Методика встроенного контроля деталей и конструкций из углепластиков ультразвуковыми волнами Лэмба

В данной работе была проверена работоспособность методики встроенного контроля деталей и конструкций из углепластиков ультразвуковыми волнами Лэмба. Проведены эксперименты по локации искусственных дефектов и ударных повреждений углепластикового образца, а также рассчитаны индексы поврежденности.In this paper, the efficiency of the procedure for the integrated control of carbon plastic parts and structures by ultrasonic Lamb waves was tested. Experiments were conducted to locate artificial defects and impact damage of the carbon-plastic sample, and damage indices were calculated

Степень и глубина наклепа поверхности отверстия при глубоком сверлении твердосплавными сверлами одностороннего резания

A comprehensive set of experimental and analytical methods has been used to characterise the sealing and fluid -transport properties of fine-grained (pelitic) sedimentary rocks under the pressure and temperature conditions of geological CO2 storage. The flow experiments were carried out on cylindrical sample plugs of 28.5 or 38 mm diameter and 10-20 mm length. The capillary sealing effici ncy of the lithotypes was determined by repetitive gas breakthrough experiments to test for reproducibility and to detect petrophysical changes of the rock samples resulting from CO2/water/rock interactions. These tests were performed with both, Helium and sc CO2 on the initially water-saturated sample plugs. Although molecular diffusion is not considered as an efficient leakage mechanism it represents a rate-determining step in mineral reactions and reactive transport. Therefore repetitive CO2 diffusion experiments were carried out on selected samples in the water-saturated state. These measurements provide information on the molecular mobility of CO2 and its hydrolysis products and on the physical and chemical storage capacity of the rock for these species. Before and after each experiment a steady -state fluid flow of water was established across the samples by applying high pressure gradients. This procedure ensured a defined state of saturation. Permeability coefficients derived from these tests were used to detect changes in the transport properties resulting from exposure to CO2. The fluid transport experiments were complemented by petrophysical (BET specific surface area, mercury porosimetry) and mineralogical analyses (X-ray diffraction; XRD ) of the original and post -experiment samples. The experiments revealed significant changes in the transport properties and the sealing efficiency of the samples. The gas breakthrough tests resulted in reduced capillary entry pressures and increased effective gas permeability as a result of repetitive exposure to CO2. Repeated diffusion tests revealed a faster diffusive transport in the second experiment. An increase in water permeability was consistently observed after both, capillary breakthrough tests and diffusi on experiments with CO2. The BET and mercury porosimetry results were not significantly affected by the CO2 treatment. XRD measurements before and after CO2 treatment revealed significant variations in the mineral compositions of the samples upon exposure to CO2. © 2009 Elsevier Ltd. All rights reserved

Quality of Graphite Target for Biological/Biomedical/Environmental Applications of 14C-Accelerator Mass Spectrometry

Catalytic graphitization for 14C-accelerator mass spectrometry (14C-AMS) produced various forms of elemental carbon. Our high-throughput Zn reduction method (C/Fe = 1:5, 500 °C, 3 h) produced the AMS target of graphite-coated iron powder (GCIP), a mix of nongraphitic carbon and Fe3C. Crystallinity of the AMS targets of GCIP (nongraphitic carbon) was increased to turbostratic carbon by raising the C/Fe ratio from 1:5 to 1:1 and the graphitization temperature from 500 to 585 °C. The AMS target of GCIP containing turbostratic carbon had a large isotopic fractionation and a low AMS ion current. The AMS target of GCIP containing turbostratic carbon also yielded less accurate/precise 14C-AMS measurements because of the lower graphitization yield and lower thermal conductivity that were caused by the higher C/Fe ratio of 1:1. On the other hand, the AMS target of GCIP containing nongraphitic carbon had higher graphitization yield and better thermal conductivity over the AMS target of GCIP containing turbostratic carbon due to optimal surface area provided by the iron powder. Finally, graphitization yield and thermal conductivity were stronger determinants (over graphite crystallinity) for accurate/precise/high-throughput biological, biomedical, and environmental14C-AMS applications such as absorption, distribution, metabolism, elimination (ADME), and physiologically based pharmacokinetics (PBPK) of nutrients, drugs, phytochemicals, and environmental chemicals

Biological/Biomedical Accelerator Mass Spectrometry Targets. 2. Physical, Morphological, and Structural Characteristics

The number of biological/biomedical applications that require AMS to achieve their goals is increasing, and so is the need for a better understanding of the physical, morphological, and structural traits of high quality of AMS targets. The metrics of quality included color, hardness/texture, and appearance (photo and SEM), along with FT-IR, Raman, and powder X-ray diffraction spectra that correlate positively with reliable and intense ion currents and accuracy, precision, and sensitivity of fraction modern (Fm). Our previous method produced AMS targets of gray-colored iron−carbon materials (ICM) 20% of the time and of graphite-coated iron (GCI) 80% of the time. The ICM was hard, its FT-IR spectra lacked the sp2 bond, its Raman spectra had no detectable G′ band at 2700 cm−1, and it had more iron carbide (Fe3C) crystal than nanocrystalline graphite or graphitizable carbon (g-C). ICM produced low and variable ion current whereas the opposite was true for the graphitic GCI. Our optimized method produced AMS targets of graphite-coated iron powder (GCIP) 100% of the time. The GCIP shared some of the same properties as GCI in that both were black in color, both produced robust ion current consistently, their FT-IR spectra had the sp2 bond, their Raman spectra had matching D, G, G′, D+G, and D′′ bands, and their XRD spectra showed matching crystal size. GCIP was a powder that was easy to tamp into AMS target holders that also facilitated high throughput. We concluded that AMS targets of GCIP were a mix of graphitizable carbon and Fe3C crystal, because none of their spectra, FT-IR, Raman, or XRD, matched exactly those of the graphite standard. Nevertheless, AMS targets of GCIP consistently produced the strong, reliable, and reproducible ion currents for high-throughput AMS analysis (270 targets per skilled analyst/day) along with accurate and precise Fm values

Jasmonic Acid-Induced Changes in Brassica oleracea Affect Oviposition Preference of Two Specialist Herbivores

Jasmonic acid (JA) is a key hormone involved in plant defense responses. The effect of JA treatment of cabbage plants on their acceptability for oviposition by two species of cabbage white butterflies, Pieris rapae and P. brassicae, was investigated. Both butterfly species laid fewer eggs on leaves of JA-treated plants compared to control plants. We show that this is due to processes in the plant after JA treatment rather than an effect of JA itself. The oviposition preference for control plants is adaptive, as development time from larval hatch until pupation of P. rapae caterpillars was longer on JA-treated plants. Total glucosinolate content in leaf surface extracts was similar for control and treated plants; however, two of the five glucosinolates were present in lower amounts in leaf surface extracts of JA-treated plants. When the butterflies were offered a choice between the purified glucosinolate fraction isolated from leaf surface extracts of JA-treated plants and that from control plants, they did not discriminate. Changes in leaf surface glucosinolate profile, therefore, do not seem to explain the change in oviposition preference of the butterflies after JA treatment, suggesting that as yet unknown infochemicals are involved