Chapter 10 Options Engineering with Applications

SHIMADZU LC-10/20PUMPClarity Control Module ENGCode/Rev.:M091/80BDate:8/24/2020Phone:+420251013400DataApex Ltd. Fax:+420251013401Petrzilkova2583/13 ********************15800Prague5 The Czech RepublicClarity®,DataApex®and®are trademarks of DataApex Ltd.Microsoft®and Windows TM aretrademarks of Microsoft Corporation.DataApex reserves the right to make changes to manuals without prior notice.Updated manuals can be downloaded from .Author:DMContents1Shimadzu LC-10/20Pump1 2Requirements2 3Installation Procedure33.1Shimadzu LC-10/20Pump communication33.2Clarity Configuration54Using the control module74.1Method Setup-LC Gradient74.1.1Gradient Options104.2Method Setup-Advanced114.3Device Monitor124.3.1LC Control Manual Flow144.4Shimadzu LC-10/20Pump Setup155Report Setup17To facilitate the orientation in the Shimadzu LC-10/20Pump manual and Clarity chromatography station,different fonts are used throughout the manual.Meanings of these fonts are: Instrument(blue text)marks the name of the window to which the text refers.Open File(italics)describes the commands and names of fields in Clarity,parameters that can be entered into them or a window or dialog name(when you already are in the topic describing the window).WORK1(capitals)indicates the name of the file and/or directory.ACTIVE(capital italics)marks the state of the station or its part.The bold text is sometimes also used for important parts of the text and the name of the Clarity station.Moreover,some sections are written in format other than normal text.These sections are formatted as follows:Note:Notifies the reader of relevant information.Caution:Warns the user of possibly dangerous or very important information.▌Marks the problem statement or trouble question.Description:Presents more detailed information on the problem,describes its causes, etc.Solution:Marks the response to the question,presents a procedure how to remove it.Shimadzu LC-10/20Pump1Shimadzu LC-10/20Pump 1Shimadzu LC-10/20PumpThis manual describes the setting of the Shimadzu LC-10/20Pump,which may be used to create high-pressure or low-pressure gradient.Thecontrol module enables direct control of the LC-10ADvp,LC-10ATvp andLC-20A(whole series,LC-10emulation mode)over serial line.Caution:The Shimadzu LC-10/20Pump control module can not be combinedwith Shimadzu LC-10/20System control module on a single PC where Framework is installed.The Shimadzu LC-10/20Pump control module can control only a singlepump on a single PC,which means that it is not possible to control morethan one(of above mentioned)pump on a single PC through this controlmodule.Fig1:Shimadzu LC-10ADvp PumpDirect control means that the pump can be completely controlled from theClarity environment.Instrument method controlling the analysisconditions will be saved in the measured chromatograms.Shimadzu LC-10/20Pump2Requirements 2RequirementsClarity Installation CD ROM with LC Control module(p/n A24).Free USB port in the PC.Opt-USB convertor(p/n OPT01).Note:The DataApex Opt-USB converter conforms to the similar Shimadzuconverter(Shimadzu p/n22-35480-91).Pump firmware version2.2or greater.Caution:Minimal required firmware version for LC-10ADvp is5.26and for LC-10ATvp is5.27.3Installation Procedure3.1Shimadzu LC-10/20Pump communicationThe Shimadzu LC-10/20Pump is controlled by serial(RS232)communication.The communication is provided via the Optical to USBconvertor connected to the computer via USB A-A cable(p/n SK10)and tothe pump via optical cable(p/n SK15).Both of these cables are part of theDataApex Opt-USB converter set(p/n OPT01),but can also be orderedseparately.Optical to USB converterFor communication an OPT-RS232converter is needed.It can either bethe DataApex Opt-USB converter(p/n OPT01)or Shimadzu adaptor(Shimadzu p/n22-35480-91).Pump SettingsCommunication parameters should be set on the pump in the SERVICEMODE(see pump documentation)as follows:Baud rate2400,parity N,bits8,stop bit1.SYS(Set System Parameter)has to be set to5for isocratic mode or to6for gradient mode from the pump keyboard.Caution:These values are not documented in the pump manual.The other Pump system parameters should be set to:Local=0(Remote)ADRS=any value(not used)CBM LINK=0(not used)Shimadzu LC-20settingsShimadzu LC-20pumps have to be set to the LC-10emulation mode inorder to be able to work in Clarity.This is done from the pump's keyboardaccording to this procedure:Press the VP button on the pump's front keyboard until the CALIBRATIONinscription is shown on the pump's display.Press the func button to enter the pump's configuration.The passwordhas to be filled in.Note:The default password is00000.Press the func button repeatedly until the OP MODE inscription is shownon the pump's display.Enter the desired number(1)to switch the pump to the SCL-10Avpemulation mode and press the enter button.Switch the pump off and on again.The new communication parametersshould be saved and used.The procedure is in detail described in the LC-20hardware manual provided by the Shimadzu company.3.2Clarity ConfigurationIn the System Configuration dialog press the Add button(①on Fig5)toinvoke the Available Control Modules dialog.Fig2:Available Control ModulesSelect the Shimadzu LC-10/20Pump in the LC section and press the Add(②on Fig5)button.The Shimadzu LC-10/20Pump Setup dialog will appear.Fig3:Shimadzu LC-10/20Pump SetupSelect the correct communication Port and fill the other necessaryparameters in this dialog.Note:Other fields and parameters of the Shimadzu LC-10/20Pump Setupdialog are described later in the manual(for more details see the chapterShimadzu LC-10/20Pump Setup on pg15)..The Shimadzu LC-10/20Pump item③with the number of solvents set inthe Shimadzu LC-10/20Pump Setup dialog will appear in the SetupControl Modules list of the System Configuration dialog.Drag the LC chromatograph icon from the Setup Control Modules liston the left side to the desired Instrument tab④on the right side⑤,or usethe button⑥to do so.Note:The Shimadzu LC-10/20Pump can be used for the low-pressuregradient with the use of switching valves as the pump can handle up to4solvents.Fig4:System Configuration4Using the control moduleNew LC Gradient tab appears in the Method Setup dialog,enabling thesetting of the LC gradient program.4.1Method Setup-LC GradientThe Method Setup-LC Gradient dialog serves for setting up the LCinstrument method.Fig5:Method Setup-LC GradientGradient TableA table for setting the composition of the mobile phase and the overallflow rate as a function of time.Operation is analogous to that ofspreadsheets(Excel,Quatro Pro,etc.).To prepare the cell to receivevalues,click it by the left mouse button;the cell will highlight by dots.A cellthat fails to highlight is not available for editing.Time[min.]Sets the time at which the ratio of flow rates and the overall flow ratecorrespond to the values entered in the corresponding row.(Thesevalues vary continuously from one time to the next in a mannerensuring that the conditions specified in the next row are satisfied).XXX1(..4)[%]Represents the percentage of a component.The designation XXX1-4is in fact replaced by the name of the component(items Solvent1-4in the Gradient Options dialog).Should you enter a component value such that the sum of all values exceeds100%,the percentage in the last column is automatically adjusted;if the percentage of the last compound is already zero,the value of the currently entered component is adjusted instead.The flow rate of a compound is calculated by multiplying the overall flow rate(indicated in the Flow column)by the corresponding percentage divided by100.Flow[ml/min]Indicates the overall flow rate through the column.The entered value applies to the time specified in the corresponding row.GraphThe graph depicts the percentage of components as a function of time together with the overall flow rate.Data are taken over from the Gradient Table.Changes effected in this table are immediately reflected in the graph.Legend in the header of the graph indicates the assignment of colors to individual components.The assignment is fixed and individual components are displayed in the graph from bottom to top.The flow rate is displayed as a black line.The graph has two vertical axes:the axis on the left refers to the mixing ratio,the one on the right to the overall flow rate.ParametersStandby FlowSets the overall flow rate through the column in the STANDBY state reached after the last row of the table has been performed and the time period defined in the Time to Standby field has passed.The duration of this state is defined by the Standby Time item.The ratio of individual components in the respective STANDBY and IDLE states is given by the first row of the Gradient Table(the Initial row).Time to Standby[min]Indicates the time during which the flow rate and mobile phase composition changes continuously between the last values entered in the table and the values defined by Standby Flow field and the Initial row mobile phase composition.This time is included in the analysis time(the Instrument is in the CONTROL state).In case when the Time to Standby is zero,there is step change from flow and components percentage specified on the last row of gradient table to that specified for STANDBY state.Standby Time[min]The time during which the flow rate is maintained at Standby Flow.This time is included in the analysis time(the Instrument is in the CONTROL state).Initial-StandbyThe Shimadzu LC-10/20Pump control module doesn't support thisoption.Idle StateAn item specifying the overall flow rate through the column outside the instrument method.The following options are possible:Pump OffThe flow rates of all components are zero.Caution:Be careful as this setting may damage the column in some cases.InitialThe flow rate is defined by the first row of the gradient table(the Initialrow).StandbyThe flow rate is the same as in the STANDBY mode and,accordingly,corresponds to the value entered in Standby Flow field.The IDLE state comes into effect each time an Instrument is opened,at the end or after abortion of an analysis by the Abort command,and is also maintained after the Clarity program is shut down.The mixing ratio of individual components in both the IDLE and STANDBY states is given by the first row of the Gradient Table(the Initial row). Note:There is a step change in the flow and components percentage from the values specified for the STANDBY state to those specified for the IDLEstate if the Idle State field is not set to Standby.4.1.1Gradient OptionsInvoke the Options...button in the Method Setup-LC Gradient dialog toopen the Gradient Options dialog.This dialog allows to set the customname for particular solvents,to switch whether they are used or not in thegradient and to set the warning levels for pressure to prevent the damageto hardware.Fig6:Gradient OptionsMin.PressureSets the minimum pressure for the given pump.When pressure drops tothe set value,the pump will shut down.This prevents the solvent leakage.Max.PressureSets the maximum pressure for the given pump.When pressure reachesthe set value,the pump will shut down.This serves to prevent the damageto the pump when the column is blocked.Max.Pressure for Set FlowSets the maximum pressure to be used in the Set Flow dialog in theDevice Monitor.Initial value is1MPa.Solvent1(..4)It is possible to enable/disable particular solvent,as well as to set customname to it.4.2Method Setup-AdvancedFig7:Method Setup-AdvancedShimadzu LC-10/20Pump provides the pump flow and pressure auxiliarysignals for use in Clarity.To save the auxiliary signals into eachchromatogram measured according to the given method,check theparticular checkbox in the lower section of the Method Setup-Advanceddialog.4.3Device MonitorThe pump status dialog can be invoked by the Monitor-Device Monitorcommand from the Instrument window or using the Device Monitoricon.It displays the actual flows of particular solvents,as well as the totalflow,the total pressure and the analysis time.In the individual section ofthe Shimadzu LC-10/20Pump the status of the pump may be seen.Fig8:LC MonitorStop FlowThe pumps can be stopped from this window using the Stop Flow button.This action will stop the pump only,the analysis run will continue andmust be stopped or aborted separately by the Stop/Abort button in thetoolbar.Set Flow...Sets the desired total flow and solvent ratios in the opened Set Flowdialog.Max.Pressure allows to set a different pressure than set in the"Gradient Options"on page 10of a given method.Fig9:Set FlowResume IdleReturns the pumps to IDLE state as defined in the appropriate field on the LC Gradient tab of the Method Setup dialog.Hold/ResumeClicking on the Hold button will keep the current gradient conditions until Resume is clicked.Modify Gradient...Opens the LC Control Manual Flow dialog allowing to set custom flow and mobile phase composition,disregarding the Gradient Table set in the method.The command is only available during the analysis run.4.3.1LC Control Manual FlowThe LC Control Manual Flow dialog accessible through using the ModifyGradient…button from Device Monitor window allows the user to set acustom mobile phase composition and flow while the analysis is running.It resembles the Method Setup-LC Gradient tab in functionality.Fig10:LC Control Manual Flow dialogThe LC Control Manual Flow dialog is only available during the analysisrun.When it is invoked and the OK button is pressed,the originalGradient Table from the acquisition method is discarded and replaced bythe Gradient Table from the LC Control Manual Flow dialog.Any suchoperation is recorded in the audit trail of the measured chromatogram.Caution:After the analysis run which used manual flow changes ends,the originalmethod is automatically sent to all controlled devices to make sure Claritystation returns to the original method.4.4Shimadzu LC-10/20Pump SetupShimadzu LC-10/20Pump Setup dialog(accessible through the SystemConfiguration dialog)is used to set the connection to the pump,select it'stype and set some other basic parameters.Fig11:Shimadzu LC-10/20Pump SetupPortSets the COM port to which the Shimadzu LC-10/20Pump pump isconnected.Pump ModelAllows to select from several types of Shimadzu pumps.LC-10ADvp andLC-10ATvp models are supported at the moment.Note:If any LC-20type pump should be connected,it is necessary to set the LC-10emulation mode on the pump(for more details see the chapterInstallation Procedure on pg3)..Sys ModeSets the pump operation mode.Isocratic and Low Pres.Grad.options areavailable.Note:The pump hardware must be set accordingly(for more details see thechapter Installation Procedure on pg3)..SolventsSets the number of solvents when the Low Pres.Grad.mode is used.Max PressureSets the maximum pressure allowance of the pump.This value is sent tothe pump and when the pressure exceeds this value,pump will react on it.The pressure check is also present in Clarity,in the Method Setup-LCGradient-Gradient Options dialog.Value of Max Pressure set thereshould be lower than in the Shimadzu LC-10/20Pump Setup dialog,asClarity reacts on exceeding of that value and should react before thepump does so.Min PressureSets the minimum pressure allowance of the pump.This value is sent to the pump and when the pressure falls below this value,pump will react on it.The pressure check is also present in Clarity,in the Method Setup-LC Gradient-Gradient Options dialog.Value of Min Pressure set there should be higher than in the Shimadzu LC-10/20Pump Setup dialog,as Clarity reacts on falling below that value and should react before the pump does so.Key LockServes for making the Shimadzu LC-10/20Pump keyboard inactive.Shimadzu LC-10/20Pump5Report Setup 5Report SetupFig12:Shimadzu LC-10/20Pump report previewAll general LC settings(such as the Gradient Table from the MethodSetup-LC Gradient tab)are reported as a part of the data displayed bythe use of Instrument Control checkbox of the Report Setup-Methoddialog.-17-。

Principle of Operation:SM Series Valves are designed specifically for use with matching orifice Medium Pressure Cone & Thread Fittings and Tubing for the most efficient flow path possible using Cone & Thread style connections. Designed for a maximum of 20,000 psi MAWP using high tensile strength UNS S31600 cold worked 316 Stainless Steel material as standard, we include larger ID tubing rated to 15,000 psi (15SM valves) for even higher flow rate capability.Medium Pressure Valve Features:Temperature Rated -423° to 1200°F (-252° to 650°C) with associated packing/material options • Designed for use with Medium Pressure cold worked 316/316L stainless steel tubing as standard • 15SM Series Hi-Flow valves available in sizes from 9/16" to 1-1/2" (See matched-bore tubing)• 20SM Series valves available in sizes from 1/4" to 1" (See matched-bore tubing)• UNS S31600, CW 316 Stainless Steel body construction as standard. See Technical brochure for additional material options• Non-rotating stem prevents stem/seat galling• Metal-to-Metal seating achieves bubble-tight shut-off, longer stem/seat life, greater durability for repeated on/off cycles and excellent corrosion resistance. These valves can be used with liquid or gas.• PTFE packing below stem threads provides dependable stem and body sealing. Optional packing materials available.• Choice of Vee (shutoff) or Regulating (Flow Control) stem tips • Replaceable Seat Option available with Right Angle 2-way body style• Optional N-Dura Stem and Seat coating or Stellite material option for severe service available • Pneumatic and Electric Actuator Options available - see page 8 for more detailsTraceability is ensured by use of heat and purchase order codes etched on valve body that also includes model number, MAWP rating, and material type references. All valves include connection collar and gland nut unlessrequested otherwise. Parker Autoclave Engineers’ valves are complemented by a complete line of Medium Pressure Cone & Thread fittings, tubing, check valves, relief valves, and line filters.Note: SM Series fully replaces 20SC, 20SV , and 15SV Series. 15SM Series replaces 10SM Series. 20SM and 15SM repair kits are used to repair these valve types.All Parker Autoclave Engineers products are designed in accordance with ASME B31.3 Chapter IX High Pressure Piping standards.Needle ValveMedium Pressure Cone & Thread 20,000 psi (1380 bar)15SM and 20SM Series2Needle Valves: SM Series 02-0112SE 0520SM Series Needle Valve:Pressures to 20,000 psi (1379 bar)* C v values shown are for 2-way straight valve pattern. For 2-way angle patterns, increase C V value 50%. (Based on water). Formula for converting Cv to volumetric flow can be found in Technical Information section.** Maximum Allowable Working Pressures decrease as temperatures increase - see pressure/temperature rating guide in Technical Information section.Valve Packing Options:Standard Parker Autoclave Engineers valves with PTFE packing may be operated from 0°F (-18°C) to 450°F (232°C). High and Cryogenic temperature packing and/or extended stuffing box are available for service from -423°F (-252°C) to 1200°F (650°C) by adding the following suffixes to catalog order number: -BCryogenic trim materials and PTFE packing required when below 0°F (-18°C) to -100°F (-73°C) -LT Extended packing option with PTFE packing and Cryogenic trim materials to -423°F (-252°C)-TG Standard valve with PTFE-Glass packing -100°F (-73°C) to 600°F (316°C) (See also -B option above when below 0°F (-18°C) -GY Standard valve with Graphite Yarn packing 32°F (0°C) to 800°F (427°C). Used when selecting HT option. (Note: 3/4” valve rated 8000 psi (552 bar) and 1” rated 6000 psi (412 bar) max with Graphite Yarn packing.) -HT Extended stuffing box valve with Graphite Braided Yarn packing to 1200°F (650°C)For the effect on max pressure due to High Temperatures, please see “Technical Brochure” in main catalog.Note: Refer to Tools, Installation & Operation catalog for proper connection, packing, seating & running torques.Generalized Flow Coefficient Curves (C v )% of rated C vN u m b e r o f t u r n s o p e n10 20 30 40 50 60 70 80 90 10076543210Vee StemRegulating StemSM Series Flow Curve for Vee and Regulating Stem Valves3Needle Valves: SM Series 02-0112SE 0520Ordering Guide:For complete information on available stem types, optional connections and additional valve options, see pages 8-9 or contact your Sales Representative. SM Series valves are furnished complete with connection components, unlessotherwise specified.Notes:Valve Manuals can be found on our website at . Connection, Running and Seating Torques can be found in the productmanual or in our Tools and Installation Catalog Section. Valves that have not been cycled for a substantial period of time may require higher initial actuation torque.*Replaceable seat option is sold with two (2) seat surfaces 180º apart.Notes:316 SS valve bodies are cold worked and not suitable for use in NACE (ISO 15156) applications. If required, contact factory for options.* SOG suffix also changes CW 316 SS Body material to Annealed 316 SS suitable for NACE service, Pressure reduction of 60% possible*** Special Materials often have reduced MAWP ratings, see Technical brochure for assistance and for additional material options.4 - GY packing increases friction on stem which can limit max pressure in larger valves (3/4" is limited to 8,000 psi and 1" is limited to 6000 psi)Note: use of optional material only changes “wetted parts” to selected material. Items like collars and glands remain CW 316/316L SS. Use -SOG (Includes hardness check for NACE) or -AP suffixNeedle Valve Panel MountPanel Hole Size:Basic Repair Kits for 316 SS Material:Material of Construction:4Needle Valves: SM Series 02-0112SE 0520All dimensions for reference only and subject to change • For prompt service, Parker Autoclave stocks select products. Consult factory.5 Needle Valves: SM Series 02-0112SE 05206Needle Valves: SM Series 02-0112SE 0520H* - Dimension is with stem in closed positionAll dimensions for reference only and subject to change • For prompt service, Parker Autoclave stocks select products. Consult factory.7Needle Valves: SM Series 02-0112SE 0520H* - Dimension is with stem in closed positionAll dimensions for reference only and subject to change • For prompt service, Parker Autoclave stocks select products. Consult factory.8Needle Valves: SM Series 02-0112SE 0520Electric Valve Actuators :Remotely controlling process flow at high pressure enhances safety and low-ers labor costs. Parker Autoclave Engineers developed a flow control valve available in several models including weatherproof and explosionproof options.The Electrically Actuated Shut-off/Flow Regulating Actuator (FRC Series) is available for most of our SM Series Valves through 9/16" tubing size and full working pressure. Explosion proof version is rated for hydrogen service and can withstand wide process temperature ranges.Pneumatic Valve Actuators :The need to control process and vent valves from a remote location makes air operated valves a vital component to many processing operations. All Parker Autoclave Engineers’ valves are available with piston type actuators. Five sizes of air actuators (light, mini-light, medium, heavy duty or extra heavy, single and double stage) are offered to meet the service require-ments of Parker Autoclave Engineers’ Low, Medium and High Pressure needle valves. Both air-to-open (normally closed) and air-to-close (normally open) designs are included in the product line. Optional air to open AND close actuators available upon request. Please see our Pneumatic ValveActuator Brochure to help size the proper actuator for your application.Stem Options :both control and shut-off. While it is not as precise as the control associated with the MicroMetering stem, especially with smaller flows, it does offer substantially better control than the Vee stem.increase service life.9Needle Valves: SM Series 02-0112SE 0520High/Low Temperature Extension:Used in extreme temperature applications to move packing from flow stream with heatsink to moderate temperature.-HT High Temperature (over 800°F (427°C))-LTLow Temperature (under -100°F (-73°C))ES Stem Extender:Stem extenders are offered for High and Low temperature operation or to extend through panel or barricade.To order valve with Stem Extender, add “ES-” and length (6”, 12”, 18”, 24”) to beginning of valve part number e.g. ES12-20SM6071. Other lengths to special order.To order Stem Extender only, provide valve model prefix e.g. ES12-20SM6. Handle not included – use same provided with original valve.Needle Valve Clam Shell Handle Lockout:(order separately using part numbers shown below, padlock not included)Clam Shell Handle locks are provided to lockout valves in open or closed position preventing unauthorized personnel from actuating valve during shutdown or emergency situations.This clamshell design is available in four (4) sizes dependent on handle length:P/N AE004855 – 1" to 2.5" handle length P/N 90088 – 2.5" to 5.0" handle length P/N 90194 – 6.5" to 10" handle lengthP/N AE004350 – 8" to 13" handle length10Needle Valves: SM Series 02-0112SE 0520SM Medium Pressure Connection: Step by Step Assembly InstructionsAssembly InstructionsSM Series Medium Pressure Needle Valve - Pressures to 20,000 psi (1379 bar)Parker’s Motion & Control TechnologiesAt Parker, we’re guided by a relentless drive to help our customers become more productive and achieve higher levels of profitability by engineeringthe best systems for their requirements. It means looking at customer applications from many angles to find new ways to create value. Whateverthe motion and control technology need, Parker has the experience, breadth of product and global reach to consistently deliver. No company knows more about motion and control technology than Parker. For further information call 1-800-C-Parker.11Needle Valves: SM Series 02-0112SE 0520! CAUTION !Do not mix or interchange component parts or tubing with those of other manufacturers. Doing so is unsafe and will void warranty.Parker Autoclave Engineers Valves, Fittings, and Tools are not designed to interface with common commercial instrument tubing and are designed to only connect with tubing manufactured toParker Autoclave Engineers AES specifications. Failure to do so is unsafe and will void warranty.Offer of SaleThe items described in this document are available for sale by Parker Hannifin Corporation, its subsidiaries or its authorized distributors. Any sale contract entered by Parker will begoverned by the provisions stated in Parker's standard terms and conditions of sale (copy available upon request).©2020 Parker Hannifin Corporation | Autoclave Engineers is a registered trademark of the Parker Hannifin Corporation Literature #: 02-0112SE May 2020ISO-9001 CertifiedInstrumentation Products Division Autoclave Engineers Operation 8325 Hessinger Drive Erie, PA 16509-4679Tel: 814 860 5700Fax: 814 860 /ipdInstrumentation Products Division Division Headquarters 1005 A Cleaner WayHuntsville, AL 35805 USA Tel: 256 881 2040Fax: 256 881 5072Parker Hannifin Manufacturing Ltd.Instrumentation Products Division, EuropeRiverside RoadPottington Business ParkBarnstaple, UK, EX31 1NP , UK Tel: 44 1271 313131Fax: 44 1271 373636WARNINGFAILURE, IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS AND/OR SYSTEMS DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH,PERSONAL INJURY AND PROPERTY DAMAGE.This document and other information from Parker Hannifin Corporation, its subsidiaries and authorized distributors provide product and/or system options for further investigation by users having technical expertise. It is important that you analyze all aspects of your application and review the information concerning the product or system in the current product catalog. Due to the variety of operating conditions and applications for these products or systems, the user, through its own analysis and testing, is solely responsible for making the final selection of the products and systems and assuring that all performance, safety and warning requirements of the application are met. The prod-ucts described herein, including without limitation, product features, specifications, designs, availability and pricing, are subject to change by Parker Hannifin Corporation and its subsidiaries at any time without notice.Needle Valves: SM Series 02-0112SE 0520Parker WorldwideNorth AmericaUSA – Corporate, Cleveland, OH Tel: +1 256 896 3000USA – IPD, Huntsville, AL Tel: +1 256 881 2040*****************USA – IPD, (Autoclave), Erie, PA Tel: +1 814 860 5700*******************CA – Canada, Grimsby, Ontario Tel +1 905-945-2274*********************South AmericaAR – Argentina, Buenos Aires Tel: +54 3327 44 4129 ******************BR – Brazil, Diadema, SP Diadema, SPTel: +55 11 4360 6700******************CL – Chile, Santiago Tel: +56 (0) 2 2303 9640******************MX – Mexico, Toluca Tel: +52 722 275 4200*******************Asia PacificAU – Australia, Dandenong Tel: +61 (0)2 9842 5150******************************CN – China, Shanghai Tel: +86 21 2899 5000*****************************HK – Hong Kong Tel: +852 2428 8008IN – India, MumbaiTel: +91 22 6513 7081-85ID – Indonesia, Tangerang Tel: +62 2977 7900********************JP – Japan, Tokyo Tel: +(81) 3 6365 4020******************KR – South Korea, Seoul Tel: +82 2 559 0400*******************MY – Malaysia, Selangor Tel: +603 784 90 800*******************SG – Singapore,Tel: +65 6887 6300*******************TH – Thailand, Bangkok Tel: +66 2 186 7000*********************TW – Taiwan, Taipei Tel: +886 2 2298 8987*************************VN – Vietnam, Hochi Minh City Tel: +848 382 508 56**********************Europe, Middle East, AfricaAE – UAE, Dubai Tel: +971 4 812 7100********************AT – Austria, Wiener Neustadt Tel: +43 (0)2622 23501-0*************************AT – Eastern Europe, Wiener Neustadt Tel: +43 (0)2622 23501 900****************************AZ – Azerbaijan, Baku Tel: +994 50 2233 458****************************BE/LU – Belgium, Nivelles Tel: +32 (0)67 280 900*************************BG – Bulgaria, Sofia Tel: +359 2 980 1344**************************BY – Belarus, Minsk Tel: +48 (0)22 573 24 00*************************CH – Switzerland, Etoy Tel: +41 (0) 21 821 87 00*****************************CZ – Czech Republic, Klecany Tel: +420 284 083 111*******************************DE – Germany, Kaarst Tel: +49 (0)2131 4016 0*************************DK – Denmark, Ballerup Tel: +45 43 56 04 00*************************ES – Spain, Madrid Tel: +34 902 33 00 01***********************FI – Finland, VantaaTel: +358 (0)20 753 2500*************************FR – France, Contamine s/Arve Tel: +33 (0)4 50 25 80 25************************GR – Greece, Athens Tel: +30 210 933 6450************************HU – Hungary, Budapest Tel: +36 223 885 470*************************IE – Ireland, DublinTel: +353 (0)1 466 6370*************************IT – Italy, Corsico (Ml)Tel: +39 02 45 19 21***********************KZ – Kazakhstan, Almaty Tel: +7 7273 561 000****************************NL – The Netherlands, Oldenzaal Tel: +31 (0)541 585 000********************NO – Norway, Stavanger Tel: +47 66 75 34 00************************PL – Poland, Warsaw Tel: +48 (0)22 573 24 00************************PT – Portugal, Leca da Palmeira Tel: +351 22 999 7360**************************RO – Romania, Bucharest Tel: +40 21 252 1382*************************RU – Russia, Moscow Tel: +7 495 645-2156************************SE – Sweden, Spånga Tel: +46 (0)8 59 79 50 00************************SK – Slovakia, Banská Bystrica Tel: +421 484 162 252**************************SL – Slovenia, Novo Mesto Tel: +386 7 337 6650**************************TR – Turkey, Istanbul Tel: +90 216 4997081************************UA – Ukraine, KievTel: +48 (0)22 573 24 00*************************UK – United Kingdom, Warwick Tel: +44 (0)1926 317 878********************ZA – South Africa, Kempton Park Tel: +27 (0)11 961 0700*****************************。

Chapter 1 Computer Networks and the Internet1．The ( ) is a worldwide computer network, that is, a network that interconnects millions of computing devices throughout the world. ppt3A public InternetB IntranetC switch netD television net2．Which kind of media is not a guided media? ( )A twisted-pair copper wireB a coaxial cableC fiber opticsD digital satellite channel3．Which kind of media is a guided media? ( )A geostationary satelliteB low-altitude satelliteC fiber opticsD wireless LAN4．The units of data exchanged by a link-layer protocol are called ( ).A FramesB SegmentsC DatagramsD bit streams5．Which of the following option belongs to the circuit-switched networks? ( )A FDMB TDMC VC networksD both A and B6．( )makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast.A Reliable data transferB Flow controlC Congestion controlD Handshaking procedure7．( ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Store-and-forward transmissionB FDMC End-to-end connectionD TDM8．Datagram networks and virtual-circuit networks differ in that ( ).A datagram networks are circuit-switchednetworks, and virtual-circuit networks arepacket-switched networks.B datagram networks are packet-switchednetworks, and virtual-circuit networks arecircuit-switched networks.C datagram networks use destinationaddresses and virtual-circuit networks useVC. numbers to forward packets toward theirdestination.D datagram networks use VC. numbers andvirtual-circuit networks use destinationaddresses to forward packets toward theirdestination.9．In the following options, which one is not a guided media? ( )A twisted-pair wireB fiber opticsC coaxial cableD satellite10．Processing delay does not include the time to ( ).A examine the packet’s headerB wait to transmit the packet onto the linkC determine where to direct the packetD check bit-error in the packet11．In the following four descriptions, which one is correct? ( )A The traffic intensity must be greater than1.B The fraction of lost packets increases asthe traffic intensity decreases.C If the traffic intensity is close to zero,the average queuing delay will be close tozero.D If the traffic intensity is close to one,the average queuing delay will be close toone.12．The Internet’s network layer is responsible for moving network-layer packets known as ( ) from one host to another.A frameB datagramC segmentD message13．The protocols of various layers are called ( ).A the protocol stackB TCP/IPC ISPD network protocol14．There are two classes of packet-switched networks: ( ) networks and virtual-circuit networks.A datagramB circuit-switchedC televisionD telephone15．Access networks can be loosely classified into three categories: residential access, company access and ( ) access.A cabledB wirelessC campusD city areaQuestion 16～17Suppose, a is the average rate at which packets arrive at the queue, R is the transmission rate, and all packets consist of L bits, then the traffic intensity is ( 16 ), and it should no greater than ( 17 ).16． A LR／aB La／RC Ra／LD LR／a17．A 2B 1C 0D -118．In the Internet, the equivalent concept to end systems is ( ).A hostsB serversC clientsD routers19．In the Internet, end systems are connected together by ( ).A copper wireB coaxial cableC communication linksD fiber optics20．End systems access to the Internet through its ( ).A modemsB protocolsC ISPD sockets21．End systems, packet switches, and other pieces of the Internet, run ( ) that control thesending and receiving of information within the Internet.A programsB processesC applicationsD protocols22．There are many private networks, such as many corporate and government networks, whose hosts cannot exchange messages with hosts outside of the private network. These private networks are often referred to as ( ).A internetsB LANC intranetsD WAN23．The internet allows ( ) running on its end systems to exchange data with each other.A clients applicationsB server applicationsC P2P applicationsD distributed applications24．The Internet provides two services to its distributed applications: a connectionlessunreliable service and () service.A flow controlB connection-oriented reliableC congestion controlD TCP25．It defines the format and the order of messagesexchanged between two or more communicatingentities, as well as the actions taken on the transmission and/or receipt of a message orother event. The sentence describes ( ).A InternetB protocolC intranetD network26．In the following options, which does not define in protocol? ( )A the format of messages exchanged betweentwo or more communicating entitiesB the order of messages exchanged betweentwo or more communicating entitiesC the actions taken on the transmission ofa message or other eventD the transmission signals are digitalsignals or analog signals27．In the following options, which is defined in protocol? ( )A the actions taken on the transmission and/orreceipt of a message or other eventB the objects exchanged between communicating entitiesC the content in the exchanged messagesD the location of the hosts28．In the following options, which does not belong to the network edge? ( )A end systemsB routersC clientsD servers29．In the following options, which belongs to the network core? ( )A end systemsB routersC clientsD servers30．In the following options, which is not the bundled with the Internet’sconnection-oriented service? ( )A reliable data transferB guarantee of the transmission timeC flow controlD congestion-control31．An application can rely on the connection to deliver all of its data without error and in the proper order. The sentence describes ( ).A flow controlB congestion-controlC reliable data transferD connection-oriented service32．It makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast. The sentence describes ( ).A flow controlB congestion-controlC connection-oriented serviceD reliable data transfer33．It helps prevent the Internet from entering a state of gridlock. When a packet switch becomes congested, its buffers can overflow and packet loss can occur. The sentence describes ( ).A flow controlB congestion-controlC connection-oriented serviceD reliable data transfer34．The Internet’s connection-oriented service has a name, it is ( ).A TCPB UDPC TCP/IPD IP35．In the following options, which service does not be provided to an application by TCP?( )A reliable transportB flow controlC video conferencingD congestion control36．The Internet’s connectionless service is called ( ).A TCPB UDPC TCP/IPD IP37．In the following options, which does not use TCP?( )A SMTPB internet telephoneC FTPD HTTP38．In the following options, which does not use UDP?( )A Internet phoneB video conferencingC streaming multimediaD telnet39．There are two fundamental approaches to buildinga network core, ( ) and packet switching.A electrical current switchingB circuit switchingC data switchingD message switching40．In ( ) networks, the resources needed along a path to provide for communication between the end system are reserved for the duration of the communication session.A packet-switchedB data-switchedC circuit-switchedD message-switched41．In ( ) networks, the resources are not reserved;a session’s messages use the resources ondemand, and as a consequence, may have to wait for access to communication link.A packet-switchedB data-switchedC circuit-switchedD message-switched42．In a circuit-switched network, if each link has n circuits, for each link used by the end-to-end connection, the connection gets ( ) of thelink’s bandwidth for the duration of theconnection.A a fraction 1/nB allC 1/2D n times43．For ( ), the transmission rate of a circuit is equal to the frame rate multiplied by the number of bits in a slot.A CDMAB packet-switched networkC TDMD FDM44．( ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Queuing delayB Store-and-forward transmissionC Packet lossD Propagation45．The network that forwards packets according to host destination addresses is called ( )network.A circuit-switchedB packet-switchedC virtual-circuitD datagram46．The network that forwards packets according to virtual-circuit numbers is called ( ) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram47．In the following entries, which is not a kind of access network?( )A residential accessB company accessC wireless accessD local access48．Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and thereceiving host are R1 and R2, respectively.Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L? (Ignorequeuing delay, propagation delay, andprocessing delay.) ( )A L/R1＋L/R2B L/R1C L/R2D none of the above49．The time required to examine the packet’s headerand determine where to direct the packet is part of the ( ).A queuing delayB processing delayC propagation delayD transmission delay50．The time required to propagate from the beginning of the link to the next router is ( ).A queuing delayB processing delayC propagation delayD transmission delay51．Consider sending a packet of 3000bits over a path of 5 links. Each link transmits at 1000bps. Queuing delays, propagation delay and processing delay are negligible. (6 points)(1).Suppose the network is a packet-switched virtual circuit network. VC setup time is 0.1 seconds. Suppose the sending layers add a total of 500 bits of header to each packet. How long does it take to send the file from source to destination?(2).Suppose the network is a packet-switched datagram network and a connectionless service is used. Now suppose each packet has 200 bits of header. How long does it take to send the file?(3).Suppose that the network is a circuit-switched network. Further suppose that the transmission rate of the circuit between source and destination is 200bps. Assuming 0.02s setup time and 200 bits of header appended to the packet, how long does it take to send the packet?Solution:?(1) .?t=5*(3000+500)/1000+0.1=17.6s?(2). t=5*(3000+200)/1000=16s(3). t=(3000+200)/200+0.02=16.02s。

Name_______________________ Period___________ Chapter 20: BiotechnologyThe AP Biology exam has reached into this chapter for essay questions on a regular basis over the past 15 years. Student responses show that biotechnology is a difficult topic. This chapter requires a strong conceptual understanding of the technological processes and the underlying biology that guides the procedure. With a little careful work, this chapter will give you insights into the incredible advancements already made and a basis for understanding the new marvels yet to be discovered in biotechnology.Overview1. It is important to understand the meaning of the three terms in bold to start this chapter.recombinant DNAbiotechnologygenetic engineeringConcept 20.1 DNA cloning yields multiple copies of a gene or other DNA segment2. Plasmids are important in biotechnology. Give a full and complete definition of plasmid.3. The production of multiple copies of a single gene is called ____________________________.4. Using Figure 20.2, label and explain the four steps in this preview of gene cloning.5. Read the description of restriction enzymes on page 398 carefully. Then draw and explain eachstep of Figure 20.3. When you finish, you should have recreated Figure 20.3 in the space below.6. What is a cloning vector?7. Figure 20.4 is a more detailed discussion of the gene cloning procedure shown in Figure 20.2.Explain the following key points.a)Explain why the plasmid is engineered with amp R and lacZ.b)After transformation has occurred, why are some colonies blue?c)Why are some colonies white? Why is this important?8. The cloning procedure described in question 7 and Figure 20.4 will produce many differentfragments of hummingbird DNA. These fragments may be stored in a genomic library.a)What is the purpose of a genomic library?b)Explain how a bacterial artificial library (BAC) and a cDNA library are formed.9. Once the hummingbird DNA is cloned, we have the problem of finding the piece of DNA thatholds our gene of interest. Explain how nucleic acid hybridization will accomplish this task. 10. Describe how a radioactively labeled nucleic acid probe can locate the gene of interest on amultiwell plate. (Use Figure 20.7 to guide your response.)11. What are two problems with bacterial gene expression systems?12. The polymerase chain reaction (PCR) is a Nobel Prize–winning idea that is used by scientiststo amplify DNA, particularly when the quantity of DNA is very small or contaminated. Explain the three initial steps that occur in cycle 1 of PCR.13. How many molecules will be produced by four PCR cycles?Concept 20.2 DNA technology allows us to study the sequence, expression, and function of a gene This section begins with a discussion of gel electrophoresis, a technique covered in AP Biology Lab 6. It is important to understand the principles of gel electrophoresis.14. ____________________ is a technique used to separate nucleic acids or proteins that differ insize or electrical charge.15. Why is the DNA sample to be separated by gel electrophoresis always loaded at the cathodeor negative end of the power source?16. Explain why shorter DNA molecules travel farther down the gel than larger molecules.17. To the right of the β-globin alleles, draw a gel showing the different pattern obtained from anormal patient and a sickle-cell patient. For help, examine Figure 20.10.18. A patient who is a carrier for sickle-cell anemia would have a gel electrophoresis patternshowing four bands. Add this pattern to your gel in number 17 and explain why the gel shows a four-band pattern.19. What is the purpose of a Southern blot?20. What two techniques discussed earlier in this chapter are used in performing a Southern blot?21. In working toward the general idea of how DNA sequencing was mechanized, look at Figure20.12 to answer the following general questions about the dideoxy chain termination methodfor sequencing DNA.a)Why does a dideoxyribonucleotide terminate a growing DNA strand? (You may need torefer to Figure 16.14, as suggested in the text, to answer this question).b)Why are the four nucleotides in DNA each labeled with a different color of fluorescenttag?Use unlabeled Figure 20.15 to explain the four steps of DNA microarray assays.(1)(2)(3)(4)22. Explain how microarrays are used in understanding patterns of gene expression in normal andcancerous tissue.Concept 20.3 Cloning organisms may lead to production of stem cells for research and other applications23. What is a totipotent cell?24. How is nuclear transplantation performed in animals?25. Use unlabeled Figure 20.18 to explain the six steps in reproductive cloning for mammals.(1)(2)(3)(4)(5)(6)26. What are stem cells?27. What is the major difference between embryonic stem cells (ES) and adult stem cells?28. How might induced pluripotent stem cells (iPS) resolve the debate about using stem cells formedical treatments?Concept 20.4 The practical applications of DNA technology affect our lives in many ways29. In question 17, you used two ideas that are featured in the first part of this concept. Explainhow single-nucleotide polymorphisms (SNPs) and restriction fragment length polymorphisms (RFLPs) were demonstrated in analyzing sickle-cell alleles.30. Explain the idea of gene therapy,and discuss the problems with this technique as demonstratedin the treatment of SCID.31. Explain how transgenic “pharm” animals might be able to produce human proteins.32. Describe how short tandem repeats can produce a sensitive genetic profile.33. How does the Ti plasmid make genetic engineering in plants a possibility?34. What are genetically modified organisms, and why are they controversial? Testing Your Knowledge: Self-Quiz AnswersNow you should be ready to test your knowledge. Place your answers here:1._______2._______3._______4._______5._______6._______7._______8._______9. Use the space below for the drawing.。

高中生要提前规划大学专业的英语作文全文共10篇示例，供读者参考篇1I'm gonna tell you about how us high school students need to start planning for what college major we wanna choose. It's super important to think ahead and figure out what we're interested in and good at before we head off to college.First off, we gotta start thinking about what subjects we enjoy in school. Do you like math and science? Maybe engineering or computer science could be a good major for you. Or if you're more into reading and writing, you might wanna consider majoring in English or journalism.Next, we gotta think about what careers we might wanna pursue in the future. If you love animals, maybe becoming a veterinarian is your thing. Or if you're passionate about helping people, being a nurse or social worker could be a good fit for you.It's also important to do some research on different majors and the job opportunities they can lead to. Some majors mighthave more job openings and higher salaries than others, so it's good to keep that in mind when making your decision.Overall, it's never too early to start thinking about what you wanna study in college. By planning ahead and exploring your interests and career goals, you'll be on the right track to choosing the perfect major for you. So start thinking about it now and you'll be one step closer to achieving your dreams!篇2Hey guys, do you know that as high school students, we need to start planning our college majors ahead of time? It's super important to choose a major that we are passionate about and that will help us achieve our future goals.First of all, we need to think about our interests and strengths. Do you enjoy science and math? Maybe a major in engineering or computer science would be a good fit for you. Are you more of a creative type? You might consider studying art or journalism.Next, we should research different majors and career paths. It's a good idea to talk to professionals in the field and ask them about their jobs. We can also take career aptitude tests to help narrow down our options.Once we have an idea of what we want to study, we should start preparing for college. This means taking challenging courses in high school and maintaining good grades. We should also participate in extracurricular activities and volunteer work to build a strong resume.Lastly, don't forget to visit college campuses and talk to admissions counselors. They can provide valuable information about different majors and help us make informed decisions.In conclusion, it's never too early to start thinking about our college majors. By following these steps and planning ahead, we can set ourselves up for success in the future. Let's work hard and aim for the stars!篇3Hey guys! Today I want to talk about something really important for us high school students. Can you guess what it is? That's right, it's about planning our future majors in college!It's super important to start thinking about what we want to study in college because it can really help us prepare for our future careers. We need to think about what we're interested in, what we're good at, and what kind of job we want to have in the future. Maybe you love animals and want to become aveterinarian, or maybe you're really good at math and want to become an engineer. Whatever it is, we need to start planning now!One thing we can do is research different majors and careers to see what interests us. We can talk to our teachers, school counselors, and even professionals in the field to get more information. We can also take elective classes in high school that relate to our interests to see if we enjoy them.Another thing we can do is visit college campuses and attend career fairs to learn more about different majors and what they involve. It's never too early to start exploring our options!By planning our college majors early, we can make surewe're on the right track to achieving our goals and having a successful future. So let's start thinking about our futures now and make a plan to reach our dreams!篇4Hey guys, do you know that as a high school student, it's super important to start thinking about what major you want to study in college? Yeah, I know it sounds kinda crazy to be thinking about that already, but trust me, it's never too early to start planning for your future!First of all, you gotta figure out what subjects you're good at and what you're interested in. Like, are you really good at math and science? Maybe you should consider studying engineering or medicine. Or maybe you're more into art and music, in which case you could think about majoring in fine arts or music composition. There are so many options out there, so think about what really makes you excited to learn more!Next, it's important to do some research about different college majors and what kinds of jobs you could do with each one. Like, if you want to study business, you could become a manager or start your own company someday. Or if you're interested in psychology, you could become a therapist or a counselor. It's cool to know what your options are so you can start planning your path to success!Lastly, don't be afraid to change your mind along the way. It's totally okay to be unsure about what you want to study in college, and it's normal to explore different options before you make a decision. Just remember to follow your heart and choose a major that makes you happy and excited to learn more!So yeah, start thinking about your future now and make a plan for what you want to study in college. It's never too early to start planning for your dream career! Go for it, guys!篇5Oh my gosh! Do you know that high school students need to plan their college major in advance? It's like super important to choose the right major, you know? So like, let's talk about it!First of all, we need to think about what we are interested in. Maybe you like to draw, so you can study art or design. Or maybe you love animals, so you can study veterinary science. It's so cool to study something you love!But we also need to think about the job market. Some majors have more job opportunities than others. Like, if you study computer science or engineering, you can probably find a job more easily than if you study music or theater. So it's important to think about what you want to do in the future.Also, we can talk to our teachers or guidance counselors for advice. They can help us figure out what major is best for us based on our interests and skills. They can also tell us about different colleges and universities that offer the majors we are interested in.And remember, it's okay to change your major if you realize it's not the right fit for you. It's better to study something you enjoy and are good at than to stick with a major you don't like.So yeah, planning your college major is like a big decision, but it's also super exciting to think about all the possibilities! Let's do it!篇6Hey guys, do you know that it's important for high school students to plan ahead for their college majors? Yeah, that's right! Choosing a major is a big decision, and it can really impact your future career and opportunities.First of all, think about what you're interested in and what you're good at. If you love animals, maybe you could study biology or veterinary science. If you're really into art, you might consider majoring in fine arts or graphic design. It's important to pick a major that you enjoy and that you're passionate about, because you'll be studying it for the next few years.Next, do some research on different majors and careers. Find out what kind of jobs you can get with each major, and what your earning potential might be. Talk to people who are already working in the field you're interested in, and ask them about their experiences. The more you know about your potential major, the better prepared you'll be to make a decision.Finally, don't be afraid to change your mind. It's totally normal to switch majors or career paths as you learn more about yourself and your interests. College is a time for exploration and growth, so don't feel like you have to have your whole life figured out right now.Remember, it's never too early to start thinking about your future. By planning ahead and choosing a major that you're passionate about, you'll be setting yourself up for success in college and beyond. So go out there, do your research, and get ready to embark on an exciting new chapter in your life!篇7As a high school student, it's important to start thinking about which college major you want to pursue in the future. Planning ahead can help you make the best choices for your future career.First of all, you should consider your interests and strengths. Think about what subjects you enjoy the most and what you are good at. If you're passionate about science, you might want to consider majoring in biology, chemistry, or physics. If you love working with numbers, a major in mathematics or economics might be a good fit for you.You should also think about your career goals. What do you want to do after college? If you have a specific career in mind, you can choose a major that will help you achieve your goals. For example, if you want to become a doctor, you will need to major in pre-med or biology. If you want to work in business, a major in marketing or finance might be a good choice.It's also important to research different majors and their requirements. Some majors have specific prerequisites or coursework that you will need to complete in order to graduate. Make sure you understand what is required for each major you are considering.Finally, don't be afraid to seek advice from teachers, counselors, and professionals in the fields you are interested in. They can offer valuable insight and guidance as you make your decision. Remember, choosing a college major is an important decision, but it's not set in stone. You can always change your major or pursue different opportunities in the future. Just make sure to plan ahead and make the best choices for your future success.篇8As a primary school student, I think it's important for high school students to plan ahead for their college majors. Choosing a major is a big decision and can have a big impact on your future. Here are some things high school students should consider when thinking about their college major.First, think about what you are passionate about. Do you love math, science, or art? Choosing a major that you are passionate about will make studying and working in that field much more enjoyable.Next, consider your strengths and weaknesses. Are you good at writing, problem-solving, or working with your hands? Play to your strengths when choosing a major, but also think about how you can improve in areas where you are not as strong.It's also important to think about your long-term goals. What kind of career do you want to have? Do you want to make a lot of money, help people, or make a difference in the world? Your college major can help you achieve these goals.Lastly, do some research on different majors and the careers they can lead to. Talk to current college students, professionals in the field, and your school counselors to get more information.Overall, by thinking ahead and planning for your college major, you can set yourself up for success in the future. Choose a major that you are passionate about, play to your strengths, consider your long-term goals, and do your research. Good luck!篇9Hey guys, do you know that as high school students, we need to start planning our future university majors early? It's super important to have a clear idea of what we want to study in college so we can prepare ourselves for it. Let's talk about why it's so crucial to plan ahead when it comes to choosing a major.First of all, picking the right major can set us up for success in the future. If we choose a major that we're passionate about and good at, we'll be more motivated to work hard and excel in our studies. This can lead to better job opportunities and a fulfilling career down the road. So, it's essential to think about our interests, strengths, and career goals when selecting a major.Secondly, planning ahead can help us make informed decisions about our academic path. By researching different majors, talking to current college students, and exploring various career options, we can gain a better understanding of what each major entails and what kind of jobs it can lead to. This knowledgewill help us make a more educated choice when it comes time to declare our major.Lastly, starting early gives us more time to explore our interests and narrow down our options. We can take advantage of internships, volunteer opportunities, and extracurricular activities to gain hands-on experience in different fields. By trying out different things, we can figure out what we enjoy doing and what we're good at, which can guide us in choosing the right major.In conclusion, it's never too early to start thinking about our future. By planning ahead and considering our interests and goals, we can choose a major that's right for us and set ourselves up for success in college and beyond. So let's put on our thinking caps and start exploring our options – our future selves will thank us for it!篇10Well, hello everyone! Today I want to talk about something super important for all of you in high school – planning your future college major! It's never too early to start thinking about what you want to study in college, because it can have a big impact on your future career.First of all, you should think about what subjects you enjoy the most. Do you love math and science? Maybe you should consider a major in engineering or computer science. Are you a creative soul who loves to write and draw? Then maybe a major in English or art would be a good fit for you.Next, you should also think about what kind of job you might want to have after college. Do you dream of being a doctor and helping people? Then a major in biology or pre-med might be the right choice. Or maybe you're passionate about the environment and want to work in conservation – then a major in environmental science could be perfect for you.It's also important to consider what skills you already have and what skills you want to develop. If you're great at problem-solving and critical thinking, a major in philosophy or psychology could be a good match. Or if you're a whiz with numbers and data, you might excel in a major like economics or statistics.Remember, it's okay to change your mind and explore different options. The most important thing is to find a major that you're passionate about and that will help you reach your goals. So start researching different majors, talking to yourteachers and counselors, and thinking about what you want to study in college. Your future self will thank you for it!。