scholarly journals Analysis of catalyst surface wetting: the early stage of epitaxial germanium nanowire growth

2020 ◽  
Vol 11 ◽  
pp. 1371-1380 ◽  
Author(s):  
Owen C Ernst ◽  
Felix Lange ◽  
David Uebel ◽  
Thomas Teubner ◽  
Torsten Boeck
Keyword(s):  
Interfacial Energy ◽  
Silicon Oxide ◽  
Ostwald Ripening ◽  
Early Stage ◽  
Point Of View ◽  
Thin Metal ◽  
Surface Wetting ◽  
Germanium Nanowires ◽  
Semi Empirical ◽  
Metal Layers

The dewetting process is crucial for several applications in nanotechnology. Even though not all dewetting phenomena are fully understood yet, especially regarding metallic fluids, it is clear that the formation of nanometre-sized particles, droplets, and clusters as well as their movement are strongly linked to their wetting behaviour. For this reason, the thermodynamic stability of thin metal layers (0.1–100 nm) with respect to their free energy is examined here. The decisive factor for the theoretical considerations is the interfacial energy. In order to achieve a better understanding of the interfacial interactions, three different models for estimating the interfacial energy are presented here: (i) fully theoretical, (ii) empirical, and (iii) semi-empirical models. The formation of nanometre-sized gold particles on silicon and silicon oxide substrates is investigated in detail. In addition, the strengths and weaknesses of the three models are elucidated, the different substrates used are compared, and the possibility to further process the obtained particles as nanocatalysts is verified. The importance of a persistent thin communication wetting layer between the particles and its effects on particle size and number is also clarified here. In particular, the intrinsic reduction of the Laplace pressure of the system due to material re-evaporation and Ostwald ripening describes the theoretically predicted and experimentally obtained results. Thus, dewetting phenomena of thin metal layers can be used to manufacture nanostructured devices. From this point of view, the application of gold droplets as catalysts to grow germanium nanowires on different substrates is described.

scholarly journals Analysis of catalyst surface wetting: the early stage of epitaxial germanium nanowire growth

2020 ◽  
Author(s):  
Owen C Ernst ◽  
Felix Lange ◽  
David Uebel ◽  
Thomas Teubner ◽  
Torsten Boeck
Keyword(s):  
Silicon Oxide ◽  
Ostwald Ripening ◽  
Catalyst Surface ◽  
Early Stage ◽  
Thin Metal ◽  
Surface Wetting ◽  
Dewetting Process ◽  
Germanium Nanowires ◽  
Semi Empirical ◽  
Metal Layers

In several nanotechnological applications the dewetting process is crucial. Although not all phenomena of dewetting are fully understood yet, especially with regard to metallic fluids, it is clear that the formation of nanoparticles, -droplets, and -clusters and their movement is strongly linked to their wetting behaviour. For this reason, the thermodynamic stability of thin metal layers (0.1 – 100 nm) with respect to its free energy is examined here. The decisive factor for the theoretical consideration is the interfacial energy. In order to achieve a better understanding of the interface interactions, three different models for the estimation of this energy are presented: i. fully theoretical, ii. empirical and iii. semi-empirical. The formation of nanometre-sized gold particles on silicon and silicon oxide is investigated in detail, elucidating the strengths and weaknesses of the three models, comparing the different substrates, and verifying the possibility of further processing of the gained particles as nanocatalysts. The importance of a persistent thin communication wetting layer between the particles and its effects on their size and number also becomes clear. In particular, the intrinsic reduction of the Laplace pressure of the system by material re-evaporation and Ostwald ripening is considered to describe the theoretically predicted and experimentally found effects. Thus dewetting phenomena of thin metal layers can be well-directed used for the manufacturing of nanostructured devices. From this viewpoint, the behaviour of gold droplets as catalysts to grow germanium nanowires on different substrates is described.

Phase Separation: From the Initial Nucleation Stage to the Final Ostwald Ripening Regime

1997 ◽  
Vol 481 ◽  
Author(s):  
Celeste Sagui ◽  
Dean Stinson O'Gorman ◽  
Martin Grant
Keyword(s):  
Phase Separation ◽  
Late Stage ◽  
Ostwald Ripening ◽  
Early Stage ◽  
Classical Problem ◽  
Nucleation And Growth ◽  
New Model ◽  
Nucleation Stage ◽  
Initial Nucleation

ABSTRACTIn this work we have re-examined the classical problem of nucleation and growth. A new model considers the correlations among droplets and naturally incorporates the crossover from the early-stage, nucleation dominated regime to the scaling, late-stage, coarsening regime within a single framework.

Observation of Fatigue Damage to Gear Tooth Using Image Processing

2007 ◽  
Author(s):  
Tomoya Masuyama ◽  
Takuya Ikeda ◽  
Satoshi Yoshiizumi ◽  
Katsumi Inoue
Keyword(s):  
Image Processing ◽  
Acoustic Emission ◽  
Strain Distribution ◽  
Cyclic Load ◽  
Early Stage ◽  
Gear Tooth ◽  
Digital Camera ◽  
Correlation Method ◽  
Point Of View ◽  
Strain Diagram

The detection of damage in early stage of fatigue is important for a reliable evaluation of gear life and strength. From this point of view, the variation of strain distribution in a tooth due to cyclic load contains useful information because the fatigue crack will initiate as a result of the accumulation of plastic strain. Meanwhile, digital image equipments are widely used in our life and the performance is in progress. We took digital pictures of cyclic loaded tooth by the digital camera and compared with the picture of no load to find displacement. The strain distribution of tooth is calculated by the correlation method using those pictures. The initiation of a micro crack is observed by the method. It is also confirmed by the detection of acoustic emission wave with higher energy. The variation of stress-strain diagram in fatigue process is presented, and this illustrates the increase of strain in the final stage of fatigue.

Early Warning Mechanism for the Surge of Passengers in Metro Systems Based on Automated Fare Collection Data: Case Study of Guangzhou, China

2019 ◽  
Vol 2673 (4) ◽  
pp. 917-929 ◽  
Author(s):  
Ning Huan ◽  
Enjian Yao ◽  
Binbin Li
Keyword(s):  
Early Warning ◽  
Traffic Control ◽  
Safety Management ◽  
Early Stage ◽  
Point Of View ◽  
Control Measures ◽  
Passenger Flow ◽  
Early Warning Mechanism ◽  
Metro Systems

Recently, surges of passengers caused by large gatherings, temporary traffic control measures, or other abnormal events have frequently occurred in metro systems. From the standpoint of the operation managers, the available information about these outside events is incomplete or delayed. Unlike regular peaks of commuting, those unforeseen surges pose great challenges to emergency organization and safety management. This study aims to assist managers in monitoring passenger flow in an intelligent manner so as to react promptly. Compared with the high cost of deploying multisensors, the widely adopted automated fare collection (AFC) system provides an economical solution for inflow monitoring from the application point of view. In this paper, a comprehensive framework for the early warning mechanism is established, including four major phases: data acquisition, preprocessing, off-line modeling, and on-line detection. For each station, passengers’ tapping-on records are gathered in real time, to be further transformed into a dynamic time series of inflow volumes. Then, a sequence decomposition model is formulated to highlight the anomaly by removing its inherent disturbances. Furthermore, a novel hybrid anomaly detection method is developed to monitor the variation of passenger flow, in which the features of inflow patterns are fully considered. The proposed method is tested by a numerical experiment, along with a real-world case study of Guangzhou metro. The results show that, for most cases, the response time for detection is within 5 min, which makes the surge phenomenon observable at an early stage and reminds managers to make interventions appropriately.

scholarly journals Effect of Mg Treatment on the Nucleation and Ostwald Growth of Inclusions in Fe-O-Al-Mg Melt

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3355
Author(s):  
Yutang Li ◽  
Linzhu Wang ◽  
Chaoyi Chen ◽  
Junqi Li ◽  
Xiang Li
Keyword(s):  
Nucleation Rate ◽  
Ostwald Ripening ◽  
Critical Size ◽  
Early Stage ◽  
Inclusion Size ◽  
Nucleation Theory ◽  
Mg Addition ◽  
Homogeneous Nucleation Theory ◽  
Mg Melt ◽  
Size Of Nuclei

This study aimed to investigate the effect of Mg treatment on the nucleation and ostwald growth of inclusions. Deoxidized experiments with Al (0.05%Al) and Al-Mg (0.05%Al + 0.03%Mg) were carried out at 1873 K, and the composition, number, and size of inclusions were studied as a function of holding time. Homogeneous nucleation theory and ostwald ripening were utilized to calculate the nucleation rate, the critical size of nuclei, and coarsening rate of inclusions. The results show that small inclusions were more easily found in the steels with Al-Mg complex deoxidation, and the number of inclusions with Al-Mg complex deoxidation is larger at an early stage of deoxidation. The critical size of nuclei increases in the order of MgAl2O4 (0.3–0.4 nm) < Al2O3 (0.4–0.6 nm), and the nucleation rate increases in the order of Al2O3 (1100 cm−3 s−1) < MgAl2O4 (1200 cm−3s−1), which is consistent with the experimental results. Moreover, the coarsening rate of MgAl2O4 inclusions was smaller than Al2O3 inclusions in both the value of kd(cal.) from ostwald growth and the value of kd(obs.) from inclusion size. The effect of Mg addition on coarsening of inclusion was analyzed and their mechanism was discussed based on ostwald ripening theory and Factsage calculation.

scholarly journals Entre La Creación Y La Crí­tica Literaria. Letras De Alfonso Reyes Y Martí­n Luis Guzmán

Xihmai ◽  
2014 ◽  
Vol 9 (17) ◽  
Author(s):  
Isabel Lincoln Strange Reséndiz
Keyword(s):  
Literary Criticism ◽  
Mexican Revolution ◽  
Early Stage ◽  
Intimate Relationship ◽  
Point Of View ◽  
Palabras Clave ◽  
Alfonso Reyes ◽  
Personal Interests

  ¡Pobre hombre de Dios! El mundo está necesitado de realidades externas, objetivas, vulgares, y Usted a través del zodiaco de sus cartas actuales se me esfuma en radiosas visiones de poetas o se me rompe en un fracaso de cristales… CARTA DE REYES A GUZMÁN, 1914. Resumen El presente artí­culo analiza la crí­tica literaria contenida en la correspondencia que mantuvieron los Ateneí­stas Alfonso Reyes y Martí­n Luis Guzmán, a partir de 1913 y hasta 1959. Dichas cartas exponen el punto de vista de ambos autores sobre la configuración de la obra propia y la ajena. La correspondencia dibuja un panorama de la relación í­ntima entre Reyes y Guzmán, que se vio afectada desde un momento temprano en la vida de ambos, debido al estallido de la Revolución Mexicana y a partir de la Decena trágica, en la que fallece Bernardo Reyes. El resultado de sus intereses personales se manifiesta en estas cartas; Reyes se muestra como autor cosmopolita y Guzmán como un narrador con profundas preocupaciones polí­ticas. Palabras clave: Literatura, crí­tica, correspondencia, Reyes, Guzmán. Abstract   This article analyzes the literary criticism that exists in the letters written by Alfonso Reyes and Martin Luis Guzman, from 1913 and until 1959. These letters outlined the point of view of both authors on setting their own work and that of others. The correspondence paints a picture of the intimate relationship between Reyes and Guzman, who were affected from an early stage in the life of both, due to the outbreak of the Mexican Revolution and from La Decena trágica, in which Bernardo Reyes dies. The results of their personal interests are manifested in those letters; Reyes is seen as a cosmopolitan author and Guzman as a writer with deep political concerns.   Keywords: Literature, criticism, correspondence, Reyes, Guzmán.

scholarly journals Detection limits of significant prostate cancer using multiparametric MR and digital rectal examination in men with low serum PSA: Up-date of the Italian Society of Integrated Diagnostic in Urology

2021 ◽  
Vol 93 (1) ◽  
pp. 92-100
Author(s):  
Andrea B. Galosi ◽  
Erika Palagonia ◽  
Simone Scarcella ◽  
Alessia Cimadamore ◽  
Vito Lacetera ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Practice ◽  
Early Stage ◽  
Specific Antigen ◽  
Digital Rectal Examination ◽  
Point Of View ◽  
Italian Society ◽  
Rectal Examination ◽  
Normal Limits ◽  
Low Serum

Reasons why significant prostate cancer is still missed in early stage were investigated at the 22nd National SIEUN (Italian Society of integrated diagnostic in Urology, Andrology, Nephrology) congress took place from 30th November to 1st December 2020, in virtual modality. Even if multiparametric magnetic resonance (MR) has been introduced in the clinical practice several, limitations are emerging in patient with regular digital rectal examination (DRE) and serum prostate specific antigen (PSA) levels approaching the normal limits. The present paper summarizes highlights observed in those cases where significant prostate cancer may be missed by PSA or imaging and DRE. The issue of multidisciplinary interest had been subdivided and deepened under four main topics: biochemical, clinical, pathological and radiological point of view with a focus on PI-RADS 3 lesions.

scholarly journals Development of a competitive intelligence maturity model: Insights from Moroccan companies

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Mourad Oubrich ◽  
Abdelati Hakmaoui ◽  
Robert Bierwolf ◽  
Mouna Haddani
Keyword(s):  
Early Stage ◽  
Business Environment ◽  
Point Of View ◽  
Competitive Intelligence ◽  
Maturity Model ◽  
Maturity Level ◽  
World Class ◽  
Model Point ◽  
Research Show ◽  
Do So

This paper aims to assess the maturity level of competitive intelligence (CI) in Moroccan companies, so as to improve theirs practices, and to justify their investment in competitive intelligence. To do so, we have identified the maturity model based on a comprehensive review of recent literature. The objectives of this paper are threefold: (1) to determine the major purposes of a CI maturity model (CIMM), (2) to identify the types of CI dimensions and levels of maturity, (3) to evaluate Moroccan companies in terms of CI practice. Our approach is to develop a conceptual framework of the CI maturity model that articulates (1) dimensions of CI, and (2) maturity levels of CI. We note that little attention has been given in previous research to how CI is actually conducted in Moroccan companies. For this purpose, an empirical study was conducted. The results discuss various perspectives and insights from a competitive intelligence maturity model point of view in the Moroccan context. The results show that the majority of the Moroccan companies are in an early stage of the CI levels, where the CI practice is only to employ environment scanning and the competition in the business environment is not intense. We also note the absence of CI structure at this level. Most of these Moroccan companies are not able to cope with changes in the business environment. The CI systems and processes are released on an irregular basis. This study is the first to investigate the Competitive Intelligence Maturity Model (CIMM) in the Moroccan context. The findings of this research show that there are six CI dimensions (CI culture of an organization; CI deliverables; CI sourcing; CI cycle; CI investment in terms of resources; CI users and CI application) that should be taken into account in CI implementation with regard to the CI level (early, mid, world class).

scholarly journals Transition of Care in Paediatric Surgery: Current practices and perspectives of paediatric surgeons in Malaysia

2019 ◽  
Vol 19 (4) ◽  
pp. 352
Author(s):  
Shung K. Tan ◽  
Anand Sanmugam ◽  
Mahmoud Danaee ◽  
Tindivanam M. Ramanujam ◽  
Mohan A. Nallusamy ◽  
...  
Keyword(s):  
Professional Practice ◽  
Early Stage ◽  
Point Of View ◽  
Transition To Adult Care ◽  
Transition Of Care ◽  
Paediatric Surgery ◽  
Adult Care ◽  
Survey Response Rate ◽  
Surgical Conditions ◽  
Current Practices

Objectives: Transition of care (TOC) from paediatric to adult care is still at an early stage in Malaysia. This study aimed to explore current practices and perspectives regarding TOC among paediatric surgeons in Malaysia. Methods: This study was carried out between June and December 2017. All 48 paediatric surgeons currently working in Malaysia were invited to participate in a questionnaire-based survey to assess demographic characteristics and practices and perspectives regarding TOC. Results: A total of 38 paediatric surgeons participated in the survey (response rate: 79.2%). Overall, 97.4% did not have an organised TOC model in their institution, with most (65.8%) caring for paediatric patients with complex surgical conditions until adulthood. Although the majority (86.8%) felt that care should be transitioned to adult surgeons with appropriate credentials, most surgeons (84.2%) nevertheless preferred to be involved in the management of adolescent patients after transition. However, there was no consensus regarding the most suitable age to begin the transition. Years of experience as a paediatric surgeon and place of practice did not affect overall TOC practice scores (P >0.050 each). The presence of adult comorbidities was considered the most common reason to initiate TOC (81.6%), while the lack of TOC guidelines was perceived to be the greatest barrier (84.2%). Conclusion: This study provides a better understanding of TOC from the point of view of paediatric surgeons in Malaysia. However, further studies involving other stakeholders (i.e. patients and adult surgeons) are needed to help formulate a suitable and successful TOC model in this setting.Keywords: Transition to Adult Care; Pediatrics; Adolescents; Surgery; Attitudes; Professional Practice; Malaysia.

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