现行家蚕一代杂交种散卵种和平附种抽样检疫方法比较分析

采用数理统计分析方法对现行家蚕一代杂交种散卵种和平附种的2种母蛾微粒子病抽样检疫方法的判别标准和判别信赖度进行比较;为探索适合广西应用的家蚕一代杂交种母蛾微粒子病检疫方法,提出一些建议。

散卵种不良卵剔除新方法试验

结果表明 :采用浸酸液中添加福尔马林液稍固定洗除散卵的新方法 ,对散卵不良卵的剔除工效高。尤其以不良卵分布较集中的蚕种剔除效率高 ,但不良卵较分散的蚕种则稍差 ,此法可应用于生产。

秋用散卵蚕种孵化不齐的原因与防止措施

散卵秋浸,我省是1987年全面推广,但因第一年大批量生产浸酸技术不规范,设备配套不齐全,致使蚕种孵化不齐,经过4～5天。据阆中、苍溪、南部、仪陇四县调查。均有不同程度的反映。最大二日实用孵化率正反交8个不同杂交型式平均82.2％,其中不到80％的4个,最低的仅73.8％。

机械化实现平作散播技术的研究

分析了国内现有条播机和宽带播种机进行平作散播作业时存在的问题,提出了机械挤压式压坑(压沟)装置和散种装置的设计思想。通过理论分析和对关键部件的试验研究,探讨机械化实现平作散播技术的新途径。

对广西现行桑蚕一代杂交种母蛾微粒子病检疫方法的利弊分析

广西现行的桑蚕一代杂交种母蛾微粒了病检疫方法执行的是农业部行业标准《散卵种母蛾微粒子病集团磨蛾检验标准与实施方法》,笔者认为,此标准是针对江浙地区品种(高丝量)和散卯种的情况而制定的,而广西品种特点及制种方式(平附种)与江浙不同,目前仍套用这一标准,不太合适,有待今后改革。本文就这一问题谈谈看法。

Time-dependent effects in transient liquid phase bonding of 304L and Cp-Ti using an Ag-Cu interlayer

One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.

蚕种冷藏加工的实践与体会(上)

蚕种冷藏加工是蚕种生产的重要组成部分,包括蚕种保护、冷藏浸酸、浴消整理等工作,其工作质量对蚕种质量影响巨大。蚕种质量标准的＂四率＂中,孵化率以及尚未列入的蚁蚕绝食生命率与蚕种处理的关系最为密切。蚕种冷藏加工环节多、技术强、工作苦、风险大。现就做好蚕种冷藏加工、提高蚕种质量,谈谈体会,与同行交流。1蚕种冷藏加工的要件人与蚕种的关系,人是主体。做人的工作是领导的职责。

Synthesis and optical properties research of gold nanoparticles with different morphologies

This paper presents an approach to synthesis of gold nanoparticles with different morphologies and investigation of the relationship between morphologies and their optical properties.Spherical gold nanoparticles with different sizes are synthesized via reduction method.Using seed-mediated solution growth method,gold nanoparticles with shuttle,star and stick shapes can be obtained.The sizes and morphologies of the gold nanoparticles are characterized by transmission electron microscopy （TEM）.The characterization results illustrate the growth process of the gold nanoparticles with different morphologies.Absorption spectroscopy and Raman spectroscopy measurements are performed to demonstrate the relationship between the morphologies and optical properties.The results of Raman characterization show that the gold nanoparticles with different morphologies can be used to probe molecules with different concentrations.

Synthesis of Silica Particles with Precisely Tailored Diameter

A modified seeded growth process of silica particles with a continuous addition of tetraethyl orthosilicate （TEOS） was presented to control the diameter of silica particles. The diameter of particles was monitored by dynamic light scattering to control the addition of TEOS. The increase in the diameter of the silica particles with time and the addition of TEOS was investigated. The diameter of silica seeds increased from 193 nm to 446 nm in 4 h. The final diameter of silica particles was tailored within the range of ±5 nm to the target diameter. Silica particles with diameter of 446 nm were synthesized and assembled into photonic crystals with a pseudo band gap centered at just 1000 nm. The feasibility and practicability of this modified seeded growth process was verified.

Effect of joining temperature on microstructure and properties of diffusion bonded Mg/Al joints

The joining of AZ31B Mg alloy to 6061 Al alloy was investigated at different joining temperatures by vacuum diffusion bonding method. The microstructures of Mg/Al dissimilar joints were studied by means of optical microscopy （OM）, scanning electron microscopy （SEM） and energy dispersive X-ray （EDX）. The results show that the thickness of each layer in the diffusion zone increases with the increase of joining temperature, and the microstructure changes obviously. At joining temperature of 440 °C, the diffusion zone is composed of Mg2Al3 layer and Mg17Al12 layer. At joining temperatures of 460 and 480 °C, the diffusion zone is composed of Mg2Al3 layer, Mg17Al12 layer, eutectic layer of Mg17Al12 and Mg-based solid solution. The width of high-hardness zone in the joint increases with increasing joining temperature, and the micro-hardnesses at different locations in the diffusion zone are significantly different. The joining temperature of 440 °C offers the highest tensile strength of 37 MPa, and the corresponding joint exhibits brittle fracture at the intermetallic compound layer of Mg17Al12.

Effect of Seed Coat on Drying Kinetics of Kidney Bean Seed

Kidney bean seed was dried in a laboratory scale fixed bed. The effect of seed coat on drying dynamic characteristics and the changes of seed coat structure were investigated. A mathematical model was established to simulate the drying process and determine the moisture diffusivity. Numerical results agree well with the experimental data. The average moisture diffusivity of the seed with separated coat is 1.67 times larger than that of the seed with coat, and the moisture diffusivity of seed cotyledon is 3.2 times larger than that of the seed coat. It is proved that the seed coat is the most main resistance of mass transfer and is also one of the key points of the optimization of heat and mass transfer for seed drying.

Diffusion of chemically reactive species in third grade fluid flow over an exponentially stretching sheet considering magnetic field effects

This article addresses the magnetohydrodynamics(MHD) flow of a third grade fluid over an exponentially stretching sheet. Analysis is carried out in the presence of first order chemical reaction. Both cases of constructive and destructive chemical reactions are reported. Convergent solutions of the resulting differential systems are presented in series forms. Characteristics of various sundry parameters on the velocity, concentration, skin friction and local Sherwood number are analyzed and discussed.

Experimental Studies on Debris Flow with Logs Focusing on Specific Weight Difference of Log Species

There are many experimental approaches,field investigations and numerical calculations for movements of woods in a clear water and debris flow.However,kinematic conditions for accumulated logs and the interactions between a main flow and logs have not been fully evaluated.Mitigations for woods need taking into account the characteristics of tree species such as conifer and broad-leaf trees and of shapes such as root swells and crown.In the present study,we focus on the differences in specific weight of conifer and broad-leaf trees with some moisture in a sediment-water mixture flow with narrow flow width,and consider that conifer and broad-leaf tree are floating and submerged solid phase,respectively.Flume tests are conducted in steady flow of clear and debris flow over a rigid bed in order to evaluate conifer and broad-leaf tree movement in clear water and debris flow.Experimental data indicates that dimensionless transverse diffusion coefficient can be 0.1 to 0.4 and 0.3 to 0.9 in flow direction.Those diffusive characteristics seem to be independent of Reynolds number and Froude number,but dependent of bed slope,i.e.,gravity,though detailed considerations are needed to discuss about flow characteristics such as spatial eddy structures,momentum transfer induced by interactions of logs and so on.

Combination of Ecoprofile and Least-cost Model for Eco-network Planning

The protecting requirements and functional connectivity of species in isolated habitat patches are crucial factors of eco-network planning.This study aimed to improve the method of eco-network planning for species conservation.Ecoprofiling was used to group the species by similar behavior types,namely,choice of ecosystem,area requirement,and short distance dispersal abilities.A least-cost model was used to simulate the optimal corridor location to maintain functional connectivity.A combination of ecoprofile and least-cost model was hired to develop an eco-network that promoted species conservation.A case study was also conducted in Beijing,China.In addition to the required ecosystem,habitat area is an important parameter for habitat extraction.Habitat area can remove noise habitat patches because of lacking area.Short-distance dispersal can be used to identify corridor requirements and avoid unnecessary building requirements.Species with various dispersal abilities exhibit significant differences in terms of corridor length and location requirement.Habitat isolation is the main threat for weakly mobile species,and habitat loss is the major risk of mobile species protection.Different species groups also exhibit distinct landscape pattern demands for an eco-network,and the eco-network planning based on specific species can not protect other species.We proposed that a combination of ecoprofile and least-cost model improved the efficiency of species conservation by eco-network planning.

The Value of Divulgation for the Protection of Rare Species： The Ceroplastics

The purpose of this work has been to carry out a didactic exhibit at the Botanical Museum of the Department of Life and Environment of the University of Cagliari devoted to vegetal endemic or threatened species present at the Mediterranean Basin. The Ceroplastics （wax sculpting） plays a very important role in this project. Species that have become rare or are somehow threatened in the natural environment and have fortunately been preserved ＂ex situ＂ at the Botanical Garden of Cagliari are reproduced as wax models. Models are made by cutting and shaping wax sheets over the flame of an alcohol lamp. Each model has been created by copying a real specimen cultivated at the Botanical Garden and as a ＂unique piece＂ without using preparatory moulds. The result has been to have at our disposal a collection of very realistic models and magnified particulars as for example the pollen grains. The accuracy of the representation gives visitors the chance to know the considered species by means of the models. In order to preserve the natural heritage it is of the utmost importance that divulgation and information be made available to everyone. The Botanical Museum of the University of Cagliari rediscovers the noble art of wax sculpting, which has been strongly linked to the spreading of scientific knowledge since the XVII century and nowadays it may contribute to raise the citizens＇ awareness of the most common environmental issues.

DPM simulation in an underground entry: Comparison between particle and species models

The diesel particulate matter(DPM) emission from diesel powered equipment in underground mines can cause health hazards including cancer to the miners. The understanding of the DPM propagation pattern under realistic mining condition is required for selecting proper DPM control strategies and to improve working practices in underground mines. In this paper, three dimensional simulations of DPM emission from the exhaust tail pipe of a load-haul-dump(LHD) vehicle and its subsequent distribution inside an isolated zone in the typical underground mine are carried out using two different solution models available in Ansys Fluent. The incoming fresh air into the isolated zone is treated as a continuous phase and DPM is treated either as a continuous phase(gas) or as a secondary discrete phase(particle). Species transport model is used when DPM is treated as gas and discrete phase model is used when DPM is assumed to behave like a particle. The distributions of DPM concentration inside the isolated zone obtained from each method are presented and compared. From the comparison results, an accurate and economical solution technique for DPM evaluation can be selected.

A Population Balance Model for Disperse Systems:Particle Size Distribution in Suspension Polymerization

On the basis of population balance a mathematical model is developed to describe the formation of polymer particle in styrene suspension polymerization. The characteristics of coalescence and breakage of droplets and the gel effect are analyzed in particular. Parameters of the models are estimated by experimental data on reaction conversion and particle size distribution. The results show that the model is suitable for predicting polymerization processes.

Electrostatic Waves in Weakly Magnetized Quantum Plasmas

By using the quantum magnetohydrodynamic model, the electrostatic waves in weakly magnetized quantum plasmas are investigated. The electrons are treated as a quantum and magnetized species, while the ions are classical unmagnetized ones. The general dispersion relations are derived. It is shown that, both the high frequency electron waves （Langmuire wave and upper-hybrid wave） and the low frequency ion acoustic wave can propagate when the plasmas are cold.

Synthesis of crosslinked polystyrene particles by seeded batch polymerization with monomer absorption

A highly crosslinked, monodispersed polystyrene（PS） particle was prepared by a seeded batch dispersion polymerization with a monomer absorption method. Prior to polymerization, 1,9 lam monodispersed PS seed particles were treated under an optimum condition of monomer absorption. The effects of divinylbenzebe（DVB） concentration and polymerization temperature were examined for styrene（in PS seed）/styrene（in the second stage） mass ratio of 1：1 in the medium range of EtOH/water mass ratio of 100/0-80/20 and 2.3 μm uniform crosslinked PS particles containing 15%-20% （mass fraction） DVB were prepared at 60-70 ℃. The results show that monomer absorption before the second stage of polymerization is more effective to prepare highly crosslinked monodispersed PS particles.