This article aims to compare the behaviour of four types of lattice structures named Cartesian, Rhomboid, Octagonal, and Starlit under tensile stress loading. The structures were made of Acrylonitrile Butadiene Styrene (ABS) material using the Fused Filament Fabrication (FFF) technique with three different specific volumes (24, 42, and 60%). Five samples of each type were produced, and a total of 60 samples were tested. Experimental testing was performed according to EN ISO 527-1:2012 and EN ISO 527-2:2012. The obtained data were statistically processed, while no outliers were identified. The experimental results pointed out that the specimens' topology, together with the specific volume, very significantly affected the resultant ABS properties of the tested samples made of the same material. The comparative study showed that in terms of ultimate strength, yield strength, and Young's modulus, the Cartesian structure appeared to be the most suitable for tensile stress, and the least suitable structure was the Rhomboid structure. On the other hand, the Rhomboid-type of the structure showed not only the highest amount of absorbed energy but also the highest toughness among the investigated lattice structures, so in the near future, its behaviour under an impact test should be studied.
- Keywords
- Acrylonitrile Butadiene Styrene (ABS), additive manufacturing, lattice structure, tensile properties,
- Publication type
- Journal Article MeSH
The article deals with the comparison of the bending behavior of cylindrical lattice samples with radially and orthogonally arranged cells made of ABS material. The structures were designed in PTC Creo Parametric 8 software, while four types of lattice structures were evaluated: Rhombus, Cuboidal BCC, Octagon, and Starry, in three material volume fractions: 44, 57, and 70%, together with tubular and rod-shaped samples. The Fused Filament Fabrication (FFF) technique was chosen for the production of ABS plastic samples. Based on the bending tests, the dependences of the force on the deflection were recorded and the obtained data were statistically processed to identify outliers using the Grubbs test. The maximum stresses were calculated and the dependences of the stresses on the volume fractions were plotted. Along with energy absorption, ductility indices were also specified. Although the Rhombus structure appears to be the best based on the ductility indices obtained, on the other hand, the structure showed the lowest values of bending stresses (in the range from 10.6 to 12.6 MPa for volume fractions ranging from 44 to 70%, respectively). Therefore, from a synergic point of view of both factors, stress and ductility, the Starry structure exhibits the best flexural properties among those investigated.
- Keywords
- ABS plastics, bending behavior, cell arrangement, ductility index, lattice structure,
- Publication type
- Journal Article MeSH
- MeSH
- Adult MeSH
- Fluorescent Antibody Technique MeSH
- Middle Aged MeSH
- Humans MeSH
- Antibodies, Bacterial analysis MeSH
- Syphilis diagnosis drug therapy MeSH
- Treponema pallidum immunology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Names of Substances
- Antibodies, Bacterial MeSH
BACKGROUND: Hospital antibiotic stewardship (ABS) programs are essential for ensuring long-lasting quality of antibiotic usage and for controlling antimicrobial resistance in the hospital setting. METHODS: A questionnaire for self-assessment of a hospital's ABS maturity was sent to 80 Czech hospitals in May 2007. The survey was focused on diagnostic issues, control of antibiotic consumption, antibiotic-related organization and tools, antibiotic-related personnel development and antibiotic-related relationships to relevant environments. RESULTS: Of 80 addressed hospitals, 45 sent back processed questionnaires (response rate 56.3%). These 80 hospitals cover about 85% of the Czech population. All Czech university hospitals were included in the replying group. The listed diagnostic tools were declared available by all hospitals; 44 of 45 hospitals have surveillance systems for antibiotic resistance rates. Control of antibiotic consumption was available only partially in 42 of 45 hospitals. Some antibiotic tools need to be improved and must be used more frequently. Official recognition, job descriptions and better funding of antibiotic personnel are needed, as well as support for further development of ABS structures and functions. DISCUSSION: The basic structure of ABS is well developed in the Czech hospitals. A network of antibiotic centers focusing their services on optimization of antibiotic usage has been in place in the Czech Republic since the 1970s. Nevertheless, the survey revealed a clear need and many opportunities for further improvement. Control of antibiotic consumption is not implemented in all Czech hospitals and some of the essential antibiotic tools should be used more widely.
- MeSH
- Anti-Bacterial Agents administration & dosage MeSH
- Drug Resistance, Microbial MeSH
- Anti-Infective Agents MeSH
- Bacterial Infections drug therapy epidemiology MeSH
- Disease Outbreaks prevention & control statistics & numerical data MeSH
- Incidence MeSH
- Cross Infection epidemiology prevention & control MeSH
- Humans MeSH
- Hospitals statistics & numerical data MeSH
- Surveys and Questionnaires MeSH
- Population Surveillance methods MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Czech Republic epidemiology MeSH
- Names of Substances
- Anti-Bacterial Agents MeSH
- Anti-Infective Agents MeSH
- MeSH
- Fluorescent Antibody Technique MeSH
- Humans MeSH
- Syphilis Serodiagnosis * MeSH
- Treponema Immobilization Test MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
Noise pollution is a negative factor that affects our environment. It is, therefore, necessary to take appropriate measures to minimize it. This article deals with the sound absorption properties of open-porous Acrylonitrile Butadiene Styrene (ABS) material structures that were produced using 3D printing technology. The material's ability to damp sound was evaluated based on the normal incidence sound absorption coefficient and the noise reduction coefficient, which were experimentally measured by the transfer function method using an acoustic impedance tube. The different factors that affect the sound absorption behavior of the studied ABS specimens are presented in this work. In this study, it was discovered that the sound absorption properties of the tested ABS samples are significantly influenced by many factors, namely by the type of 3D-printed, open-porous material structure, the excitation frequency, the sample thickness, and the air gap size behind the sound-absorbing materials inside the acoustic impedance tube.
- Keywords
- 3D printing technology, Acrylonitrile Butadiene Styrene, air gap, frequency, sound absorption, thickness,
- Publication type
- Journal Article MeSH
Noise has a negative impact on our environment and human health. For this reason, it is necessary to eliminate excessive noise levels. This paper is focused on the study of the sound absorption properties of materials with open-porous structures, which were made of acrylonitrile butadiene styrene (ABS) material using additive technology. Four types of structures (Cartesian, octagonal, rhomboid, and Starlit) were evaluated in this work, and every structure was prepared in three different volume ratios of the porosity and three different thicknesses. The sound absorption properties of the investigated ABS specimens were examined utilizing the normal incidence sound absorption and noise reduction coefficients, which were experimentally determined by the transfer function method using a two-microphone acoustic impedance tube. This work deals with various factors that influence the sound absorption performance of four different types of investigated ABS material's structures. It was found, in this study, that the sound absorption performance of the investigated ABS specimens is strongly affected by different factors, specifically by the structure geometry, material volume ratio, excitation frequency of an acoustic wave, material´s thickness, and air space size behind the tested sound-absorbing materials.
- MeSH
- False Positive Reactions * MeSH
- Flocculation MeSH
- Fluorescent Antibody Technique * MeSH
- Complement Fixation Tests MeSH
- Latex Fixation Tests MeSH
- Humans MeSH
- Neoplasms diagnosis MeSH
- Antibodies analysis MeSH
- Rheumatoid Factor analysis MeSH
- Serologic Tests * MeSH
- Syphilis diagnosis MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Antibodies MeSH
- Rheumatoid Factor MeSH
Currently, there is an increasing use of machine parts manufactured using 3D printing technology. For the numerical prediction of the behavior of such printed parts, it is necessary to choose a suitable material model and the corresponding material parameters. This paper focuses on the determination of material parameters of the Anand material model for acrylonitrile butadiene styrene (ABS-M30) material. Material parameters were determined using the genetic algorithm (GA) method using finite element method (FEM) calculations. The FEM simulations were subsequently adjusted to experimental tests carried out to achieve the possible best agreement. Several experimental tensile and indentation tests were performed. The tests were set up in such a way that the relaxation and creep behaviors were at least partially captured. Experimental tests were performed at temperatures of 23 °C, 44 °C, 60 °C, and 80 °C. The results obtained suggest that the Anand material model can also be used for ABS-M30 plastic material, but only if the goal is not to detect anisotropic behavior. Future work will focus on the search for a suitable material model that would be able to capture the anisotropic behavior of printed plastic materials.
- Keywords
- ABS-M30, Anand material model, genetic algorithm, indentation test, material parameters,
- Publication type
- Journal Article MeSH
Natural antibodies (Abs) can target host glycans on the surface of pathogens. We studied the evolution of glycan-reactive B cells of rhesus macaques and humans using glycosylated HIV-1 envelope (Env) as a model antigen. 2G12 is a broadly neutralizing Ab (bnAb) that targets a conserved glycan patch on Env of geographically diverse HIV-1 strains using a unique heavy-chain (VH) domain-swapped architecture that results in fragment antigen-binding (Fab) dimerization. Here, we describe HIV-1 Env Fab-dimerized glycan (FDG)-reactive bnAbs without VH-swapped domains from simian-human immunodeficiency virus (SHIV)-infected macaques. FDG Abs also recognized cell-surface glycans on diverse pathogens, including yeast and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike. FDG precursors were expanded by glycan-bearing immunogens in macaques and were abundant in HIV-1-naive humans. Moreover, FDG precursors were predominately mutated IgM+IgD+CD27+, thus suggesting that they originated from a pool of antigen-experienced IgM+ or marginal zone B cells.
- Keywords
- FDG Abs, Fab dimerization, HIV-1 Env glycans, IgM-memory B cells, SARS-CoV-2 spike glycans, glycan-dependent Ab binding, marginal zone B cells, natural Abs,
- MeSH
- B-Lymphocytes immunology MeSH
- COVID-19 immunology MeSH
- Dimerization MeSH
- Epitopes immunology MeSH
- env Gene Products, Human Immunodeficiency Virus chemistry genetics immunology MeSH
- Spike Glycoprotein, Coronavirus immunology MeSH
- Glycosylation MeSH
- HIV Infections immunology MeSH
- HIV Antibodies immunology MeSH
- HIV-1 immunology MeSH
- Immunoglobulin Fab Fragments chemistry immunology MeSH
- Humans MeSH
- Macaca mulatta MeSH
- Antibodies, Neutralizing immunology MeSH
- Polysaccharides chemistry immunology MeSH
- Receptors, Antigen, B-Cell chemistry MeSH
- SARS-CoV-2 immunology MeSH
- Broadly Neutralizing Antibodies immunology MeSH
- Vaccines immunology MeSH
- Simian Immunodeficiency Virus genetics immunology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Names of Substances
- Epitopes MeSH
- env Gene Products, Human Immunodeficiency Virus MeSH
- Spike Glycoprotein, Coronavirus MeSH
- HIV Antibodies MeSH
- Immunoglobulin Fab Fragments MeSH
- Antibodies, Neutralizing MeSH
- Polysaccharides MeSH
- Receptors, Antigen, B-Cell MeSH
- Broadly Neutralizing Antibodies MeSH
- spike protein, SARS-CoV-2 MeSH Browser
- Vaccines MeSH
