Context. Helium accretion induced explosions in CO white dwarfs (WDs) are considered promising candidates for a number of observed types of stellar transients, including supernovae (SNe) of Type Ia ...and Type Iax. However, a clear favorite outcome has not yet emerged. Aims. We explore the conditions of helium ignition in the WD and the final fates of helium star-WD binaries as functions of their initial orbital periods and component masses. Methods. We computed 274 model binary systems with the Binary Evolution Code, in which both components are fully resolved. Both stellar and orbital evolution were computed including mass and angular momentum transfer, tides, gravitational wave emission, differential rotation, and internal hydrodynamic and magnetic angular momentum transport. We worked out the parts of the parameter space leading to detonations of the accreted helium layer on the WD, likely resulting in the complete disruption of the WD to deflagrations, where the CO core of the WD may remain intact and where helium ignition in the WD is avoided. Results. We find that helium detonations are expected only in systems with the shortest initial orbital periods, and for initially massive WDs (MWD ≥ 1.0 M⊙) and lower mass donors (Mdonor ≤ 0.8 M⊙), which have accumulated helium layers mostly exceeding 0.1 M⊙. Upon detonation, these systems would release the donor as a hypervelocity pre-WD runaway star, for which we predict the expected range of kinematic and stellar properties. Systems with more massive donors or initial periods exceeding 1.5 h likely undergo helium deflagrations after accumulating 0.1 − 0.001 M⊙ of helium. Helium ignition in the WD is avoided in systems with helium donor stars below ∼0.6 M⊙, and leads to three distinctly different groups of double WD systems. Conclusions. The size of the parameter space open to helium detonation corresponds to only about 3% of the galactic SN Ia rate and to 10% of the SN Iax rate, while the predicted large amounts of helium (0.1 M⊙) in progenitors cannot easily be reconciled with observations of archetypical SN Ia. However, the transients emerging from these systems may contribute significantly to massive helium novae, calcium-rich SNe Ib, and, potentially, very close double degenerate systems that may eventually produce either ordinary or peculiar SNe Ia, or, for the smallest considered masses, R Coronae Borealis stars.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
A new class of layered cathodes, LiNixCoyB1−x−yO2 (NCB), is synthesized. The proposed NCB cathodes have a unique microstructure in which elongated primary particles are tightly packed into spherical ...secondary particles. The cathodes also exhibit a strong crystallographic texture in which the a–b layer planes are aligned along the radial direction, facilitating Li migration. The microstructure, which effectively suppresses the formation of microcracks, improves the cycling stability of the NCB cathodes. The NCB cathode with 1.5 mol% B delivers a discharge capacity of 234 mAh g−1 at 0.1 C and retains 91.2% of its initial capacity after 100 cycles (compared to values of 229 mAh g−1 at 0.1 C and 78.8% for pristine LiNi0.9Co0.1O2). This study shows the importance of controlling the microstructure to obtain the required cycling stability, especially for Ni‐rich layered cathodes, where the main cause of capacity fading is related to mechanical strain in their charged state.
A new class of layered cathodes, LiNixCoyB1−x−yO2 (NCB), is proposed. NCB cathodes have a highly oriented microstructure in which the primary particle widths can be controlled by varying the boron fraction in the composition. The unique microstructural configuration of the NCB cathodes effectively suppress the formation of microcracks and significantly improve the cycling stability compared to a conventional cathode.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Bioelectrical impedance analysis (BIA) and especially its derived parameter phase angle have been widely used in different populations. The variability of BIA measures has often been cited as a major ...limitation for its clinical use in evaluating nutritional status and overall health of patients. Cancer patients often present with malnourishment and cachexia, which complicate the course of treatment and affect outcomes. PubMed, CINAHL, EBSCO and Cochrane Library have been searched for relevant publications in English for BIA in cancer patients. Out of 197 total results, 27 original research articles related to BIA measures in cancer patients were included in this review. Studies indicate that the use of BIA and phase angle measures can benefit in the clinical management of cancer patients in multiple ways: in the prevention; diagnosis; prognosis; and outcomes related to treatments that affect nutritional and overall health status. Phase angle and fat-free mass measures were most commonly evaluated and correlated with nutritional status and survival rate. One limitation of BIA measures is the high interpatient variability which requires careful interpretation of results in the context of the individual patient rather than comparison with population data. The BIA and phase angle provide practitioners for the evaluation of nutritional and overall health status in cancer patients with a convenient and non-invasive technique and should be encouraged.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, VSZLJ, ZAGLJ
BACKGROUND In mammals, oocyte activation at fertilization is thought to be induced by the sperm-specific phospholipase C zeta (PLCζ). However, it still remains to be conclusively shown that PLCζ is ...the endogenous agent of oocyte activation. Some types of human infertility appear to be caused by failure of the sperm to activate and this may be due to specific defects in PLCζ. METHODS AND RESULTS Immunofluorescence studies showed PLCζ to be localized in the equatorial region of sperm from fertile men, but sperm deficient in oocyte activation exhibited no specific signal in this same region. Immunoblot analysis revealed reduced amounts of PLCζ in sperm from infertile men, and in some cases, the presence of an abnormally low molecular weight form of PLCζ. In one non-globozoospermic case, DNA analysis identified a point mutation in the PLCζ gene that leads to a significant amino acid change in the catalytic region of the protein. Structural modelling suggested that this defect may have important effects upon the structure and function of the PLCζ protein. cRNA corresponding to mutant PLCζ failed to induce calcium oscillations when microinjected into mouse oocytes. Injection of infertile human sperm into mouse oocytes failed to activate the oocyte or trigger calcium oscillations. Injection of such infertile sperm followed by two calcium pulses, induced by assisted oocyte activation, activated the oocytes without inducing the typical pattern of calcium oscillations. CONCLUSIONS Our findings illustrate the importance of PLCζ during fertilization and suggest that mutant forms of PLCζ may underlie certain types of human male infertility.
Autism spectrum disorders (ASDs) are neurodevelopmental disorders caused by various genetic and environmental factors that result in synaptic abnormalities. ASD development is suggested to involve ...microglia, which have a role in synaptic refinement during development. Autophagy and related pathways are also suggested to be involved in ASDs. However, the precise roles of microglial autophagy in synapses and ASDs are unknown. Here, we show that microglial autophagy is involved in synaptic refinement and neurobehavior regulation. We found that deletion of atg7, which is vital for autophagy, from myeloid cell-specific lysozyme M-Cre mice resulted in social behavioral defects and repetitive behaviors, characteristic features of ASDs. These mice also had increases in dendritic spines and synaptic markers and altered connectivity between brain regions, indicating defects in synaptic refinement. Synaptosome degradation was impaired in atg7-deficient microglia and immature dendritic filopodia were increased in neurons co-cultured with atg7-deficient microglia. To our knowledge, our results are the first to show the role of microglial autophagy in the regulation of the synapse and neurobehaviors. We anticipate our results to be a starting point for more comprehensive studies of microglial autophagy in ASDs and the development of putative therapeutics.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the supine position, forced-air warming is more effective on the lower body than on the upper body to prevent intraoperative hypothermia. However, it is unknown in the lateral decubitus position. ...We thus compared forced-air warming on the upper and lower bodies in the lateral position.
Patients (n=123) were randomised to receive forced-air warming on the upper body or lower body during thoracoscopic surgery in the lateral position. We measured the nasopharyngeal temperature at 0, 30, 60, 90, and 120 min after lateral positioning during surgery and the infrared tympanic membrane temperature at 0, 30, 60, 90, and 120 min after surgery. Patients received both upper and lower body warming at a temperature of <35.5°C. The primary outcome was the incidence of intraoperative hypothermia with a temperature of <36.0°C.
Intraoperative hypothermia was less frequent with the upper body warming than with the lower body warming {21/62 vs 35/61, risk ratio 95% confidence interval (CI) 0.6 (0.4–0.9), P=0.011}. The intraoperative temperature was higher with the upper body warming than with the lower body warming at 30 (P=0.002), 60 (P<0.001), and 90 (P<0.001) min after lateral positioning, and the postoperative temperature was higher at 0 (P<0.001) and 30 (P=0.001) min after surgery. Fewer patients received both upper and lower body warming in the upper body warming group than in the lower body warming group during surgery (1 vs 7, P=0.032).
Forced-air warming was more effective on the upper body than on the lower body to prevent hypothermia during thoracoscopic surgery in the lateral decubitus position.
NCT02993666.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In acid hydrolysis of plant biomass, polysaccharides are converted to monosaccharides, which is basic raw material for biorefinery for fermentation based process. These monosaccharides, however, are ...not stable in acidic reaction medium, and are converted to organic acids via furans. Impact of hemicelluloses and lignin on acid hydrolysis of cellulose was investigated to focus on monosaccharide production with different degrees of cellulose purity. Two-step concentrated sulphuric acid process was applied to biomass for monosaccharide conversion. Kinetics of cellulose hydrolysis was analysed using 1H NMR spectroscopy. Higher reaction temperature in secondary hydrolysis caused severe degradation of the monosaccharides. In pure and holocellulose, further reaction of glucose in acidic reaction medium produced formic acid and levulinic acid. However, lignocellulosic biomass generated much less formic acid and levulinic acid under the same reaction condition. Humin (or pseudo-lignin) was also formed by the condensation of lignin and furans from monosaccharides in acidic reaction condition. Thus, the fermentation inhibitors, furans and formic acid, were generated in low quantities by lignocellulosic biomass than by delignified biomass such as pure cellulose or holocellulose.
•Higher second hydrolysis temperature in concentrated sulphuric acid hydrolysis process led to more gluocose degradation products (formic acid, 5-hydroxymethylfurfural).•Lignin in goat willow biomass could hinder the formation of formic acid by bypath reaction to humin (or pseudo-lignin) formation.•Xylan in avicell cellulose promoted the formation of formic acid than pure cellulose.•For higher yield of glucose, careful control of second hydrolysis temperature in concentrated sulphuric acid hydrolysis is critical.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Development of advanced high energy density lithium ion batteries is important for promoting electromobility. Making electric vehicles attractive and competitive compared to conventional automobiles ...depends on the availability of reliable, safe, high power, and highly energetic batteries whose components are abundant and cost effective. Nickel rich LiNi x Co y Mn 1−x−y O 2 layered cathode materials ( x > 0.5) are of interest because they can provide very high specific capacity without pushing charging potentials to levels that oxidize the electrolyte solutions. However, these cathode materials suffer from stability problems. We discovered that doping these materials with tungsten (1 mol%) remarkably increases their stability due to a partial layered to cubic (rock salt) phase transition. We demonstrate herein highly stable Li ion battery prototypes consisting of tungsten-stabilized Ni rich cathode materials ( x > 0.9) with specific capacities >220 mA h g -1 . This development can increase the energy density of Li ion batteries more than 30% above the state of the art without compromising durability.
Context. The progenitors of many Type II supernovae have been observationally identified but the search for Type Ibc supernova (SN Ibc) progenitors has thus far been unsuccessful, despite the ...expectation that they are luminous Wolf-Rayet (WR) stars. Aims. We investigate how the evolution of massive helium stars affects their visual appearances, and discuss the implications for the detectability of SN Ibc progenitors. Methods. Evolutionary models of massive helium stars are analysed and their properties compared to Galactic WR stars. Results. Massive WR stars that rapidly lose their helium envelopes through stellar-wind mass-loss end their lives when their effective temperatures – related to their hydrostatic surfaces – exceed about 150 kK. At their pre-supernova stage, their surface properties resemble those of hot Galactic WR stars of WO sub-type. These are visually faint with narrow-band visual magnitudes Mv = −1.5 ··· −2.5, despite their high bolometric luminosities (log L/L⊙ = 5.6···5.7), compared to the bulk of Galactic WR stars (Mv < −4). In contrast, relatively low-mass helium stars that retain a thick helium envelope appear fairly bright in optical bands, depending on the final masses and the history of the envelope expansion during the late evolutionary stages. Conclusions. We conclude that SNe Ibc observations have so far not provided strong constraints on progenitor bolometric luminosities and masses, even with the deepest searches. We also argue that Ic progenitors are more challenging to identify than Ib progenitors in any optical images.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
Context.The collapsar model for long gamma-ray bursts requires a rapidly rotating Wolf-Rayet star as progenitor. Aims.We test the idea of producing rapidly rotating Wolf-Rayet stars in massive close ...binaries through mass accretion and consecutive quasi-chemically homogeneous evolution – the latter had previously been shown to provide collapsars below a certain metallicity threshold. Methods.We use a 1D hydrodynamic binary evolution code to simulate the evolution of a 16+15 $M_{\odot}$ binary model with an initial orbital period of 5 days and SMC metallicity ($Z=0.004$). Internal differential rotation, rotationally induced mixing and magnetic fields are included in both components, as well as non-conservative mass and angular momentum transfer, and tidal spin-orbit coupling. Results.The considered binary system undergoes early Case B mass transfer. The mass donor becomes a helium star and dies as a type Ib/c supernova. The mass gainer is spun-up, and internal magnetic fields efficiently transport accreted angular momentum into the stellar core. The orbital widening prevents subsequent tidal synchronization, and the mass gainer rejuvenates and evolves quasi-chemically homogeneously thereafter. The mass donor explodes 7 Myr before the collapse of the mass gainer. Assuming the binary to be broken-up by the supernova kick, the potential gamma-ray burst progenitor would become a runaway star with a space velocity of 27$\, {\rm km}\, {\rm s}^{-1}$, traveling about 200 pc during its remaining lifetime. Conclusions.The binary channel presented here does not, as such, provide a new physical model for collapsar production, as the resulting stellar models are almost identical to quasi-chemically homogeneously evolving rapidly rotating single stars. However, it may provide a means for massive stars to obtain the required high rotation rates. Moreover, it suggests that a possibly large fraction of long gamma-ray bursts occurs in runaway stars.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
PDF
