Investigation of Surface Phase Layers on GaAs after Selective Chemical Etching

2015 ◽  
Vol 1085 ◽  
pp. 91-94
Author(s):  
Oksana N. Zarubina ◽  
Gennady M. Mokrousov ◽  
Alexander G. Touryanski ◽  
Igor V. Pirshin ◽  
Liubov V. Maliy
Keyword(s):  
Phase Distribution ◽  
Theoretical Data ◽  
Selective Dissolution ◽  
Phase Layers ◽  
Interfacial Boundary ◽  
Combination Of Methods ◽  
Elemental Arsenic ◽  
The Stability ◽  
First Time

Normal 0 false false false RU X-NONE X-NONE The combination of methods of voltammetry, Raman spectroscopy, and X-ray reflectometry for the first time has been applied for the more comprehensive investigation of interfacial boundaries of GaAs, i.e. determination of phase distribution and thickness of the phase layers. The conditions for the formation of elemental arsenic on a GaAs surface in the process of selective dissolution are discussed. The stability of interfacial boundaries in air has also been studied. The investigations have shown that air storage lead to the oxidation of formed As0 and reorganization of GaAs interfacial boundary accompanied by the formation of Ga2O3 and As0 as a result of a reaction between As2O3 and GaAs. The results on interfacial boundaries composition were found to be correlated with the theoretical data. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

scholarly journals Improved Determination of Mercury Complex with Thiomicher’s Ketone by β-Correction Spectrophotometry

2000 ◽  
Vol 83 (1) ◽  
pp. 231-236 ◽  
Author(s):  
Hong-Wen Gao ◽  
Sheng-Yi Zhang ◽  
Su-Mei Ye
Keyword(s):  
Stability Constant ◽  
Nonionic Surfactant ◽  
Molar Absorptivity ◽  
Mercury Complex ◽  
Relative Standard ◽  
Standard Deviations ◽  
Wastewater Samples ◽  
The Stability ◽  
First Time

Abstract Determination of the mercury complex formed with Thiomicher's ketone (TMK) was improved by β-correction spectrophotometry in the presence of a nonionic surfactant at pH 5. The complex formed was Hg(TMK)2, and its true molar absorptivity is reported for the first time: εHg(TMK)2560 = 1.04 × 105 L/mol·cm. In addition, the stability constant of Hg(TMK)2 was equal to 3.64 × 1010 at an ion strength of 0.01 at 20°C. Results from analyses of wastewater samples showed that the relative standard deviations were ≤8.3%, and the recoveries of mercury ranged from 90 to 110%.

scholarly journals Tales of the Unexpected: The Case of Zirconium(IV) Complexes with Desferrioxamine

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2098 ◽  
Author(s):  
Matteo Savastano ◽  
Carla Bazzicalupi ◽  
Giovanni Ferraro ◽  
Emiliano Fratini ◽  
Paola Gratteri ◽  
...  
Keyword(s):  
Stability Constants ◽  
Density Functional ◽  
Maldi Mass Spectrometry ◽  
Binuclear Complexes ◽  
X Ray Scattering ◽  
Complex Solutions ◽  
The Stability ◽  
Ph Range ◽  
First Time

The Zr4+ complexes with desferrioxamine (H3DFO) and its derivatives are the only 89Zr-based imaging agents for proton emission tomography (PET) that have been used so far in clinical trials. Nevertheless, a complete speciation of the Zr4+/H3DFO system in solution has never been performed and the stability constants of the relevant complexes are still unknown. Here we report, for the first time, the speciation of this system in water, performed by potentiometric titrations, and the determination of the stability constants of all complexes formed in the pH range 2.5–11.5. Surprisingly, although desferrioxamine gives rise to very stable 1:1 complexes with Zr4+ (logK = 36.14 for Zr4+ + DFO3− = [ZrDFO]+), 2:2 and 2:3 ones are also formed in solution. Depending on the conditions, these binuclear complexes can be main species in solution. These results were corroborated by small-angle X-ray scattering (SAXS) and MALDI mass spectrometry analyses of complex solutions. Information on complex structures was obtained by means of density functional theory (DFT) calculations.

scholarly journals Synthesis and properties of dehydroabietyl glycidyl ether grafted hydroxypropyl chitosan

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 4110-4123
Author(s):  
Wei Guo ◽  
Zhaosheng Cai ◽  
Qi Xu ◽  
Kaiyong Sun ◽  
Xujuan Huang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Nonionic Surfactant ◽  
Foam Stability ◽  
Glycidyl Ether ◽  
Surface Activities ◽  
The Stability ◽  
Stability Time ◽  
First Time ◽  
Emulsifying Ability

A nonionic surfactant based on chitosan and rosin, i.e. dehydroabietyl glycidyl ether grafted hydroxypropyl chitosan (DAGE-g-HPCS), was synthesized for the first time through reaction between hydroxypropyl chitosan (HPCS) and dehydroabietyl glycidyl ether (DAGE). The surface activities of DAGE-g-HPCS in aqueous solution were investigated via determination of surface tension, and its emulsifying ability was evaluated according to the stability time of emulsion composed of benzene-water with DAGE-g-HPCS as emulsifier; the foam stability was evaluated using the oscillation method. Through modulating the molecular weight of HPCS and the grafting degree (DG) of DAGE-g-HPCS, the emulsion stability and foam stability were surprisingly controllable. Compared to HPCS and specific emulsifier, the stability time of emulsion composed of benzene-water with DAGE-g-HPCS showed a remarkable performance with DG of 16.5% as the emulsifier was 7320 s, and the foam retention of DAGE-g-HPCS with 2.0 g·L-1 was 91.5%. Simultaneously, the critical micelle concentration (CMC) of DAGE-g-HPCS decreased with increased DG, while the emulsifying ability and foam stability exhibited opposite trend. The CMC, emulsifying ability, and foam stability of DAGE-g-HPCS increased with decreased HPCS molecular weight. These results demonstrated that the DAGE-g-HPCS was an excellent surfactant that should be considered as a promising substitute for petrochemical nonionic surfactant.

The Crystal Structure of WC Type ZrTe. Advantages in Chemical Bonding as Contrasted to NiAs Type ZrTe

1999 ◽  
Vol 54 (9) ◽  
pp. 1125-1128 ◽  
Author(s):  
Gissur Örlygsson ◽  
Bernd Harbrecht
Keyword(s):  
Crystal Structure ◽  
Local Minimum ◽  
Structure Type ◽  
Metal Deficiency ◽  
Nias Type Structure ◽  
The Stability ◽  
Nias Type ◽  
First Time ◽  
Extended Hückel Calculations

Single crystals of WC type ZrTe were prepared from the elements. A single crystal structure determination of this structure type was performed for the first time: ZrTe (WC) crystallizes in the hexagonal space group P6̄m2 (No. 187), hP2, Z - 1, a - 377.06(5), c = 386.05(8) pm; 84 reflections, 5 variables, R(F) = 0.037. The distinctions in bonding for ZrTe (WC) and a hypothetical stoichiometric ZrTe crystallizing in the NiAs type structure were analyzed on the basis of extended Hückel calculations. Heteronuclear interactions contribute most strongly to the stability of both structures. Attractive Zr-Zr interactions energetically favour ZrTe (WC) relative to ZrTe (NiAs). The Fermi level of ZrTe (WC) resides in a local minimum of the DOS, whereas that of ZrTe (NiAs) intersects a local DOS maximum, and is pushed up by about 0.5 eV, expressing the decisive destabilization of NiAs type ZrTe. As a consequence, metal deficiency is observed for ZrTe (NiAs), in contrast to ZrTe (WC).

Effect of Heating Treatment of Fresh Rice Bran on Stabilization

2012 ◽  
Vol 602-604 ◽  
pp. 1200-1205
Author(s):  
Zhu Gong ◽  
Guo Ping Yu ◽  
Chao Ran Dou ◽  
Man Xu Xu
Keyword(s):  
Heat Treatment ◽  
Rice Bran ◽  
Peroxidase Activity ◽  
Direct Determination ◽  
Material Resources ◽  
Total Antioxidant ◽  
Heating Treatment ◽  
The Stability ◽  
First Time

In the research of rice bran stabilization, most of the literature only study the lipase which is explained by the changes in free fatty acids in the storage experiment or peroxidase activity. It leads results not comprehensive, extends the experiment time, increases the experimental difficulty and wastes of manpower and material resources. For the first time, the effect of heat treatment on fresh rice bran stability is examined in terms of direct determination of water content, lipase activity, peroxidase activity and total antioxidant capacity. The optimal condition is that 120 degrees for 22 min. The results show that the heat treatment can reduce the enzyme activity of rice bran to improve the stability of rice bran.

scholarly journals Stability of Glutaraldehyde in Biocide Compositions

2020 ◽  
Vol 21 (9) ◽  
pp. 3372
Author(s):  
Alina Matei ◽  
Cristina Puscas ◽  
Iulia Patrascu ◽  
Maria Lehene ◽  
Julia Ziebro ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Density Functional ◽  
Theoretical Data ◽  
Dependent Manner ◽  
Chemical Equilibria ◽  
Sds Page ◽  
The Stability ◽  
Hospital Wastewaters ◽  
Over Time

Glutaraldehyde (GA) is used as biocide in hospitals. Recent public investigations on the chemical composition of biocides used in Romania have in some cases found GA, as a key ingredient, to be apparently diluted. However, these data did not explicitly consider the complex chemical equilibria inherent to GA. An investigation of experimental and theoretical data is reported here, assessing the stability of GA solutions relevant for biocide compositions. GA solutions of various chemical composition and under varying circumstances were analyzed using spectroscopy (UV-VIS, Raman, NMR) coupled with density functional theory (DFT) calculations, as well as chemically, such as via the formation of imines in reaction/titration with glycine monitored at 270 nm; using LC-MS; or using SDS-PAGE analysis with GA as reagent in the polymerization of two test proteins- hemoglobin and myoglobin. The spectral properties of GA changed significantly over time, in a temperature-dependent manner; titration with glycine confirmed the spectral data. SDS-PAGE experiments demonstrated a non-linear and apparently unpredictable change in the reactivity of GA over time. The results may be relevant for the determination of GA concentration in various settings such as biocide analysis, hospital wastewaters, and others.

"DYNAMICAL CONFINEMENT" IN NEURAL NETWORKS

1995 ◽  
Vol 03 (04) ◽  
pp. 1157-1165 ◽  
Author(s):  
C. JÉZÉQUEL ◽  
O. NÉROT ◽  
J. DEMONGEOT
Keyword(s):  
Phase Transition ◽  
Neural Networks ◽  
Invariant Measure ◽  
Hopfield Model ◽  
Stability Boundaries ◽  
Contour Lines ◽  
The Stability ◽  
Unique Invariant Measure ◽  
First Time

Randomisation of a well known mathematical model is proposed (i.e. the Hopfield model for neural networks) in order to facilitate the study of its asymptotic behavior: in fact, we replace the determination of the stability basins for attractors and for stability boundaries by the study of a unique invariant measure, whose distribution function maxima (or respectively, percentile contour lines) correspond to the location of the attractors (or respectively, boundaries of their stability basins). We give the name of "confinement" to this localization of the mass of the invariant measure. We intend to show here that the study of the confinement is in certain cases easier than the study of underlying attractors, in particular if these last are numerous and possess small stability basins (for example, for the first time we calculate the invariant measure in the random Hopfield model in a case for which the deterministic version exhibits many attractors, and after in a case of phase transition).

Disability as a social phenomenon

2020 ◽  
pp. 22-38
Author(s):  
Natalia Guseva ◽  
Vitaliy Berdutin
Keyword(s):  
Social Protection ◽  
Russian Society ◽  
Stage Model ◽  
High Quality ◽  
Rehabilitation Programs ◽  
Current State ◽  
The Social ◽  
Consistent Solution ◽  
First Time

At present, the problem of establishing disability is a point at issue in Russia. Despite the fact that medical criteria for disability are being developed very actively, high-quality methods for assessing social hallmarks are still lacking. Since disability is a phenomenon inherent in any society, each state forms a social and economic policy for people with disabilities in accordance with its level of development, priorities and opportunities. We have proposed a three-stage model, which includes a system for the consistent solution of the main tasks aimed at studying the causes and consequences of the problems encountered today in the social protection of citizens with health problems. The article shows why the existing approaches to the determination of disability and rehabilitation programs do not correspond to the current state of Russian society and why a decrease in the rate of persons recognized as disabled for the first time does not indicate an improvement in the health of the population. The authors proposed a number of measures with a view to correcting the situation according to the results of the study.

Phytochemical Constituents of Annona reticulata and their Cytotoxic Activity

2020 ◽  
Vol 17 (3) ◽  
pp. 206-210
Author(s):  
Ty Viet Pham ◽  
Thang Quoc Le ◽  
Anh Tuan Le ◽  
Hung Quoc Vo ◽  
Duc Viet Ho
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Structural Determination ◽  
Phytochemical Investigation ◽  
Ic50 Values ◽  
Phytochemical Constituents ◽  
First Time ◽  
Annona Reticulata

A phytochemical investigation of the leaves of Annona reticulata led to the isolation and structural determination of β-sitosterol (1), ent-pimara-8(14),15-dien-19-oic acid (2), ent-pimara- 8(14),15-dien-19-ol (3), quercetin (4), quercetin 3-O-α-L-arabinopyranoside (5), and a mixture of quercetin 3-O-β-D-galactopyranoside (6a) and quercetin 3-O-β-D-glucopyranoside (6b). Of these, compounds 2 and 3 were isolated from the genus Annona for the first time. Compound 3 showed strong cytotoxicity against SK-LU-1 and SW626 cell lines with IC50 values of 17.64 ± 1.07 and 19.79 ± 1.41 μg mL-1, respectively.

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