scholarly journals Nernst equation applied to electrochemical systems and centenary of his Nobel Prize in chemistry

2020 ◽  
Vol 8 (11) ◽  
pp. 670-683
Author(s):  
Breno Nascimento Ciribelli ◽  
Flavio Colmati ◽  
Elki Cristina de Souza
Keyword(s):  
Nobel Prize ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Standard Potential ◽  
Nernst Equation ◽  
Cell Potential ◽  
Ion Concentrations ◽  
The Third ◽  
Different Temperatures ◽  
Third Law Of Thermodynamics

Walther Hermann Nernst received the Nobel Prize in Chemistry in 1920 for the formulation of the third law of thermodynamics, thus celebrating a century in this 2020 year. His work helped the establishment of modern physical chemistry, since he researched into fields, such as thermodynamics and electrochemistry, in which the Nernst equation is included. This paper reports on several experiments that used a Daniell galvanic cell working in different electrolyte concentrations for comparing results with the theoretical values calculated by the Nernst equation. The concentration and activity coefficients values employed for zinc sulfate and copper electrolytes showed activity can replaces concentrations in thermodynamic functions, and the results are entirely consistent with experimental data. The experimental electromotive force from standard Daniell cell, for ZnSO4 and CuSO4, with unitary activity and in different concentrations at room temperature is in agreement with those from theoretical calculations. Cu2+ ion concentrations and temperature were simultaneously varied; however, the cell potential cannot be included in calculations of Nernst equation for different temperatures than 25 °C because the standard potential value was set at 25 °C. The cell potential decreases drastically when the Cu2+ concentration was reduced and the temperature was above 80 oC.

scholarly journals Technical Note: Using DEG CPCs at upper tropospheric temperatures

2014 ◽  
Vol 14 (9) ◽  
pp. 12797-12817 ◽  
Author(s):  
D. Wimmer ◽  
K. Lehtipalo ◽  
T. Nieminen ◽  
J. Duplissy ◽  
S. Ehrhart ◽  
...  
Keyword(s):  
Gas Phase ◽  
Growth Rates ◽  
Room Temperature ◽  
Size Range ◽  
Theoretical Calculations ◽  
Sulfuric Acid Concentration ◽  
Technical Note ◽  
Different Temperatures ◽  
Consistent Picture ◽  
High Uncertainty

Abstract. Over the last few years, several Condensation Particle Counters (CPC) capable of measuring in the sub-3 nm size range have been developed. Here we study the performance of Diethylene glycol (DEG) based CPCs at different temperatures during Cosmics Leaving Outdoor Droplets (CLOUD) measurements at CERN. The data shown here is the first set of verification measurements for sub-3 nm CPCs under upper tropospheric temperatures using atmospherically relevant aerosol particles. To put the results in perspective we calibrated the DEG-CPC at room temperature, resulting in a cut-off diameter of 1.4 nm. All diameters refer to mobility equivalent diameters in this manuscript. At upper tropospheric temperatures between −25 °C and −65 °C, we found cut-off sizes in the range of 2.5 and 2.8 nm. Due to low number concentration after size classification, the cut-off diameters have a high uncertainty (±0.3 nm) associated with them. Operating two laminar flow DEG CPCs with different cut-off sizes together with other aerosol instruments, we looked at the growth rates of aerosol population in the CLOUD chamber for particles smaller than 10 nm at different temperatures. A more consistent picture emerged when we normalized the growth rates to a fixed gas-phase sulfuric acid concentration. All of the instruments detected larger growth rates at lower temperatures, and the observed growth rates decreased as a function of temperature, converging with each other at temperatures over 0 °C. The theoretical calculations had a much smaller temperature dependency.

scholarly journals Technical Note: Using DEG-CPCs at upper tropospheric temperatures

2015 ◽  
Vol 15 (13) ◽  
pp. 7547-7555 ◽  
Author(s):  
D. Wimmer ◽  
K. Lehtipalo ◽  
T. Nieminen ◽  
J. Duplissy ◽  
S. Ehrhart ◽  
...  
Keyword(s):  
Gas Phase ◽  
Growth Rates ◽  
Room Temperature ◽  
Size Range ◽  
Theoretical Calculations ◽  
Sulfuric Acid Concentration ◽  
Technical Note ◽  
Different Temperatures ◽  
Consistent Picture ◽  
High Uncertainty

Abstract. Over the last few years, several condensation particle counters (CPCs) capable of measuring in the sub-3 nm size range have been developed. Here we study the performance of CPCs based on diethylene glycol (DEG) at different temperatures during Cosmics Leaving OUtdoor Droplets (CLOUD) measurements at CERN. The data shown here are the first set of verification measurements for sub-3 nm CPCs under upper tropospheric temperatures using atmospherically relevant aerosol particles. To put the results in perspective we calibrated the DEG-CPC at room temperature, resulting in a cut-off diameter of 1.4 nm. All diameters refer to mobility equivalent diameters in this paper. At upper tropospheric temperatures ranging from 246.15 K to 207.15 K, we found cut-off sizes relative to a particle size magnifier in the range of 2.5 to 2.8 nm. Due to low number concentration after size classification, the cut-off diameters have a high uncertainty (±0.3 nm) associated with them. Operating two laminar flow DEG-CPCs with different cut-off sizes together with other aerosol instruments, we looked at the growth rates of aerosol population in the CLOUD chamber for particles smaller than 10 nm at different temperatures. A more consistent picture emerged when we normalized the growth rates to a fixed gas-phase sulfuric acid concentration. All of the instruments detected larger growth rates at lower temperatures, and the observed growth rates decreased as a function of temperature, showing a similar trend for all instruments. The theoretical calculations had a similar but much smaller temperature dependency.

Molecular and crystal properties of E-1,2-bis(3-methoxy-2-thienyl)ethene: static disorder in the crystal

2003 ◽  
Vol 59 (6) ◽  
pp. 770-778 ◽  
Author(s):  
Frank Blockhuys ◽  
Christophe M. L. Vande Velde ◽  
Stefan T. Maes ◽  
Carl Peten ◽  
Herman J. Geise ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Atomic Charges ◽  
Free Molecule ◽  
Static Disorder ◽  
Carbon Backbone ◽  
Crystal Properties ◽  
Different Temperatures

The crystal structure of E-1,2-bis(3-methoxy-2-thienyl)ethene (C12H12O2S2) has been determined at five different temperatures, i.e. room temperature (293 ), 223, 173, 123 and 93 K. The solid-state work is complemented by the results of theoretical calculations of energies, geometries, difference electron densities and atomic charges of the free molecule. Analysis revealed static disorder caused by a higher energy conformer of the title compound, probably contaminating the crystal during its growth. The results support the contention that the electrical properties are mainly governed by the carbon backbone.

scholarly journals Use of sonoelastography to evaluate texture modifications of mozzarella di bufala campana D.O.P. during storage at different temperatures

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Nicola Costanzo ◽  
Adriano Michele Luigi Santoro ◽  
Eleonora Sarno ◽  
Antonio Di Loria ◽  
Rosa Daniela Grembiale ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dairy Product ◽  
Buffalo Milk ◽  
Local Market ◽  
High Humidity ◽  
Mozzarella Cheese ◽  
The Third ◽  
Significant Difference ◽  
Different Temperatures ◽  
White Colour

Mozzarella cheese from buffalo milk is a fresh, stringy-textured dairy product, exhibiting a porcelain white colour, a smooth, bright, and humid surface, an extremely thin rind and delicate taste. The high humidity typical of this cheese, reduces its shelf-life and it is cause of dramatic organoleptic changes during storage. In this study we tested sonoelastography to evaluate texture changes of mozzarella cheese from buffalo milk during storage. Cheeses form local market produced in the same condition were divided in three batches and stored in different conditions: the first (B1) was stored in preserving liquid at room temperature (20°C); the second (B2) was stored without preserving liquid at 4°C; and the third (B3) was stored at 4°C in preserving liquid. In B1 sonoelastography showed a reduction of the hardness and stiffness of rind, while in B2 inelastic tissue increased its thickness. Best results were obtained in B3, where no significant difference was evidenced during storage.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

The Third Law of Thermodynamics

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Absolute Zero ◽  
The Third ◽  
Third Law Of Thermodynamics ◽  
Third Law ◽  
The Absolute

The Third Law was introduced in Chapter 9; this chapter develops the Third Law more fully, introducing absolute entropies, and examining how adiabatic demagnetisation can be used to approach the absolute zero of temperature.

scholarly journals Temperature-Dependent Stimulated Emission Cross-Section in Nd3+:YLF Crystal

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 431
Author(s):  
Giorgio Turri ◽  
Scott Webster ◽  
Michael Bass ◽  
Alessandra Toncelli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Room Temperature ◽  
Radiative Decay ◽  
Emission Cross Section ◽  
Spectroscopic Properties ◽  
Stimulated Emission ◽  
Different Temperatures ◽  
Stimulated Emission Cross Section ◽  
Semi Empirical

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for the most intense transitions to the 4I11/2 and 4I13/2 levels.

Proteinase and phospholipase activities and development at different temperatures of yeasts isolated from bovine milk

2011 ◽  
Vol 78 (4) ◽  
pp. 385-390 ◽  
Author(s):  
Priscilla A Melville ◽  
Nilson R Benites ◽  
Monica Ruz-Peres ◽  
Eugenio Yokoya
Keyword(s):  
Dairy Products ◽  
Room Temperature ◽  
Bovine Milk ◽  
Raw Milk ◽  
Pathogenic Potential ◽  
Proteinase Production ◽  
Different Temperatures ◽  
Quality Of Milk ◽  
Means Of Transmission

The presence of yeasts in milk may cause physical and chemical changes limiting the durability and compromising the quality of the product. Moreover, milk and dairy products contaminated by yeasts may be a potential means of transmission of these microorganisms to man and animals causing several kinds of infections. This study aimed to determine whether different species of yeasts isolated from bovine raw milk had the ability to develop at 37°C and/or under refrigeration temperature. Proteinase and phospholipase activities resulting from these yeasts were also monitored at different temperatures. Five genera of yeasts (Aureobasidium sp., Candida spp., Geotrichum spp., Trichosporon spp. and Rhodotorula spp.) isolated from bovine raw milk samples were evaluated. All strains showed one or a combination of characteristics: growth at 37°C (99·09% of the strains), psychrotrophic behaviour (50·9%), proteinase production (16·81% of the strains at 37°C and 4·09% under refrigeration) and phospholipase production (36·36% of the isolates at 37°C and 10·9% under refrigeration), and all these factors may compromise the quality of the product. Proteinase production was similar for strains incubated at 37°C (16·81% of the isolates) and room temperature (17·27%) but there was less amount of phospholipase-producing strains at room temperature (15·45% of the isolates were positive) when compared with incubation at 37°C (36·36%). Enzymes production at 37°C by yeasts isolated from milk confirmed their pathogenic potential. The refrigeration temperature was found to be most efficient to inhibit enzymes production and consequently ensure better quality of milk. The viability of yeasts and the activity of their enzymes at different temperatures are worrying because this can compromise the quality of dairy products at all stages of production and/or storage, and represent a risk to the consumer.

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