Hydrogen sensing kinetics of laterally aligned MoO3 nanoribbon arrays with accelerated response and recovery performances at room temperature

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

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

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

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).

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Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

Revista de Chimie ◽

10.37358/rc.08.12.2067 ◽

2009 ◽

Vol 59 (12) ◽

Author(s):

Mihai Contineanu ◽

iulia Contineanu ◽

Ana Neacsu ◽

Stefan Perisanu

Keyword(s):

Thermal Resistance ◽

Aspartic Acid ◽

Room Temperature ◽

Esr Spectra ◽

Complex Mechanism ◽

Radical Species ◽

Mechanisms Of Formation ◽

Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

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The Reactivity of Different Active Forms of Sodium Carbonate with Respect to Sulfur Dioxide

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19922302 ◽

1992 ◽

Vol 57 (11) ◽

pp. 2302-2308

Author(s):

Karel Mocek ◽

Erich Lippert ◽

Emerich Erdös

Keyword(s):

Thermal Decomposition ◽

Liquid Phase ◽

Sulfur Dioxide ◽

Specific Surface ◽

Surface Area ◽

Sodium Carbonate ◽

Room Temperature ◽

Active Form ◽

The Other ◽

Kinetics Of

The kinetics of the reaction of solid sodium carbonate with sulfur dioxide depends on the microstructure of the solid, which in turn is affected by the way and conditions of its preparation. The active form, analogous to that obtained by thermal decomposition of NaHCO3, emerges from the dehydration of Na2CO3 . 10 H2O in a vacuum or its weathering in air at room temperature. The two active forms are porous and have approximately the same specific surface area. Partial hydration of the active Na2CO3 in air at room temperature followed by thermal dehydration does not bring about a significant decrease in reactivity. On the other hand, if the preparation of anhydrous Na2CO3 involves, partly or completely, the liquid phase, the reactivity of the product is substantially lower.

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Pd Nanocluster/Monolayer MoS2 Heterojunctions for Light-Induced Room-Temperature Hydrogen Sensing

ACS Applied Materials & Interfaces ◽

10.1021/acsami.0c20475 ◽

2021 ◽

Author(s):

Hien Duy Mai ◽

Sangmin Jeong ◽

Tri Khoa Nguyen ◽

Jong-Sang Youn ◽

Seungbae Ahn ◽

...

Keyword(s):

Room Temperature ◽

Monolayer Mos2 ◽

Hydrogen Sensing

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On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

Journal of Elastomers & Plastics ◽

10.1177/00952443211020330 ◽

2021 ◽

pp. 009524432110203

Author(s):

Sudhir Bafna

Keyword(s):

Mechanical Properties ◽

Activation Energy ◽

Weight Loss ◽

Oxygen Consumption ◽

Dwell Time ◽

Room Temperature ◽

Elevated Temperatures ◽

Degradation Mechanism ◽

Kinetics Of ◽

Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

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Transforming Pt-SnO2 Nanoparticles into Pt-SnO2 Composite Nanoceramics for Room-Temperature Hydrogen-Sensing Applications

Materials ◽

10.3390/ma14092123 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2123

Author(s):

Ming Liu ◽

Caochuang Wang ◽

Pengcheng Li ◽

Liang Cheng ◽

Yongming Hu ◽

...

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Sintering Temperature ◽

Sno2 Nanoparticles ◽

Hydrogen Sensing ◽

Sensing Applications ◽

Nanostructured Metal Oxides ◽

Low Dimensional ◽

Sensing Characteristics ◽

Nanostructured Metal

Many low-dimensional nanostructured metal oxides (MOXs) with impressive room-temperature gas-sensing characteristics have been synthesized, yet transforming them into relatively robust bulk materials has been quite neglected. Pt-decorated SnO2 nanoparticles with 0.25–2.5 wt% Pt were prepared, and highly attractive room-temperature hydrogen-sensing characteristics were observed for them all through pressing them into pellets. Some pressed pellets were further sintered over a wide temperature range of 600–1200 °C. Though the room-temperature hydrogen-sensing characteristics were greatly degraded in many samples after sintering, those samples with 0.25 wt% Pt and sintered at 800 °C exhibited impressive room-temperature hydrogen-sensing characteristics comparable to those of their counterparts of as-pressed pellets. The variation of room-temperature hydrogen-sensing characteristics among the samples was explained by the facts that the connectivity between SnO2 grains increases with increasing sintering temperature, and Pt promotes oxidation of SnO2 at high temperatures. These results clearly demonstrate that some low-dimensional MOX nanocrystals can be successfully transformed into bulk MOXs with improved robustness and comparable room-temperature gas-sensing characteristics.

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Electrochemical Kinetics of Ag|Ag+and TMPD|TMPD+•in the Room-Temperature Ionic Liquid [C4mpyrr][NTf2]; toward Optimizing Reference Electrodes for Voltammetry in RTILs

The Journal of Physical Chemistry C ◽

10.1021/jp0737754 ◽

2007 ◽

Vol 111 (37) ◽

pp. 13957-13966 ◽

Cited By ~ 49

Author(s):

Emma I. Rogers ◽

Debbie S. Silvester ◽

Sarah E. Ward Jones ◽

Leigh Aldous ◽

Christopher Hardacre ◽

...

Keyword(s):

Ionic Liquid ◽

Room Temperature ◽

Room Temperature Ionic Liquid ◽

Electrochemical Kinetics ◽

Reference Electrodes ◽

Kinetics Of

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Functionalized Reduced Graphene Oxide Thin Films for Ultrahigh CO2 Gas Sensing Performance at Room Temperature

Nanomaterials ◽

10.3390/nano11030623 ◽

2021 ◽

Vol 11 (3) ◽

pp. 623

Author(s):

Monika Gupta ◽

Huzein Fahmi Hawari ◽

Pradeep Kumar ◽

Zainal Arif Burhanudin ◽

Nelson Tansu

Keyword(s):

Thin Films ◽

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Gas Sensor ◽

Functional Groups ◽

Recovery Time ◽

Room Temperature ◽

Co2 Gas ◽

Reduced Graphene ◽

Response And Recovery

The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.

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The Spectral Dependence of the Non-Radiative Efficiency in Hydrogenated Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-258-789 ◽

1992 ◽

Vol 258 ◽

Author(s):

J. Fan ◽

J. Kakalios

Keyword(s):

Amorphous Silicon ◽

Room Temperature ◽

Hydrogenated Amorphous Silicon ◽

Free Carrier ◽

Radiative Efficiency ◽

Sharp Minimum ◽

Carrier Thermalization ◽

Hydrogenated Amorphous ◽

Kinetics Of ◽

Heat Released

ABSTRACTThe room temperature non-radiative efficiency, defined as the ratio of the heat released per absorbed photon for doped and undoped hydrogenated amorphous silicon (a-Si:H) has been measured using photo-pyroelectric spectroscopy (PPES) for photon energies ranging from 2.5 to 1.6 eV. There is a fairly sharp minimum in the non-radiative efficiency when the a-Si:H is illuminated with near bandgap photons. We describe a model wherein this minimum arises from the variation in the amount of heat generated by free carrier thermalization as the incident photon energy is varied, and report measurements of the excitation kinetics of the non-radiative efficiency which support this proposal.

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