Delamination of carbon-fiber strengthening layer from concrete beam during deformation (infrared thermography)

Technology of strengthening reinforced concrete structures with composite materials has found wide application. The effectiveness of strengthening of concrete structures with externally bonded reinforcement is supported by a great deal of experimental evidence. However, the problem of serviceability of such structures has not been adequately explored. The present work describes the results of experimental studies on the loadcarrying capacity of concrete beams strengthened with carbon fiber reinforced plastic (CFRP). Special emphasis is placed on studying the debonding of the strengthening layer from the concrete surface and analyzing its influence on the load-carrying capacity of beams. Infrared thermography is used to detect the first signs of debonding and to assess the debond growth rate

Process of cracking in reinforced concrete beams (simulation and experiment)

The paper presents the results of experimental and theoretical investigations of the mechanisms of crack formation in reinforced concrete beams subjected to quasi-static bending. The boundary-value problem has been formulated in the framework of brittle fracture mechanics and solved using the finite-element method. Numerical simulation of the vibrations of an uncracked beam and a beam with cracks of different size serves to determine the pattern of changes in the spectrum of eigenfrequencies observed during crack evolution. A series of sequential quasi-static 4-point bend tests leading to the formation of cracks in a reinforced concrete beam were performed. At each loading step, the beam was subjected to an impulse load to induce vibrations. Two stages of cracking were detected. During the first stage the nonconservative process of deformation begins to develope, but has not visible signs. The second stage is an active cracking, which is marked by a sharp change in eingenfrequencies. The boundary of a transition from one stage to another is well registered. The vibration behavior was examined for the ordinary concrete beams and the beams strengthened with a carbon-fiber polymer. The obtained results show that the vibrodiagnostic approach is an effective tool for monitoring crack formation and assessing the quality of measures aimed at strengthening concrete structures

EVALUATION OF FCR THERAPY EFFICACY IN PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA BASED ON IMMUNOGENETIC CRITERIA

A number of studies have shown that distinct common variants of the genes controlling immune/inflammatory response may affect efficiency of chronic lymphocytic leukemia (CLL) treatment. In a recently published paper, we reported polymorphic variants of some immune response genes in CLL patients to be associated with different rates of disease progression. Correlations between the distribution of gene modification profiles in indolent and agressive forms of CLL have been established. The present study describes results of pharmacogenetic studies aimed for identifying associations between the immune response genes polymorphism, and efficacy of FCR treatment regimen in CLL patients. 19 polymorphic loci of 14 immune response genes were studied in 33 patients with CLL who received FCR therapy. The TLR2, TLR3, TLR4, TLR6, TLR9, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-17A, CD14, TNFα, FCGR2A genotypes were determined by polymerase chain reaction with allele-specific primers. CLL patients were divided into several groups depending on the terms of response to FCR treatment, i.e., achieving partial/complete remission after two, four, six courses of treatment, and those who did not respond to the therapy. Statistically significant differences in the distribution of haplotype frequencies were detected for the following genes: IL-1β (C-3953T, p = 0.02-0.009); IL-10 (C-819T, p = 0.04); IL-10 (G-1082A, p = 0.04-0.002-0.006), FCGR2A (His166Arg, p = 0.006); TLR4 (Thr399Ile, p = 0.02); TLR6 (Ser249Pro, p = 0.04); TLR9 (A2848G, p = 0.04-0.007); CD14 (C-159T, p = 0.03). When testing the significance hypothesis by multiple comparisons, the difference for the detected events was confirmed only for IL-10 gene (G-1082A, p < 0.01; χ2 = 20,082). The results show a relationship between the allelic status of the IL-10-1082 gene and the timing of response to FCR therapy, as well as predict a group of patients with primary-resistant CLL before treatment. The role of the relationship between IL-10 gene polymorphism and IL-10 production is discussed in connection with occurrence risk and clinical course of mature B-cell lymphoid malignancies. IL-10 is thought to be a growth factor for normal and transformed human B-lymphocytes, it controls a balance between cellular and humoral immune responses while exerting a pronounced immunosuppressive activity, along with ability to stimulate tumor cell proliferation. A rationale for conducting pharmacogenomic studies in CLL is provided, in order to predict efficiency of a specific drug or their combination in a distinct patient, thus representing chances to detect a factor which may influence success of the therapy since its earlier stage

DEVELOPMENT OF A BASIC OPTICAL SCHEME FOR DETERMINING INTERNAL STRESSES IN A COMPOSITE MATERIAL LIKE "METAL-GLASS-CERAMICS"

A basic optical scheme for determining internal mechanical stresses in a composite material like “metal-glass-ceramics” is developed. Basic elements and components of the installation are selected, their main characteristics are calculated

МОДИФИКАЦИИ ГЕНОВ ИММУННОГО ОТВЕТА ПРИ РАЗЛИЧНЫХ ТИПАХ ТЕЧЕНИЯ ХРОНИЧЕСКОГО ЛИМФОЛЕЙКОЗА

Genetic factors not only contribute to the development of chronic lymphocytic leukemia (CLL), but also can affect the nature of the pathological process. The study included 30 patients with CLL with indolent and progressive course of the disease. The patients were tested on prevalence of genetic polymorphisms in the genes of the innate immune response. Nineteen polymorphic loci in 14 genes were tested. It was found that with indolent course of CLL, mutant alleles of genes of tumor necrosis factor (TNF) (G-308A), Toll-like receptor (tolllike receptor - TLR) TLR9 (T-1237C) and TLR2 (Arg753Gln) (OR: 4.70, p = 0.05 and OR: 8.33, p = 0.03 and OR: 5.50, p = 0.05, respectively) statistically, were encountered much more frequently . In contrast, combination of normal homozygotes of these genes greatly increased the risk of progressive form of the disease. Presence of TNF gene polymorphism in the polymorphic locus -308, TLR2-753, TLR9-1237 can be associated with the nature of the clinical course of CLL to encourage use these markers as early additional diagnostic and prognostic criteria for unfavorable form of leukemic process in order to optimize chemotherapy.Генетические факторы не только вносят вклад в развитие хронического лимфолейкоза (ХЛЛ), но и могут оказывать влияние на характер течения патологического процесса. Обследовали 30 больных ХЛЛ с доброкачественным и прогрессирующим течением заболевания. У пациентов определяли распространенность генетических полиморфизмов в генах врожденного иммунного ответа. Протестировано 19 полиморфных локусов в 14 генах. Об наружено, что при доброкачественном течении ХЛЛ статистически значимо чаще встречались мутантные аллели генов фактора некроза опухоли (TNF) (G-308A), толлподобного рецептора (toll-like receptor - TLR) TLR9 (T-1237C) и TLR2 (Arg753Gln) (OR: 4,70, p = 0,05 и OR: 8,33, р = 0,03 и OR: 5,50, р = 0,05 соответственно). Напротив, сочетание нормальных гомозигот данных генов многократно увеличивало риск развития прогрессирующей формы заболевания. Можно связать наличие полиморфизма генов TNF в полиморфном локусе -308, TLR2-753, TLR9-1237 с характером клинического течения ХЛЛ и рекомендовать использовать данные маркеры в качестве ранних дополнительных диагностических и прогностических критериев неблагоприятной формы лейкозного процесса с целью оптимизации химиотерапии

Delamination of carbon-fiber strengthening layer from concrete beam during deformation (infrared thermography)

Technology of strengthening reinforced concrete structures with composite materials has found wide application. The effectiveness of strengthening of concrete structures with externally bonded reinforcement is supported by a great deal of experimental evidence. However, the problem of serviceability of such structures has not been adequately explored. The present work describes the results of experimental studies on the loadcarrying capacity of concrete beams strengthened with carbon fiber reinforced plastic (CFRP). Special emphasis is placed on studying the debonding of the strengthening layer from the concrete surface and analyzing its influence on the load-carrying capacity of beams. Infrared thermography is used to detect the first signs of debonding and to assess the debond growth rat

Process of cracking in reinforced concrete beams (simulation and experiment)

The paper presents the results of experimental and theoretical investigations of the mechanisms of crack formation in reinforced concrete beams subjected to quasi-static bending. The boundary-value problem has been formulated in the framework of brittle fracture mechanics and solved using the finite-element method. Numerical simulation of the vibrations of an uncracked beam and a beam with cracks of different size serves to determine the pattern of changes in the spectrum of eigenfrequencies observed during crack evolution. A series of sequential quasi-static 4-point bend tests leading to the formation of cracks in a reinforced concrete beam were performed. At each loading step, the beam was subjected to an impulse load to induce vibrations. Two stages of cracking were detected. During the first stage the nonconservative process of deformation begins to develope, but has not visible signs. The second stage is an active cracking, which is marked by a sharp change in eingenfrequencies. The boundary of a transition from one stage to another is well registered. The vibration behavior was examined for the ordinary concrete beams and the beams strengthened with a carbon-fiber polymer. The obtained results show that the vibrodiagnostic approach is an effective tool for monitoring crack formation and assessing the quality of measures aimed at strengthening concrete structure

Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials (PCM). Conventional methods of registration and evaluation of process-induced strains can be laborious, time-consuming and demanding in terms of technical applications. The employment of embedded fibre-optic strain sensors (FOSS) offers a real prospect of measuring residual strains. This paper demonstrates the potential for using embedded FOSS for recording technological strains in a PCM plate. The PCM plate is manufactured from prepreg, using the direct compression-moulding method. In this method, the prepared reinforcing package is placed inside a mould, heated, and then exposed to compaction pressure. The examined technology can be used for positioning FOSS between the layers of the composite material. Fibre-optic sensors, interacting with the material of the examined object, make it possible to register the evolution of the strain process during all stages of polymer-composite formation. FOSS data were recorded with interrogator ASTRO X 327. The obtained data were processed using specially developed algorithms

Influence of heat treatment on the transparency of silicate thin films in the near-IR range

The influence of heat treatment on the transmission of silicate thin films prepared by gelation from aqueous solutions of sodium silicate (water glass) is investigated. It is demonstrated that the initial films are characterized by a strong absorption in the IR range due to the presence of hydroxyl groups. The heat treatment of the films at temperatures in the range 150-250°C leads to the step-by-step removal of water from the films and, as a consequence, to an almost complete transmission in the high-frequency IR spectral range. An increase in the heat treatment temperature to 580°C is accompanied by the loss of transparency, most likely, as a result of the pore formation in the film. © 2008 MAIK Nauka