[ China Instrument Network Instrument Research and Development ] August 14th, "13th Five-Year" National Key Research and Development Program "National Quality Foundation Common Technology Research and Application" Key Special (hereinafter referred to as "NQI Special Project") "Food, Environmental Field Instruments and Methods The “Measurement and Traceability Technology Research†project implementation plan demonstration meeting was held at the China Institute of Metrology (hereinafter referred to as “China Metrology Instituteâ€).
The responsible persons from relevant functional departments such as Tsinghua University, the Chinese Academy of Sciences' Ecological Environment Research Center, the Beijing Institute of Metrology and Measurement Science, and the technical backbone of the project participants participated in the demonstration meeting.
The demand for on-site rapid detection instruments in the food and environmental fields in China is increasing year by year. However, due to the variety of instrument principles and types, and the lack of measurement standards, the accuracy and traceability of measurement results are difficult to guarantee.
To this end, the China Metrology Institute and the Agricultural Research Institute of the Chinese Academy of Agricultural Sciences, the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences, the Shanghai Metrology and Testing Technology Research Institute, the Jiangsu Institute of Metrology, and other six units to carry out scientific and technological research, began "food, Research on the project traceability technology of environmental field instruments and methods.
The research content of the project is mainly the calibration technology of food and environmental field instruments; the common technology of on-site rapid inspection technology and the key technology of characteristic verification; the rapid analysis method and the traceability and evaluation technology of portable on-site detection instruments combined with electrochemistry and biotechnology; Basic indicators such as protein in raw milk, non-fat soluble solids, lean meat concentrates in animal body fluids, heavy metal elements in aquatic products, and other standard foods for calibration of environmental analysis instruments.
The assessment criteria of the project mainly include the formulation of food and environmental field instrument calibration specifications or national standards (for review) 4 kinds of measurement verification techniques for enzyme-linked immunoassay, infrared spectroscopy and biosensing on-site rapid inspection technology; national standards 12 kinds of substances: provide 6 basic indicators including protein, lean meat, heavy metal elements, 12 kinds of national standard materials for environmental morphology analyzer calibration, no less than 30 characteristic quantities, synthetic standard uncertainty u: purity The reference material is ≤0.5%, the solution reference material is ≤1.5%, the matrix reference material is ≤6%, the application for invention patent is not less than 5, and the measurement and calibration capability (CMC) for reporting international mutual recognition is not less than 2.
At the meeting held, the project leader and deputy researcher of the Institute of Chemistry of China Metrology Institute introduced the overall situation and implementation plan of the project. The responsible persons of each project reported the implementation plan of the project.
The consulting expert group listened carefully to the report, focusing on the classification of the rapid inspection equipment in the food field and the optimization of the parameter indicators. After discussion, the participating experts agreed that the project implementation plan has clear objectives, reasonable research content, practical technical route, and strong safeguard measures, and agreed to pass the argument.
The successful research and development of the results of this project is expected to meet the flattening requirements of the measurement value of various rapid inspection instruments in the food and environmental fields. It has important practical significance for improving the rapid detection level of related fields in China, promoting the quality improvement of related instrument products, and ensuring the safety of people's livelihood. .
(Source: China Institute of Metrology, Ministry of Science and Technology, Instrument Information Network)
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The color mixer is a machine that uses mechanical force and gravity to evenly mix two or more materials. Color mixing machines are widely used in various industries and daily life.
The color mixer can mix a variety of materials into a uniform mixture, such as cement, sand, crushed stone and water into wet concrete; It can also increase the contact surface area of materials to promote chemical reaction; It can also accelerate physical changes, such as adding solvent to granular solute, and accelerating dissolution and mixing through the action of mixing machinery.
Commonly used color mixers are divided into four categories: gas and low-viscosity liquid mixers, medium-high viscosity liquid and paste mixing machines, thermoplastic material mixers, and powder and granular solid material mixing machines. The gas and low viscosity liquid color mixing machine is characterized by simple structure, no rotating parts, small maintenance and low energy consumption. This type of mixing machinery is divided into four types: air flow mixing, pipe mixing, jet mixing and forced circulation mixing.
The color mixing machine of medium and high viscosity liquid and paste generally has strong shearing effect; Thermoplastic material mixer is mainly used for mixing thermoplastic materials (such as rubber and plastic) with additives; The mixing machines for powdery and granular solid materials are mostly intermittently operated, and also include machines with mixing and grinding functions, such as wheel rolling machines. During mixing, all materials involved in mixing shall be evenly distributed. The degree of mixing can be divided into three states: ideal mixing, random mixing and complete non-mixing. The mixing degree of various materials in the mixing machine depends on the proportion, physical state and characteristics of the materials to be mixed, as well as the type of mixing machine used and the duration of mixing operation.
The mixing of liquid mainly depends on the mechanical stirrer, air flow and the jet of the liquid to be mixed, so that the materials to be mixed are stirred to achieve uniform mixing. Stirring causes part of the liquid to flow, and the flowing liquid pushes the liquid around it, resulting in the formation of a circulating liquid flow in the solvent. The resulting diffusion between liquids is called the main body convection diffusion. When the liquid flow velocity caused by agitation is very high, there will be shear action at the interface between the high-speed liquid flow and the surrounding low-speed liquid flow, thus generating a large number of local vortices. These vortices spread rapidly around and bring more liquid into the vortex. The turbulent convection diffusion formed in a small range is called eddy diffusion.
The mixing mechanism of a small amount of insoluble powdery solid and liquid is different from the density component, and the mixing mechanism of immiscible liquid is the same, but stirring cannot change the particle size of powdery solid. If the settling velocity of solid particles cannot be less than the flow velocity of liquid before mixing, no matter what mixing method is used, it will not form a uniform suspension.
The mixing of different pastes is mainly to divide the materials to be mixed repeatedly and make them subject to the strong shearing effect caused by the actions of pressing, rolling, squeezing, etc., and then merge and knead repeatedly to reach the required mixing degree. This kind of mixing is difficult to achieve ideal mixing and can only achieve random mixing. The powdery solid is mixed with a small amount of liquid to form a paste, and its mixing mechanism is the same as that of paste material.
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