Intraspecific variability in the response of bloom-forming marine microalgae to changed climate conditions

Phytoplankton populations can display high levels of genetic diversity that, when reflected by phenotypic variability, may stabilize a species response to environmental changes. We studied the effects of increased temperature and CO2 availability as predicted consequences of global change, on 16 genetically different isolates of the diatom Skeletonema marinoi from the Adriatic Sea and the Skagerrak (North Sea), and on eight strains of the PST (paralytic shellfish toxin)-producing dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Maximum growth rates were estimated in batch cultures of acclimated isolates grown for five to 10 generations in a factorial design at 20 and 24°C, and present day and next century applied atmospheric pCO2, respectively. In both species, individual strains were affected in different ways by increased temperature and pCO2. The strongest response variability, buffering overall effects, was detected among Adriatic S. marinoi strains. Skagerrak strains showed a more uniform response, particularly to increased temperature, with an overall positive effect on growth. Increased temperature also caused a general growth stimulation in A. ostenfeldii, despite notable variability in strain-specific response patterns. Our data revealed a significant relationship between strain-specific growth rates and the impact of pCO2 on growth—slow growing cultures were generally positively affected, while fast growing cultures showed no or negative responses to increased pCO2. Toxin composition of A. ostenfeldii was consistently altered by elevated temperature and increased CO2 supply in the tested strains, resulting in overall promotion of saxitoxin production by both treatments. Our findings suggest that phenotypic variability within populations plays an important role in the adaptation of phytoplankton to changing environments, potentially attenuating short-term effects and forming the basis for selection. In particular, A. ostenfeldii blooms may expand and increase in toxicity under increased water temperature and atmospheric pCO2 conditions, with potentially severe consequences for the coastal ecosystem

EFFECT OF CARBON CONTENT ON THE PHASE TRANSFORMATION CHARACTERISTICS, MICROSTRUCTURE AND PROPERTIES OF 500 MPa GRADE MICROALLOYED STEELS WITH NONPOLYGONAL FERRITE MICROSTRUCTURES

The influence of C in the range of 0.011-0.043 wt-% on the phase transformation characteristics, mechanical properties andmicrostructure of Fe-2.0Mn-0.25Mo-0.8Ni-0.05Nb-0.03Ti steel was investigated. In the dilatometric experiments, it wasfound that a reduction in the C content increased the phase transformation temperatures, decreased the hardness andpromoted quasi-polygonal ferrite (QF) formation over granular bainitic ferrite (GBF) and bainitic ferrite (BF), but at the sametime the sensitivity of the phase transformation temperatures and hardness to cooling rates was reduced. Mechanical testingof laboratory hot rolled plates revealed that the targeted yield strength of 500 MPa was reached even in the steel withthe lowest C content (0.011wt-%). An increase in C content did not considerably increase the yield strength, although thetensile strength was more significantly increased. Impact toughness properties, in turn, were markedly deteriorated due to thisC content increment. Microstructural analysis of the hot rolled plates showed that an increase in C content decreased thefraction of QF and consequently increased the fraction of GBF and BF, as well as the size and fraction of C-enriched secondarymicroconstituents. In addition, the size of the coarsest crystallographic packets seemed to be finer in the low C steelwith QF dominated microstructure than in its higher C counterparts with higher fractions of GBF-BF, even thought theaverage crystallographic packet size was slightly finer in these higher C steels.Mechanical testing of the simulated CGHAZ’s showed that their toughness properties are not strongly dependenton C content, although there exists a general trend for toughness to slightly weaken with increasing C content. Itcould be concluded that HAZ toughness properties of these types of steels are acceptable. On the basis of dilatometricexperiments, mechanical testing and microstructural analysis it can be stated that a good combination of strength,toughness and weldability as well as microstructural stability can be reached in very low C steels with QF dominatedmicrostructures. Finally, an example of this type of microstuctural concept, which has been successfull

Crystallographic Analysis of Martensite in 0.2C-2.0Mn-1.5Si-0.6Cr Steel by EBSD

The crystallography of martensite formed in 0.2C-2.0Mn-1.5Si-0.6Cr steel was studied using the EBSDtechnique. The results showed that the observed orientation relationship was closer to the Nishiyama-Wassermann (N-W) than to the Kurdjumov-Sachs (K-S) orientation relationship (OR). The microstructure ofmartensite consisted of parallel laths forming morphological packet-like structures. Typically, there were threedifferent lath orientations in a morphological packet consisting of three specific N-W OR variants sharing thesame {111} austenite plane. A packet of martensite laths with common {111} austenite plane was termed as acrystallographic packet. Generally, the crystallographic packet size corresponded to the morphological packetsize, but occasionally the morphological packet was found to consist of two or more crystallographic packets.Therefore, the crystallographic packet size appeared to be finer than the morphological packet size. Therelative orientation between the variants in crystallographic packets was found to be near 60°/<110>. Thisappears to explain the strong peak observed near 60° in the grain boundary misorientation distribution.Martensite also contained a high fraction of boundaries with their misorientation in the range 2.5-8°.Typically these boundaries were found to be located inside the martensite laths forming lath-like sub-grains,whose long axes were parallel with the long axis of the martensite laths

Preterm birth and subsequent timing of pubertal growth, menarche, and voice break

Background: We evaluated pubertal growth and pubertal timing of participants born preterm compared to those born at term. Methods: In the ESTER Preterm Birth Study, we collected growth data and measured final height of men/women born very or moderately preterm (<34 gestational weeks, n = 52/55), late preterm (34–<37 weeks, 94/106), and term (≥37 weeks, 131/151), resulting in median 9 measurements at ≥6 years. Timing of menarche or voice break was self-reported. Peak height velocity (PHV, cm/year) and age at PHV (years) were compared with SuperImposition by Translation And Rotation (SITAR) model (sexes separately). Results: Age at PHV (years) and PHV (cm/year) were similar in all gestational age groups. Compared to term controls, insignificant differences in age at PHV were 0.1 (95% CI: −0.2 to 0.4) years/0.2 (−0.1 to 0.4) for very or moderately/late preterm born men and −0.0 (−0.3 to 0.3)/−0.0 (−0.3 to 0.2) for women, respectively. Being born small for gestational age was not associated with pubertal growth. Age at menarche or voice break was similar in all the gestational age groups. Conclusions: Timing of pubertal growth and age at menarche or voice break were similar in participants born preterm and at term

Preterm birth and subsequent timing of pubertal growth, menarche, and voice break

Background We evaluated pubertal growth and pubertal timing of participants born preterm compared to those born at term. Methods In the ESTER Preterm Birth Study, we collected growth data and measured final height of men/women born very or moderately preterm (= 37 weeks, 131/151), resulting in median 9 measurements at >= 6 years. Timing of menarche or voice break was self-reported. Peak height velocity (PHV, cm/year) and age at PHV (years) were compared with SuperImposition by Translation And Rotation (SITAR) model (sexes separately). Results Age at PHV (years) and PHV (cm/year) were similar in all gestational age groups. Compared to term controls, insignificant differences in age at PHV were 0.1 (95% CI: -0.2 to 0.4) years/0.2 (-0.1 to 0.4) for very or moderately/late preterm born men and -0.0 (-0.3 to 0.3)/-0.0 (-0.3 to 0.2) for women, respectively. Being born small for gestational age was not associated with pubertal growth. Age at menarche or voice break was similar in all the gestational age groups. Conclusions Timing of pubertal growth and age at menarche or voice break were similar in participants born preterm and at term. Impact Pubertal growth and pubertal timing were similar in preterm and term participants in a relatively large cohort with a wide range of gestational ages. Previous literature indicates that small for gestational age is a risk for early puberty in term born children. This was not shown in preterm children. While our study had limited power for children born very preterm, all children born preterm were not at increased risk for early puberty.Peer reviewe

Excavation damage zone fracture modelling for seismic tomography : a comparison of explicit fractures and effective medium approaches

We model the full wavefield produced by a seismic velocity survey and optimise the representation of the fracture zone to best match field waveforms. The velocity survey was part of a mapping study on fractures in the Excavation Damage Zone (EDZ) of ONKALO underground research facility at Olkiluoto. The EDZ results from excavation of the rock mass, which modifies stress conditions changing the nature and behaviour of pre-existing fractures and generating new fracturing. These fractures act as the main transport pathways for contaminants both in and out of a geological disposal facility (GDF). Our goal is to test different representations of the fracture zone and to determine which models most successfully improve the interpretation of the fracture zone, producing estimates of a key unknown parameter, fracture stiffness, in addition to fracture sizes, fracture geometry, fracture density and crack density. We use modelling techniques previously tested in theoretical and laboratory studies and assess their performance on a real engineering problem. The paper introduces the field experiment and relevant information from the GDF in Finland. It describes the methodologies used for representing the fracture networks in the models — Explicit Fracture models with two approximations called Pixelised Fracture Model (PFM) and Equivalent Discrete Fracture Medium (EDFM), the Effective Medium (EM) model, and two versions of the Localised Effective Medium (LEM) model (LEM fine, LEM thick). These alternative representations were used within models of the field experiment and the calculated waveforms were used in an iterative inversion for fracture stiffness. Results show that the EM model and the EDFM model were unsuccessful in matching recorded waveforms. The fine LEM model and the explicit PFM model produced the best results especially after iterative optimisation of the fracture stiffness, giving confidence that further optimisation will lead to improved characterisation of the fracturing from the full waveform data

Avoimen systeemin magmaattisten prosessien diagnosointi Magmakammiosimulaattorilla. Osa I: pääalkuaineet ja faasitasapainot

The Magma Chamber Simulator (MCS) is a thermodynamic tool for modeling the evolution of magmatic systems that are open with respect to assimilation of partial melts or stoped blocks, magma recharge + mixing, and fractional crystallization. MCS is available for both PC and Mac. In the MCS, the thermal, mass, and compositional evolution of a multicomponent-multiphase composite system of resident magma, wallrock, and recharge reservoirs is tracked by rigorous self-consistent thermodynamic modeling. A Recharge-Assimilation (Assimilated partial melt or Stoped blocks)-Fractional Crystallization (R(n)AS(n)FC;n(tot) The trace element and isotope MCS computational tool (MCS-Traces) is described in a separate contribution (part II).Peer reviewe

The microstructure and technological properties of ultra high strength 1100MPa grade strip steel

The article describes the microstructure and the technological properties of a direct quenched ultrahighstrength strip steel with the minimum specific yield strength of 1100MPa. The microstructure of thislow carbon, Mn-Cr-Mo-Cu-Ni alloyed steel consists mainly of auto-tempered lath martensite. Due to thesophisticated thermo-mechanical controlled processing schedule, the martensite transformation takesplace from a fine and uniform austenite grain structure. State-of-the-art steelmaking and continuous castingoperations guarantee a good inclusion cleanness and low level of segregation. The steel has excellent impactand fracture toughness properties with respect to its ultra-high strength level. The determined transitiontemperature for 28J in Charpy-V test and fracture toughness characteristic temperature, T0, were below-100°C. The weldability tests indicated that the impact toughness of the heat affected zone (HAZ) is excellentand there is no significant softening in the HAZ or in the welded joint in the wide range of t8/5 cooling times.The steel allows crack-free bending with a minimum inside bending radius equal to 3 times material thicknessirrespective of the bending direction. In addition, the steel has a good resistance to atmospheric corrosion