Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
Tumour Biol ; 36(6): 4441-52, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25874491

RESUMO

Special AT-rich sequence-binding protein 1 (SATB1) is a 'genome organizer,' and it has been proposed as a factor that affects the development and progression of various human neoplasms, including colorectal cancer (CRC). This study aimed to compare SATB1 expression in a group of CRC patients and healthy subjects at the mRNA and protein levels. We collected paired tumor tissue and unchanged mucosa of the large intestine from 102 CRC patients as well as 53 biopsies of normal colon mucosa obtained from healthy patients during screening colonoscopy. Tissue samples were quantified for SATB1 mRNA by quantitative PCR, while SATB1 protein expression was determined by Western blotting and immunohistochemistry. SATB1 mRNA level in tumor tissues was over twofolds lower than in samples of corresponding unchanged tissues and fourfolds lower than in biopsies of healthy colon mucosa. Western blotting analysis revealed that SATB1 protein content in tumor and unchanged tissues of CRC patients was over sixfold and fivefolds higher than in biopsies of healthy colon mucosa, respectively. Immunohistochemical staining demonstrated higher nuclear and cytoplasmic SATB1 reactivity in the tumor tissue compared to unchanged mucosa of CRC patients. Despite these differences, SATB1 mRNA, protein, and immunoreactivity levels did not correlate with patients' clinicopathological data and their overall survival, but the latter analysis was limited by a relatively short period of follow-up. In conclusion, we suggest that some as yet unidentified posttranscriptional mechanisms that regulate SATB1 expression may be altered in the CRC tissue.


Assuntos
Biomarcadores Tumorais/biossíntese , Neoplasias Colorretais/genética , Proteínas de Ligação à Região de Interação com a Matriz/biossíntese , RNA Mensageiro/biossíntese , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/genética , Linhagem Celular Tumoral , Neoplasias Colorretais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Estimativa de Kaplan-Meier , Masculino , Proteínas de Ligação à Região de Interação com a Matriz/genética , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , RNA Mensageiro/genética
2.
Sci Rep ; 14(1): 3339, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38336884

RESUMO

This paper demonstrates the application of the Johnson-Holmquist II (JH-2) model with correlated and validated parameters to simulate the behavior of a sandstone. The JH-2 model is used to simulate various tests, including single-element tests, structural quasi-static uniaxial and triaxial compression tests, and the split Hopkinson pressure bar test. Additionally, the model is used to simulate drop-weight impact test using a ball bearing and two loading scenarios involving small-scale blasting and projectile impacts. Quantitative and qualitative comparisons demonstrate that the JH-2 model agrees well with both experimental and analytical results. Limitations of the model are also highlighted, particularly for quasi-static problems, as the model was originally developed for high-strain-rate simulations. Ultimately, this study demonstrates that the JH-2 rock constitutive model can obtain reasonable results for a material other than the material for which the model was originally correlated and validated. This paper provides valuable guidance for modeling and simulating sandstone and other rock materials subjected to dynamic loadings.

3.
ChemSusChem ; 17(6): e202301232, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-37975580

RESUMO

Block copolymers utilizing oligomeric poly(pentylene-co-hexylene carbonate)diol modified with 2,4-diisocyanatotoluene and further with 2-bromo-N-(3-hydroxypropyl)-2-methylpropanamide were synthesized and utilized as Activators ReGenerated by Electron Transfer Atom Transfer Radical Polymerization macroinitiators to obtain a first generation of multifunctional recycling additives with poly(glycidyl methacrylate-co-butyl methacrylate-co-methyl methacrylate) side chains, which could act as chain extenders. Then, chosen additive was reacted with a radical scavenger, 3,5-ditertbutyl-4-hydroxybenzoic acid (DHBA), to obtain a second generation of reactive additives. Those copolymers had different numbers of epoxy groups per polymer chain, and different number of epoxides opened with DHBA, hence showed a range of properties, and were utilized as reactive modifiers for polylactide (PLA) extrusion melting. The first-generation modifiers caused an increase in PLA's blends relative melt viscosity, stabilized material properties, and enhanced impact strength, while the second-generation modifiers with more than 8 % of epoxide ring opened showed worse properties. However, they managed to suppress the UV degradation of PLA blend plates.

4.
Materials (Basel) ; 16(9)2023 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-37176411

RESUMO

Porous materials are very efficient in absorbing mechanical energy, for instance, in combined armor, in order to improve the anti-ballistic protection characteristics. In the present study, porous titanium-based structures were manufactured via three different powder metallurgy methods using titanium hydride (TiH2) powder, which provided activated sintering, owing to dehydrogenation. The emission of hydrogen and shrinkage of powder particles on dehydrogenation also added an additional potential to control the sintering process and create desirable porosities. TiH2 powder was sintered with additions of NaCl or ammonium carbide as pore holding removable agents, while highly porous Ti-Al structures were formed via liquid phase reactive sintering of TiH2 and Al powders. The microstructures and porosities of sintered dehydrogenated titanium and Ti-Al structures were comparatively studied. Mechanical characteristics were evaluated using compression testing with strain rates varying from quasi-static to high levels. The resonant frequency method was also employed to determine damping parameters and elastic modulus of these materials. All testing methods were aimed at characterizing the energy-absorbing ability of the obtained porous structures. The desired strength, plasticity and energy-absorbing characteristics of porous titanium-based structures were assessed, and the possibilities of their application were also discussed. Based on the obtained results, it was found that porous titanium materials produced with the use of ammonium carbonate showed promising energy absorption properties.

5.
PLoS One ; 17(3): e0265546, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35333882

RESUMO

The formation of craters is an important issue in the investigations of the surface of the earth and other planets. The aim of the study was to check whether the different textures of sand beds affect the size and dynamics of the formation of craters and ejection curtain after high-velocity impacts. The experiments were conducted using an aluminium impactor at two impact speeds (~700 and ~1300 m∙s-1) and a sand bed composed of either a broad range of sizes (<2.0 mm) or any of the three fractions obtained from it (<0.5, 0.5-1, 1-2 mm). The diameters, depths, wall slope, and rim heights of the resulting craters were measured. The ejecta curtain was characterized by the inclination angle of walls, base diameter, and expansion velocity. The mass of the transferred material and the depth of the impactor penetration were also determined. Additionally, the results were used to calculate dimensionless parameters commonly considered in crater studies (πV, π2 and α). The texture of the sand most clearly influenced the diameters of the craters, its effect could also be seen in the case of the distance covered by the ejected material. This information appears to be relevant for future research, providing some rationale to help assess in which aspects of the phenomenon the texture may be important.


Assuntos
Planetas , Areia , Planeta Terra
6.
Materials (Basel) ; 14(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070356

RESUMO

The crushing response of a laser-welded square tube absorber made of two commercial steel grades, Docol 1000DP and Docol 1200M, is presented in the paper. Crush experiments are performed at two different loading conditions, namely, quasi-static loading at 0.5 mm/s deformation speed and impact loading at 25-28 m/s. A new approach has been proposed to study the square tube absorber under impact loading using a direct impact Hopkinson (DIH) method. To characterize the mechanical properties of the tested steels, tensile quasi-static and high strain rate testing are also performed with the use of specimens with a 7 mm gauge length. The applied strain rates are 10-3, 100, and above 103 s-1. The laser-welded joints are also characterized by microhardness test involving the base material, heat-affected zone, and fusion zone. The crashworthiness of model square tube absorbers is estimated based on the following parameters: absorbed energy, mean force, crushing force efficiency factor, and specific energy absorbed. It has been found that the square tube absorbers made of Docol 1200M steel show a higher potential in mechanical energy absorption capacity than Docol 1000DP absorber. Moreover, crushing tests prove that laser-welded joints in 0.6 mm sheets made of Docol 1000DP and Docol 1200M steels reveal high cracking toughness. In turn, strength testing at different strain rates confirms the higher strain rate sensitivity of Docol 1000DP steel than in the case of Docol 1200M steel as well as an increase in the high ductility properties of both steel grades under the high strain rate loading conditions.

7.
Materials (Basel) ; 14(20)2021 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-34683654

RESUMO

The effects of thermomechanical processing (TMP) on the mechanical response of microalloyed steels subjected to dynamic loading conditions were examined. The deformation conditions in the thermomechanical laboratory rolling processes were selected on the basis of dilatometric tests. It allowed (with a constant value of total deformation) us to obtain microstructures with different compositions and morphology of the particular components. Several samples characterized by a particularly complex and unexpected representation of the obtained microstructures were selected for further research. Plastometric tests, i.e., compression and tensile tests, were performed under quasi-static loading with digital image correlation (DIC) analysis, and under dynamic loading on the Split Hopkinson Pressure Bar (SHPB) apparatus with strain rates of 1400 and 2000 s-1. Samples deformed in such conditions were subjected to microstructural analysis and hardness measurements. It has been observed that the use of various combinations of TMP parameters can result in the formation of specific microstructures, which in turn are the source of an attractive mechanical response under dynamic loading conditions. This opens up new possible areas of application for such popular structural materials which are microalloyed steels.

8.
Materials (Basel) ; 14(22)2021 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-34832239

RESUMO

The mechanical behavior of titanium alloys has been mostly studied in quasi-static conditions when the strain rate does not exceed 10 s-1, while the studies performed in dynamic settings specifically for Ti-based composites are limited. Such data are critical to prevent the "strength margin" approach, which is used to assure the part performance under dynamic conditions in the absence of relevant data. The purpose of this study was to obtain data on the mechanical behavior of Ti-based composites under dynamic condition. The Metal Matrix Composites (MMC) on the base of the alloy Ti-6Al-4V (wt.%) were made using Blended Elemental Powder Metallurgy with different amounts of reinforcing particles: 5, 10, and 20% of TiC or 5, 10% (vol.) of TiB. Composites were studied at high strain rate compression ~1-3 × 103·s-1 using the split Hopkinson pressure bar. Mechanical behavior was analyzed considering strain rate, phase composition, microstructure, and strain energy (SE). It is shown that for the strain rates up to 1920 s-1, the strength and SE of MMC with 5% TiC are substantially higher compared to particles free alloy. The particles TiC localize the plastic deformation at the micro level, and fracturing occurs mainly by crushing particles and their aggregates. TiB MMCs have a finer grain structure and different mechanical behavior. MMC with 5 and 10% TiB do not break down at strain rates up to almost 3000 s-1; and 10% MMC surpasses other materials in the SE at strain rates exceeding 2200 s-1. The deformation mechanism of MMCs was evaluated.

9.
Przegl Lek ; 67(5): 405-8, 2010.
Artigo em Polonês | MEDLINE | ID: mdl-20684348

RESUMO

The thesis presents a short history and organization of an acute poisoning centre in the1995 functioning within the internal diseases department in a multi-profile provincial hospital. The data show the number of patients treated beetween 1995-2009 an the types of toxic substances that caused poisoning. The conclusions presented refer to the role of the centre to help people suffering from acute poisoning within the city of Tarnow.


Assuntos
Hospitalização/estatística & dados numéricos , Pacientes Internados/estatística & dados numéricos , Intoxicação/epidemiologia , Venenos/classificação , Feminino , Humanos , Incidência , Masculino , Polônia/epidemiologia , Distribuição por Sexo , Taxa de Sobrevida
10.
Materials (Basel) ; 13(9)2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32403406

RESUMO

Nine variants of regular lattice structures with different relative densities have been designed and successfully manufactured. The produced structures have been subjected to geometrical quality control, and the manufacturability of the implemented selective laser melting (SLM) technique has been assessed. It was found that the dimensions of the produced lattice struts differ from those of the designed struts. These deviations depend on the strut orientation in relation to the specimen-building direction. Additionally, the microstructures and phase compositions of the obtained structures were characterized and compared with those of conventionally produced 316L stainless steel. The microstructure analysis and X-ray diffraction (XRD) patterns revealed a single austenite phase in the SLM samples. Both a certain broadening and a displacement of the austenite peaks were observed due to residual stresses and a crystallographic texture induced by the SLM process. Furthermore, the mechanical behavior of the lattice structure material has been defined. It was demonstrated that under both quasi-static and dynamic testing, lattice structures with high relative densities are stretch-dominated, whereas those with low relative densities are bending-dominated. Moreover, the linear dependency between the value of energy absorption and relative density under dynamic loading conditions has been established.

11.
Materials (Basel) ; 13(14)2020 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-32708266

RESUMO

The geometric burning law of gun propellants is widely used in computer codes used for the simulations of the internal ballistics of guns. However, the results of closed vessel tests prove that the burning process of some propellants deviates from the geometric law. Validation of the hypothesis that observed deviations can be attributed to the cracking of propellant grains was the aim of this work. In order to verify the hypothesis, three types of gun propellants were chosen with considerably differing mechanical strengths: a single-base propellant, a double-base propellant, and a composite propellant. The mechanical properties of the gun propellants were tested using a quasi-static compression method with strain rate values of the order of 0.001 s-1 and the Split Hopkinson Pressure Bar technique with the strain rate in the range of 1000-6000 s-1. The mechanical responses of the propellants were assessed on the basis of the true stress-strain curves obtained and from the point of view of the occurrence of cracks in the propellant grains specimens. Moreover, closed vessel tests were performed to determine experimental shape functions for the considered gun propellants. Juxtaposition of the stress‒strain curves with the experimental shape functions proved that the observed deviations from the geometrical burning law can be attributed mainly to the cracking of propellant grains. The results obtained showed that the rheological properties of propellants are important not only from the point of view of logistical issues but also for the properly controlled burning process of propellants during the shot.

12.
Polymers (Basel) ; 12(9)2020 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-32957601

RESUMO

The main aim of this article is the analysis of the deformation process of regular cell structures under quasi-static load conditions. The methodology used in the presented investigations included a manufacturability study, strength tests of the base material as well as experimental and numerical compression tests of developed regular cellular structures. A regular honeycomb and four variants with gradually changing topologies of different relative density values have been successfully designed and produced in the TPU-Polyflex flexible thermoplastic polyurethane material using the Fused Filament Fabrication (FFF) 3D printing technique. Based on the results of performed technological studies, the most productive and accurate 3D printing parameters for the thermoplastic polyurethane filament were defined. It has been found that the 3D printed Polyflex material is characterised by a very high flexibility (elongation up to 380%) and a non-linear stress-strain relationship. A detailed analysis of the compression process of the structure specimens revealed that buckling and bending were the main mechanisms responsible for the deformation of developed structures. The Finite Element (FE) method and Ls Dyna software were used to conduct computer simulations reflecting the mechanical response of the structural specimens subjected to a quasi-static compression load. The hyperelastic properties of the TPU material were described with the Simplified Rubber Material (SRM) constitutive model. The proposed FE models, as well as assumed initial boundary conditions, were successfully validated. The results obtained from computer simulations agreed well with the data from the experimental compression tests. A linear relationship was found between the relative density and the maximum strain energy value.

13.
Materials (Basel) ; 13(6)2020 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-32235797

RESUMO

The main aim of this study was to investigate the influence of different energy density values used for the additively manufactured elements using selective laser melting (SLM).The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples manufactured using three different sets of parameter values were subjected to static tensile and compression tests. The samples were also subjected to dynamic Split-Hopkinson tests. To verify the microstructural changes after the dynamic tests, microstructural analyses were conducted. Additionally, the element deformation during the tensile tests was analyzed using digital image correlation (DIC). To analyze the influence of the selected parameters and verify the layered structure of the manufactured elements, sclerometer scratch hardness tests were carried out on each sample. Based on the research results, it was possible to observe the porosity growth mechanism and its influence on the material strength (including static and dynamic tests). Parameters modifications that caused 20% lower energy density, as well as elongation of the elements during tensile testing, decreased twice, which was strictly connected with porosity growth. An increase of energy density, by almost three times, caused a significant reduction of force fluctuations differences between both tested surfaces (parallel and perpendicular to the building platform) during sclerometer hardness testing. That kind of phenomenon had been taken into account in the microstructure investigations before and after dynamic testing, where it had been spotted as a positive impact on material deformations based on fused material formation after SLM processing.

15.
World J Gastroenterol ; 18(20): 2582-5, 2012 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-22654458

RESUMO

The first-ever case of a 54-year-old woman who overdosed on non-steroidal anti-inflammatory drugs in an attempt at suicide. Before that incident, she had not been treated for coexisting diseases such as rheumatoid arthritis or depression. At the time of admission to the General Surgery Department, the patient reported pains in the epigastric region with accompanying nausea and vomiting with mucous content as well as the inability to ingest food orally. Despite parenteral and enteral feeding, the patient exhibited a drop in body mass. The histopathologic examination of a sample taken from the stomach during gastroscopy showed some non-specific necrotic and inflammatory masses with granulation. Intraoperatively, a very small, infiltrated stomach with an initial section of duodenum was identified. A total stomach resection together with the reconstruction of digestive tract continuity was performed using the Roux-Y method. Histopathologic examination of the stomach revealed a deep, chronic and exacerbated inflammatory condition with an extensive ulceration over the entire length of the stomach, reaching up to the pylorus. Additionally, numerous lymphatic glands with inflammatory reaction changes were observed.


Assuntos
Anti-Inflamatórios não Esteroides/intoxicação , Gastrectomia , Gastropatias/induzido quimicamente , Gastropatias/cirurgia , Feminino , Humanos , Pessoa de Meia-Idade , Entorpecentes/intoxicação , Tentativa de Suicídio , Tramadol/intoxicação
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa