Cooling process: By cooling down the material through some chemical reactions in which energy absorbing (endothermic) processes triggered by additives and/or the chemical release of water cool the substrate to a temperature below that required for sustaining the combustion process, e.g. magnesium hydroxide [26,13,20]. Coating process: By forming a protective layer or coating that prevents or shields the underlying combustible layer of material with a solid or gaseous protective layer from heat and oxygen necessary for the combustion process, e.g. phosphorous and boron compounds [26,13,20]. Dilution process: By incorporating inert substances (e.g.
By applying DC power supply to a TEC, heat will be transferred from one side of the conductor to the other. It creates a cold and a hot side. They are widely used in industrial areas, for example, computer CPU, Servers, portable refrigerator, medical instruments, and so on. voltage, it is also desirable in a precision temperature control to take advantage of this heat/cool capability. Thermoelectric coolers operate by the Peltier effect (which also goes by name thermoelectric effect).
It consists of sample injection port, carrier gas cylinder with pressure regulator, column oven, column (open tubular column and packed column), detector and data system. 1. Sample injection port A sample injection port is used to introduce the sample at the head of column. For optimum column efficiency, the sample should not be too large, and should be introduced into the column in vapour form. The slow injection of large samples may results in loss of resolution and band broadening.
When a heat pump is used for heating, it employs the same basic refrigeration-type cycle used by an air conditioner or a refrigerator, but in the opposite direction - releasing heat into the conditioned space rather than the surrounding environment. In this use, heat pumps generally draw heat from the cooler external air or from the ground. In accordance with heat pump center in heating mode,
Basic Principles and Modes of Capillary Electrophoresis Harry Whatley 1. BASIC PRINCIPLES OF CAPILLARY ELECTROPHORESIS 1.1. Fundamentals of Electrophoresis Capillary electrophoresis (CE) is a special technique that uses an electrical field in order to separate the components present in a mixture. Electrophoresis in a capillary can be differentiated from other types of electrophoresis that it is done within the walls of a narrow tube. To understand the functioning of molecules influenced by an electrical field inside a capillary it is important to know the phenomena that result from the geometry of a capillary.
Line-voltage thermostats are easily identified as they have thick wires, usually 2 or 4. The current passes through both the control unit and the heating equipment. In this case, the line-voltage thermostat is switched off when reaching the preset temperature, even if the heater didn't warm up the room to the preset temperature. Low-voltage thermostats A more efficient solution for electric current control is exactly the low-voltage thermostats, which in turn are used to control central heating systems. Moreover, the systems can use either or gas, or electricity, or even oil.
4) Sintering has three stages namely, slow heating during burn off, a constant temperature period, and cooling after sintering. The non-uniform and non- steady heating and cooling can results into formation of non- equilibrium structures and composites. 5) The porosity in the die pressed mechanical induces structural heterogeneity hence the properties like ultimate tensile strength, and elongation are inferior to wrought materials. 6) Some thermal difficulties are experienced with low melting point metals such as Sn, Pb, Zn and Cd. During sintering the atmosphere in the furnace should be controlled to avoid the formation of oxides as oxide will have adverse effects on the sintering process and results in inferior quality
The liquid will slowly raise up the plate by capillary action causing the sample to become distributed between the stationary phase and the moving liquid phase. Because most compounds are colourless, the materials must be visualized by placing the plates under ultraviolet light or spraying the plate with a chemical reagent. The distance a spot travels up a thin-layer plate can be assigned a numerical value known as the Rf value. Theory: The technique of thin-layer chromatography (TLC) uses a solid stationary phase and a moving liquid phase to separate the constituent of a mixture. A thin-layer plate is prepared by coating a glass plate with a thin film of a granular material, usually silica gel or aluminium oxide.