.The low pulling velocity and anisotropic strength are both key parameters for maintaining the stable morphology of seaweed during competitive growth in a bicrystal,showing that the lateral branching behavior is the root of the dendrites that can ultimately dominate the growth.And it is clarified that the lateral branching behavior and lateral blocking are the root causes of the final dominant growth of dendrites.With the increase of anisotropy strength,the seaweed is eliminated fastest in case 1,the seaweed is transformed into degenerate dendritic morphology,and eliminates the seaweed by promoting the generation and lateral growth of the lateral branches of the dendrites.The increase of pulling velocity is to increase the undercooling of favorable oriented grain and accelerate the growth rate of dendrites,thus producing more new primary dendrites for lateral expansion and accelerating the elimination rate of unfavorable oriented grain.     

Complete Assignment of the 1H and 13C NMR Spectra of Carthamin Potassium Salt Isolated from Carthamus tinctorius L.

Carthamin potassium salt isolated from Carthamus tinctorius L. was purified by an improved traditional Japanese method, without using column chromatography. The ¹H and ¹³C nuclear magnetic resonance (NMR) signals of the pure product were fully assigned using one- and two-dimensional NMR spectroscopy, while the high purity of the potassium salt and deprotonation at the 3′ position of carthamin were confirmed by atomic adsorption spectroscopy and nano-electrospray ionization mass spectrometry.