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Articles 31 - 60 of 124

Full-Text Articles in Physical Sciences and Mathematics

Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu Jan 2007

Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu

Duane D. Johnson

We present ab initiodensity functional theory calculations of twinning energy pathways for two opposite twinning modes, (111)[112¯] and (111)[1¯1¯2], in fcc materials to examine the directional nature of twinning which cannot be explained by classical twin nucleationmodels or the “twinnability” criterion. By accounting for these energy pathways in a multiscale model, we quantitatively predict the critical twinning stress for the (111)[1¯1¯2] mode to be substantially higher compared to the favorable (111)[112¯] mode (whose predicted stresses are in agreement with experiment), thus, ruling out twinning in the (111)[1¯1¯2] mode.

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Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du Feb 2006

Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du

Journal of Electrochemistry

The anticorrosion action of EDA on copper in dilute HCl solution and the effect of sulfide ions on the inhibiting efficiency were studied by the Tafel plot method.The corrosion potential of Cu shifted to more positive value and the corrosion current density decreased after the addition of Na_(2)S to the solution.The results indicated that sulphide ions could increase the inhibiting efficiency of EDA because of the synergistic inhibition effect between EDA and Na_2S,resulting from the adsorption of HS~(-)on the surface of Cu,facilitated the adsorption of EDA to form a highly protective adsorbed layer which prevented Cu from corrosion.

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Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu Jan 2006

Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu

Duane D. Johnson

We report ab initio density functional theory calculations of generalized planar fault energies of fcc Cu–xAl (x=0, 5.0, and 8.3at.%) alloys. We investigate the effects of substitutional solute Al on the unstable intrinsic γus and twin γutstacking faultenergies (SFEs). Our results reveal an increased tendency of Cu–Al to deform preferentially by twinning with increasing Al content, consistent with experiment. We attribute this mechanical behavior to appreciable lowering of the twinning barrier γut, along with the stable intrinsic and twin SFEs.

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Copper Electrodeposition Under The Perturbation Of Hard Particles, Zeng-Wei Zhu, Di Zhu Nov 2005

Copper Electrodeposition Under The Perturbation Of Hard Particles, Zeng-Wei Zhu, Di Zhu

Journal of Electrochemistry

Copper electrodepositon was carried out on the rotating cathode,with hard particles(such as ceramic beads) filling between the electrodes.The rotation of cathode led hard particles to polish and impact the surface of deposit during electrodeposition.Copper deposits with a mass of cuspidal nodules were produced in acid sulfate solutions while brittle deposits without nodules were produced in alkaline sulfate solutions.It was also found that brightening and smoothing deposit could be obtained from the alkaline solution,and the deposit was approximatively disordered orientation with granular morphology of about 100~300 nm.The results show that the polishing and impact of hard particles can effectively disturb the …

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Electrodeposition Of Copper Into Trenches Under Rotating Hydrodynamic Condition, Jian-Jun Sun May 2004

Electrodeposition Of Copper Into Trenches Under Rotating Hydrodynamic Condition, Jian-Jun Sun

Journal of Electrochemistry

Silicon chips patterned with treneches were fixed onto a rotating electrode. Copper was electrodeposited into the trenches under rotating hydrodynamic conditions The sizes of the trenches are 1 m in height and 0.35 m, 0.50 m and 0.70 m in width, respectively. The effects of rotating of the chip, the current density and the concentration of Cu~(2+ )on the filling of thetrenches were studied. It is found that lower current density and moderate concentration of Cu~(2+)resulted in a void free filling of the trenches.

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Effect Of Dissolved Oxygen On The Corrosion Behavior Of Coalesced Copper And Stainless Steel-206 In Acetic Solutions, Rong-Zong Hu, Xiong-Cao Zhao, Yu-Hua Weng, Chang-Jian Lin Nov 2002

Effect Of Dissolved Oxygen On The Corrosion Behavior Of Coalesced Copper And Stainless Steel-206 In Acetic Solutions, Rong-Zong Hu, Xiong-Cao Zhao, Yu-Hua Weng, Chang-Jian Lin

Journal of Electrochemistry

Linear sweeping technique and dissolving oxygen sensor were used to study the effect of dissolved oxygen and relating factors on the corrosion behavior of coalesced copper and stainless steel-206 in acetic solutions. It was found: 1. The existing of dissolved oxygen is one of the important factors, which strongly influenced the corrosion behavior of coalesced copper and stainless steel-206 in acetic solution. 2. The existing of dissolved oxygen is benefitial to the preventing stainless steel-206 from corrosion in acetic solutions, but damage to the preventing coalesced copper from corrosion. 3. At the high temperature since the dissolved oxygen was escaping …

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Determination Of Copper In The Waste Water Of Plating By Chronocoulometry For Flowing Solution, Xin-Hua Lin, Wei Chen Feb 2002

Determination Of Copper In The Waste Water Of Plating By Chronocoulometry For Flowing Solution, Xin-Hua Lin, Wei Chen

Journal of Electrochemistry

The chronocoulometry for flowing solution was devoloped and applied to the detemination of copper(Ⅱ) in the waste water of plating.The linear range of copper(Ⅱ) was 2～16mg/L,and the relative standard deviation was less than 0.1% ( n =8).The recovery was 98%～103% for copper(Ⅱ) in the waste water.Chronocoulometry for flowing solution overcomed noise disturbance resulting from capacity current and variety of property of electrode surface.This method was sensitive,accurate and well reproducible.

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High-Efficiency Solar Cells Based On Cu(Inal)Se[Sub 2] Thin Films, S. Marsillac, P. D. Paulson, M. W. Haimbodi, R. W. Birkmire, W. N. Shafarman Jan 2002

High-Efficiency Solar Cells Based On Cu(Inal)Se[Sub 2] Thin Films, S. Marsillac, P. D. Paulson, M. W. Haimbodi, R. W. Birkmire, W. N. Shafarman

Electrical & Computer Engineering Faculty Publications

A Cu(InAl)Se2solar cell with 16.9% efficiency is demonstrated using a Cu(InAl)Se2thin film deposited by four-source elemental evaporation and a device structure of glass/Mo/Cu(InAl)Se2/CdS/ZnO/indium tin oxide/(Ni/Algrid)/MgF2. A key to high efficiency is improved adhesion between the Cu(InAl)Se2 and the Mo back contact layer, provided by a 5-nm-thick Ga interlayer, which enabled the Cu(InAl)Se2 to be deposited at a 530 °C substrate temperature. Film and device properties are compared to Cu(InGa)Se2 with the same band gap of 1.16 eV. The solar cells have similar behavior, with performance limited by recombination through …

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Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang Sep 1997

Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang

Alexander H. King

Bismuth segregation in copper has been studied using energy-dispersive X-ray spectrometry (EDX) in a JEOL 2010F transmission electron microscope. In addition to the expected solute enrichment at grain boundaries, we have observed extremely high concentrations of bismuth at certain triple junctions, with significantly greater enrichment factors than in the adjacent grain boundaries. It is shown here that the triple junction segregation is a function of the parameters of the grain boundaries at the triple line, and existence of this type of segregation implies that the affected triple junctions embody excess free energy. At least one of the observed triple junctions …

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Behavior Of Copper In Hydrogen Storage Alloy Microencapsulated By Copper, Dawei Zhang, Huatang Yuan, Huabin Yang, Zuoxiang Zhou, Yunshi Zhang Aug 1997

Behavior Of Copper In Hydrogen Storage Alloy Microencapsulated By Copper, Dawei Zhang, Huatang Yuan, Huabin Yang, Zuoxiang Zhou, Yunshi Zhang

Journal of Electrochemistry

Negative electrode made from Cu microencapsulated hydrogen storage alloy was studied by using cyclic voltammetry method. The results showed that copper as a coating material was of a certain stability in 5 mol/L KOH solution within the range of charge and discharge voltage. But when expanding the sweep voltage, the CV curve showed a pair of distinct oxidation reduction current peaks of Cu 2O formation at E =-0.3 V and Cu 2O reduction at E =-0.6 V. With charging discharging cycles, copper is liable to be oxidized to Cu 2O and further oxidized into CuO 2- 2. When charged again, …

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Electrochemical Studies On Chemical Polishing Of Copper, Keping Han, Jingli Fang Aug 1996

Electrochemical Studies On Chemical Polishing Of Copper, Keping Han, Jingli Fang

Journal of Electrochemistry

Changes in specular reflectivity,weight loss,surface topograph and potential with time and current-potential curves during chemical polishing were determined.The results showed that chemical polishing was composed of the etching,polishing and pitting stage.The passivating film theory also applied to the chemical polishing.

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Electrochemical Study Of The Corrosion Behavior Of Coalesced Copper And Sw-206 Stainless Steel In The Acetic-Acid Solution, Rongzong Hu, Changjian Lin, Jianguang Tan Aug 1996

Electrochemical Study Of The Corrosion Behavior Of Coalesced Copper And Sw-206 Stainless Steel In The Acetic-Acid Solution, Rongzong Hu, Changjian Lin, Jianguang Tan

Journal of Electrochemistry

In order to provide a theoretic and experimental consideration for the material selection and anit-corrosion in the petrochemical industries the corrosion behavior of coalesced copper and sw-206 stainless steel in the acetic acid solution was studied by electrochemical impedance spectroscopy and polarization techniques. The effects of the temperature,acetic acid concentration and solubilized oxygen in the acetic acid solution on the corrosion process of this two metals were analyzed. It was found that these effects obviously accelerate corrosion process for the coalesced copper,but no apparent influnce for the sw-206 stainless steel.In the the acetic acid solution,containing water and oxygen were beneficial …

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Cyclic Voltammetric Calorimetry Studying The Deposition Of Copper Of Pt Electrodes, Yongchun Zhu, Robin H J Clark Nov 1995

Cyclic Voltammetric Calorimetry Studying The Deposition Of Copper Of Pt Electrodes, Yongchun Zhu, Robin H J Clark

Journal of Electrochemistry

In the present paper,cyclic voltammetric calorimetry has been used to study thedeposition of copper on platinum electrode from LiClO_4 aqueous solution. Cyclic voltammetricthermogram and cyclic voltammetric differential thermogram show that the deposition of copper on theelectrode is an exothermal process with a strong interaction between copper and platinum layer(-3227.0 kJ /mol).The electrochemical oxidation of the deposited copper is composed of twoprocesses :an endothermal activation process with 747.0 kJ/mol of activation enthalpy,and anexothermal oxidation reaction with-189.9 kJ/mol of the reaction enthalpy, which are accord withthe data from the theoritical estimation and thermodynamic handbook respectively.

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Electrochemically Modified Glassy Carbon Electrode And Determination Of Copper By Anodic Stripping Voltammetry, Jinrui Xu, Yie Liu, Xiurun Zhuang May 1995

Electrochemically Modified Glassy Carbon Electrode And Determination Of Copper By Anodic Stripping Voltammetry, Jinrui Xu, Yie Liu, Xiurun Zhuang

Journal of Electrochemistry

This paper reported the glassy carbon electrode modified by cyclic voltammetrybetween-0. 1and + 1. 5 V(vs. SCE)in an aqueous solution containing catechol,formaldehyde andtalium hydroxide. The modified electrode can be applied to the determination of copper(Ⅱ) in water,and its sensitivity is about 35 times higher than that of unmedified glassy carbon electrede, Thequantitative limit with this modified electrede is 0. 1 ng/ml.

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Compensation And Characterization Of Gallium Arsenide, Randy A. Roush Jan 1995

Compensation And Characterization Of Gallium Arsenide, Randy A. Roush

Electrical & Computer Engineering Theses & Dissertations

The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow …

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Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola Jan 1990

Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola

Electrical & Computer Engineering Faculty Publications

The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (NCu/NSi) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined.

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An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko Jan 1988

An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko

Electrical & Computer Engineering Faculty Publications

A concept for a bulk semiconductor switch is presented, where the conductivity is increased and reduced, respectively, through illumination with light of different wavelengths. The increase in conductivity is accomplished by electron ionization from deep centers and generation of bound holes. The reduction of conductivity is obtained by hole ionization from the excited centers and subsequent recombination of free electrons and holes. The transient behavior of electron and hole density in a high power semiconductor (GaAs:Cu) switch is computed by means of a rate equation model. Changes in conductivity by five orders of magnitude can be obtained.

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Oxidized Copper Mineralization Along The Continental Fault Near Butte, Montana, Theodore H. Eyde May 1955

Oxidized Copper Mineralization Along The Continental Fault Near Butte, Montana, Theodore H. Eyde

Bachelors Theses and Reports, 1928 - 1970

Located in the fault zone of the Continental fault near the western edge of Boulder batholith of southwestern Montana the oxidized copper deposits are developed by three open pit mines, one of which is a presently in operation. Copper has been deposited by descending cold solutions which have leached copper from the surrounding quartz monzonite and deposited within the crushed fault zone. Local high grade 'bunches' of ore occur along narrow limonite veins, remnants of primary sulfide veins which have been enriched by the descending cold solutions.

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Effect Of Recovery On The Recrystallized Grain-Size Of High Purity Aluminum, Rodney L. Helterline Jun 1954

Effect Of Recovery On The Recrystallized Grain-Size Of High Purity Aluminum, Rodney L. Helterline

Bachelors Theses and Reports, 1928 - 1970

When a cold-worked metal is annealed, it’s physical properties hange as a result of a new grain structure. The annealing treatment is divided into three stages according to the changes that occur in the distorted metal: (1) recovery, (2) recrystallization, and (3) grain growth.

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The Application Of Electric Energy To The Metallurgy Plants In Montana, Edwin J. Duncan Sep 1953

The Application Of Electric Energy To The Metallurgy Plants In Montana, Edwin J. Duncan

Bachelors Theses and Reports, 1928 - 1970

Since the year 1800, metallurgy has been affiliated with electricity. In fact, the two industries have grown side by side, being naturally dependent upon each other and having a parallel growth.

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The Construction And Operation Of A Universal Specimen Mount With Protective Lead Shield For The Purpose Of Determining Pole Figures Using The Schulz-Decker Transmission Technique, Richard L. Fausner Jun 1953

The Construction And Operation Of A Universal Specimen Mount With Protective Lead Shield For The Purpose Of Determining Pole Figures Using The Schulz-Decker Transmission Technique, Richard L. Fausner

Bachelors Theses and Reports, 1928 - 1970

It was the purpose of this study to construct a universal mount, to construct a protective lead shield, to operate the instrument, and to provide a pole figure using the transmission method of Schulz and Decker. There are at present several lengthy x-ray methods of determining the grain orientation of metals. These methods are mainly photographic. In order to provide a rapid means of obtaining the necessary information concerning the grain orientation of a metal, a universal mount was constructed.

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Host Rocks And Gangue Minerals Associated With Copper Deposits In Plutonic Igneous Rocks, Richard D. Montgomery May 1953

Host Rocks And Gangue Minerals Associated With Copper Deposits In Plutonic Igneous Rocks, Richard D. Montgomery

Bachelors Theses and Reports, 1928 - 1970

All of the information on the various districts has come directly from published reports. The investigation was suggested by Mr. Forbes Robertson. The geographical extent of the deposits was confined to the western United States. Many of these deposits are of the disseminated porphyry type. A few of the de­posits, such as at Butte, Montana, were of the fissure vein type.

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The Effect Of Manganese On The Age Hardening Of Aluminum-Copper Alloys, Keith P. Burgess May 1953

The Effect Of Manganese On The Age Hardening Of Aluminum-Copper Alloys, Keith P. Burgess

Bachelors Theses and Reports, 1928 - 1970

It is known that age-hardening occurs in alloys of the solid solution type containing a hardening constituent, of a metal or metallic compound which is more soluble in the solvent phase at higher tempertures than at lower temperatures.

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The Benefication Of A Low-Grade, Montana Scheelite Ore, Walter G. Parker May 1953

The Benefication Of A Low-Grade, Montana Scheelite Ore, Walter G. Parker

Bachelors Theses and Reports, 1928 - 1970

The increasing importance of tungsten as an industrial metal and the recent discoveries of extensive deposits of low-grade tungsten ores in Montana led to the investigation which is reported in this paper. The purpose of this investigation was to determine if a saleable concentrate could be obtained from one of these low-grade, Montana scheelite ores.

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The Effect Of Ferric Iron Upon The Current Efficiency And The Deposition Of Copper In The Electrowinning Of Copper From Copper Sulphate Solutions, James L. Owings May 1952

The Effect Of Ferric Iron Upon The Current Efficiency And The Deposition Of Copper In The Electrowinning Of Copper From Copper Sulphate Solutions, James L. Owings

Bachelors Theses and Reports, 1928 - 1970

In the hydrometallurgy of copper, probably the most widely used method for the precipitation of copper is by electrolysis using insoluble anodes. The process is similar in many respects to the electrolytic refining of copper; one of the main differences is the use of insoluble anodes in electrowinning as compared to the use of impure copper anodes in electrorefining. Impurities, however, are common to both processes. The nature of these impurities differ and the problem of purifying the electrolyte is also different.

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Variation Of Induction And Hysteresis Curves For The Heusler Alloy, Cu2mna1, Ford W. Knight May 1952

Variation Of Induction And Hysteresis Curves For The Heusler Alloy, Cu2mna1, Ford W. Knight

Bachelors Theses and Reports, 1928 - 1970

The purpose of this investigation is to determine the fundamental magnetic characteristics of induction and hysteresis, for the alloy Cu2MnAl. This is a ternary, ferromagnetic Heusler alloy. The problem is not only to determine these characteristics for the alloy as-cast but to heat treat it and observe the manner in which different heat treat­ments affect these two fundamental magnetic characteristics.

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An Investigation Of The Hardening Properties Of Some Alpha Copper Indium Alloys, Charles W. Mcpherson May 1952

An Investigation Of The Hardening Properties Of Some Alpha Copper Indium Alloys, Charles W. Mcpherson

Bachelors Theses and Reports, 1928 - 1970

Precipitation hardening alloys has assumed a major role in modern day development of alloys. In his search for stronger, harder materials, the metallurgist has often been limited by the cost of metals which posses the needed properties.

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The Effect Of Iron Upon The Electrowinning Of Copper With An Amalgam Electrode, John A. Alexander May 1952

The Effect Of Iron Upon The Electrowinning Of Copper With An Amalgam Electrode, John A. Alexander

Bachelors Theses and Reports, 1928 - 1970

Current commercial use of the mercury cathode cell is limited to two types of electrolytic sodium cells-­the Castner cell and the Sorenson cell. Mercury as a cathode medium has also found application in polarographic analysis, a method of a simultaneous quantitative and qualitative analysis of several metal components of solution.

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Polarographic Analysis Applied To Metallurgical Solutions And Products, Donald W. Johnson May 1951

Polarographic Analysis Applied To Metallurgical Solutions And Products, Donald W. Johnson

Bachelors Theses and Reports, 1928 - 1970

The polarograph has been applied to a large number of chemical and metallurgical analyses, and is especially applicable to solution control analysis and to the deter­mination of minute quantities of ions in the presence of large amounts of other ions.

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Vacuum Distillation Of Zinc And Cadmium From Zinc Leach Purification Cake, Stiles R. Slosson May 1951

Vacuum Distillation Of Zinc And Cadmium From Zinc Leach Purification Cake, Stiles R. Slosson

Bachelors Theses and Reports, 1928 - 1970

The term "vacuum distillation" is used to des­cribe the process employed when certain elements are separated either from their mother compounds or from one another by distilling them under reduced atmos­pheric pressure.

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