scholarly journals Multilevel Tunnelling Systems and Fractal Clustering in the Low-Temperature Mixed Alkali-Silicate Glasses

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Giancarlo Jug ◽  
Maksym Paliienko
Keyword(s):  
Low Temperature ◽  
Statistical Physics ◽  
Physical Origin ◽  
Tunneling Model ◽  
Magnetic Effects ◽  
Mixed Alkali ◽  
Organic Glasses ◽  
Two Level Systems ◽  
Mixed Glasses ◽  
The Right

The thermal and dielectric anomalies of window-type glasses at low temperatures (T<1 K) are rather successfully explained by the two-level systems (2LS) standard tunneling model (STM). However, the magnetic effects discovered in the multisilicate glasses in recent times, magnetic effects in the organic glasses, and also some older data from mixed (SiO2)1−x(K2O)xand (SiO2)1−x(Na2O)xglasses indicate the need for a suitable extension of the 2LS-STM. We show that—not only for the magnetic effects, but also for the mixed glasses in the absence of a field—the right extension of the 2LS-STM is provided by the (anomalous) multilevel tunnelling systems (ATS) proposed by one of us for multicomponent amorphous solids. Though a secondary type of TS, different from the standard 2LS, was invoked long ago already, we clarify their physical origin and mathematical description and show that their contribution considerably improves the agreement with the experimental data. In spite of dealing with low-temperature properties, our work impinges on the structure and statistical physics of glasses at all temperatures.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Microstructure of Porous V2O-CeO2-SiO2 Catalyst for SCR of NO with NH3 at Low Temperature

2014 ◽  
Vol 875-877 ◽  
pp. 213-217 ◽  
Author(s):  
Mohd Razali Sohot ◽  
Umi Sarah Jais ◽  
Muhd Rosli Sulaiman
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Reduction Process ◽  
No Emission ◽  
Scr Of No ◽  
Before And After ◽  
The Right ◽  
Proven Method

Selective catalytic reduction (SCR) is a well-proven method to reduce NO emission. However, to choose the right catalyst that provides a surface for reaction between NO and ammonia at low temperatures is a challenging task for a catalysts developers. In an earlier study, we prepared V2O5-CeO2-SiO2 catalyst with increasing V2O5 content by sol-gel route and found that the catalytic activity improved with increasing the V2O5 loading up to 0.5%. The catalytic activity, however, dropped when V2O5 loading was about 1% and increased back when the loading of V2O5 was about 5%. In this study, we looked into the microstructural relationship to explain these findings. The microstructures of the catalysts before and after exposure to NO gas revealed that the catalysts with 0.2% and 0.5% V2O5 were more porous after the reduction process possibly due to improved breakdown of (NH4)HCO3 to NH3 by the possible interaction with the V2O5 and CeO2-containing catalysts which consequently resulted in a more efficient NO reduction to N2 and H2O at low temperature. The microstructure of the catalyst with 1% V2O5 content to 5%, improved back the efficiency although clogging by CeVO4 phase still possible due to its presence based on XRD. The well-ordered micropores before exposure to NO and the more efficient breakdown of (NH4)HCO3 could have contributed to increase back the catalytic activity at low temperature.

Chapter 22. Connections to Statistical Physics

2021 ◽  
Author(s):  
Fabrizio Altarelli ◽  
Rémi Monasson ◽  
Guilhem Semerjian ◽  
Francesco Zamponi
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Statistical Mechanics ◽  
Cost Function ◽  
Computer Science ◽  
Statistical Physics ◽  
Energy Landscape ◽  
Research Activity ◽  
Detailed Picture ◽  
Intense Research

This chapter surveys a part of the intense research activity that has been devoted by theoretical physicists to the study of randomly generated k-SAT instances. It can be at first sight surprising that there is a connection between physics and computer science. However low-temperature statistical mechanics concerns precisely the behaviour of the low-lying configurations of an energy landscape, in other words the optimization of a cost function. Moreover the ensemble of random k-SAT instances exhibit phase transitions, a phenomenon mostly studied in physics (think for instance at the transition between liquid and gaseous water). Besides the introduction of general concepts of statistical mechanics and their translations in computer science language, the chapter presents results on the location of the satisfiability transition, the detailed picture of the satisfiable regime and the various phase transitions it undergoes, and algorithmic issues for random k-SAT instances.

Research Regarding Heat Treatment Influence on Properties of Chromic Steel 40H GOST 4543-71(DIN 41Cr4, Gb 40Cr, ASTM 5140) with Quenching in Polymer Solution with Purpose of Matching Tubing Pipes which Used in Oil and Gas Extraction

2018 ◽  
Vol 284 ◽  
pp. 402-407 ◽  
Author(s):  
S.N. Dzhabbarov ◽  
E.I. Pryakhin ◽  
A.A. Germanov
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Low Temperature ◽  
Oil And Gas ◽  
Constructional Steel ◽  
Gas Extraction ◽  
Research Activity ◽  
The Right ◽  
Production Tubing ◽  
Selection Of

According to GOST 4543-71, steel 40H refers to the group of chromium steels. It is a low-alloy constructional steel of pearlite class. The paper presents a theoretical and experimental research activity carried out in order to improve the properties of the 40H steel. The results permit the selection of the right heat-treatment parameters that offer the best combination between the yield strength, tensile strength, elongation, necking, impact strength at low temperature and hardness, in order to obtain a better behavior of the material for production tubing pipes in accordance with GOST 633 Tubing pipes and couplings for them, for strength group M and L.

scholarly journals What Do We Know About the Genetic Basis of Seed Desiccation Tolerance and Longevity?

2020 ◽  
Vol 21 (10) ◽  
pp. 3612
Author(s):  
Hanna Kijak ◽  
Ewelina Ratajczak
Keyword(s):  
Low Temperature ◽  
Desiccation Tolerance ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Seed Storage ◽  
Water Losses ◽  
Economic Interests ◽  
Seed Desiccation ◽  
Orthodox Seeds ◽  
The Right

Long-term seed storage is important for protecting both economic interests and biodiversity. The extraordinary properties of seeds allow us to store them in the right conditions for years. However, not all types of seeds are resilient, and some do not tolerate extreme desiccation or low temperature. Seeds can be divided into three categories: (1) orthodox seeds, which tolerate water losses of up to 7% of their water content and can be stored at low temperature; (2) recalcitrant seeds, which require a humidity of 27%; and (3) intermediate seeds, which lose their viability relatively quickly compared to orthodox seeds. In this article, we discuss the genetic bases for desiccation tolerance and longevity in seeds and the differences in gene expression profiles between the mentioned types of seeds.

Comparison of low-temperature-sensitive liposome encapsulated docetaxel and doxorubicin in a murine model of prostate cancer.

2011 ◽  
Vol 29 (7_suppl) ◽  
pp. 31-31 ◽  
Author(s):  
S. Chokshi ◽  
A. Ranjan ◽  
C. J. Benjamin ◽  
P. H. Chung ◽  
A. Rastinehad ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Low Temperature ◽  
Tumor Growth ◽  
Temperature Sensitive ◽  
Complete Regression ◽  
Hyperthermia Treatment ◽  
Treatment Volume ◽  
Survival Studies ◽  
The Right ◽  
To Receive

31 Background: Low-temperature-sensitive liposomes (LTSLs) release their encapsulated drug into targeted tissue when activated by a source of hyperthermia. The efficacy of an LTSL formulation of docetaxel (DOC) or doxorubicin (DOX) was compared against prostate cancer in a xenograft mouse model. Methods: Under an approved IACUC protocol, Luciferase transfected human prostate PC-3M-luciferase cells were inoculated (3x106 cells) subcutaneously in the right hind leg of 8 wk old female athymic nude mice. When tumors reached a volume of 200–300 mm3, mice were randomized to receive one intravenous injection of saline, Stealth liposomal DOX (5 mg/kg), LTSL DOX (5 mg/kg), or LTSL DOC (15 mg/kg), with or without hyperthermia treatment (LTSL DOX and LTSL DOC were supplied by Celsion Corp., Columbia MD). Mice undergoing hyperthermia treatment were anesthetized and stabilized in a holder that allowed for only the leg with tumor to be heated to 41–42°C that triggered LTSL drug release. Mice were monitored daily for tumor volume and body weight. Study end-points included growth of tumor to 5x the initial treatment volume or monitoring of survival for 60 days. Results: The LTSL DOC delayed tumor growth longer (> 14 days) than DOX (0 day) and LTSL DOX (1 day) with hyperthermia (P<0.05). Mice treated with LTSL DOC and hyperthermia survived longest (60 days) compared to all other mice (range 6–8 days, P<0.05). LTSL in the setting of hyperthermia demonstrated complete regression of tumor in 57% of mice. Conclusions: LTSL DOC with hyperthermia delayed tumor growth more than all other treatments. Survival studies suggest LTSL DOC is a more effective temperature sensitive delivery system against PC-3M prostate tumors. No significant financial relationships to disclose.

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