scholarly journals Identification of Key Odorants in Semi-Fermented Tea Made in Taiwan by Using Solvent-Assisted Flavor Evaporation Apparatus under High Vacuum and Application of the Aroma Extract Dilution Analysis

2017 ◽  
Vol 2017 (123) ◽  
pp. 9-16
Author(s):  
Yuzo Mizukami
Keyword(s):  
High Vacuum ◽  
Aroma Extract Dilution Analysis ◽  
Evaporation Apparatus ◽  
Key Odorants ◽  
Made In

Recent progress in the freeze-etching technique

1971 ◽  
Vol 261 (837) ◽  
pp. 121-131 ◽  
Keyword(s):  
High Vacuum ◽  
Molecular Size ◽  
Etching Technique ◽  
Structural Distortions ◽  
Shadow Casting ◽  
Structural Details ◽  
Freeze Etching ◽  
The One ◽  
Insight Into ◽  
Made In

The freeze-etching technique must be improved if structures at the molecular size level are to be seen. The limitations of the technique are discussed here together with the progress made in alleviating them. The vitrification of living specimens is limited by the fact that very high freezing rates are needed. The critical freezing rate can be lowered on the one hand by the introduction of antifreeze agents, on the other hand by the application of high hydrostatic pressure. The fracture process may cause structural distortions in the fracture face of the frozen specimen. The ‘double-replica’ method allows one to evaluate such artefacts and provides an insight into the way that membranes split. During etching there exists the danger of contaminating the fracture faces with condensable gases. Because of specimen temperatures below —110 °C, special care has to be taken in eliminating water vapour from the high vacuum. An improvement in coating freeze-etched specimens has resulted from the application of electron guns for evaporation of the highest melting-point metals. If heat transfer from gun to specimen is reduced to a minimum, Pt, Ir, Ta, W and C can be used for shadow casting. Best results are obtained with Pt-C and Ta-W . With the help of decoration effects Pt-C shadow castings give the most information about the fine structural details of the specimen.

scholarly journals Device for calibration of low pressure gauges development

2002 ◽  
Vol 2 (4) ◽  
pp. 189-195
Author(s):  
Z.D. Nikitovic
Keyword(s):  
High Vacuum ◽  
Low Pressure ◽  
Calibration Procedure ◽  
Vacuum System ◽  
Molecular Collision ◽  
Gas Discharges ◽  
Dry Air ◽  
Vacuum Region ◽  
Set Up ◽  
Made In

Vacuum system set-up is presented and used for calibration of pressure gauges in the region of rough vacuum, from 103 mbar to 10-1 mbar, with dry air. The capacitance manometer is used for the calibration of piezoresistant manometer, oil, mercury and mercury micrometers U manometers. The applicability of the experimental set-up and obtained results for the low pressure gauges calibration in the medium and high vacuum region is approved. It was shown how calibration of some cheaper pressure gauges might be performed and reliable measurements of the pressure may be made in the region that is of interest for atomic and molecular collision physics and low-pressure gas discharges. It was also shown that mentioned calibration procedure could be used for calibration of different U manometer types in order to renormalize older atomic and molecular collision data.

scholarly journals Characterization of the Key Aroma Compounds in Traditional Hunan Smoke-Cured Pork Leg (Larou, THSL) by Aroma Extract Dilution Analysis (AEDA), Odor Activity Value (OAV), and Sensory Evaluation Experiments

Foods ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 413
Author(s):  
Dandan Pu ◽  
Yuyu Zhang ◽  
Huiying Zhang ◽  
Baoguo Sun ◽  
Fazheng Ren ◽  
...  
Keyword(s):  
Active Regions ◽  
Aroma Compounds ◽  
Aroma Extract Dilution Analysis ◽  
Sensory Qualities ◽  
Key Odorants ◽  
Potent Odorants ◽  
Odor Activity Value ◽  
First Time ◽  
Ranking Analysis

The key aroma compounds in smoke-cured pork leg were characterized by gas chromatography–olfactometry coupled with aroma extract dilution analysis (GC–O/AEDA), odor activity value (OAV), recombination modeling, and omission tests. Ranking analysis showed that pork leg smoke-cured for 18 days had the best sensory qualities, with strong meaty, smoky, roasty, woody, and greasy attributes. Thirty-nine aroma-active regions with flavor dilution (FD) factors ranging from 9 to 6561 were detected. Overall, 3-ethylphenol had the highest FD factor of 6561, followed by 2,6-dimethoxyphenol, 3,4-dimethylphenol, 4-ethylguaiacol, 4-methylguaiacol, 3-methylphenol, and 2-acetyl-1-pyrroline, with FD ≥243. Among 39 aroma compounds, 27 compounds with OAVs ≥1 and were potent odorants. A similarity of 90.73% between the recombination model and traditional Hunan Smoke-cured Pork Leg (THSL) sample was obtained. Omission tests further confirmed that (E)-2-nonenal, 2-methoxy-4-vinylphenol, guaiacol, 3-ethylphenol, 2,6-dimethylphenol, 2-acetyl-1-pyrroline, and methional were key odorants in smoke-cured pork leg. Additionally, 2-acetyl-1-pyrroline (38.88 μg/kg), which contributes to a roasty aroma, was characterized here as a key odorant of smoke-cured pork leg for the first time.

scholarly journals Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7647
Author(s):  
Binshan Liu ◽  
Shiqi Xu ◽  
Zhizhong Dong ◽  
Yuping Liu ◽  
Xiaoming Wei ◽  
...  
Keyword(s):  
Aroma Extract Dilution Analysis ◽  
Flavor Compound ◽  
Aroma Profile ◽  
Extraction Solvent ◽  
Dipropyl Disulfide ◽  
Gas Chromatography Olfactometry ◽  
Key Odorants ◽  
First Time ◽  
Methyl Propyl Disulfide

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.

Identification of the Key Odorants in Tahitian Cured Vanilla Beans (Vanilla tahitensis) by GC-MS and an Aroma Extract Dilution Analysis

2013 ◽  
Vol 77 (3) ◽  
pp. 601-605 ◽  
Author(s):  
Makoto TAKAHASHI ◽  
Yoko INAI ◽  
Norio MIYAZAWA ◽  
Yoshiko KUROBAYASHI ◽  
Akira FUJITA
Keyword(s):  
Aroma Extract Dilution Analysis ◽  
Key Odorants

scholarly journals Some investigations in röntgen spectra. Part III. -Fine structure of K-absorption edge of SiO 2

1931 ◽  
Vol 131 (818) ◽  
pp. 654-658 ◽  
Keyword(s):  
Fine Structure ◽  
Silicon Oxide ◽  
Wave Length ◽  
High Vacuum ◽  
Short Wave ◽  
X Rays ◽  
Pure Silicon ◽  
Short Wave Length ◽  
Low Dispersion ◽  
Made In

It is now well known from the works of Lindh, Fricke and others that the principal K or L edge is attended on its short wave-length side by a number of secondary edges. The usual method of obtaining this structure consists in putting absorbing screens in the path of X-rays before or after they are analysed by a suitable crystal. The chief difficulty in this is the preparation of absorbing screen of suitable thickness. Fricke as well as Lindh have used this method for the study of absorption spectra of several substances. The former author failed to obtain any K-absorption limit at all for silicon. This was probably due to his using thick absorbing screens coupled with the low dispersion which he obtained with a sugar crystal. Later Lindh succeeded in obtaining K-limits for both silicon and silicon oxide, and showed that as in so many other cases the K-edge of pure silicon is softer than that of the compound. He, however, did not succeed in getting any fine structure. The probable cause of this was again the use of screens of unsatisfactory thickness. This difficulty may be avoided by using the analysing crystal itself as an absorber when a suitable crystal is available. Lindsay and Van Dyke used this method successfully to study the fine structure of the calcium K-edge in calcite, gypsum and fluorite crystals. Nuttall has made partial use of this method in his study of structure of K-absorption edges of potassium and chlorine. Later Lindsay and Voorhees made use of this method to study the fine structure for different crystals containing iron. Following the same method the fine structure for silicon oxide was photographed and measured by using quartz as the analysing and absorbing crystal. The apparatus used was a high vacuum spectrograph of Professor Siegbahn’s design made in the laboratory workshop. Its adjustment and use is described in Part I. The continuous radiation was obtained from a tungsten anticathode formed by dovetailing a plate of this material on the copper anticathode which as already described had four sides.

scholarly journals The emissions of soft X-rays by different elements

1927 ◽  
Vol 115 (771) ◽  
pp. 280-290 ◽  
Keyword(s):  
Atomic Number ◽  
High Vacuum ◽  
X Rays ◽  
X Ray ◽  
Square Roots ◽  
Comparative Efficiency ◽  
Electronic Distribution ◽  
Different Sources ◽  
Opening Up ◽  
Made In

In a paper by Richardson and Chalkin it was shown that the efficiency of different elements as emitters of soft X-rays increased with increasing atomic number-of the respective elements far less rapidly than does the corresponding property for ordinary X-rays. Whereas the efficiency for the latter is proportional to the atomic number, it was found that the efficiency for soft X-rays was roughly proportional to the square roots of the atomic numbers for the elements tested. The experiments were confined to the four elements carbon (At. No. 6), iron (26), nickel (28) and tungsten (74), and were spread over a long period of time, during which various changes were made in the apparatus. They were neither primarily intended nor well adapted to investigate with any accuracy the comparative efficiency of different sources of the rays. Accordingly, the apparatus described in this paper has been constructed. By means of it, six elements can be tested in quick succession under similar conditions without opening up the apparatus. We have tested the 14 elements tabulated below. These are all that we have been able to obtain which are sufficiently refractory to stand purification by high vacuum bombardment and which we have been able, by one means or another, to form into plates or sheets of the requisite size. As a result of these experiments it is quite clear that the efficiency for soft X-ray emission is a periodic function of the atomic number , like other phenomena which depend on the superficial electronic distribution.

Fullerene Based n-type Organic Thin-Film Transistors

2005 ◽  
Vol 871 ◽  
Author(s):  
Joshua Haddock ◽  
Benoit Domercq ◽  
Bernard Kippelen
Keyword(s):  
Organic Semiconductors ◽  
Field Effect Transistors ◽  
High Vacuum ◽  
Channel Length ◽  
Organic Films ◽  
Limiting Factor ◽  
Organic Field Effect Transistors ◽  
Organic Thin Film ◽  
P Type ◽  
Made In

AbstractSignificant progress has been made in the area of p-type organic field effect transistors while progress in developing n-type materials and devices has been comparatively lacking, a limiting factor in the pursuit to develop complementary organic electronic circuits. Given the need for n-type organic semiconductors we have carried out studies using two different fullerene molecules, C60 and C70. Here, we report mobilities for C60 ranging from 0.02 cm2/Vs up to 0.65 cm2/Vs (depending on channel length), and mobilities from 0.003 cm2/Vs up to 0.066 cm2/Vs for C70. All devices were fabricated with organic films deposited under high vacuum but tested at ambient pressures under nitrogen.

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