syringe titrator stopcock. Insert the stopcock onto the threaded tip of the syringe. syringe titrator stopcock

 
 Insert the stopcock onto the threaded tip of the syringesyringe titrator stopcock 00/Item) FREE delivery Tue, Nov 28 on $35 of items shipped by Amazon

Fisher Scientific, Bishop Meadow Road, Loughborough, Leicestershire, LE11 5RG © Fisher Scientific UK Ltd All rights reserved. j) Turn the patient line stopcock to the “Drainage Only” position (“off” – prong points toward stopcock). Adjustable dosing rate, filling rate and adjustable filling between each dose step makes these units… Stopcocks Narrow Results 1 – 30of42 Results 1 Thermo Scientific™ Nalgene™ Three-way Stopcock Experience in-house fluid transfer system flexibility with this three-way stopcock, arranged in a T-shape to simply any two — or all three — arms of the stopcock with ease. Catalog No. tions in the infusion administration system. See Figure 2. A stopcock is a form of valve used to control the flow of a liquid or gas. Titration. Safety, Gloves, Glasses & Cleaning. Find the stopcock and shut it off immediately to prevent flooding. A solution who's molarity is calculated. ₹53800. 3-Way Stop Cock facilitates multiple lines through single IV access. SP-3005-CK-02 Contents List To ensure that you are prepared for your first lab, please immediately compareThe stopcock is opened and the plunger moves to inject the trapped air into a rigid container that initially holds 1 lb of air at 1. Burette, DURAN®, class B, blue graduated, lateral glass stopcock Hirschmann Laborgerate Burettes 50:0. Prime the Unit. 2-way and 3-way Connections This polypropylene stopcock has a detachable, watertight and inert Teflon® PTFE plug that contacts any fluid being dispensed. EXCHANGE transfusions through the umbilical vein may be performed in several ways. The most common reservoirs associated with extrinsic contamination of propofol are syringes or micro-droppers, vials, and IV stopcock dead space. Manufacturer Part No:. Titrator and small stopcock. 1-arm-stopcock 2-arms-stopcock 2-arms-stopcock acc. Turn the stopcock so that the valve handle points upward to set the volume of air in the syringe to 10 cm3. 24. Total views 100+ Northern Kentucky University. pH and Electrochemistry. A buret is a cylinder similar to a syringe, with measurement markings and a stopcock on the bottom. Unlike a pipette, the sample quantity delivered by a burette is changeable. Figure 3 shows an image of the titrator and small stopcock. Contact Now. Mettler Toledo ™ Siphon Tip For Titration Sens. 0 mL mark. •. The main purpose of putting a 4-way in-line (two consecutive 3-way stopcocks) is for having a way of returning the waste in a blood draw without disconnecting the waste syringe. See Figure 6. Saf-T Holder™ devices come with the back-end needle and multi-sample Luer permanently attached to the holder to minimize potential exposures and holder re-use. Stopcocks are used to grossly regulate the flow of tap water in residential and commercial. With the completely depressed syringe screwed onto the stopcock, open the stopcock and retract the plunger to the 20 mL mark to remove air from the flask and then close the stopcock. Preferred method using a stopcockCombine the adenosine and flush solution in one syringe. 2 for the 6 post-years assessed. Basic of titration - Download as a PDF or view online for free. Electrochemistry Accessories. 5 mL in Pipet 2 Pipet, Empty Short Stem 1 Sodium Hydroxide, 0. When TIVA is administered manually (i. Level of Risk and. other burets readable to 0. top with a 41mm (1-5/8") O. , Determine whether the stopcock should be completely open, partially open, or completely closed for each activity involved with titration. The concentration of acetic acid in vinegar may be expressed as a molarity (in mol/L): Molarity = Moles of Acetic Acid Volume of Vinegar (in L) (11. Photo by: wp. 67/10 Items) List: $24. For filling 25 or 50 mL glass or plastic burets Nalge 3645 Self-zeroing Kit includes a 1,000 mL LDPE squeeze-bottle; 1. Standardization of the organolithium reagent may be employed via titration with dibromoethane 28,. Avoid drug traveling retrograde. c. 09 – R 501. We will need to gather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the lab kit or 5-6 thick textbooks . 64 Incl VAT. 05 mL, while 25 mL and 50 mL burettes are usually graduated each 0. A precise mass of a solid substance measured on a balance, dissolved in water, and reacted with analyzed substance. Cap and septum included. The TitroLine® 7500 KF is a compact, easy-to-use volumetric titrator for water determination according to Karl Fischer (KF) with a typical operating range of 0. Lower 3-way valve (C) allows for solvent return to flask,…Take the white cap off the saline syringe and remove the air from the syringe by gently screwing the syringe onto the stopcock. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and 2 thick textbooks and the LabPaq box or 5-6 thick textbooks. 2. These 30mL PYREX® pear-shaped separatory funnels have glass No. Operation of PCA pumps by nursing staff or family members may cause excessive sedation of the patient by overriding theOpen the stopcock and add 1 drop of (EDTA 0. See Figure 6. b. The opposite end and the side ports have a female port design to accept the male luer-locking connection of an administration set or syringe. 4AJ-6802187Propofol is an intravenous anesthetic used for procedural sedation, during monitored anesthesia care, or as an induction agent for general anesthesia. Increases accuracy of titrations for measuring TA, SO2, and Alcohol by Volume. Stopcocks are also offered in a manifold design, aBurettes. 3. 01-910-718. D. Administer via fast IV push (can be through a running IV line). Thermometers, Timers and pH. $196. Allow this excess solution to drain into a waste flask. Samples of dithionite solutions re- Test Tubes with Rack, YGDZ 50pcs 16x100mm Clear Plastic Test Tubes with Caps and Holder Rack for Nurse Party Decorations Halloween Party Favors. Burettes. 0. Remove the plunger from the titrator and place it back in your lab kit. Expert Answer. 1 4. Bel-Art™ SP Scienceware™ Two-Piece Stopcocks. Learn More. Remove the plunger from the titrator and place it back in your LabPaq box. The most. Screw the stopcock back on to the syringe. 2022-08-31. Stopcock connects to and forms a tight seal with Luer Lock syringes. a. Clean the injection cap on the stopcock with alcohol. at 100°C before using. (If there is still an air bubble in the tip, consult your teacher. View Formal lab report_ Titration for Acetic Acid in Vinegar. Filter & Sort. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the lab kit or 5-6 thick textbooks. With nitrogen gas flowing through the tonometer, the modified syringe could be attached, filled with dithionite solution, and then removed from the tonometer and attached to the titration cell as described above. gas flowing rapidly through the titration cell and out the stopcock 1 The abbreviations used are: cyt ~111, horse heart ferricyto- chrome c; kobs, observed first order rate constant. 1 Instrument description ■July 7, 2015. PTFE stopcock. Unscrew the blue cap on the stopcock valve that connects to your drainage tube. Fill the syringe with about 10 mL of the. Each buret is supplied with a dust cover. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and 2 thick textbooks and the LabPaq box or 5-6 thick textbooks. Includes everything listed on product sheet, which is as follows: -Beaker 100ml, glass -SyriTo gain experience monitoring a titration with a pH electrode and determining the equivalence point. Glass and metall syringe, capacity 10ml:0,5ml, Luer tip, autoclavable at 134°C and interchangeable glass cylinder with steel piston and conformity. Use a pipette to fill the syringe with 15 mL of 0. These titrators feature a motor-driven piston burette for precise titrations and dosing of dispensable liquids. Make sure that the stopcock on the syringe is in the closed position (horizontal). Question: Exercise 1: Determining the Concentration of Acetic Acid Data Table 1. measure exactly 5 mL of titrant. Unit 7 Lab: Water Hardness CHEM 1806Purpose: To determine the hardness of your drinking water and the technique of titration Materials: Student Supplied –distilled water,. 13-0. 240 V) – • • • Power cable (country-specific)– • • • 10 Volumetric KF TitratorWhen using TIVA in the obese, titration to clinical effect and pEEG monitoring is recommended. d. 6. The borosilicate glass buret is filled by pressure supplied by the rubber bulb. …10 mL buret readable to 0. Three-way models allow connection of two or three arms. Needles & Syringes to Protective Apparel. Pricing & AvailabilityManual Titrator found in: TITRONIC® 300 Manual Titrators, TITRONIC® 500 Manual Titrators, Titratable Total Acidity Mini-Titrator, EasyPlus™ Semi-Automated. Move the beaker away from the titrator and place a crumpled paper towel directly below the titrator. Titration for Acetic Acid in Vinegar Lab Experiment Summary Students will have the opportunity to use titration techniques to determine. In titration, a known volume of one solution (the titrant) is slowly added to another solution (the analyte) until the desired endpoint is reached. Pipettes & Syringes Made of Plastic. Figure 4. Remove the plunger from the titrator and place it back in your STEMpaq box. 12. Repeat this step so the syringe receives a total of two rinses. f E 1064. 5. Fill the syringe to the point where the bottom of the meniscus touches the 20. 32. Electrochemistry. 3. Vinegar is essentially a solution of acetic acid ( HC2H3O2 HC 2 H 3 O 2) in water. It is used for syringe changing the liquid. If SVT termination failed, a second dose of adenosine (12 mg per 4 ml) in a 5 ml syringe was administered. Class A, ASTM E-284, meets USP standards, individually serialized and certified. Download. Schellbach stripe. 01 Total volume of NaOH used (mL) 8. The cost depends on what tier of titrator you are looking to purchase, as well as any connectivity/add-ons. The flask will contain the air that you will be measuring the pressure of. ”. release one drop at a time from the titrator. Discard the solution and replace 10. Burette. Titrando). See Figure 6. Figure 4. In the open method, a nurse draws donor blood through a two-way stopcock which is connected to the bottle by autoclaved polyvinyl tubing. Hamilton ® syringe, 1000 series GASTIGHT ®, LTN (fixed needle). 00/Item) FREE delivery Tue, Nov 28 on $35 of items shipped by Amazon. See Figure 6. Discard the solution and replace with fresh titration solution if a stable reading cannot be obtained. 4 M hydrochloric acid into the burette, with the tap open and a beaker under the open tap. 0 ml Concentration CHCOOH in Vinega ml) 0. 50 mL, plastic 1 Cylinder-25-mL 1 Syringe-Titrator-10mL 1 Syringe-Titrator-Stopcock 1 Test-tube-clamp-holder Experiment Bag Titration for Acetic Acid in Vinegar 1 Phenolphthalein Solution, 1% - 0. 3. The barbed fitting end accepts 6. 1-arm-stopcock 2-arms-stopcock 2-arms-stopcock acc. Unit 7 Lab: Water Hardness CHEM 1806Purpose: To determine the hardness of your drinking water and the technique of titration Materials: Student Supplied –distilled water, tap water, books or other height riser LabPaq materials: 100mL glass beaker, toothpicks, 25 mL Graduated cylinder, test tube clamp holder, 10mL syringe titrator, syringe stopcock, Determination of water harness bag. 32 / Piece. Also used as a replacement stopcock for the Poor Man's Burets and the Economy Choice Burets. Expert Help. 15 and 20 Burets provide 7 inches clearance for titration vessel and 2001G50 Buret provides 8 7/8 inch clearance 2001F10. Products. Question: Procedure Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the lab kit or 5-6 thick textbooks. The Continuous series can be used for titration agents up to a concentration of 1 Mol/l. Satisfactory Essays. This ELISA kit provides an easy, accurate, and reproducible method for AAV2 titration. Additional studies highlight fluid flow dynamics associated with. 07 mL. False. Order number: 5 497 050. DYNJSC306HP. In this method, we connected two no-return valves (JMS, Hiroshima, Japan) to both sides of a three-way stopcock (JMS) ( Fig. While there are numerous devices used in conjunction with central venous catheters in the ICU to infuse medications and control the flow of fluids, none has held the promise, or created controversy, like the stopcock. Results Syringe dead space for 1 and 2. Unscrew the stopcock and depress the plunger completely. Move the beaker away from the titrator and place a crumpled paper towel directly below the titrator. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the lab kit or 5-6 thick textbooks. Make additions to burettes and narrow neck containers easily with this flared top thistle tube. (01TF111314Y; Scale-Digital-600 g = Solar cell assembly Thermometer, analog R 1 Item Description Tubing — Black latex 16. Three-way models allow connection of two or three arms. Hide. Figure 4. The funnel was placed on top of the syringe and a clean 100 mL beaker was placed below the. Burettes. KIM-KAP dust cap is included White ceramic enamel scale. Numbers and graduation on buret remain easy to read. flare. C3310 BD™ Syringe, Male Luer Lock 20 ml. These products are not for medical or on human use. )Glass burette with either 10 mL titration volume and 0. A manual burette fulfills these requirements - Stopcock: add small volumes - Grading: accurate volume reading 15. Record this value in your data table alongside the measured volume. Mettler Toledo ™ Siphon Tip For Titration Sens. Titrator and small stopcock. During the past 20 years, a growing number of studies have validated concern about the risk of the open lumen allowing intraluminal contamination. Also used as a. The stopcock should fit tightly into the titrator so that the liquid will not leak. Touch the tip of the buret to the inside of the vessel to remove the suspended droplet. Contact Now. 7280. A small hole in the filling tube at the "O" line permits setting of the liquid level and excess titrant is returned to…. WARNING If the flow into syringe stops, close the stopcock, re-position the catheter and open the stopcock toPerfektum ® one-way high pressure stopcock. With state-of-the-art performance features, like a fritless cell option, the AQ-300 offers the same fast and accurate results you've come to expect from other Aquacounter® products. Pressure rating…. 70. 5mm (1/4 to 3/8") I. 1. Titration (also known as titrimetry [1] and volumetric analysis) is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte (a substance to be analyzed). Injecting drugs or taking. Position the Transducer . burette, laboratory apparatus used in quantitative chemical analysis to measure the volume of a liquid or a gas. Leave the stopcock turned towards the drainage bag for 1 to 2 hours to allow the povidone-iodine to work. Tapered tip can be connected to 1/8 inside diameter tubing. . Fill the syringe with about 10 mL of the liquid to be distilled. 1 mlExpert Answer. Three Way Stop Cock, which is also referred as “ 3-way tap ”, is a device with 2 female Luer ports and a male Luer lock that provide the ability to open, close, and even reduce lines down to one for drug infusion. $1899 ($3. Study Resources. Disassemble the stopcock, noting carefully how it is assembled, then clean the bore of the buret with a warm solution of Alconox. If the approximate concentration is known, the titration will proceed quickly until shortly before the end point. 2. 4. Stopcocks (Per Pack 100), 3-Way Nylon Stopcocks with Clear PC Lock Rotating Ring or Tomopal Nylon Stopcock with Clear PC Lock Rotating Ring for Industrial and Laboratory uses. , Ltd. Using a clean 25-mL pipet (volumetric), carefully place 25. Stopcock, translucent wash bottles and may also be used for disposable or plastic beakers. Patients randomized into the DST group received the first dose of adenosine (6 mg per 2 ml) in a 5‐ml syringe with a subsequent 20 ml bolus of NSS in another 20‐ml syringe connected by a T‐way stopcock via the cubital vein (Figure 1). The barbed fitting end accepts 6. End Point: You may add the titration solution quickly until a few milliliters less than the endpoint. These stopcocks are easily integrated with other stopcocks, manifolds,. A buret should be cleaned and primed before use. See Figure 4. Figure 4. Includes Schellbach backing for easy reading of liquid levels. Materials and Methods: Items out of the lab pack: goggles, gloves, 25mL cylinder, 100mL beaker, the corresponding experiment bag, along with a sample of my tap water, toothpicks, and distilled water. The stopcock is usually placed between two pieces of equipment, such as an IV drip and a syringe. 8976 mg/mL). Related Products: Solvent Bottle Adapter. Glass or PTFE burettes (also buret) is a graduated glass tube with a tap at one end, for delivering known volumes of a liquid, especially in titrations. About 1 mL of ethanol is added with the syringe into the titration beaker. 99ml are simply controlled by the touch screen display module. Open the stopcock of the buret and add ~2. Cadence Science® stopcocks are precision-machined, individually lapped, and carefully mated to maintain pressure characteristics. The software guided workflow is also shown in the following table. 5 mL was less than 0. Titration for Acetic Acid in Vinegar-Lab Report Exercise 1: Determining the Concentration of Acetic Acid Data Table 1. United Scientific Supplies. The stopcock barrel has a smooth micro-finish to ensure leak-resistant performance. Dispense approximately 0. During titration, a stopcock is used to _____. Procedure 1 Remove the outer leaves of the red cabbage. to the accuracy requirements found in ASTM specification E 694 Kimax precision bore buret has a side filling tube with a separate stopcock to control liquid within the permanently attached reservoir, approximately 70 mL in capacity. A stopcock for use with a syringe, the stopcock comprising: a stopcock body including: a central axial opening formed in the stopcock body; a first stopcock luer connector extending radially from the stopcock body and in fluid communication with the central axial opening; and a second stopcock luer connector. All Syringes and Needles; View All Lab Consumables; Recombinant Proteins. Objectives To develop familiarity with the concepts and techniques of titration To determine the concentration of an acetic acid solution 117 ©Hands-On Labs, Inc. Titrator. The buret tip should fill with solution, leaving no air bubbles. Information on pin assignment and status diagrams of the Eco KF Titrator remote interface. KIMAX Dispensing Burets With Straight-Bore PTFE Stopcock. Using a small funnel, pour a few cubic centimetres of 0. 2 micron filter (1. A 100 mL graduated cylinder was used to pour 20 mL of sodium hydroxide (NaOH) into a new 250 mL beaker. )Clean the flushing port with alcohol and attach the flush syringe. After that, the drift is often still very high. The Thermo Scientific Orion Star T900 Series Automated Titrators are designed to make performing titrations easier, more reliable, and more reproducible than manual titrations. US & Canada: (800) 852-3504 Worldwide: (706) 353-6547. Collect Discard Sample (Venous Samples). Dripping: Open the stopcock and slowly allow the liquid to drain into the receiving vessel until it approaches the end point. Draining the buret. Stopcocks. com: Industrial & Scientific. Using “High Vacuum Grease” to re-coat the core should fix your problem. . Includes a PTFE needle valve stopcock, intermediate stopcock and rubber bellows. Procedure I gather the test tube holder small stopcock 10 mL syringe and some from CHE 112L at Northern Kentucky University Set up a 10 mL syringe and the drop counter so that liquid will flow through from the syringe, through the sensor on the drop counter, and into a clean beaker as shown. 83016 Y Connector, Male Luer Connector with Spin Lock and Two Female Luer Lock Ports, Blue Tint. Includes ten 0. When using Dial-A-Flow tubing, you may adjust the dial to a value that. 2-way and 3-way Connections This polypropylene stopcock has a detachable, watertight and inert Teflon® PTFE plug that contacts any fluid being dispensed. 741 Words; 3 Pages. Titrator Accessories. Stopcocks Narrow Results 1 – 30of42 Results 1 Thermo Scientific™ Nalgene™ Three-way Stopcock Experience in-house fluid transfer system flexibility with this three-way. In contrast to coulometry, opening a volumetric titration cell for a short period of time does not falsify the results. 3. Procedure: Procedure 1. It is a long, graduated glass tube, with a stopcock at its lower end and a tapered capillary tube at the stopcock's outlet. This setup can be referenced in Photo #3 below. PDF from SPAN 3005 at Old Dominion University. (D) Transfer obtained via the classic metal device. Read More. Spiros is now permanently attached to luer. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and 2 thick textbooks and the LabPaq box or 5-6 thick textbooks. You'll get a detailed solution from a subject matter expert that helps you learn core concepts. 70Sunton China Medical Latex Foley Catheters 300-400mm Length Disposable All Silicone Urinary Catheter Factory Surgical Grade Latex Foley Male Urinary Catheter. 6. one hand and quickly open the stopcock for a second and re– close it while simultaneously giving the burette a little downward jerk. Purpose: The purpose of this lab is to learn how to use titration to determine the molar concentration of acetic acid in vinegar. The most common method for delivering titrant is a buret (Figure 9. Doc Preview. 1-Way Stopcock with OFF Handle Position, High Pressure, Fixed Male Luer Lock, Female Fitting, 700 PSI. However, If you don’t know where your stopcock is, you’ve got a problem! This article will tell you all. This can be accomplished with a 50-mL syringe or by partially draining the solution if the titration chamber is provided with a stopcock. The Buret. Explain how EDTA titration is used to measure CaCO 3 water hardness. d. Standard equipment for the titrator types varies. Shop Mettler Toledo™ StopcockGather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the lab kit or 5-6 thick textbooks. Stopcocks have been used for decades to deliver infusion therapy in patients of all ages and in all health care settings. Amber reservoir bottles block ultraviolet light, while borosilicate bottles are stronger than regular. Needles & Syringes; Orthopedic & Physical Therapy;. 10 mL Plastic Syringe, Pack of 100 (1) 100 mL Glass Titration Vessel, Pack of 20 (1) 250 mL Glass Titration Vessel, Pack of 10 (1) 3-Part Tube Set (1) 3/2-Way Valve (1) 500 g Silica Gel (1) 80 x 0. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and 2 thick textbooks and the LabPaq box or 5-6 thick textbooks. Favorite item to keep tabs on it! Saved! Mettler Toledo™. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and either 2 thick textbooks and the STEMpaq box or 5-6 thick textbooks. Purpose: To become familiar with the concept of water hardness, practice a titration technique using a titrator, and determine the hardness of the local water supply. Vee Gee Scientific. We present a useful method using a three-way stopcock with two no-return valves for rapid infusion. Each for $284. ) Finally, use the stopcock to lower the liquid(A) The traditional metal transfer system, which connects 2 syringes. : Changzhou SUNTON Medical Technology Co. Used with the 50 ml Glass Syringes for DGA testing kit. Fill your syringe with approximately 5 mL of distilled water. 2. A gray intermediate color may develop. 1. Titrator and small stopcock. Open the stopcock wide open to force trapped air bubbles from the stopcock and tip. 1 % - 100 % water. The LifeFlow system with its proprietary 10 mL syringe was connected to the 500 mL fluid bag using the manufacturer-provided tubing setup. 4 for the 5 pre-years assessed versus 35. 5M NaOH. D. Gather the test tube holder, small stopcock, 10-mL syringe (titrator), and 2 thick textbooks and the LabPaq box or 5-6 thick textbooks. Remove the dressing and clean around the tube with sterile saline using a cotton ball or Q-tip. A small hole in the filling tube at the "O" line permits setting of the liquid level and…DWK Life Sciences (Kimble) KIMAX buret with a PTFE plug. 51107525. 2 Stopcocks have a male port that luer locks to the hub of the VAD, or the female end of an administration set. D) The analyte solution is being stirred too quickly. Declaration of conformity acc. 01 mL. The stopcock valve controls the fluid flow from the burette, either in a steady stream or drop by drop. Class A, ASTM E-284, meets USP standards, individually serialized and certified. Compare this item. 08. Ceramic valve disc. Needles & Syringes to Protective Apparel. Volume. Contact Supplier. The plunger maintains the state of the injected air constant. Figure 1. First, the O-ring is designed to prevent the stopcock from falling out if it becomes dislodged. Throw the syringe away in your regular trash. These are the instructions for the lab and I have posted my data table results. Close the syringe stopcock and begin filling the syringe with the sodium hydroxide solution. Mini-titrators; Lab equipment. 1%, and that’s about maximum precision that we can get from volume measurement when using burette. Cantaloupe melon juice. Lateral PTFE-spindle without intermediate stopcock. Syringe A medical apparatus that has a small tube with a thin hollow needle at the end. 1 mL gradations. 0 mL mark. Order: 10,000 Pieces. Unopened, original contents sealed within. Some information has been provided for you, but you can add additional details to those sections. Slowly turn your stopcock to allow the water to drip slowly (this will be not quite to. For height adjustments, recompress mechanism and slide buret up or down and…. FREE delivery Thu, Nov 2 on $35 of items shipped by Amazon. The stopcock is opened and the plunger is moved to inject the trapped air into a container that initially holds 1 lb of air at 1.