Biology • Environment • Chemistry MEMORABLE TEACHING MADE EASY!
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Electrowinning of Tellurium by Means of PLS Modelling
2009:056 MASTER'S THESIS Optimisation of Influential Factors in Electrowinning of Tellurium by Means of PLS Modelling Seyed Mohammad Khosh Khoo Sany Luleå University of Technology Master Thesis, Continuation Courses Minerals and Metallurgical Engineering Department of Chemical Engineering and Geosciences Division of Process Metallurgy 2009:056 - ISSN: 1653-0187 - ISRN: LTU-PB-EX--09/056--SE Optimisation of Influential Factors in Electrowinning of Tellurium by Means of PLS Modelling Master Thesis By: Seyed Mohammad Khoshkhoo Sany [email protected] Supervisors: Prof. Åke Sandström (Luleå University of Technology) Dr. Nils Johan Bolin (Boliden Mineral AB) Abstract Electrowinning of tellurium is a relatively simple process that can be carried out effectively by employing the existing technology. In order to obtain tellurium with the least amount of impurities, the effects of three main factors were studied, namely current density, free concentration of caustic soda and initial concentration of tellurium. Five elements were chosen as the main impurities: Ag, Bi, Cd, Ni and Pb. A series of 17 experiments arranged in a CCF (central composite faced-centred) design has been carried out and the results were fitted using PLS (partial least squares) method. The effect of free caustic concentration was found to be the most important of the three parameters studied. Current density was also important, yielding the least amount of impurities at high current densities. Tellurium concentration had the smallest effect of the three parameters studied. From the model, current densities of 330-350 A/m2, tellurium concentrations of 90-120 g/l and free sodium hydroxide concentration of around 120 g/l are suggested as optimal conditions for obtaining the purest tellurium. -
Volvox Barberi Flocks, Forming Near-Optimal, Two
bioRxiv preprint doi: https://doi.org/10.1101/279059; this version posted March 8, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Volvox barberi flocks, forming near-optimal, two-dimensional, polydisperse lattice packings Ravi Nicholas Balasubramanian1 1Harriton High School, 600 North Ithan Avenue, Bryn Mawr, PA 19010, USA Volvox barberi is a multicellular green alga forming spherical colonies of 10000-50000 differentiated somatic and germ cells. Here, I show that these colonies actively self-organize over minutes into “flocks" that can contain more than 100 colonies moving and rotating collectively for hours. The colonies in flocks form two-dimensional, irregular, \active crystals", with lattice angles and colony diameters both following log-normal distributions. Comparison with a dynamical simulation of soft spheres with diameters matched to the Volvox samples, and a weak long-range attractive force, show that the Volvox flocks achieve optimal random close-packing. A dye tracer in the Volvox medium revealed large hydrodynamic vortices generated by colony and flock rotations, providing a likely source of the forces leading to flocking and optimal packing. INTRODUCTION behavior (see, e.g., [8, 9] and references therein) but their interactions are often dominated by viscous forces (e.g. fluid drag) unlike larger organisms which are The remarkable multicellular green alga Volvox barberi dominated by inertial forces. Here, I show that V. [1] forms spherical colonies of 10,000 to 50,000 cells barberi colonies, which are themselves composed of many embedded in a glycol-protein based extra cellular matrix individual cells acting together, show collective behavior (ECM) and connected by cytoplasmic bridges that may at a higher level of organization. -
Introduction to the Cell Cell History Cell Structures and Functions
Introduction to the cell cell history cell structures and functions CK-12 Foundation December 16, 2009 CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the “FlexBook,” CK-12 intends to pioneer the generation and distribution of high quality educational content that will serve both as core text as well as provide an adaptive environment for learning. Copyright ©2009 CK-12 Foundation This work is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. Contents 1 Cell structure and function dec 16 5 1.1 Lesson 3.1: Introduction to Cells .................................. 5 3 www.ck12.org www.ck12.org 4 Chapter 1 Cell structure and function dec 16 1.1 Lesson 3.1: Introduction to Cells Lesson Objectives • Identify the scientists that first observed cells. • Outline the importance of microscopes in the discovery of cells. • Summarize what the cell theory proposes. • Identify the limitations on cell size. • Identify the four parts common to all cells. • Compare prokaryotic and eukaryotic cells. Introduction Knowing the make up of cells and how cells work is necessary to all of the biological sciences. Learning about the similarities and differences between cell types is particularly important to the fields of cell biology and molecular biology. -
Algae of the Genus Volvox (Chlorophyta) in Sub-Extreme Habitats T A.G
Short Communication T REPRO N DU The International Journal of Plant Reproductive Biology 12(2) July, 2020, pp.156-158 LA C P T I F V O E B Y T I DOI 10.14787/ijprb.2020 12.2. O E I L O C G O S I S T E S H Algae of the genus Volvox (Chlorophyta) in sub-extreme habitats T A.G. Desnitskiy Department of Embryology, Saint-Petersburg State University, Saint-Petersburg, 199034, Universitetskaya nab. 7/9, Russia e-mail: [email protected]; [email protected] Received: 18. 05. 2020; Revised: 08. 06. 2020; Accepted and Published online: 15. 06. 2020 ABSTRACT Literature data on the life of green colonial algae of the genus Volvox (Chlorophyta) in sub-extreme habitats (polar, sub-polar and mountain regions) are critically considered. Very few species (primarily homothallic Volvox aureus) are able to thrive in such conditions. Keywords : Geographical distribution, reproduction, sub-extreme habitats, Volvox. The genus Volvox Linnaeus (Volvocaceae, Chlorophyta) Peru (South America) at the elevation of more than five includes more than 20 species of freshwater flagellate algae thousand meters above sea level seems to be doubtful. The (Nozaki et al. 2015), providing an opportunity to study the illustration from this article (which focuses mainly on developmental mechanisms in a relatively simple system diatoms) shows a spherical colony with a diameter of about 14 consisting of two cellular types (somatic and reproductive). μm, consisting of several hundred very small cells (Fritz et al. Volvox carteri f. nagariensis Iyengar is a valuable model of 2015, p. -
Laboratory Exercises in Microbiology: Discovering the Unseen World Through Hands-On Investigation
City University of New York (CUNY) CUNY Academic Works Open Educational Resources Queensborough Community College 2016 Laboratory Exercises in Microbiology: Discovering the Unseen World Through Hands-On Investigation Joan Petersen CUNY Queensborough Community College Susan McLaughlin CUNY Queensborough Community College How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/qb_oers/16 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] Laboratory Exercises in Microbiology: Discovering the Unseen World through Hands-On Investigation By Dr. Susan McLaughlin & Dr. Joan Petersen Queensborough Community College Laboratory Exercises in Microbiology: Discovering the Unseen World through Hands-On Investigation Table of Contents Preface………………………………………………………………………………………i Acknowledgments…………………………………………………………………………..ii Microbiology Lab Safety Instructions…………………………………………………...... iii Lab 1. Introduction to Microscopy and Diversity of Cell Types……………………......... 1 Lab 2. Introduction to Aseptic Techniques and Growth Media………………………...... 19 Lab 3. Preparation of Bacterial Smears and Introduction to Staining…………………...... 37 Lab 4. Acid fast and Endospore Staining……………………………………………......... 49 Lab 5. Metabolic Activities of Bacteria…………………………………………….…....... 59 Lab 6. Dichotomous Keys……………………………………………………………......... 77 Lab 7. The Effect of Physical Factors on Microbial Growth……………………………... 85 Lab 8. Chemical Control of Microbial Growth—Disinfectants and Antibiotics…………. 99 Lab 9. The Microbiology of Milk and Food………………………………………………. 111 Lab 10. The Eukaryotes………………………………………………………………........ 123 Lab 11. Clinical Microbiology I; Anaerobic pathogens; Vectors of Infectious Disease….. 141 Lab 12. Clinical Microbiology II—Immunology and the Biolog System………………… 153 Lab 13. Putting it all Together: Case Studies in Microbiology…………………………… 163 Appendix I. -
Recommendation for Use Hofmann Voltameter for Educational Purposes
Glaswarenfabrik Tel. +49 (0) 9779 808 0 Karl Hecht Fax +49 (0) 9779 808 88 GmbH & Co KG Email: [email protected] Stettener Straße 22-24 Internet: www.assistent.eu 97647 Sondheim/Rhön VAT No. DE132198535 Germany Recommendation for use Hofmann voltameter for educational purposes Product number: 44285010 and 44286010 A water decomposition apparatus is used for the demonstration of electrolysis, i. e. for the decomposition of water into hydrogen and oxygen by means of electric current. The apparatus is consisting of a glass tube with pear-shaped funnel and two lateral measuring tubes 60 ml : 0.2 ml with glass stopcocks. There are two versions available: Product number 44285010 Spare parts Glass part No. 44287010 Metal tripod 2 Clamps No. 40870010 2 Platinum electrodes No. 44288010 Product number 44286010 Spare parts Glass part No. 44287010 Metal tripod 2 Clamps No. 40870010 2 Carbon electrodes No. 44289010 Experimental setup and test procedure Attach the voltameter with two clamps to the support. Insert the carbon or platinum electrodes into the measuring tubes. The stoppers have to be firmly in position in order to avoid leakage of liquid. For safety reasons place the apparatus into a glass tray. Pour in the electrolyte through the funnel while stopcocks are both open to let the air escape. Close the stopcocks as soon as the electrolyte has reached the level of stopcock bores. Connect the electrodes and the pole terminals at the tripod by means of two short connecting cables. Connect a DC voltage source and supply with electrical energy. The required direct voltage is about 10 V to 20 V at max. -
3B Scientific® Physics
3B SCIENTIFIC® PHYSICS Hofmann's Voltameter, S U58010 Instruction Sheet 11/08 ALF 1 Stand base with rod 2 Sockets 3 Gold leaf electrodes 4 Gas collection tube 5 Stop cock 6 Water reservoir 1. Safety instructions Since the conductivity of distilled water is too low electrolysis is carried out using dilute sulphuric acid The apparatus is made of glass. There is a risk of (c = 1 mol/l approx.). Students should always be breakage and resulting injury. informed of the dangers of the chemicals needed for • Handle the apparatus with care when carrying it the experiment. and make sure it is stable on the desk. • Carefully add the sulphuric acid to the water • Do not subject the glass components to while stirring. Never do this the other way round. mechanical stress. • Wear protective goggles when mixing the solution Hydrogen and oxygen form an explosive mixture. and when releasing the gases. • Never re-combine the gases in a test tube. Caution! Any acid that escapes can cause irreparable stains and holes in clothing. 1 2. Description 5. Example experiments Hofmann's voltameter is used for the electrolysis of 5.1 Investigation of the conductivity and composition water (converting electrical energy into chemical of water energy), quantitative determination of the resulting • Pour distilled water into the water reservoir with gases and confirmation of Faraday’s laws. both stopcocks open until both tubes are full. The apparatus consists of three vertical glass tubes Then close the stopcocks. connected to each other at the bottom. Taps at the • Turn on the power supply and observe the top ends of the outside tubes are closed whilst the electrodes. -
Chemistry Unit: 4CH0 Paper: 2CR
Write your name here Surname Other names Centre Number Candidate Number Pearson Edexcel International GCSE Chemistry Unit: 4CH0 Paper: 2CR Wednesday 13 June 2018 – Morning Paper Reference Time: 1 hour 4CH0/2CR You must have: Total Marks Ruler, calculator Instructions • Use black ink or ball-point pen. • Fill in the boxes at the top of this page with your name, centre number and candidate number. • Answer all questions. • Answer the questions in the spaces provided – there may be more space than you need. • Show all the steps in any calculations and state the units. • Some questions must be answered with a cross in a box . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross . Information • The total mark for this paper is 60. • The marks for each question are shown in brackets – use this as a guide as to how much time to spend on each question. Advice • Read each question carefully before you start to answer it. • Write your answers neatly and in good English. • Try to answer every question. • Check your answers if you have time at the end. Turn over P53147A ©2018 Pearson Education Ltd. *P53147A0120* 1/1/1/1/1/1/ DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA *P53147A0220* 2 Answer ALL questions. 1 The table shows some information about five gases. Formula Boiling point Gas of molecule in °C chlorine Cl2 –35 oxygen O2 –183 carbon monoxide CO –191 nitrogen N2 –196 DO NOT WRITE IN THIS AREA WRITE IN DO NOT hydrogen H2 –253 Choose gases from the table to answer this question. -
And Development Could Be Examined in Detail. Prior to Darden's Work
CELLULAR DiFPERLENTIA TION IN VOLVOX* BY RICHARD C. STARR DEPARTMENT OF BOTANY, INDIANA UNIVERSITY, BLOOMINGTON Communicated by R. E. Cleland, January 29, 1968 MIicroorganiisms have become important research materials in the study of differentiation at all levels of organization from the molecular to the cellular, but there remains a wealth of species whose potential has not as yet been realized due to problems of isolation, cultivation, or manipulation of the various phases of the life cycle. In this latter group the green alga Volvox has for many years been recognized as having aspects of organization and development that would make it a prime species for investigation of differentiation at the cellular level. The Volvox individual is a spheroid in which the biflagellate cells are arranged in a single peripheral layer. Two types of cells are always present: somatic cells which characteristically make up the bulk of the organism; and reproductive cells which occur in small numbers and which may be differentiated as gonidia, i.e., asexual cells capable of reproducing new individuals without fertilization, or sexual cells capable of becoming eggs, or of forming packets of sperm cells. It is of special interest that many of the species of Volvox were delimited by such early workers as Powers' and Shaw2 using as taxonomic criteria the type and degree of differentiation, and the time at which such differentiation occurred during the development of the young individuals. The pioneering work by Darden3 on Volvox aureus showed the possibility of studying the control of the reproductive cells in cultured material where growth and development could be examined in detail. -
Electrolysis of Water - Wikipedia 1 of 15
Electrolysis of water - Wikipedia 1 of 15 Electrolysis of water Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to the passage of an electric current. This technique can be used to make hydrogen gas, a main component of hydrogen fuel, and breathable oxygen gas, or can mix the two into oxyhydrogen, which is also usable as fuel, though more volatile and dangerous. It is also called water splitting. It ideally requires a potential difference of 1.23 volts to split water. Simple setup for demonstration of Contents electrolysis of water at home History Principle Equations Thermodynamics Electrolyte selection Electrolyte for water electrolysis Pure water electrolysis Techniques Fundamental demonstration Hofmann voltameter Industrial High-pressure High-temperature An AA battery in a glass of tap water Alkaline water with salt showing hydrogen Polymer electrolyte membrane produced at the negative terminal Nickel/iron Nanogap electrochemical cells Applications Efficiency Industrial output Overpotential Thermodynamics https://en.wikipedia.org/wiki/Electrolysis_of_water Electrolysis of water - Wikipedia 2 of 15 See also References External links History Jan Rudolph Deiman and Adriaan Paets van Troostwijk used, in 1789, an electrostatic machine to make electricity which was discharged on gold electrodes in a Leyden jar with water.[1] In 1800 Alessandro Volta invented the voltaic pile, and a few weeks later the English scientists William Nicholson and Anthony Carlisle used it for the electrolysis of water. In 1806 -
We Would Like to Thank WSGC and Dr. William Farrow for Making This Project Possible 2015 WSGC Elijah High-Altitude Balloon Paylo
2015 WSGC Elijah High-Altitude Balloon Payload Project Final Report September 14, 2015 Ben Jensen1, Nate Klassen2, Woodrow Walker1, Scott Frazier3, Kai Swanson1, Taylor Davitz1 1Milwaukee School of Engineering, 2University of Wisconsin-Whitewater, 3University of Wisconsin- Milwaukee Abstract The purpose of this report is to discuss the research, development, and findings of several experiments performed on a high-altitude balloon payload platform. The team decided of the following five experiments to be performed during the flight: Oxygen Generation, Internal Heating, Speed of Sound Properties, Ozone Levels, and a new payload structure concept. The entire team was required to research and develop new skills to effectively design our experiments, including: Arduino programming, 3-D modeling/printing, soldering, launch equipment handling, and construction techniques. While the launch was successful, we did fall short of our overall goal in terms of data acquisition. The internship proved to be a rewarding introductory experience to real-world engineering. The project help us learn how to implement the entirety of the engineering process, using each person’s strengths to achieve an objective. Introduction The goal for the internship team was to research, design, and execute experiments aboard a high- altitude balloon platform. The team would collect and analyze data from each experiment. There were several constraints for the project, including budget, weight, and size. The team was given full control over what we wanted to research, and decided five upon concepts: Oxygen Generation, Internal Heating, Speed of Sound Properties, Ozone Levels, and a new payload structure concept. Oxygen Generation As the altitude increases, we see a corresponding decrease in air pressure. -
Electrochemistry SECTION
Electrochemistry SECTION – 1 : STRAIGHT OBJECTIVE TYPE 1.1 The E° in the given diagram is, (A) 0.5 (B) 0.6 (C) 0.7 (D) 0.8 1.2 What is cell entropy change of the following cell? Pt(s) | H2(g) | CH3COOH, HCl || KCl (aq) |Hg2Cl2| (s) | Hg P = 1 atm 0.1M 0.1M Emf of the cell is found to be 0.045 V at 298 K and temperature coefficient is 3.4 10 – 4 V K – 1 – 5 Given Ka (CH3COOH) = 10 M (A) 60 (B) 65.2 (C) 69.2 (D) 63.5 1.3 Following cell has EMF 0.7995 V. Pt | H2 (1 atm) | HNO3 (1M) || AgNO3 (1M) | Ag If we add enough KCl to the Ag cell so that the final Cl- is 1M. Now the measured emf of the cell is 0.222 V. The Ksp of AgCl would be : (A) 1 10 – 9.8 (B) 110 – 19.6 (C) 210– 10 (D) 2.6410–14 1.4 Zn Amalgam is prepared by electrolysis is aqueous ZnCl2 using Hg cathode (9gm). How much current is to be passed through ZnCl2 solution for 1000 seconds to prepare a Zn Amalgam with 25% Zn by wt. (Zn = 65.4) (A) 5.6 amp (B) 7.2 amp (C) 8.85 amp (D) 11.2 amp 1.5 The solubility of [Co(NH3)4Cl2] CIO4_________ if the λ = 50, λ = Co(NH3 ) 4 Cl 2 CIO4 70, and the measured resistance was 33.5 in a cell with cell constant of 0.20 is ____.