《专业英语阅读》PPT课件.ppt

Unit 2 Reaction Engineering,May 25th, 2011 Ying Xiaoguang,Lesson 1 Reactor Types,1 Stirred tank reactor A batch stirred tank reactor is the simplest type of reactor. It is composed of a reactor and a mixer such as a stirrer, a turbine wing or a propeller. The batch stirred tank reactor is illustrated below:,enzaim,The batch system is generally suitable for the production of rather small amounts of chemicals. A continuous stirred tank reactor is shown below. The continuous stirred tank reactor is more efficient than a batch stirred tank reactor but the equipment is slightly more complicated.,2 Tubular Reactor Tubular reactors are generally used for gaseous reactions, but are also suitable for some liquid-phase reactions. If high heat-transfer rates are required, small-diameter tubes are used to increase the surface area to volume ratio.,Several tubes may be arranged in parallel, connected to a manifold(多支管) or fitted into a tube sheet in a similar arrangement to a shell and tube heat exchanger. For high-temperature reactions the tubes may be arranged in a furnace.,3 Fluidized bed Reactor A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions.,In this type of reactor, a fluid (gas or liquid) is passed through a granular solid material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. This process, known as fluidization, imparts many important advantages to the FBR. As a result, the fluidized bed reactor is now used in many industrial applications.,Unit 3 Biochemistry,Biochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules.,The term carbohydrate reflects the fact that many of the compounds in this category have the empirical formula (经验式) CH2O. Carbohydrates are the primary source of food energy for most living systems. They include simple sugars such as glucose (C6H12O6) and sucrose (C12H22O11) as well as polymers of these sugars such as starch, glycogen, and cellulose. Carbohydrates are produced from CO2 and H2O during photosynthesis and are therefore the end products of the process by which plants capture the energy in sunlight.,Lipids, on the other hand, are defined on the basis of their physical properties. Any molecule in a biological system that is soluble in nonpolar solvents is classified as a lipid. The lipid known as cholesterol, for example, is virtually insoluble in water, but it is soluble in a variety of nonpolar solvents including the nonpolar region between the inner and outer surfaces of a membrane.,The name nucleic acid was originally given to a class of relatively strong acids that were found in the nuclei of cells. As monomers, nucleic acids such as adenosine triphosphate (ATP) are involved in the process by which cells capture food energy and make it available to fuel the processes that keep cells alive. As polymers, they store and process the information that allows the organism to grow and eventually reproduce.,Although there are a vast number of different biomolecules, many are complex and large molecules (called polymers) that are composed of similar repeating subunits (called monomers). Each class of polymeric biomolecule has a different set of subunit types. For example, a protein is a polymer whose subunits are selected from a set of 20 or more amino acids. Biochemistry studies the chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions.,DNA,The biochemistry of cell metabolism and the endocrine(内分泌) system has been extensively described. Other areas of biochemistry include the genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction.,DNA structure Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information.,DNA is often compared to a set of blueprints(蓝图) or a recipe(药方), or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.,Chemically, DNA consists of two long polymers of simple units called nucleotides(核苷酸), with backbones made of sugars and phosphate groups joined by ester bonds.,These two strands(链) run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases.,It is the sequence of these four bases along the backbone that encodes(编码) information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches(伸展的形态) of DNA into the related nucleic acid RNA, in a process called transcription.,Within cells, DNA is organized into structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication.,Eukaryotic(真核) organisms (animals, plants, fungi菌类, and protists原生生物) store their DNA inside the cell nucleus, while in prokaryotes (原核) (bacteria and archae) it is found in the cells cytoplasm.,Within the chromosomes, chromatin (染色质) proteins such as histone