Identification of low cycle fatigue parameters of high strength low-alloy (hsla) steel at room temperature

Low cycle fatigue test was performed in ambient atmosphere at room temperature. cycle loading of material, in case of High strength low-alloy steel, entails modifications of its properties and in this paper is therefore shown behavior of fatigue life using low cycle fatigue parameters. Mere precisely, crack initiation life of tested specimens Was computed using theory of Coffin-Manson relation during the fatigue loading. The geometry Of the stabilized hysteresis loop of welded joint HSLA steel, marked as Nionikral 70, is also analyzed. This stabilized hysteresis loop is very important for determination of materials properties

Effect of microstructure on tensile properties of austenite-ferrite welded joint

Complex microstructure of austenite-ferrite welded joint has been investigated, focused on its influence on Focal tensile properties. Tensile properties (yield strength and hardening coefficient) have been evaluated by using finite element method to simulate the strain distributions obtained experimentally. The three-dimensional model of V-joint specimen has been used with seven different materials, simulating two base metals, the weld metal and two sub-regions of two heat-affected zones - fine grain and coarse grain. In this way local tensile properties of the whole austenite-ferrite welded joint have been evaluated

Fracture behavior of reactor steel 20MnMoNi 55 in the transition temperature region

The fracture represents the final phase of crack propagation, and the causes of their occurrence or partial crack propagation in the real constructions made of ferritic steels can be different. Along with cracks, influences such as stress concentration and low temperature contribute to fracture being “faster” and have an impact on the fracture mechanics parameters, as well as on the fact that fracture is more likely to occur due to cleavage. The parameters discussed in this study are Jc and rc (parameter, i.e. distance between fatigue crack tip and cleavage initiation site) by testing of C(T)50 specimen in the transition temperature region. Grooved C(T) specimens were made of reactor steel 20MnMoNi 55 with two thickness values, since an additional goal of this study was to present the influence of thickness of tested specimens. Along with it, other parameters that have influence on the understanding of transition temperature region and fracture in this region of ferritic steel are presented

Fracture behavior of reactor steel 20MnMoNi 55 in the transition temperature region

The fracture represents the final phase of crack propagation, and the causes of their occurrence or partial crack propagation in the real constructions made of ferritic steels can be different. Along with cracks, influences such as stress concentration and low temperature contribute to fracture being “faster” and have an impact on the fracture mechanics parameters, as well as on the fact that fracture is more likely to occur due to cleavage. The parameters discussed in this study are Jc and rc (parameter, i.e. distance between fatigue crack tip and cleavage initiation site) by testing of C(T)50 specimen in the transition temperature region. Grooved C(T) specimens were made of reactor steel 20MnMoNi 55 with two thickness values, since an additional goal of this study was to present the influence of thickness of tested specimens. Along with it, other parameters that have influence on the understanding of transition temperature region and fracture in this region of ferritic steel are presented

Root malate efflux and expression of TaALMT1 in Serbian winter wheat cultivars differing in Al tolerance

Aluminium (Al) toxicity in acid soils is a global problem. Here, we investigated Al tolerance in high yielding winter wheat (Triticum aestivum L.) cultivars bred in Serbia. The common relative mot length (RRL) test for Al tolerance, and both physiological (malate efflux) and molecular (Aluminium-Activated Malate Transporter 1 [TaALMT1] expression) approaches were used for this characterization. Both moderately Al-tolerant cvs. Ljiljana and Arabeska showed significantly higher malate efflux rate from the root tips in comparison to moderately Al-sensitive cv. Pobeda and followed the RRL pattern. Irrespectively of Al supply, moderately Al-tolerant cultivars showed significantly higher relative TaALMT1 expression than the Al-sensitive ones. A considerably high level of Al tolerance was found in cv. Ljiljana, which showed the highest Al-induced malate efflux along with the highest constitutive expression level of TaALMT1 transcripts. Our results also demonstrate that Al tolerance is based on a constitutive trait of high TaALMT1 expression and malate efflux in wheat roots, resulting in a decrease in root length reduction

Importance of pharmacogenetic markers in the methylenetetrahydrofolate reductase gene during methotrexate treatment in pediatric patients with acute lymphoblastic leukemia

Despite remarkable progress in survival of children with acute lymphoblastic leukemia (ALL) which has reached about 85%, early toxicity and relapse rate remain issues that need to to be resolved. Genetic variants are important factors influencing the metabolism of cytotoxic drugs in ALL treatment. Variants in genes coding for methotrexate (MTX)-metabolizing enzymes are under constant scientific interest due to their potential impact on drug toxicity and relapse rate. We investigated methylenetetrahydrofolate reductase (MTHFR) c.677C gt T and MTHFR c.1298A gt C variants as pharmacogenetic markers of MTX toxicity and predictors of relapse. The study enrolled 161 children with ALL, treated according to the current International Berlin-Frankfurt-Munster group (BFM) for diagnostics and treatment of leukemia and lymphoma protocols. Genotyping was performed using PCR-RFLP and allele-specific PCR assays. Our results revealed similar distributions of MTHFR c.677C gt T and MTHFR c.1298A gt C genotypes among 104 healthy individuals as compared to pediatric ALL patients. A lower incidence of early MTX toxicity was noted in the MTHFR c.677TT genotype (p=0.017), while MTHFR c.1298A gt C genotypes were not associated with MTX toxicity. Carriers of any MTHFR c.677C gt T and MTHFR c.1298A gt C genotypes did not experience decreased overall survival (OAS) or higher relapse rates. Genetic variants in the MTHFR gene are not involved in leukemogenesis in pediatric ALL. The presence of the MTHFR c.677TT genotype was recognized as a predictive factor for decreased MTX toxicity during the intensification phase of therapy. Neither MTHFR c.677C gt T nor MTHFR c.1298A gt C genotypes correlated with an increased number of toxic deaths or relapse rate. Our study emphasizes the importance of implementing pharmacogenetic markers in order to optimize pediatric ALL therapy

Monitoring of focusing tube wear during abrasive waterjet (AWJ) cutting of AISI 309

The paper deals with the investigating the possibility of using vibrations as a potential source of information for the detection of the malfunctions during the abrasive supplying and focusing tube wear in the process of AWJ. The tested material was the stainless steel AISI 309. Variable factors in the experiment were the abrasive mass flow ma and the focusing tube diameter df. The scanned vibration signal of the material was subjected to frequency analysis. With the increase of the abrasive mass flow, the shift of the amplitudes will follow the opposite direction and decrease. Frequency spectra of all assessed signals are similar by shape in the high-frequency area

Phenylketonuria screening and management in southeastern Europe - survey results from 11 countries

Background: We aimed to assess the current state of PKU screening and management in the region of southeastern Europe. Methods: A survey was performed involving all identified professionals responsible for the PKU management in the 11 countries from South-Eastern region of Europe (Albania, Bulgaria, Bosnia and Herzegovina, Croatia, Kosovo, Macedonia, Moldova, Montenegro, Romania, Serbia, Slovenia). The questionnaire was designed to assess the characteristics regarding PKU management in three main areas: nation-wide characteristics, PKU screening, and characteristics of the PKU management in the responding centre. It consisted of 56 questions. The distribution and collection of the questionnaires (via e-mail) was taking place from December 2013 to March 2014. Results: Responses from participants from 11 countries were included; the countries cumulative population is approx. 52.5 mio. PKU screening was not yet introduced in 4 of 11 countries. Reported PKU incidences ranged from 1/7325 to 1/39338 (and were not known for 5 countries). National PKU guidelines existed in 5 of 11 countries and 7 of 11 countries had PKU registry (registries included 40 to 194 patients). The number of PKU centers in each country varied from1 to 6. Routine genetic diagnostics was reported in 4 of 11 countries. Most commonly used laboratory method to assess phenylalanine levels was fluorometric. Tetrahydrobiopterine was used in only 2 of 11 countries. Most frequently, pediatricians were caring for the patients. Dietitian was a member of PKU team in only 4 of 11 countries, while regular psychological assessments were performed in 6 of 11 countries. Patient's PKU society existed in 7 of 11 countries. Conclusions: The region of southeastern Europe was facing certain important challenges of PKU screening and management. Neonatal PKU screening should be introduced throughout the region. Furthermore, PKU management was falling behind internationally established standards-of-care in many aspects

Phenylketonuria screening and management in southeastern Europe - survey results from 11 countries

Background: We aimed to assess the current state of PKU screening and management in the region of southeastern Europe. Methods: A survey was performed involving all identified professionals responsible for the PKU management in the 11 countries from South-Eastern region of Europe (Albania, Bulgaria, Bosnia and Herzegovina, Croatia, Kosovo, Macedonia, Moldova, Montenegro, Romania, Serbia, Slovenia). The questionnaire was designed to assess the characteristics regarding PKU management in three main areas: nation-wide characteristics, PKU screening, and characteristics of the PKU management in the responding centre. It consisted of 56 questions. The distribution and collection of the questionnaires (via e-mail) was taking place from December 2013 to March 2014. Results: Responses from participants from 11 countries were included; the countries cumulative population is approx. 52.5 mio. PKU screening was not yet introduced in 4 of 11 countries. Reported PKU incidences ranged from 1/7325 to 1/39338 (and were not known for 5 countries). National PKU guidelines existed in 5 of 11 countries and 7 of 11 countries had PKU registry (registries included 40 to 194 patients). The number of PKU centers in each country varied from1 to 6. Routine genetic diagnostics was reported in 4 of 11 countries. Most commonly used laboratory method to assess phenylalanine levels was fluorometric. Tetrahydrobiopterine was used in only 2 of 11 countries. Most frequently, pediatricians were caring for the patients. Dietitian was a member of PKU team in only 4 of 11 countries, while regular psychological assessments were performed in 6 of 11 countries. Patient's PKU society existed in 7 of 11 countries. Conclusions: The region of southeastern Europe was facing certain important challenges of PKU screening and management. Neonatal PKU screening should be introduced throughout the region. Furthermore, PKU management was falling behind internationally established standards-of-care in many aspects