The influence of zirconium on microstructure and toughness of low-alloy steel weld metal was studied. Weld metals with different
zirconium contents were obtained adding iron-zirconium alloy in the welding flux formulation. Weld metal chemical composition
proved that zirconium was able to be transferred from the flux to the weld metal. The addition of zirconium refined the weld
metal microstructure, increasing the acicular ferrite content. Weld metal toughness, determined by means of impact Charpy-V
tests, showed that the zirconium addition is beneficial up to a content of 0.005 wt.%. Above this level, zirconium was not
able to produce further microstructure refinement, although the toughness was reduced, possibly due to the formation of microconstituent
such as the martensite-austenite constituent (M-A), which is considered to be deleterious to the weld metal toughness. 相似文献
Silicon - A previously synthesized PABA-MCM-41 mesoporous material was used to remove Cr(VI) in leather samples. The optimization step was performed using univariate method for the following... 相似文献
Polymer/clay composite hydrogels were prepared based on PVA hydrogels containing 3–10 wt.‐% MOM. Their microstructure and morphology were studied by FT‐IR, WAXS and SEM, whereas the interactions between MOM and PVA were evaluated by thermal analyses. The swelling ratios for the PVA/MOM hydrogels decrease with increasing MOM content. WAXS results indicate that MOM was intercalates, and DSC results show a strong interaction between PVA and MOM. This interaction results in a stable network, which is confirmed by the elastic modulus and the thermal decomposition behavior of the hydrogels. Therefore, MOM acts as a co‐crosslinker, improving the stability of the network.
Assisted reproductive techniques (ART) and parental nutritional status have profound effects on embryonic/fetal and placental development, which are probably mediated via “programming” of gene expression, as reflected by changes in their epigenetic landscape. Such epigenetic changes may underlie programming of growth, development, and function of fetal organs later in pregnancy and the offspring postnatally, and potentially lead to long-term changes in organ structure and function in the offspring as adults. This latter concept has been termed developmental origins of health and disease (DOHaD), or simply developmental programming, which has emerged as a major health issue in animals and humans because it is associated with an increased risk of non-communicable diseases in the offspring, including metabolic, behavioral, and reproductive dysfunction. In this review, we will briefly introduce the concept of developmental programming and its relationship to epigenetics. We will then discuss evidence that ART and periconceptual maternal and paternal nutrition may lead to epigenetic alterations very early in pregnancy, and how each pregnancy experiences developmental programming based on signals received by and from the dam. Lastly, we will discuss current research on strategies designed to overcome or minimize the negative consequences or, conversely, to maximize the positive aspects of developmental programming. 相似文献
This paper reports the occurrence of dehydroacetic acid in cheese and cheese coatings collected in Italy during Agricultural Ministry Official control. Dehydroacetic acid is an antimicrobial substance not allowed to be used in EU countries as a food additive, with unknown effects on human health. Dehydroacetic acid was measured by a validated HPLC method according to Commission Decision 2002/657/EC criteria in terms of specificity, linearity, precision and accuracy, limit of detection, and limit of quantification. The method was successfully applied to 129 samples of commercial cheese coatings and related treated cheeses collected in Italy during 2017. The overall results demonstrated that about 40% of the investigated cheese coatings contained dehydroacetic acid, ranging from 0.010% to 2.5% w/w, evidencing illicit employment of this substance. Moreover, about 25% of treated cheeses contained dehydroacetic acid, from 5 to 250 mg/Kg, proving transfer of this substance from crust to cheese. 相似文献
We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser. 相似文献