Global modeling of the SiC sublimation growth process: prediction of thermoelastic stress and control of growth conditions

2001 ◽  
Vol 226 (4) ◽  
pp. 501-510 ◽  
Author(s):  
M Selder ◽  
L Kadinski ◽  
F Durst ◽  
D Hofmann
Keyword(s):  
Growth Process ◽  
Thermoelastic Stress ◽  
Growth Conditions ◽  
Global Modeling ◽  
Process Prediction ◽  
And Control ◽  
Sublimation Growth

Characterization and Control of Erwinia spp. and Pluralibacter sp. in Tuna Salad Preparations

2019 ◽  
Vol 82 (6) ◽  
pp. 1071-1081
Author(s):  
KRISTIN BJORNSDOTTIR-BUTLER ◽  
SUSAN McCARTHY ◽  
RONALD A. BENNER
Keyword(s):  
Growth Conditions ◽  
Whole Genome ◽  
Processing Conditions ◽  
Optimum Growth ◽  
Significant Growth ◽  
Ph Values ◽  
Histamine Production ◽  
Different Temperatures ◽  
And Control ◽  
Erwinia Persicina

ABSTRACT Histamine-producing Erwinia and Pluralibacter spp. capable of producing toxic histamine levels were isolated from ingredients commonly used in tuna salad preparations. The characterization and control of these histamine-producing bacteria are necessary to prevent illness from tuna salad consumption. We confirmed the identity of two Erwinia spp. and one Pluralibacter sp. previously isolated from tuna salad ingredients through whole genome sequencing and phylogenic analysis and characterized them for growth and histamine production at different temperatures, pH values, and salt concentrations. In addition, we examined the effects of dried vinegar (DV) powder on growth and histamine production of these strains in inoculated tuna salad preparations. Optimum growth temperatures in tryptic soy broth (TSB) for the two Erwinia spp. and one Pluralibacter sp. were 30.1, 31.1, and 33.9°C, respectively, and growth in TSB was observed at 5°C for both genera. Optimum histamine production of Erwinia persicina, Erwinia spp., and Pluralibacter spp. in TSB with histidine occurred from 25 to 30°C, pH 4 to 6, and 0 to 4% NaCl. No significant growth or histamine production was observed in tuna salad preparations stored at 4°C. Growth and histamine production by Erwinia or Pluralibacter spp. was inhibited in tuna salad containing celery and onion and 2% DV, whereas significant growth and histamine production occurred in tuna salad without DV. Understanding optimum growth conditions and histamine production can provide guidance to tuna salad manufacturers in formulating products and adjusting processing conditions that minimize hazards from these histamine-producing bacteria. Addition of 2% DV to tuna salad preparations may prevent histamine production in the event of temperature abuse. HIGHLIGHTS

scholarly journals Screening of Highly Expressed Mycobacterial Genes Identifies Rv3615c as a Useful Differential Diagnostic Antigen for the Mycobacterium tuberculosis Complex

2008 ◽  
Vol 76 (9) ◽  
pp. 3932-3939 ◽  
Author(s):  
Ben Sidders ◽  
Chris Pirson ◽  
Philip J. Hogarth ◽  
R. Glyn Hewinson ◽  
Neil G. Stoker ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Significant Proportion ◽  
Growth Conditions ◽  
Control Measures ◽  
Human Populations ◽  
Infected Cattle ◽  
Ifn Γ ◽  
Mycobacterial Antigens ◽  
And Control ◽  
Differential Antigens

ABSTRACT Tuberculous infections caused by mycobacteria, especially tuberculosis of humans and cattle, are important both clinically and economically. Human populations can be vaccinated with Mycobacterium bovis bacille Calmette-Guérin (BCG), and control measures for cattle involving vaccination are now being actively considered. However, diagnostic tests based on tuberculin cannot distinguish between genuine infection and vaccination with BCG. Therefore, identification of differential diagnostic antigens capable of making this distinction is required, and until now sequence-based approaches have been predominant. Here we explored the link between antigenicity and mRNA expression level, as well as the possibility that we may be able to detect differential antigens by analyzing quantified global transcriptional profiles. We generated a list of 14 candidate antigens that are highly expressed in Mycobacterium tuberculosis and M. bovis under a variety of growth conditions. These candidates were screened in M. bovis-infected and naïve cattle for the ability to stimulate a gamma interferon (IFN-γ) response. We identified one antigen, Rv3615c, which stimulated IFN-γ responses in a significant proportion of M. bovis-infected cattle (11 of 30 cattle [37%] [P < 0.01]) but not in naïve or BCG-vaccinated animals. Importantly, the same antigen stimulated IFN-γ responses in a significant proportion of infected cattle that did not respond to the well-characterized mycobacterial antigens ESAT-6 and CFP-10. Therefore, use of the Rv3615c epitope in combination with previously described differential tests based on ESAT-6 and CFP-10 has the potential to significantly increase diagnostic sensitivity without reducing specificity in BCG-vaccinated populations.

Growth and Characterization of 2″ 6H-Silicon Carbide

1999 ◽  
Vol 572 ◽  
Author(s):  
Erwin Schmitt ◽  
Robert Eckstein ◽  
Martin Kölbl ◽  
Amd-Dietrich Weber
Keyword(s):  
Silicon Carbide ◽  
Boundary Conditions ◽  
Growth Process ◽  
Defect Density ◽  
Crystal Quality ◽  
Process Conditions ◽  
Thermal Boundary Conditions ◽  
Sublimation Growth ◽  
Defect Densities

ABSTRACTFor the growth of 2″ 6H-SiC a sublimation growth process was developed. By different means of characterization crystal quality was evaluated. Higher defect densities, mainly in the periphery of the crystals were found to be correlated to unfavourable process conditions. Improvement of thermal boundary conditions lead to a decreased defect density and better homogeneity over the wafer area.

Modelling and control of greenhouse system using neural networks

2016 ◽  
Vol 40 (3) ◽  
pp. 918-929 ◽  
Author(s):  
A Manonmani ◽  
T Thyagarajan ◽  
M Elango ◽  
S Sutha
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Moving Average ◽  
Growth Conditions ◽  
Operating Conditions ◽  
Adverse Weather ◽  
Control Schemes ◽  
Non Linear ◽  
Auto Regressive ◽  
And Control

A greenhouse system (GHS) is a closed structure that facilitates modified growth conditions to crops and provides protection from pests, diseases and adverse weather. However, a GHS exhibits non-linearity due to the interaction between the biological subsystem and the physical subsystem. Non-linear systems are difficult to control, particularly when their characteristics change with time. These systems are best handled with methods of computation intelligence, such as artificial neural networks (ANNs) and fuzzy systems. In the present work, the approximation capability of a neural network is used to model and control sufficient growth conditions of a GHS. An optimal neural network-based non-linear auto regressive with exogenous input (NARX) time series model is developed for a GHS. Based on the NARX model, two intelligent control schemes, namely a neural predictive controller (NPC) and non-linear auto regressive moving average (NARMA-L2) controller are proposed to achieve the desired growth conditions such as humidity and temperature for a better yield. Finally, closed-loop performances of the above two control schemes for servo and regulatory operations are analysed for various operating conditions using performance indices.

scholarly journals Macrodefects in Cubic Silicon Carbide Crystals

2010 ◽  
Vol 645-648 ◽  
pp. 375-378 ◽  
Author(s):  
Valdas Jokubavicius ◽  
Justinas Palisaitis ◽  
Remigijus Vasiliauskas ◽  
Rositza Yakimova ◽  
Mikael Syväjärvi
Keyword(s):  
Growth Rate ◽  
Silicon Carbide ◽  
Crystal Growth ◽  
High Temperature ◽  
Temperature Gradient ◽  
Early Stage ◽  
Growth Conditions ◽  
Temperature Ramp ◽  
Cubic Silicon Carbide ◽  
Sublimation Growth

Different sublimation growth conditions of 3C-SiC approaching a bulk process have been investigated with the focus on appearance of macrodefects. The growth rate of 3C-SiC crystals grown on 6H-SiC varied from 380 to 460 μm/h with the thickness of the crystals from 190 to 230 μm, respectively. The formation of macrodefects with void character was revealed at the early stage of 3C-SiC crystal growth. The highest concentration of macrodefects appears in the vicinity of the domain in samples grown under high temperature gradient and fastest temperature ramp up. The formation of macrodefects was related to carbon deficiency which appear due to high Si/C ratio which is used to enable formation of the 3C-SiC polytype.

scholarly journals Current status of GaN crystal growth by sublimation sandwich technique

1998 ◽  
Vol 3 ◽  
Author(s):  
P. G. Baranov ◽  
E. N. Mokhov ◽  
A. O. Ostroumov ◽  
M. G. Ramm ◽  
M. S. Ramm ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
Current Status ◽  
Gaseous Species ◽  
Double Crystal ◽  
Paramagnetic Resonance ◽  
Sandwich Technique ◽  
Microscopy Technique ◽  
Gan Crystal

The current status of GaN crystal growth using the Sublimation Sandwich Technique is discussed in the paper. We use modeling to analyze gas dynamics in the reactor and the supply of the main gaseous species into the growth cell under growth conditions used in experiments. Important features of growth process — non-equilibrium cracking of ammonia, partial sticking of ammonia at the growing surface and kinetic limitation of GaN thermal decomposition — are taken into account in the model. Growth is carried out on sapphire and 6H-SiC substrates in ammonia atmosphere using a Ga/GaN mixture as the group-III element source. Single crystals of GaN of size 15×15 mm and up to 0.5 mm thick are normally grown with the optimized growth rates of 0.25-0.35 mm/h. The GaN crystals are characterized by photoluminescence, by the Color Cathodoluminescence Scanning Electron Microscopy technique, by differential double-crystal and triple-crystal X-ray diffractometry, and by electron paramagnetic resonance. Mechanisms of sublimation growth of GaN and physical limitations of the growth process are discussed.

Recursive Characteristics of a Running-in Attractor in a Ring-on-Disk Tribosystem

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Cong Ding ◽  
Hua Zhu ◽  
Yu Jiang ◽  
Guodong Sun ◽  
Chunling Wei
Keyword(s):  
Dimensional Space ◽  
Recurrence Plot ◽  
Dynamic Features ◽  
Wear Process ◽  
Friction Noise ◽  
State Identification ◽  
Prediction And Control ◽  
Homogeneous Pattern ◽  
Process Prediction ◽  
And Control

To explore the recursive characteristics of a running-in attractor, recurrence plot (RP) and recursive parameters are used to investigate the dynamic features of the structure. The running-in attractor is constructed based on friction noise signals generated from the ring-on-disk wear experiments. The RPs of the running-in attractor are then reproduced in a two-dimensional space. Recursive parameters, recurrence rate (RR), entropy (ENTR), and trend of recurrence (RT) are calculated. Results show that the RP evolves from a disrupted pattern to a homogeneous pattern and then returns to a disrupted pattern in the entire wear process, corresponding to the “formation–stabilization–disappearance” stage of the running-in attractor. The RR and ENTR of the running-in attractor sharply increase at first, remain steady, and then sharply decrease. Moreover, the inclination of RT in the normal wear process is smaller than those in the other two processes. This observation reveals that the running-in attractor exhibits high stability and complexity. This finding may contribute to the running-in state identification, process prediction, and control.

On Stabilization of 3C-SiC Using Low Off-Axis 6H-SiC Substrates

2012 ◽  
Vol 717-720 ◽  
pp. 193-196 ◽  
Author(s):  
Valdas Jokubavicius ◽  
Björn Lundqvist ◽  
Philip Hens ◽  
Rickard Liljedahl ◽  
Rositza Yakimova ◽  
...  
Keyword(s):  
Growth Temperature ◽  
Growth Process ◽  
High Growth ◽  
Potential Method ◽  
High Growth Rate ◽  
Heteroepitaxial Growth ◽  
Bulk Properties ◽  
Combined Use ◽  
Sublimation Growth

Heteroepitaxial growth of 3C-SiC on 0.8 and 1.2 degree off-oriented 6H-SiC substrates was studied using a sublimation growth process. The 3C-SiC layers were grown at high growth rates with layer thickness up to 300 µm. The formation and the quality of 3C-SiC are influenced by the off-orientation of the substrate, the growth temperature (studied temperature range from 1750 °C to 1850°C), and the growth ambient (vacuum at 5*10-5mbar and nitrogen at 5*10-1mbar). The largest domains of 3C-SiC and the lowest number of double positioning boundaries were grown using nitrogen ambient and the highest growth temperature. The combined use of low off-axis substrate and high growth rate is a potential method to obtain material with bulk properties.

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