Heteroepitaxy on (001) Silicon: Growth Mechanisms and Defect Formation.

1988 ◽  
Vol 116 ◽  
Author(s):  
P. Pirouz ◽  
F. Ernst ◽  
T. T. Cheng
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Minor Role ◽  
Alternative Mechanism ◽  
Growth Mechanisms ◽  
Planar Defects ◽  
Step Process ◽  
One Step ◽  
The One ◽  
A Minor

AbstractIn the growth of thin films of compound semiconductors on (001) silicon substrates by vapor deposition techniques, it is usual to employ a two-step process. In this method, an initial (buffer) layer is first grown at a relatively low temperature; once a continuous film has formed on the substrate, its temperature is raised for the subsequent bulk growth. Carrying out the growth in a one-step process by heating the substrate to the final temperature before allowing the gases into the CVD reactor usually results in a polycrystalline aggregate. In this paper, classical nucleation and growth mechanisms are used to explain-the reasons for the different morphology of the one-step and two-step growth films.The heteroepitaxial films on (001) silicon often contain a high density of stacking faults and twins. The occurrence of these planar defects is usually attributed to stresses that arise from lattice mismatch and/or thermal mismatch (differences in coefficients of thermal expansion) between the substrate and the epilayer. It is argued that, in fact, mismatch stresses play a minor role in the generation of planar defects. Instead, an alternative mechanism for their formation is proposed which is based on the facetted shape of nuclei and errors in stacking of {111} planes which occur during deposition on the facets.Conventional and high resolution transmission electron microscopy have been used to investigate three systems grown by CVD or MOCVD: SiC/Si, GaAs/Si and GaP/Si. These systems have different lattice and thermal mismatches, and the results support the proposed model for the formation of defects.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Politeness and social utopia in Friedrich Schiller’s Wilhelm Tell

2013 ◽  
Vol 3 (1) ◽  
pp. 34-55 ◽  
Author(s):  
Christel Björkstrand
Keyword(s):  
Common Ground ◽  
Initial Study ◽  
Minor Role ◽  
Politeness Theory ◽  
Dramatic Structure ◽  
German Philosopher ◽  
Social Visions ◽  
The One ◽  
A Minor ◽  
Social Utopia

This paper is an interdisciplinary analysis of Friedrich Schiller’s play Wilhelm Tell (1804). An initial study of its dramatic structure suggests a change in the relationship between the Swiss peasants and nobles. A further analysis, based on Brown’s and Levinson’s politeness theory confirms the development of a social utopia in the play, but also reveals that Wilhelm Tell plays a minor role in the social development described. The comparison of the play with earlier versions of the Tell legend highlights the roles of peasants and nobles in the establishment of the Swiss Confederation and suggests that Schiller elaborated extensively on the idea of a ‘common ground’ among the Swiss from different classes. The comparison between Schiller’s play and the contemporary German philosopher Johann Benjamin Erhard’s essay Über das Recht des Volks zu einer Revolution illustrates that Schiller’s social utopia develops in accordance with contemporary social visions. However, Tell’s act of murder separates him from the other Swiss protagonists in Schiller’s attempt to outline a righteous revolution, different from the one in France.

The Victim – a Great Actor in a Minor Role? – A Comparative Perspective

2021 ◽  
Vol 11 (1) ◽  
pp. 112-128
Author(s):  
Łukasz Duśko ◽  
Mateusz Szurman
Keyword(s):  
Social Order ◽  
American English ◽  
Active Role ◽  
Criminal Court ◽  
Minor Role ◽  
Criminal Proceedings ◽  
The One ◽  
A Minor ◽  
To Receive

Recently, the role of the victim in criminal proceedings became more significant. An observation was made that the legal interests of the victim are much more severely affected by the crime than the collective legal interests in the form of public or social order. However, the differences in the rights the victim is vested with differ substantively between particular countries. The authors present the position of the victim in American, English and French law. The solutions provided for in these systems are confronted with legal regulations adopted in Poland, i.e. the home country of the authors. It shows, surprisingly, that the role of the victim in criminal proceedings has evolved somehow independently of the implementation of the concept of restitution. On the one hand, there are legal systems in which the criminal court may order the offender to pay compensation for the damage caused, but the role of the victim still remains marginal. On the other hand, there are systems in which the victim is not only entitled to receive restitution, but he or she also has significant powers which enable him or her to play an active role in the criminal proceedings.

Nanowire Fabrication of Silicon-Based Materials

2007 ◽  
Vol 561-565 ◽  
pp. 1197-1199
Author(s):  
Hideo Kohno ◽  
Seiji Takeda
Keyword(s):  
Electron Microscopy ◽  
Silicon Carbide ◽  
Silicon Germanium ◽  
Iron Silicide ◽  
Growth Mechanisms ◽  
Step Process ◽  
One Step ◽  
Silicon Based

This paper describes our recent achievements in fabricating various kinds of nanowires of silicon-based materials including beta iron-silicide, silicon carbide, and silicon germanium. Some of them can be grown directly at one-step process, while the others can be fabricated using nanowire templates. We discuss their structures, growth mechanisms, and properties based on electron microscopy observations.

e+ e- ANNIHILATION INTO $\overline{N}N$ PAIRS

2003 ◽  
Vol 18 (02n06) ◽  
pp. 370-373 ◽  
Author(s):  
Y. YAN ◽  
C. KOBDAJ ◽  
W. UCHAI ◽  
AMAND FAESSLER ◽  
T. GUTSCHE ◽  
...  
Keyword(s):  
Experimental Data ◽  
Vector Meson ◽  
Quark Model ◽  
Step Process ◽  
Meson Decays ◽  
Quantum Numbers ◽  
One Step ◽  
The One

The reactions of electron-position annihilation into nucleon-antinucleon pairs have been studied in a nonperturbative quark model. The work suggests that the two-step process, in which the primary [Formula: see text] pair forms first a meson and then the meson decays into baryon pair, is dominant over the one-step process in which the primary [Formula: see text] pair is directly dressed by two additional [Formula: see text] pairs to form a baryon pair. The experimental data indicates that there exists a vector meson with quantum numbers IG(JPC) = 0-(1--) and a mass around 2 GeV.

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

2021 ◽  
Vol 116 ◽  
pp. 5-14
Author(s):  
Marta Babicka ◽  
Magdalena Woźniak ◽  
Kinga Szentner ◽  
Sławomir Borysiak ◽  
Krzysztof Dwiecki ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Degree Of Crystallinity ◽  
Cellulolytic Enzyme ◽  
X Ray Diffraction ◽  
Production Methods ◽  
Step Process ◽  
X Ray ◽  
One Step ◽  
Xrd Patterns ◽  
The One

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.

The Weights of Individual Grains of the Wheat Ear in Relation to Their Growth Potential, the Supply of Assimilate and Interaction Between Grains

1978 ◽  
Vol 5 (1) ◽  
pp. 61 ◽  
Author(s):  
PM Bremner ◽  
HM Rawson
Keyword(s):  
Vascular System ◽  
Growth Potential ◽  
Assimilate Transport ◽  
Major Influence ◽  
Minor Role ◽  
Intrinsic Capacity ◽  
The Difference ◽  
The One ◽  
Individual Grains ◽  
A Minor

The work reported here was done to explore the extent to which the mature weight of a grain is determined by (i) its potential for growth, defined as its intrinsic capacity to accumulate dry matter, and (ii) the resistance to assimilate transport imposed by the vascular system of the ear. Estimation of growth potential was attempted by observing the effects of systematic patterns of grain removal on the mature weights of grains remaining, these being compared with weights of matched grains from intact ears. Resistance to transport of assimilate was inferred from the apparent order of priority between grains for the supply of assimilate, as revealed by comparing their weights when assimilate supply was either normal, or reduced by plant shading. When neighbouring grains were removed, those remaining usually grew larger to an extent that indicated growth potential appreciably in excess of that utilized in intact ears under the most favourable conditions. Although grains within a spikelet of an intact ear attain quite different weights, the experiments suggested that their differing potentials for growth seemed to play only a minor role in this, and that the major influence was the relative ease with which assimilate could reach the grains; this depended largely on the distance of the grains from the spike rachis. Comparing between spikelets, the difference found in intact ears between grains in the same spikelet location tended to persist when some grains were removed from each spikelet, indicating a possible role of growth potential as a controlling influence. This may be partly due to the sequence of morphogenesis, established as early as the double ridge stage. Although the removal of competing grains within a spikelet usually enhanced the growth of the one remaining, this was not always so; there was evidence from one experiment that removal of competing grains towards the spikelet apex represented the removal of some beneficial influence. The bearing of the results on possible limitations to grain yield are discussed.

Effects of different hydraulic models on predicting longitudinal profiles of reactive pollutants in activated sludge reactors

2008 ◽  
Vol 58 (3) ◽  
pp. 555-561 ◽  
Author(s):  
P. Zima ◽  
J. Makinia ◽  
M. Swinarski ◽  
K. Czerwionka
Keyword(s):  
Activated Sludge ◽  
Ammonia Concentration ◽  
Minor Role ◽  
Nitrification Rate ◽  
Concentration Profiles ◽  
One Dimensional ◽  
Advection Dispersion ◽  
In Series ◽  
The One ◽  
A Minor

This paper presents effects of dispersion on predicting longitudinal ammonia concentration profiles in activated sludge bioreactor located at “Wschod” WWTP in Gdansk. The aim of this study was to use the one-dimensional advection-dispersion Equation (ADE) to simulate the flow conditions (based on the inert tracer concentrations in selected points) and longitudinal profile of reactive pollutant (based on the ammonia concentration profiles in selected points). The simulation results were compared with the predictions obtained using a traditional “tanks-in-series” (TIS) approach, commonly used in designing biological reactors. The use of dispersion coefficient calculated from an empirical formula resulted in substantial differences in the tracer concentration distributions in two sampling points in the bioreactor. Simulations using the one-dimensional ADE and TIS model, with the nitrification rate incorporated as the source term, revealed that the hydraulic model plays a minor role compared to the biochemical transformations in predicting the longitudinal ammonia concentration profiles.

scholarly journals Operator Approach to the Master Equation for the One-Step Process

2016 ◽  
Vol 108 ◽  
pp. 02027 ◽  
Author(s):  
M. Hnatič ◽  
E. G. Eferina ◽  
A. V. Korolkova ◽  
D. S. Kulyabov ◽  
L. A. Sevastyanov
Keyword(s):  
Master Equation ◽  
Operator Approach ◽  
Step Process ◽  
One Step ◽  
The One

Do Prosody and Embodiment Influence the Perceived Naturalness of Conversational Agents’ Speech?

2021 ◽  
Vol 18 (4) ◽  
pp. 1-15
Author(s):  
Jonathan Ehret ◽  
Andrea Bönsch ◽  
Lukas Aspöck ◽  
Christine T. Röhr ◽  
Stefan Baumann ◽  
...  
Keyword(s):  
Masking Effect ◽  
Minor Role ◽  
Virtual Agents ◽  
Conversational Agents ◽  
Virtual Agent ◽  
Online Study ◽  
Human Voice ◽  
The One ◽  
A Minor ◽  
The Impact

For conversational agents’ speech, either all possible sentences have to be prerecorded by voice actors or the required utterances can be synthesized. While synthesizing speech is more flexible and economic in production, it also potentially reduces the perceived naturalness of the agents among others due to mistakes at various linguistic levels. In our article, we are interested in the impact of adequate and inadequate prosody, here particularly in terms of accent placement, on the perceived naturalness and aliveness of the agents. We compare (1) inadequate prosody, as generated by off-the-shelf text-to-speech (TTS) engines with synthetic output; (2) the same inadequate prosody imitated by trained human speakers; and (3) adequate prosody produced by those speakers. The speech was presented either as audio-only or by embodied, anthropomorphic agents, to investigate the potential masking effect by a simultaneous visual representation of those virtual agents. To this end, we conducted an online study with 40 participants listening to four different dialogues each presented in the three Speech levels and the two Embodiment levels. Results confirmed that adequate prosody in human speech is perceived as more natural (and the agents are perceived as more alive) than inadequate prosody in both human (2) and synthetic speech (1). Thus, it is not sufficient to just use a human voice for an agents’ speech to be perceived as natural—it is decisive whether the prosodic realisation is adequate or not. Furthermore, and surprisingly, we found no masking effect by speaker embodiment, since neither a human voice with inadequate prosody nor a synthetic voice was judged as more natural, when a virtual agent was visible compared to the audio-only condition. On the contrary, the human voice was even judged as less “alive” when accompanied by a virtual agent. In sum, our results emphasize, on the one hand, the importance of adequate prosody for perceived naturalness, especially in terms of accents being placed on important words in the phrase, while showing, on the other hand, that the embodiment of virtual agents plays a minor role in the naturalness ratings of voices.

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