Analysis of Failure Mechanisms during Powder Compaction

2007 ◽  
Vol 534-536 ◽  
pp. 237-240 ◽  
Author(s):  
Chuan Yu Wu ◽  
A.C. Bentham ◽  
A. Mills
Keyword(s):  
Early Stage ◽  
Failure Mechanisms ◽  
Shear Bands ◽  
Powder Compaction ◽  
Hydraulic Press ◽  
Practical Significance ◽  
Pharmaceutical Powders ◽  
Pharmaceutical Tablets ◽  
Failure Patterns ◽  
Wide Range

Powder compaction is a well-established process for manufacturing a wide range of products, including engineering components and pharmaceutical tablets. During powder compaction, the compacts (green bodies or tablets) produced need to sustain their integrity during the process and possess certain strength. Any defects are hence not tolerable during the production. Therefore, understanding failure mechanisms during powder compaction is of practical significance. In this paper, the mechanisms for one typical failure, capping, during the compaction of pharmaceutical powders were explored. Both experimental and numerical investigations were performed. For the experimental study, an instrumented hydraulic press (a compaction simulator) with an instrumented die has been used, which enable the material properties to be extracted for real pharmaceutical powders. Close attentions have been paid to the occurrence of capping during the compaction. An X-ray Computed Microtomography system has also used to examine the internal failure patterns of the tablets produced. Finite element (FE) methods have also been used to analyse the powder compaction. The experimental and numerical studies have shown that the shear bands developed at the early stage of unloading appear to be responsible for the occurrence of capping. It has also been found that the capping patterns depend on the compact shape.

Plausible failure mechanisms of wildlife-damaged earth levees: insights from centrifuge modeling and numerical analysis

2017 ◽  
Vol 54 (10) ◽  
pp. 1496-1508 ◽  
Author(s):  
Gholamreza Saghaee ◽  
Ahmad A. Mousa ◽  
Mohamed A. Meguid
Keyword(s):  
Pore Pressure ◽  
Failure Mechanisms ◽  
Hydraulic Gradient ◽  
The Body ◽  
Centrifuge Modeling ◽  
Silty Sand ◽  
Failure Patterns ◽  
Animal Burrows ◽  
Wide Range ◽  
The Impact

Earth levees are subject to a wide range of wildlife intrusion patterns that cause mass removal and subsequent serious deformations. Such invasive activities leave the body of an earth embankment with burrow systems too complex to map and model using conventional techniques. This study investigates the impact of different idealized configurations of animal burrows on the geotechnical performance of levees. For this purpose, centrifuge testing was conducted on homogenous scaled-down 1 horizontal : 1 vertical (1H:1V) levee models built from silty sand material. Modeling involved introducing horizontal cylinder-shaped waterside and landside burrows at different elevations within the levee section. The reference (intact) and deteriorated levee models were subject to a centrifugal acceleration of 35g, which was kept constant as the water level behind the levee model was gradually increased. The deformation profile of the model was tracked, and the crest displacements were concurrently measured. Miniature pore pressure transducers (PPTs) embedded within the levee body provided pore pressure measurements. A three-dimensional finite element model was developed to investigate the hydraulic performance and verify the failure patterns of the deteriorated levees. Compared with an intact levee, the presence of animal intrusions was found to increase the exit hydraulic gradient for both waterside and landside intrusions. Lower animal burrows appeared to cause larger exit gradients than higher ones. Similarly, waterside burrows exhibited a notably higher pore pressure and larger hydraulic gradient. Waterside damage resulted in a quicker and more violent failure than landside burrows. The failure mechanisms for both the waterside and landside burrows are dissimilar despite their similarly abrupt nature.

scholarly journals Photonic Crystal Nanobeam Cavities for Nanoscale Optical Sensing: A Review

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 72 ◽  
Author(s):  
Da-Quan Yang ◽  
Bing Duan ◽  
Xiao Liu ◽  
Ai-Qiang Wang ◽  
Xiao-Gang Li ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Optical Waveguides ◽  
Optical Sensing ◽  
Early Stage ◽  
Disease Diagnosis ◽  
Label Free ◽  
Quality Factors ◽  
Integrated Sensor ◽  
Early Stage Disease ◽  
Wide Range

The ability to detect nanoscale objects is particular crucial for a wide range of applications, such as environmental protection, early-stage disease diagnosis and drug discovery. Photonic crystal nanobeam cavity (PCNC) sensors have attracted great attention due to high-quality factors and small-mode volumes (Q/V) and good on-chip integrability with optical waveguides/circuits. In this review, we focus on nanoscale optical sensing based on PCNC sensors, including ultrahigh figure of merit (FOM) sensing, single nanoparticle trapping, label-free molecule detection and an integrated sensor array for multiplexed sensing. We believe that the PCNC sensors featuring ultracompact footprint, high monolithic integration capability, fast response and ultrahigh sensitivity sensing ability, etc., will provide a promising platform for further developing lab-on-a-chip devices for biosensing and other functionalities.

scholarly journals Non-Albumin Proteinuria (NAP) as a Complementary Marker for Diabetic Kidney Disease (DKD)

Life ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 224
Author(s):  
Jaehyun Bae ◽  
Young Jun Won ◽  
Byung-Wan Lee
Keyword(s):  
Kidney Disease ◽  
Filtration Rate ◽  
Diabetic Kidney Disease ◽  
Estimated Glomerular Filtration Rate ◽  
Early Stage ◽  
Screening Tools ◽  
Tubular Injury ◽  
Current Standard ◽  
Diabetic Kidney ◽  
Wide Range

Diabetic kidney disease (DKD) is one of the most common forms of chronic kidney disease. Its pathogenic mechanism is complex, and it can affect entire structures of the kidney. However, conventional approaches to early stage DKD have focused on changes to the glomerulus. Current standard screening tools for DKD, albuminuria, and estimated glomerular filtration rate are insufficient to reflect early tubular injury. Therefore, many tubular biomarkers have been suggested. Non-albumin proteinuria (NAP) contains a wide range of tubular biomarkers and is convenient to measure. We reviewed the clinical meanings of NAP and its significance as a marker for early stage DKD.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

scholarly journals Contagion Management at the Méditerranée Infection University Hospital Institute

2021 ◽  
Vol 10 (12) ◽  
pp. 2627
Author(s):  
Pierre-Edouard Fournier ◽  
Sophie Edouard ◽  
Nathalie Wurtz ◽  
Justine Raclot ◽  
Marion Bechet ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Early Diagnosis ◽  
Personal Protective Equipment ◽  
Early Stage ◽  
Point Of Care ◽  
University Hospital ◽  
Protective Equipment ◽  
Monitoring Point ◽  
Epidemiological Monitoring ◽  
Wide Range

The Méditerranée Infection University Hospital Institute (IHU) is located in a recent building, which includes experts on a wide range of infectious disease. The IHU strategy is to develop innovative tools, including epidemiological monitoring, point-of-care laboratories, and the ability to mass screen the population. In this study, we review the strategy and guidelines proposed by the IHU and its application to the COVID-19 pandemic and summarise the various challenges it raises. Early diagnosis enables contagious patients to be isolated and treatment to be initiated at an early stage to reduce the microbial load and contagiousness. In the context of the COVID-19 pandemic, we had to deal with a shortage of personal protective equipment and reagents and a massive influx of patients. Between 27 January 2020 and 5 January 2021, 434,925 nasopharyngeal samples were tested for the presence of SARS-CoV-2. Of them, 12,055 patients with COVID-19 were followed up in our out-patient clinic, and 1888 patients were hospitalised in the Institute. By constantly adapting our strategy to the ongoing situation, the IHU has succeeded in expanding and upgrading its equipment and improving circuits and flows to better manage infected patients.

scholarly journals Design of Personalized Devices—The Tradeoff between Individual Value and Personalization Workload

2020 ◽  
Vol 11 (1) ◽  
pp. 241
Author(s):  
Juliane Kuhl ◽  
Andreas Ding ◽  
Ngoc Tuan Ngo ◽  
Andres Braschkat ◽  
Jens Fiehler ◽  
...  
Keyword(s):  
Customer Value ◽  
Early Stage ◽  
Treatment Success ◽  
Product Family ◽  
Flow Diverter ◽  
New Method ◽  
Product Families ◽  
Wide Range ◽  
The Individual ◽  
Individual Value

Personalized medical devices adapted to the anatomy of the individual promise greater treatment success for patients, thus increasing the individual value of the product. In order to cater to individual adaptations, however, medical device companies need to be able to handle a wide range of internal processes and components. These are here referred to collectively as the personalization workload. Consequently, support is required in order to evaluate how best to target product personalization. Since the approaches presented in the literature are not able to sufficiently meet this demand, this paper introduces a new method that can be used to define an appropriate variety level for a product family taking into account standardized, variant, and personalized attributes. The new method enables the identification and evaluation of personalizable attributes within an existing product family. The method is based on established steps and tools from the field of variant-oriented product design, and is applied using a flow diverter—an implant for the treatment of aneurysm diseases—as an example product. The personalization relevance and adaptation workload for the product characteristics that constitute the differentiating product properties were analyzed and compared in order to determine a tradeoff between customer value and personalization workload. This will consequently help companies to employ targeted, deliberate personalization when designing their product families by enabling them to factor variety-induced complexity and customer value into their thinking at an early stage, thus allowing them to critically evaluate a personalization project.

scholarly journals Integration of early disease-resistance phenotyping, histological characterization, and transcriptome sequencing reveals insights into downy mildew resistance in impatiens

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ze Peng ◽  
Yanhong He ◽  
Saroj Parajuli ◽  
Qian You ◽  
Weining Wang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Transcriptome Sequencing ◽  
Early Stage ◽  
Economic Losses ◽  
Potential Candidate ◽  
Early Disease ◽  
True Leaf ◽  
Cotyledon Stage ◽  
Wide Range

AbstractDowny mildew (DM), caused by obligate parasitic oomycetes, is a destructive disease for a wide range of crops worldwide. Recent outbreaks of impatiens downy mildew (IDM) in many countries have caused huge economic losses. A system to reveal plant–pathogen interactions in the early stage of infection and quickly assess resistance/susceptibility of plants to DM is desired. In this study, we established an early and rapid system to achieve these goals using impatiens as a model. Thirty-two cultivars of Impatiens walleriana and I. hawkeri were evaluated for their responses to IDM at cotyledon, first/second pair of true leaf, and mature plant stages. All I. walleriana cultivars were highly susceptible to IDM. While all I. hawkeri cultivars were resistant to IDM starting at the first true leaf stage, many (14/16) were susceptible to IDM at the cotyledon stage. Two cultivars showed resistance even at the cotyledon stage. Histological characterization showed that the resistance mechanism of the I. hawkeri cultivars resembles that in grapevine and type II resistance in sunflower. By integrating full-length transcriptome sequencing (Iso-Seq) and RNA-Seq, we constructed the first reference transcriptome for Impatiens comprised of 48,758 sequences with an N50 length of 2060 bp. Comparative transcriptome and qRT-PCR analyses revealed strong candidate genes for IDM resistance, including three resistance genes orthologous to the sunflower gene RGC203, a potential candidate associated with DM resistance. Our approach of integrating early disease-resistance phenotyping, histological characterization, and transcriptome analysis lay a solid foundation to improve DM resistance in impatiens and may provide a model for other crops.

scholarly journals Early Dropout Prediction in MOOCs through Supervised Learning and Hyperparameter Optimization

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1701
Author(s):  
Theodor Panagiotakopoulos ◽  
Sotiris Kotsiantis ◽  
Georgios Kostopoulos ◽  
Omiros Iatrellis ◽  
Achilles Kameas
Keyword(s):  
Online Education ◽  
Online Courses ◽  
Early Stage ◽  
Activity Patterns ◽  
Daily Basis ◽  
Machine Learning Algorithms ◽  
Supervised Machine Learning ◽  
Educational Institutions ◽  
Student Dropout ◽  
Wide Range

Over recent years, massive open online courses (MOOCs) have gained increasing popularity in the field of online education. Students with different needs and learning specificities are able to attend a wide range of specialized online courses offered by universities and educational institutions. As a result, large amounts of data regarding students’ demographic characteristics, activity patterns, and learning performances are generated and stored in institutional repositories on a daily basis. Unfortunately, a key issue in MOOCs is low completion rates, which directly affect student success. Therefore, it is of utmost importance for educational institutions and faculty members to find more effective practices and reduce non-completer ratios. In this context, the main purpose of the present study is to employ a plethora of state-of-the-art supervised machine learning algorithms for predicting student dropout in a MOOC for smart city professionals at an early stage. The experimental results show that accuracy exceeds 96% based on data collected during the first week of the course, thus enabling effective intervention strategies and support actions.

scholarly journals Imaging features and differential diagnoses of non-neoplastic diffuse mediastinal diseases

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Flavian Tabotta ◽  
Gilbert R. Ferretti ◽  
Helmut Prosch ◽  
Samia Boussouar ◽  
Anne-Laure Brun ◽  
...  
Keyword(s):  
Early Stage ◽  
Specific Treatment ◽  
Imaging Features ◽  
Mediastinal Diseases ◽  
Pictorial Review ◽  
Wide Range ◽  
Chest X Ray ◽  
Delayed Recognition ◽  
Patient’S History ◽  
Contiguous Spread

Abstract Acute or chronic non-neoplastic diffuse mediastinal diseases have multiple causes, degrees of severity, and a wide range of management. Some situations require emergency care while others do not need specific treatment. Although the diagnosis may be suspected on chest X-ray, it is mainly based on CT. A delayed recognition is not uncommonly observed. Some findings may prompt the radiologist to look for specific associated injuries or lesions. This pictorial review will successively describe the various non-neoplastic causes of diffuse mediastinal diseases with their typical findings and major differentials. First, pneumomediastinum that can be provoked by extra- or intra-thoracic triggers requires the knowledge of patient’s history or recent occurrences. Absence of any usual etiological factor should raise suspicion of cocaine inhalation in young individuals. Next, acute mediastinitis may be related to post-operative complications, esophageal perforation, or contiguous spread of odontogenic or retropharyngeal infections. The former diagnosis is not an easy task in the early stage, owing to the similarities of imaging findings with those of normal post-operative appearance during the first 2–3 weeks. Finally, fibrosing mediastinitis that is linked to an excessive fibrotic reaction in the mediastinum with variable compromise of mediastinal structures, in particular vascular and airway ones. Differential diagnosis includes tumoral and inflammatory infiltrations of the mediastinum.

scholarly journals Glossary and tutorial of xenobiotic metabolism terms used during small molecule drug discovery and development (IUPAC Technical Report)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Paul Erhardt ◽  
Kenneth Bachmann ◽  
Donald Birkett ◽  
Michael Boberg ◽  
Nicholas Bodor ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Small Molecule ◽  
Chemical Structure ◽  
Early Stage ◽  
Xenobiotic Metabolism ◽  
Drug Discovery And Development ◽  
Small Molecule Drug ◽  
Technical Report ◽  
Wide Range ◽  
Draft Version

Abstract This project originated more than 15 years ago with the intent to produce a glossary of drug metabolism terms having definitions especially applicable for use by practicing medicinal chemists. A first-draft version underwent extensive beta-testing that, fortuitously, engaged international audiences in a wide range of disciplines involved in drug discovery and development. It became clear that the inclusion of information to enhance discussions among this mix of participants would be even more valuable. The present version retains a chemical structure theme while expanding tutorial comments that aim to bridge the various perspectives that may arise during interdisciplinary communications about a given term. This glossary is intended to be educational for early stage researchers, as well as useful for investigators at various levels who participate on today’s highly multidisciplinary, collaborative small molecule drug discovery teams.

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