Development of SVM rapid prototyping for scaffold fabrication

2014 ◽  
Vol 20 (2) ◽  
pp. 90-104 ◽  
Author(s):  
Thittikorn Phattanaphibul ◽  
Pisut Koomsap ◽  
Irwansyah Idram ◽  
Suchart Nachaisit
Keyword(s):  
Soft Tissue ◽  
Rapid Prototyping ◽  
Process Parameters ◽  
Tissue Growth ◽  
Dense Layer ◽  
Cytotoxicity Test ◽  
Support Material ◽  
Scaffold Fabrication ◽  
Content Type ◽  
Rp Technique

Purpose – This paper aims to introduce selective vacuum manufacturing (SVM), a powder-based rapid prototyping (RP) technique, and the ongoing development to improve its capability to apply in temporary scaffold fabrication. Design/methodology/approach – SVM employs a combination of sand casting and powder sintering process to construct a prototype layer by layer. A dense layer of support material is prepared and selectively removed to create a cavity where part material is filled and sintered to form a solid layer. In order for SVM to be considered for scaffold fabrication, besides preparing poly-lactic acid (PLA) for part material, support material preparation and process parameters identification have been studied. Redesigning of SVM machine to be more suitable for the real usage has also been presented. Findings – Particle size of salt has been controlled, and its suitable composition with flour and water has been determined. Process parameters have been identified to scale down the size of scaffolds to meso-scale and to achieve mechanical requirement. Properties of fabricated scaffolds have been enhanced and can be used for soft tissue applications. A prototype of the medical SVM machine has been constructed and tested. An examination of scaffolds fabricated on this new machine also showed their qualification for soft tissue application. Research limitations/implications – Further study will be on conducting a direct cytotoxicity test to provide the evidence for tissue growth before the clinical usage, on continuing to scaling down the scaffold size, and on improving SVM to meet the requirement of hard tissue. Originality/value – This simple, inexpensive RP technique demonstrates its viability for scaffold fabrication.

Process parameters optimization for area-forming rapid prototyping system

2015 ◽  
Vol 21 (1) ◽  
pp. 70-78
Author(s):  
Shih-Hsuan Chiu ◽  
Kun-Ting Chen ◽  
Sigit Tri Wicaksono ◽  
Jia-Rung Tsai ◽  
Sheng-Hong Pong
Keyword(s):  
Rapid Prototyping ◽  
Factorial Design ◽  
Process Parameters ◽  
Fractional Factorial Design ◽  
Fractional Factorial ◽  
Process Time ◽  
Content Type ◽  
Rapid Prototyping System ◽  
Significant Factors ◽  
Response Variables

Purpose – The aim of this study is to optimize the process parameters of area-forming rapid prototyping system to improve the model dimensional repeatability and to minimize the process time as well. Design/methodology/approach – Model dimensional repeatability is based on the dimensional standard deviation of the test sample. The significant factors that affect the model dimensional repeatability and process time are established by the fractional factorial design. Response surface methodology, based on the central composite design, is applied to evaluate the regression models of the response variables including prototype’s dimensional repeatability and processing time. Finally, a desirability function for each individual response variables is constructed to obtain the optimal process parameters. Findings – The significant factors that have an impact on the main effects of response variables model dimensional repeatability and process time found by the fractional factorial design are curing time, light flux and platform moving velocity. Originality/value – All previous studies were concerned with product accuracy in area-forming rapid prototyping system. In this work, we focus on optimization of model dimensional repeatability.

Investigating the friction coefficient in functionally graded rapid prototyping of Al–Al2O3 composite prepared by fused deposition modelling

2017 ◽  
Vol 37 (2) ◽  
pp. 154-161
Author(s):  
Rupinder Singh ◽  
Sunpreet Singh
Keyword(s):  
Friction Coefficient ◽  
Rapid Prototyping ◽  
Process Parameters ◽  
Research Work ◽  
Functionally Graded ◽  
Fused Deposition Modelling ◽  
Melt Flow ◽  
Content Type ◽  
Fused Deposition ◽  
Graded Material

Purpose The present research work aims to study the friction coefficient in functionally graded rapid prototyping of Al–Al2O3 composite prepared via fused deposition modelling (FDM)-assisted investment casting (IC) process. The optimized settings of the process parameters (namely, filament proportion, volume of FDM pattern, density of FDM pattern, barrel finishing (BF) time, BF media weight and number of IC slurry layers) suggested in the present research work will help fabricate parts possessing higher frictional coefficient. Design/methodology/approach Initially, melt flow index (MFI) of two different proportions of Nylon6-Al–Al2O3 (to be used as an alternative FDM filament material) was tested on the melt flow indexer and matched with MFI of commercially used acrylonitrile–butadiene–styrene filament. After this, the selected proportions of Nylon6-Al–Al2O3 were prepared in the form of the FDM filament by using a single screw extruder. Further, this FDM filament has been used for developing sacrificial IC patterns in the existing FDM system which was barely finished to improve their surface finish. Castings developed were tested for their wear resistance properties on a pin-on-disc-type tribo-tester under dry conditions at sliding conditions to check their suitability as a frictional device for industrial applications. In the methodology part, Taguchi L18 orthogonal array was used to study the effect of selected process variables on the coefficient of friction (μ). Findings It has been found that filament proportion, volume of FDM pattern and density of FDM pattern have significantly affected the μ-values. Further, density of the FDM pattern was found to have 91.62 per cent contribution in obtaining μ-values. Scanning electron micrographs highlighted uniform distribution of Al2O3 particles in the Al-matrix at suggested optimized settings. Practical implications The present methodology shows the development of a functional graded material that consisted of surface reinforcement with Al2O3 particles, which could have applications for manufacturing friction surfaces such as clutch plates, brake drum, etc. Originality/value This paper describes the effect of process parameters on wear properties of the Al–Al2O3 composite developed as a functionally graded material by the FDM-based pattern in the IC process.

scholarly journals Abscess or Tumor? When a Retroperitoneal Mass on Computerized Tomography Turns Out to Be a Rare Soft Tissue Growth

2021 ◽  
pp. 1025-1030
Author(s):  
Ilya Noginskiy ◽  
Neil Nimkar ◽  
Madhumati R. Kalavar
Keyword(s):  
Soft Tissue ◽  
Clinical Response ◽  
Computerized Tomography ◽  
Symptomatic Patient ◽  
Tissue Growth ◽  
Rare Tumor ◽  
Retroperitoneal Mass ◽  
Elderly Female ◽  
Desmoid Fibromatosis ◽  
Tomography Scan

A retroperitoneal finding on a computerized tomography scan, in a symptomatic patient, can harbor the clinician to many differential diagnoses from infectious to malignancy. Desmoid fibromatosis (DF), a relatively innocuous mass that can spread locally, can be found in that anatomical region. Even for a rare tumor such as DF, our patient did not meet the usual benchmarks of this cancer, being an elderly female and having it appear as an abscess radiologically. Timely clinical response with radiotherapy and tamoxifen allowed our patient’s DF to regress and resolved her symptoms.

scholarly journals Role of Antibodies in Protection Elicited by Active Vaccination with Genetically Inactivated Alpha Hemolysin in a Mouse Model of Staphylococcus aureus Skin and Soft Tissue Infections

2014 ◽  
Vol 21 (5) ◽  
pp. 622-627 ◽  
Author(s):  
Christopher P. Mocca ◽  
Rebecca A. Brady ◽  
Drusilla L. Burns
Keyword(s):  
Staphylococcus Aureus ◽  
Soft Tissue ◽  
Murine Model ◽  
Bacterial Colonization ◽  
Passive Immunization ◽  
The United States ◽  
Soft Tissue Infections ◽  
Content Type ◽  
Alpha Hemolysin ◽  
Active Vaccination

ABSTRACTDue to the emergence of highly virulent community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) infections,S. aureushas become a major threat to public health. A majority of CA-MRSA skin and soft tissue infections in the United States are caused byS. aureusUSA300 strains that are known to produce high levels of alpha hemolysin (Hla). Therefore, vaccines that contain inactivated forms of this toxin are currently being developed. In this study, we sought to determine the immune mechanisms of protection for this antigen using a vaccine composed of a genetically inactivated form of Hla (HlaH35L). Using a murine model of skin and soft tissue infections (SSTI), we found that BALB/c mice were protected by vaccination with HlaH35L; however, Jh mice, which are deficient in mature B lymphocytes and lack IgM and IgG in their serum, were not protected. Passive immunization with anti-HlaH35L antibodies conferred protection against bacterial colonization. Moreover, we found a positive correlation between the total antibody concentration induced by active vaccination and reduced bacterial levels. Animals that developed detectable neutralizing antibody titers after active vaccination were significantly protected from infection. These data demonstrate that antibodies to Hla represent the major mechanism of protection afforded by active vaccination with inactivated Hla in this murine model of SSTI, and in this disease model, antibody levels correlate with protection. These results provide important information for the future development and evaluation ofS. aureusvaccines.

The mechanism of process parameters influencing the AlSi10Mg side surface quality fabricated via laser powder bed fusion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shimin Dai ◽  
Hailong Liao ◽  
Haihong Zhu ◽  
Xiaoyan Zeng
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Process Parameters ◽  
Laser Power ◽  
Side Surface ◽  
Laser Powder Bed Fusion ◽  
Scanning Velocity ◽  
Content Type ◽  
Powder Bed

Purpose For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is generally adopted at the parts’ outline to enhance the side surface quality. However, the side surface roughness (Ra) is still larger than 10 microns even with contour in previous studies. The purpose of this paper is to study the influence of contour process parameters, laser power and scanning velocity on the side surface quality of the AlSi10Mg sample. Design/methodology/approach Using L-PBF technology to manufacture AlSi10Mg samples under different contour process parameters, use a laser confocal microscope to capture the surface information of the samples, and obtain the surface roughness Ra and the maximum surface height Rz of each sample after analysis and processing. Findings The results show that the side surface roughness decreases with the increase of the laser power at the fixed scanning velocity of 1,000 mm/s, the side surface roughness Ra stays within the error range as the contour velocity increases. It is found that the Ra increases with the scanning velocity increasing and the greater the laser power with the greater Ra increases when the laser power of contour process parameters is 300 W, 350 W and 400 W. The Rz maintain growth with the contour scanning velocity increasing at constant laser power. The continuous uniform contour covers the pores in the molten pool of the sample edge and thus increase the density of the sample. Two mechanisms named “Active adhesion” and “Passive adhesion” cause sticky powder. Originality/value Formation of a uniform and even contour track is key to obtain the good side surface quality. The side surface quality is determined by the uniformity and stability of the contour track when the layer thickness is fixed. These research results can provide helpful guidance to improve the surface quality of L-PBF manufactured parts.

The role of Staphylococcus lugdunensis as a pathogen in children: a multicentre retrospective study

2021 ◽  
Vol 70 (5) ◽  
Author(s):  
Noa Hurvitz ◽  
Lea Ohana Sarna Cahan ◽  
Itai Gross ◽  
Daniel Grupel ◽  
Orli Megged ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Blood Culture ◽  
Otitis Media ◽  
Paediatric Population ◽  
Blood Stream ◽  
Staphylococcus Lugdunensis ◽  
Content Type ◽  
Link Type ◽  
Putative Role

Introduction: Staphylococcus lugdunensis (SL), a tube coagulase negative Staphylococcus , is known to be pathogenic in adults, causing mainly skin infections. Gap Statement: Previous studies assessing SL's role in paediatric populations are sparse and are mainly limited to case reports. Aim: Present the clinical characteristics consistent with SL infections and its putative role as a pathogen in the paediatric population. Methodology: A retrospective multicentre study was conducted in four paediatric medical centres in Israel. Patients with isolates of SL presenting between 2009–2019 were included. Results: SL was isolated from 40 patients. Average (±SD) age at presentation was 5.9 (±6.2) years, with 22 (55 %) being female. Skin, soft tissue and musculoskeletal infections were the most common (n=20, 50%) followed by ear infections (n=13, 32.5%). Five cases of urine isolates and two isolates from blood culture samples were also reported. Skin abscess was the most common infection among skin and soft tissue isolates, reported in 17 children (85%) with SL being the only pathogen in 15 (75%). Otitis media was the most common ear infection accounting for 12 (92%) of all cases with SL as the only isolate reported in 6 (46%). Five cases of SL isolates from urine specimens were reported, all of which with poor growth of bacteria and normal urinalysis. Two cases of SL growth in blood culture were found in children presenting with signs and symptoms consistent with invasive blood stream infection. Conclusions: In the paediatric population, studied infections caused by SL are increasingly observed. The results of this study highlight its role as a pathogen in soft tissue infections and its putative role in otitis media and invasive blood stream infections. However, the role of SL as an uropathogen was not established.

Study Regarding the Influence of the Printing Orientation Angle on the Mechanical Behavior of Parts Manufactured by Material Jetting

2021 ◽  
Vol 58 (3) ◽  
pp. 198-209
Author(s):  
Vasile Cojocaru ◽  
Doina Frunzaverde ◽  
Dorian Nedelcu ◽  
Calin-Octavian Miclosina ◽  
Gabriela Marginean
Keyword(s):  
Additive Manufacturing ◽  
Rapid Prototyping ◽  
Tensile Test ◽  
Mechanical Behavior ◽  
Process Parameters ◽  
Orientation Angle ◽  
Tensile Tests ◽  
Anisotropic Behavior ◽  
Optimization Of Process Parameters ◽  
Printed Materials

Initially developed as a rapid prototyping tool for project visualization and validation, the recent development of additive manufacturing (AM) technologies has led to the transition from rapid prototyping to rapid manufacturing. As a consequence, increased attention has to be paid to the mechanical, chemical and physical properties of the printed materials. In mechanical engineering, the widespread use of AM technologies requires the optimization of process parameters and material properties in order to obtain components with high, repeatable and time-stable mechanical properties. One of the main problems in this regard is the anisotropic behavior of components made by additive manufacturing, determined by the type of material, the 3D printing technology, the process parameters and the position of the components in the printing space. In this paper the influence of the printing orientation angle on the tensile behavior of specimens made by material jetting is investigated. The aim was to determine if the positioning of components at different angles relative to the X-axis of the printer (and implicitly in relation to the multijet printing head) contributes to anisotropic behavior. The material used was a photopolymer with a mechanical strength between 40 MPa and 55 MPa, according to the producer. Four sets of tensile test specimens were manufactured, using flat build orientation and positioned on the printing table at angles of 0˚, 30˚, 60˚ and 90˚ to the X-axis of the printer. Comparative analysis of the mechanical behavior was carried out by tensile tests and microscopic investigations of the tensile test specimens fracture surfaces.

scholarly journals Protection againstStaphylococcus aureusColonization and Infection by B- and T-Cell-Mediated Mechanisms

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Fan Zhang ◽  
Olivia Ledue ◽  
Maria Jun ◽  
Cibelly Goulart ◽  
Richard Malley ◽  
...  
Keyword(s):  
T Cell ◽  
Soft Tissue ◽  
Bacterial Infections ◽  
Vaccine Development ◽  
Pathological Condition ◽  
Treatment Options ◽  
Immune Defense ◽  
Invasive Infection ◽  
Content Type ◽  
Increased Risk

ABSTRACTStaphylococcus aureusis a major cause of morbidity and mortality worldwide.S. aureuscolonizes 20 to 80% of humans at any one time and causes a variety of illnesses. Strains that are resistant to common antibiotics further complicate management.S. aureusvaccine development has been unsuccessful so far, largely due to the incomplete understanding of the mechanisms of protection against this pathogen. Here, we studied the role of different aspects of adaptive immunity induced by anS. aureusvaccine in protection againstS. aureusbacteremia, dermonecrosis, skin abscess, and gastrointestinal (GI) colonization. We show that, depending on the challenge model, the contributions of vaccine-inducedS. aureus-specific antibody and Th1 and Th17 responses to protection are different: antibodies play a major role in reducing mortality duringS. aureusbacteremia, whereas Th1 or Th17 responses are essential for prevention ofS. aureusskin abscesses and the clearance of bacteria from the GI tract. Both antibody- and T-cell-mediated mechanisms contribute to prevention ofS. aureusdermonecrosis. Engagement of all three immune pathways results in the most robust protection under each pathological condition. Therefore, our results suggest that eliciting multipronged humoral and cellular responses toS. aureusantigens may be critical to achieve effective and comprehensive immune defense against this pathogen.IMPORTANCES. aureusis a leading cause of healthcare- and community-associated bacterial infections.S. aureuscauses various illnesses, including bacteremia, meningitis, endocarditis, pneumonia, osteomyelitis, sepsis, and skin and soft tissue infections.S. aureuscolonizes between 20 and 80% of humans; carriers are at increased risk for infection and transmission to others. The spread of multidrug-resistant strains limits antibiotic treatment options. Vaccine development againstS. aureushas been unsuccessful to date, likely due to an inadequate understanding about the mechanisms of immune defense against this pathogen. The significance of our work is in illustrating the necessity of generating multipronged B-cell, Th1-, and Th17-mediated responses toS. aureusantigens in conferring enhanced and broad protection againstS. aureusinvasive infection, skin and soft tissue infection, and mucosal colonization. Our work thus, provides important insights for future vaccine development against this pathogen.

scholarly journals Invasion of Oral and Aortic Tissues by Oral Spirochete Treponema denticola in ApoE−/−Mice Causally Links Periodontal Disease and Atherosclerosis

2014 ◽  
Vol 82 (5) ◽  
pp. 1959-1967 ◽  
Author(s):  
Sasanka S. Chukkapalli ◽  
Mercedes F. Rivera ◽  
Irina M. Velsko ◽  
Ju-Youn Lee ◽  
Hao Chen ◽  
...  
Keyword(s):  
Periodontal Disease ◽  
Alveolar Bone ◽  
Tissue Growth ◽  
Aortic Tissue ◽  
Treponema Denticola ◽  
Rapid Progression ◽  
Causative Role ◽  
Igg Antibody ◽  
Content Type ◽  
Periodontal Infection

ABSTRACTTreponema denticolais a predominantly subgingival oral spirochete closely associated with periodontal disease and has been detected in atherosclerosis. This study was designed to evaluate causative links between periodontal disease induced by chronic oralT. denticolainfection and atherosclerosis in hyperlipidemic ApoE−/−mice. ApoE−/−mice (n= 24) were orally infected withT. denticolaATCC 35404 and were euthanized after 12 and 24 weeks.T. denticolagenomic DNA was detected in oral plaque samples, indicating colonization of the oral cavity. Infection elicited significantly (P= 0.0172) higher IgG antibody levels and enhanced intrabony defects than sham infection.T. denticola-infected mice had higher levels of horizontal alveolar bone resorption than sham-infected mice and an associated significant increase in aortic plaque area (P≤ 0.05). Increased atherosclerotic plaque correlated with reduced serum nitric oxide (NO) levels and increased serum-oxidized low-density lipoprotein (LDL) levels compared to those of sham-infected mice.T. denticolainfection altered the expression of genes known to be involved in atherosclerotic development, including the leukocyte/endothelial cell adhesion gene (Thbs4), the connective tissue growth factor gene (Ctgf), and the selectin-E gene (Sele). Fluorescentin situhybridization (FISH) revealedT. denticolaclusters in both gingival and aortic tissue of infected mice. This is the first study examining the potential causative role of chronicT. denticolaperiodontal infection and vascular atherosclerosisin vivoin hyperlipidemic ApoE−/−mice.T. denticolais closely associated with periodontal disease and the rapid progression of atheroma in ApoE−/−mice. These studies confirm a causal link for active oralT. denticolainfection with both atheroma and periodontal disease.

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