The Influence of Microstructure on Hydrogen Diffusion and Embrittlement of Multiphase Fine-Grained Steels with Increased Plasticity and Strength

The influence of microstructure on hydrogen diffusion and embrittlement of multiphase fine-grained structural steels with increased plasticity and strength was studied with electrochemical experiments which provide the hydrogenation of specimens in conditions simulating practice requirements. By means of all experimental data obtained from permeation experiments, mechanical investigations, SEM and EDS analyses, TRIP steel has shown greater resistance to hydrogen embrittlement than DP steel, testified by lower index of hydrogen embrittlement, lower diffusion coefficient, less inclusions and favourable microstructure with residual austenite. Namely, the residual austenite in the aspect of hydrogen embrittlement is a favourable phase in relation to martensite, because of its higher solubility of carbon and hydrogen and lower hardness. Therefore, TRIP steel could be considered the more suitable structural material than DP steel for application in conditions where contact with hydrogen is inevitable

Recent developments in the dynamics of wind-erosion

Those particles of the Earth's land-surface that are in contact with the atmosphere are at the mercy of two powerful natural forces, resulting from water- and air-flow. The story a single soil-grain could tell of its travels would surpass that of Marco Polo. It is unfortunate that one cannot “get the story” and thus answer many questions that are in the minds of those who wish to explain and control its behavior. The transport of granular material by fluids has been a subject of intense interest, especially in connection with flowing water. A great number of investigations have been made, both in the laboratory and in streams, on the effects of water-erosion and the underlying mechanisms of the movement of debris. As a result, at least for some phases of the process, explanations and empirical rules have been developed

Adsorption of Organic Acids on Blast Furnace Sludge

This paper describes the adsorption of two organic (acetic and citric) acids on the blast furnace sludge, a representative by-product of the steelmaking industry. By PIXE, XRD, BETand SEM methods, it was shown that blast furnace sludge is a complex heterogeneous material with a specific surface area of s = 31.46 m2 g–1, composed mainly of amorphous phase (w = 76.2 %), calcite (w = 9.9 %), magnetite (w = 6.3 %) and kaolinite (w = 2.2 %). Chemically, blast furnace sludge is dominated by O (w = 42.23 %) and C (w = 31.74 %). The adsorption process is analyzed using the theories of Freundlich and Langmuir. The experimental data were better fitted to the Langmuir isotherm. The negative Gibbs energy values indicate the spontaneous nature of adsorption. After adsorption the surface image changes in the BFS were observed, and BET surface area increased when acetic acid was adsorbed. Contrarily, blast furnace sludge became almost non-porous in the case of citric acid adsorption and BETsurface area decreased significantly

The Rocket Pioneers

An eyewitness account of the birth of the rocket age in the Arroyo Seco 50 years ago

The US Army Air Corps jet propulsion research project, GALCIT project no. 1, 1939 - 1946: A memoir

A history of the pre-World War II research and accomplishments of the Jet Propulsion Laboratory are given

America's first long-range-missile and space exploration program: The ORDCIT project of the Jet Propulsion Laboratory, 1943 - 1946: A memoir

Research and achievements of the wartime Jet Propulsion Laboratory are outlined. Accomplishments included development of the solid-propellant Private A and private R rockets and the liquid-propellant nitric acid-aniline WAC Corporal rocket

Shape-selective recognition of DNA abasic sites by metallohelices : inhibition of human AP endonuclease 1

Loss of a base in DNA leading to creation of an abasic (AP) site leaving a deoxyribose residue in the strand, is a frequent lesion that may occur spontaneously or under the action of various physical and chemical agents. Progress in the understanding of the chemistry and enzymology of abasic DNA largely relies upon the study of AP sites in synthetic duplexes. We report here on interactions of diastereomerically pure metallo–helical ‘flexicate’ complexes, bimetallic triple-stranded ferro-helicates [Fe2(NN-NN)3]4+ incorporating the common NN–NN bis(bidentate) helicand, with short DNA duplexes containing AP sites in different sequence contexts. The results show that the flexicates bind to AP sites in DNA duplexes in a shape-selective manner. They preferentially bind to AP sites flanked by purines on both sides and their binding is enhanced when a pyrimidine is placed in opposite orientation to the lesion. Notably, the Λ-enantiomer binds to all tested AP sites with higher affinity than the Δ-enantiomer. In addition, the binding of the flexicates to AP sites inhibits the activity of human AP endonuclease 1, which is as a valid anticancer drug target. Hence, this finding indicates the potential of utilizing well-defined metallo–helical complexes for cancer chemotherapy

Iron(II) supramolecular helicates interfere with the HIV-1 Tat–TAR RNA interaction critical for viral replication

The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates

Privacy-preserving security solution for cloud services

AbstractWe propose a novel privacy-preserving security solution for cloud services. Our solution is based on an efficient non-bilinear group signature scheme providing the anonymous access to cloud services and shared storage servers. The novel solution offers anonymous authenticationfor registered users. Thus, users' personal attributes (age, valid registration, successful payment) can be proven without revealing users' identity, and users can use cloud services without any threat of profiling their behavior. However, if a user breaks provider's rules, his access right is revoked. Our solution provides anonymous access, unlinkability and the confidentiality of transmitted data. We implement our solution as a proof of concept applicationand present the experimental results. Further, we analyzecurrent privacy preserving solutions for cloud services and group signature schemes as basic parts of privacy enhancing solutions in cloud services. We compare the performance of our solution with the related solutionsand schemes

A prospective analysis of the injury incidence of young male professional football players on artificial turf

Background: The effects of synthetic surfaces on the risk of injuries is still debated in literature and the majority of published data seems to be contradictory. For such reasons the understanding of injury incidence on such surfaces, especially in youth sport, is fundamental for injury prevention. Objectives: The aim of this study was to prospectively report the epidemiology of injuries in young football players, playing on artificial turfs, during a one sports season. Patients and Methods: 80 young male football players (age 16.1 ± 3.7 years; height 174 ± 6.6 cm; weight 64.2 ± 6.3 kg) were enrolled in a prospective cohort study. The participants were then divided in two groups; the first included players age ranging from 17 to 19 (OP) whereas the second included players age ranging from 13 to 16 (YP). Injury incidence was recorded prospectively, according to the consensus statement for soccer. Results: A total of 107 injuries (35 from the OP and 72 from the YP) were recorded during an exposure time of 83.760 hours (incidence 1.28/1000 per player hours); 22 during matches (incidence 2.84/1000 per player hours, 20.5%) and 85 during training (incidence 1.15/1000 per player hours, 79.5%). Thigh and groin were the most common injury locations (33.6% and 21.5%, respectively) while muscle injuries such as contractures and strains were the most common injury typologies (68.23%). No statistical differences between groups were displayed, except for the rate of severe injuries during matches, with the OP displaying slightly higher rates compared to the YP. Severe injuries accounted for 10.28% of the total injuries reported. The average time lost due to injuries was 14 days. Re-injuries accounted for 4.67% of all injuries sustained during the season. Conclusions: In professional youth soccer injury rates are reasonably low. Muscle injuries are the most common type of injuries while groin and thigh the most common locations. Artificial turf pitches don’t seem to contribute to injury incidence in young football players