scholarly journals Intermediate phases during solid to liquid transitions in long-chain n-alkanes

2017 ◽  
Vol 19 (21) ◽  
pp. 13941-13950 ◽  
Author(s):  
Stella Corsetti ◽  
Thomas Rabl ◽  
David McGloin ◽  
Johannes Kiefer
Keyword(s):  
Phase Transitions ◽  
Raman Spectra ◽  
Structural Changes ◽  
Temperature Dependent ◽  
Intermediate Phases ◽  
The Difference ◽  
Long Chain

Temperature-dependent Raman spectra of tetradecane, pentadecane and hexadecane are collected and analysed to unveil the difference in the speed of their phase transitions while gaining information about their structural changes.

An ESR Study of Structural Phase Transitions of(NH4)2Pb[Cu(NO2)6]

1986 ◽  
Vol 41 (9) ◽  
pp. 1154-1158 ◽  
Author(s):  
Tetsuo Asaji ◽  
Laxman Shrikrishna Prabhumirashi ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transitions ◽  
Structural Changes ◽  
Structural Phase ◽  
Esr Spectra ◽  
Phase Iii ◽  
Temperature Phase ◽  
Intermediate Phases ◽  
Temperature Phase Transition ◽  
G Value ◽  
Phase Iv

The structural changes of (NH4)2Pb[Cu(NO2)6] crystals during the phase transitions at 316, 287, and 95 K were studied by means of a single crystal ESR technique. Anisotropic g values [g∥ > g⊥) were obtained in the lowest temperature phase IV, whereas the ESR spectra recorded in the intermediate phases III and II, in which the crystal is known to be tetragonally compressed along the c axis, could be interpreted by use of effective g values [g(∥c) < g(⊥c)]. In the highest temperature phase I an isotropic g value was obtained. The phases I, II, and III o f the present complex can be assumed to be very similar to the corresponding phases observed above ~ 250 K for the compounds R2Pb[Cu(NO2)6] with R = K, Rb, Cs, and Tl. However, the lowest temperature phase transition transforms the phase III with an antiferrodistortive order of the elongated [Cu(NO2)6]4- octahedra into the phase IV with a ferrodistortive one. This occurs only for the complex with R = NH4 and is very unusual. The results of the 14N NQR experiments already reported for the phases III and IV could be well explained by the present newly proposed model.

Temperature-Dependent Logic Failure in a GaAs Power Amplifier-Duplexer Module Caused by a Subtle Parasitic Schottky Diode

2014 ◽  
Author(s):  
Rose Emergo ◽  
Steve Brockett ◽  
Pat Hamilton
Keyword(s):  
Power Amplifier ◽  
Schottky Diode ◽  
Production Test ◽  
Temperature Dependent ◽  
Cold Temperatures ◽  
Collector Junction ◽  
Power Mode ◽  
The Difference ◽  
Base Contact ◽  
Single Power

Abstract A single power amplifier-duplexer device was submitted by a customer for analysis. The device was initially considered passing when tested against the production test. However, further electrical testing suggested that the device was stuck in a single power mode for a particular frequency band at cold temperatures only. This paper outlines the systematic isolation of a parasitic Schottky diode formed by a base contactcollector punch through process defect that pulled down the input of a NOR gate leading to the incorrect logic state. Note that this parasitic Schottky diode is parallel to the basecollector junction. It was observed that the logic failure only manifested at colder temperatures because the base contact only slightly diffused into the collector layer. Since the difference in the turn-on voltages between the base-collector junction and the parasitic Schottky diode increases with decreasing temperature, the effect of the parasitic diode is only noticeable at lower temperatures.

scholarly journals Possibility of Human Gender Recognition Using Raman Spectra of Teeth

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3983
Author(s):  
Ozren Gamulin ◽  
Marko Škrabić ◽  
Kristina Serec ◽  
Matej Par ◽  
Marija Baković ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Principal Component ◽  
Support Vector ◽  
Gender Recognition ◽  
Proof Of Concept ◽  
Male And Female ◽  
Tooth Type ◽  
Tooth Apex ◽  
The Difference

Gender determination of the human remains can be very challenging, especially in the case of incomplete ones. Herein, we report a proof-of-concept experiment where the possibility of gender recognition using Raman spectroscopy of teeth is investigated. Raman spectra were recorded from male and female molars and premolars on two distinct sites, tooth apex and anatomical neck. Recorded spectra were sorted into suitable datasets and initially analyzed with principal component analysis, which showed a distinction between spectra of male and female teeth. Then, reduced datasets with scores of the first 20 principal components were formed and two classification algorithms, support vector machine and artificial neural networks, were applied to form classification models for gender recognition. The obtained results showed that gender recognition with Raman spectra of teeth is possible but strongly depends both on the tooth type and spectrum recording site. The difference in classification accuracy between different tooth types and recording sites are discussed in terms of the molecular structure difference caused by the influence of masticatory loading or gender-dependent life events.

The split-up of G band and 2D band in temperature-dependent Raman spectra of suspended graphene

2021 ◽  
Vol 139 ◽  
pp. 106960 ◽  
Author(s):  
Yi Liu ◽  
Yafang Shi ◽  
Wenguang Zhou ◽  
Wei Shi ◽  
Wei Dang ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Temperature Dependent ◽  
Suspended Graphene

On the nature of the phase transitions of aluminosilicate perrhenate sodalite

2020 ◽  
Vol 235 (6-7) ◽  
pp. 213-223
Author(s):  
Hilke Petersen ◽  
Lars Robben ◽  
Thorsten M. Gesing
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Decomposition Temperature ◽  
Second Phase ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Structure Property Relationships ◽  
Heat Capacity Measurements

AbstractThe temperature-dependent structure-property relationships of the aluminosilicate perrhenate sodalite |Na8(ReO4)2|[AlSiO4]6 (ReO4-SOD) were analysed via powder X-ray diffraction (PXRD), Raman spectroscopy and heat capacity measurements. ReO4-SOD shows two phase transitions in the investigated temperature range (13 K < T < 1480 K). The first one at 218.6(1) K is correlated to the transition of dynamically ordered $P\overline{4}3n$ (> 218.6(1 K) to a statically disordered (<218.6(1) K) SOD template in $P\overline{4}3n$. The loss of the dynamics of the template anion during cooling causes an increase of disorder, indicated by an unusual intensity decrease of the 011-reflection and an increase of the Re-O2 bond length with decreasing temperature. Additionally, Raman spectroscopy shows a distortion of the ReO4 anion. Upon heating the thermal expansion of the sodalite cage originated in the tilt-mechanism causes the second phase transition at 442(1) K resulting in a symmetry-increase from $P\overline{4}3n$ to $Pm\overline{3}n$, the structure with the sodalites full framework expansion. Noteworthy is the high decomposition temperature of 1320(10) K.

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