紫外-可见分光光度法测定玉米不同部位籽粒早期发育的生理指标

为测定玉米不同部位籽粒早期发育的差异及氮素对籽粒发育的影响,实验用紫外-可见分光光度法对不同施氮水平下(0,120,180,240 kg·hm-2)玉米顶部和中下部籽粒在授粉后5～20 d的生理指标进行了检测.结果表明,施氮可明显促进籽粒可溶性总糖、蔗糖、淀粉含量的增加,促进蔗糖分解转化及淀粉合成关键酶活性的增强.当施氮量为180 kg·hm-2时,顶部籽粒的体积、干重及可溶性总糖、蔗糖、淀粉含量在授粉后20 d明显高于其他处理,酸性蔗糖转化酶AI、中性蔗糖转化酶NI、蔗糖合成酶SS、腺苷二磷酸葡萄糖焦磷酸化酶ADPGase及淀粉合成酶活性在授粉后5～20 d处于较高水平,使顶部籽粒的蔗糖利用能力及淀粉合成能力得到一定程度的改善,从而促进顶部籽粒发育,减少败育,提高产量.     

Power ultrasound as a pretreatment to convective drying of mulberry (Morus alba L.) leaves: Impact on drying kinetics and selected quality properties

The effect of ultrasound pretreatment prior to convective drying on drying kinetics and selected quality properties of mulberry leaves was investigated in this study. Ultrasound pretreatment was carried out at 25.2–117.6 W/L for 5–15 min in a continuous mode. After sonication, mulberry leaves were dried in a hot-air convective dryer at 60 °C. The results revealed that ultrasound pretreatment not only affected the weight of mulberry leaves, it also enhanced the convective drying kinetics and reduced total energy consumption. The drying kinetics was modeled using a diffusion model considering external resistance and effective diffusion coefficient D_e and mass transfer coefficient h_m were identified. Both D_e and h_m during convective drying increased with the increase of acoustic energy density (AED) and ultrasound duration. However, D_e and h_m increased slowly at high AED levels. Furthermore, ultrasound pretreatment had a more profound influence on internal mass transfer resistance than on external mass transfer resistance during drying according to Sherwood numbers. Regarding the quality properties, the color, antioxidant activity and contents of several bioactive compounds of dried mulberry leaves pretreated by ultrasound at 63.0 W/L for 10 min were similar to that of mulberry leaves without any pretreatments. Overall, ultrasound pretreatment is effective to shorten the subsequent drying time of mulberry leaves without damaging the quality of final product.     

2D NMR对荠菜中的一个黄酮苷进行结构解析

对荠菜中分离得到的一个黄酮苷类化合物2″-O-α-L-阿拉伯糖异荭草苷进行了分离和结构解析,为荠菜进一步的开发利用提供依据. 利用溶剂提取法和大孔树脂色谱、聚酰胺色谱、Sephadex LH-20及高效液相半制备色谱手段进行提取分离,并通过理化性质和波谱分析鉴定了该化合物的结构,采用二维核磁共振（2D NMR）技术对其¹H和¹³C化学位移信号进行了全归属.     

Processing digital images and calculation of beam emittance (pepper-pot method for the Krion source)

Programs for the pre-processing of photographs of beam images on the mask based on Wolfram Mathematica and Origin software are described. Angles of rotation around the axis and in the vertical plane are taken into account in the generation of the file with image coordinates. Results of the emittance calculation by the Pep_emit program written in Visual Basic using the generated file in the test mode are presented.     

First-principles calculation of excited states of diatomic molecules: a benchmark for the Gutzwiller conjugate gradient minimisation method

We recently proposed the Gutzwiller conjugate gradient minimisation (GCGM) method for efficient and accurate calculation of the ground state total energy of molecular and bulk systems. The GCGM method is developed under the framework of Gutzwiller wave function but goes beyond the commonly adopted Gutzwiller approximation to improve the accuracy and flexibility in treating the correlation effects. In this conference proceeding, we benchmark the GCGM method with the calculation of excited state potential energy curves of three diatomic molecules, namely H₂, N₂, and O₂. Our calculations demonstrate the flexibility and reasonable accuracy of the method.     

Spectroscopic measurement of the source function as a test for deviations from Local Thermodynamic Equilibrium (L.T.E.) in arc plasmas

Measurement of either the source function of a strongly absorbing spectral line or the plateau width can be used to show experimentally deviations from local thermodynamic equilibrium (L.T.E.). Two new methods are proposed to determine ground state particle densities and temperature of neutrals.     

Predictions of pulsed field gradient NMR echo-decays for molecules diffusing in various restrictive geometries. Simulations of diffusion propagators based on a finite element method

Pulsed field gradient NMR diffusometry is a promising tool for investigating structures of porous material through determinations of dynamic displacements of molecules in porous systems. A problem with this approach is the lack of closed analytical expressions for echo-decays in anything but idealized pore geometries. We present here an approach based on calculating the appropriate diffusion propagator by means of finite element calculations. The suggested method is quite general, and can be applied to arbitrary porous systems. The protocol for the calculations is outlined and we show results from some different cases: diffusion in confined geometries and in systems that are spatially inhomogeneous with respect to concentration.     

Muscle and fat quantification in MRI gradient echo images using a partial volume detection method. Application to the characterization of pig belly tissue

Complete dissection is the current reference method to quantify muscle and fat tissue on pig carcasses. Magnetic resonance imaging (MRI) is an appropriate nondestructive alternative method that can provide reliable and quantitative information on pig carcass composition without losing the spatial information. We have developed a method to quantify the amount of fat tissue and muscle in gradient echo MR images. This method is based on the method proposed by Shattuck et al. [12]. It provides segmentation of pure tissue and partial volume voxels, which allows separation of muscle and fat tissue including the fine insertions of intermuscular fat. Partial volume voxel signal is expected to be proportional to the signals of pure tissue constituting them or at least to vary monotonously with the proportion of each tissue. However, it is not always the case with gradient echo sequence due to the chemical shift effect. We studied this effect on a fat tissue/muscle interface model with variable proportion of water in the fat tissue and variable TE. We found that at TE=8 ms, for a 0.2-T MRI system, the requirement of Shattuck's method were filled thanks to the presence of water in fat tissue. Moreover, we extended the segmentation method with a simple correction scheme to compute more accurately the proportions of each tissue in partial volume voxels. We used this method to evaluate the fat tissue and muscle on 24 pig bellies using a gradient echo sequence (TR 700 ms, TE 8 ms, slice thickness 8 mm, number of averages 8, flip angle 90 degrees , FOV 512 mm, matrix 512*512, Rect. FOV 4/8, 19 slices, space between slices 2 mm). The image analysis results were compared with dissection results giving a prediction error of the muscle content (mean=2.7 kg) of 88.9 g and of the fat content (mean=2.7 kg) of 115.8 g without correction of the chemical shift effect in the computation of partial volume fat content. The correction scheme improved these results to, respectively, 81.5 and 107.1 g.     

An improved pollen collection and cryopreservation method for highly recalcitrant tropical fruit species of mango (Mangifera indica L.) and litchi (Litchi chinensis Sonn.)

An improved method for pollen collection from freshly dehiscing anthers of mango (Mangifera indica L.) and litchi (Litchi chinensis Sonn.) using the organic solvent cyclohexane has been devised. Using this method pollen quantity sufficient for large scale pollinations could be collected and stored for future use. Transport of pollen in viable conditions over long distances, from site of collection (field genebank) to cryolab was successfully devised for both these fruit species. Cryopreservation was successfully applied to achieve long-term pollen storage over periods of up to four years. Pollen viability was tested using in vitro germination, the fluorochromatic reaction (FCR) method and by fruit set following field pollination. On retesting, four year cryostored pollen of different mango and litchi varieties showed high percentage viability as good as fresh control pollens. Pollens of more than 180 cultivars of mango and 19 cultivars of litchi have been stored in the cryogenebank using the technology developed, thus facilitating breeding programmes over the long-term.     

Sono-sorption as a new method for the removal of methylene blue from aqueous solution

The sorption of methylene blue as a basic dye onto cellulosic materials such as waste newspaper was examined kinetically in the presence of ultrasound (sono-sorption) and in its absence (conventional method). The effects of various experimental parameters such as the amount of sorbent, type of cellulosic sorbents, initial dye concentration, temperature, and contact time have been investigated using a batch sorption technique. The information obtained can be used for treating effluents from the dye industry which deals with this kind of dye. The results show that as the amount of sorbent is increased, the dye removal in conventional method increases accordingly. In case of sono-sorption, it was stopped at specific amount of sorbent. More than 98% removal of the dye could be achieved in a very short period of time of sonication with respect to the conventional method. This behavior is related to the cavitation process which facilitates the removal of dye from aqueous solution. The method mentioned could be employed as a low cost alternative to the commercial activated carbon currently used in wastewater treatment for the removal of dyes.     

Absorption line narrowing (A.L.N.) in a three-level system of neon under interaction with two quasi-resonant lasers

We report the observation of Absorption Line Narrowing (A.L.N.) in a Doppler-broadened three-level system of neon under interaction with two quasi-resonant single-mode lasers. The resonance signals are obtained with the laser beams propagating either in the same direction or in opposite direction. The resonance width is found to be smaller in the latter case. The isotopic shifts ²²Ne-²⁰Ne of the lines λ = 1.15μ, λ = 6096 Å and λ = 5945 Å have been measured using the A.L.N. method.     

Development of a shoot-tip vitrification protocol and comparison with encapsulation-based procedures for plum (Prunus domestica L.) cryopreservation

Cryopreservation of plum (Prunus domestica L.), cv Regina Claudia, was obtained by a vitrification/one-step cooling procedure of shoot tips from cold-hardened in vitro-grown plants. Best survival (57%) was obtained when the shoot tips were precultured at 4 degree C for 2 days on 0.09 M sucrose-containing Quoirin and Le Poivre medium, loaded for 30 min with a cryoprotectant (2 M glycerol and 0.4 M sucrose), incubated with the PVS2 solution at 0 C for 90 min, and directly plunged into liquid nitrogen. After re-warming in a waterbath at 40 degree C, the shoot tips were washed in a 1.2 M-sucrose MS solution for 20 min and finally plated on a regrowth medium. In comparison with the one-step cooling procedure, both the slow cooling (-0.5 degree C/min up to -45 degree C), and the two-step cooling (-160 degree C for 25 min, then -196 degree C) gave lower percentages of shoot-tip survival. Among the other cryogenic procedures tested, the performance of the encapsulation-vitrification method was similar to the vitrification protocol in terms of shoot-tip regrowth (47.5%), while encapsulation-dehydration was unsatisfactory.     

Carbon tetrachloride as a liquid matrix for ortho-para diagnostics of water. Capabilities of IR and NMR spectroscopy

A version of ortho-para diagnostics of water at room temperature, based on the combined use of optical and NMR spectroscopy of water dissolved in carbon tetrachloride in a monomeric form, is proposed. Within this study, the capabilities of spectral diagnostics of water with natural ortho-para composition (ortho/para = 3/1) were fully realized. An experimental technique for preparing large amounts of carbon tetrachloride dried to a high degree (water: CCl₄ < 1: 10⁵) was worked out. The results of successful NMR measurements of the ortho-isomer concentration will be published later.     

Star-shaped oligo(ethylene glycol) ethers (OEGE) as a new type of plasticizer for polymer gel electrolytes

Star-shaped oligo(ethylene glycol) methyl ethers (three and four arm molecules of various molecular weights) were synthesized and characterized with regard to viscosity, thermal transitions, ability to solvate the electrolyte LiCF₃SO₃ and the ionic conductivity of their LiCF₃SO₃ solutions in comparison to linear oligo(ethylene glycol) methyl ethers. Polymer gel electrolytes were prepared by photopolymerization of tri(ethylene glycol) dimethacrylate (EG₃DMA) or its copolymerization with the polar comonomer cyanomethyl methacrylate (CyMA) in the presence of the oligo(ethylene glycol) ethers mentioned above and of the electrolyte LiCF₃SO₃. The gels were characterized concerning their thermal transitions, thermo-mechanical properties, their ability to solvate the electrolyte and their ionic conductivity. In comparison to the linear plasticizers the star-shaped ones show a distinctly lower tendency to crystallize, which is even completely suppressed in several cases. Intensified ion association was found in LiCF₃SO₃ solutions of the star-shaped plasticizers, if the number of the ethylene glycol units per arm was lower than 4. Therefore, the conductivity of the solutions and the gels was lower than that with linear plasticizers at room temperature. The modification of the polymer matrix by copolymerization with 20 mol% CyMA resulted in a maximum of the ionic conductivity σ≈1×10⁻⁵ S/cm of gels with star-shaped plasticizers at 25 °C.     

The calculation of reactions of the type (a,ab) using the plane-wave expansion method: (I). General formalism for the direct one-step process

A formalism for the evaluation of the transition matrix element for reactions of the type (a, ab) in the direct distorted-wave approximation is presented. The plane-wave expansion method is used to represent the optical model wave function for the entrance and exit channels. Because of the use of the plane-wave expansion method the completely off-the-energy-shell behavior is easily demonstrated when distorted waves are used. The use of this expansion method also shows how difficult it is to extract the momentum dependence of the bound particle. We also apply the plane-wave expansion method to evaluate the transition matrix element for the effective f-operator DWTA approach. We also discuss an approximation to the complete transition matrix element which seems equivalent to the DWTA but yet makes use of completely off-the-energy-shell matrix elements.     

Structure analysis of the KBr(100) surface An investigation with a new method for surface analysis of insulators

The surface structure of highly insulating KBr(100) was investigated by a new technique, impact collision atom scattering spectroscopy with detection of neutrals (NICASS). By using neutral atoms in the scattering experiment as projectiles [different from conventional ion scattering (ISS)], uncertainties in the experimental data due to surface charging effects are avoided. As a result, a surface structure model for KBr(100) is presented. By comparing the experimental scattering information with computer simulated data, an inward relaxation in the first layer has been deduced. The relaxation is different for the two components K and Br: K is shifted by 0.5 Å and Br by 0.3 Å, resulting in a surface rumpling of 0.2 Å.