We present evolutionary models of primary stars with initial masses in the range of 30 to 40
M
⊙
, evolving in massive binary systems, possible progenitors of gravitational wave sources. The binary ...systems have an initial mass ratio of 0.9, an initial orbital period of 3 days and an accretion efficiency of 10%. The evolution of the primary stars in those systems is followed from the main sequence to the formation of the carbon-oxygen core. In addition, the evolution of two primaries with the lowest initial masses is calculated to the iron core formation. The masses of the helium and carbon-oxygen cores formed in primary stars are compared with the masses of cores formed in single stars with the same initial masses. The initial mass limit for the black hole formation for this selected type of massive binaries is established between 32 and 34
M
⊙
. All models are calculated with the MESA (Modules for Experiments in Stellar Astrophysics) numerical code.
Graphic abstract
During inner ear development, Notch exhibits two modes of operation: lateral induction, which is associated with prosensory specification, and lateral inhibition, which is involved in hair cell ...determination. These mechanisms depend respectively on two different ligands, jagged 1 (Jag1) and delta 1 (Dl1), that rely on a common signaling cascade initiated after Notch activation. In the chicken otocyst, expression of Jag1 and the Notch target Hey1 correlates well with lateral induction, whereas both Jag1 and Dl1 are expressed during lateral inhibition, as are Notch targets Hey1 and Hes5. Here, we show that Jag1 drives lower levels of Notch activity than Dl1, which results in the differential expression of Hey1 and Hes5. In addition, Jag1 interferes with the ability of Dl1 to elicit high levels of Notch activity. Modeling the sensory epithelium when the two ligands are expressed together shows that ligand regulation, differential signaling strength and ligand competition are crucial to allow the two modes of operation and for establishing the alternate pattern of hair cells and supporting cells. Jag1, while driving lateral induction on its own, facilitates patterning by lateral inhibition in the presence of Dl1. This novel behavior emerges from Jag1 acting as a competitive inhibitor of Dl1 for Notch signaling. Both modeling and experiments show that hair cell patterning is very robust. The model suggests that autoactivation of proneural factor Atoh1, upstream of Dl1, is a fundamental component for robustness. The results stress the importance of the levels of Notch signaling and ligand competition for Notch function.
•In this work unmodified lemon peel was investigated for purification of copper polluted water.•The maximum Langmuir adsorption capacity was evaluated to be 13.2 mg/g at optimum contact time of 15 ...minutes and at pH 4.•The lemon peel removed 89% of copper ions from wastewater for 15 min at pH3.
In this study, unmodified lemon peel, as agro-industrial waste, was used to investigate removal efficiency of copper ions from aqueous solutions and mining wastewater. The effects of solution pH, adsorption time, metal ion concentration and dose of adsorbent on sorption were studied in batch experiments. The maximum Langmuir adsorption capacity was evaluated to be 13.2 mg/g at optimum contact time of 15 min. The maximum removal of copper ions from mining-wastewater at natural pH (pH3) was 89%, indicating that lemon peel could be employed as an effective low-cost adsorbent for removal of copper ions from wastewater at acidic conditions.
This work presents a study of the applicability of laser-induced breakdown spectroscopy based on infrared transversally excited atmospheric CO
2
pulsed laser for quantitative analysis of main ...inorganic elements in lignite coals. Calibration standards were prepared by mixing and pelleting an appropriate amount of rock reference material and graphite. Time-integrated spatially resolved measurements of analyte spectra of standard samples were used to construct univariate calibration curves of Al, Si, Ca, Fe and Mg. The spectral intensities of analytical lines were normalized by the carbon spectral line to compensate for the shot-to-shot fluctuation of plasma parameters. The obtained curves of growth have good linearity in a wide range of concentrations (up to 1% for Al and 3% for Si). Correlation coefficients were in the range of 0.955–0.993, depending on the element. Measured limits of detection (from 2.4 to 25 ppm for analyzed metals and 61 ppm for Si) are low enough to control the coal combustion process in power plants. The Stark-broadening and the Boltzmann plot method were used to determine apparent values of excitation temperatures and electron number densities. A relatively small but measurable influence of the concentration of metal elements on the plasma parameters was observed, which should be considered in quantitative analysis of coal samples with higher inorganic elements content.
We traced the changes in GABAergic parvalbumin (PV)-expressing interneurons of the hippocampus and reticulo-thalamic nucleus (RT) as possible underlying mechanisms of the different local cortical and ...hippocampal electroencephalographic (EEG) microstructures during the non-rapid-eye movement (NREM) sleep compared with anesthesia-induced unconsciousness by two anesthetics with different main mechanisms of action (ketamine/diazepam versus propofol). After 3 h of recording their sleep, the rats were divided into two experimental groups: one half received ketamine/diazepam anesthesia and the other half received propofol anesthesia. We simultaneously recorded the EEG of the motor cortex and hippocampus during sleep and during 1 h of surgical anesthesia. We performed immunohistochemistry and analyzed the PV and postsynaptic density protein 95 (PSD-95) expression. PV suppression in the hippocampus and at RT underlies the global theta amplitude attenuation and hippocampal gamma augmentation that is a unique feature of ketamine-induced versus propofol-induced unconsciousness and NREM sleep. While PV suppression resulted in an increase in hippocampal PSD-95 expression, there was no imbalance between inhibition and excitation during ketamine/diazepam anesthesia compared with propofol anesthesia in RT. This increased excitation could be a consequence of a lower GABA interneuronal activity and an additional mechanism underlying the unique local EEG microstructure in the hippocampus during ketamine/diazepam anesthesia.
This study aimed to investigate the level of exposure of eye lenses in
orthopedic surgeons performing routine clinical work and to determine
future monitoring practice, as Serbian radiation ...protection law still
employs higher limits. The dose was measured monthly in terms of H (0.03)
with three different dosimeters placed on a 3-D-printed headband, worn on a
forehead by three orthopedic surgeons, during all procedures involving
fluoroscopy. The mean dose for the left and right eye was 271 ? 109 ?Sv and
269 ? 101 ?Sv, respectively, with no significant difference (p-value
0.977) between the left and right eye observed. Considering the highest
recorded monthly value, the annual dose is expected to be 4.85 mSv without
protective items, well below the new ICRP limit of 20 mSv. There was no
observed correlation between eye lens dose and both fluoroscopy time and
exposure parameters. Considering the cumulative impact of dose and the
evidence pointing to an elevated incidence of lenticular opacities for
cumulative doses exceeding 10 mSv, it is advisable to institute ongoing
monitoring, especially when new surgeons incorporate image-guided
procedures or when novel techniques are introduced into surgical practice.
We investigated the alterations of hippocampal and reticulo-thalamic (RT) GABAergic parvalbumin (PV) interneurons and their synaptic re-organizations underlying the prodromal local sleep disorders in ...the distinct rat models of Parkinson’s disease (PD). We demonstrated for the first time that REM sleep is a predisposing state for the high-voltage sleep spindles (HVS) induction in all experimental models of PD, particularly during hippocampal REM sleep in the hemiparkinsonian models. There were the opposite underlying alterations of the hippocampal and RT GABAergic PV+ interneurons along with the distinct MAP2 and PSD-95 expressions. Whereas the PD cholinopathy enhanced the number of PV+ interneurons and suppressed the MAP2/PSD-95 expression, the hemiparkinsonism with PD cholinopathy reduced the number of PV+ interneurons and enhanced the MAP2/PSD-95 expression in the hippocampus. Whereas the PD cholinopathy did not alter PV+ interneurons but partially enhanced MAP2 and suppressed PSD-95 expression remotely in the RT, the hemiparkinsonism with PD cholinopathy reduced the PV+ interneurons, enhanced MAP2, and did not change PSD-95 expression remotely in the RT. Our study demonstrates for the first time an important regulatory role of the hippocampal and RT GABAergic PV+ interneurons and the synaptic protein dynamic alterations in the distinct rat models of PD neuropathology.
The
Paulownia
leaves (PL) was used for the first time as feedstock for the potential production of novel carbon-rich materials applying hydrothermal carbonization (HTC) technology. The HTC is one of ...the suitable methods for converting biomass into high-value carbonaceous products that could replace existing fossil fuels or be used for some other application. In this study, hydrochars of PL were obtained at five different temperatures (180, 200, 220, 240, and 260 °C), and the influence of temperature on hydrochar structures was analyzed. Physicochemical composition, structural, and combustion properties were estimated for hydrochar efficient characterization. The results showed that tested hydrochars had lower moisture, volatiles, oxygen, and sulfur content compared to PL biomass. Also, the HTC process increases carbon content and created high-energy C–C bond structures in hydrochars which improved fuel ratio (FR), energy density (ED), higher heat value (HHV), and lower heating value (LHV). However, hydrochar mass yields were significantly low, which affected the lower heating value (EY). The spectroscopic and thermal analysis confirmed the formation of new aromatic structures in hydrochars and enhancement of their thermal stability and combustion ability, respectively. Before hydrochar practice, in order to enhance their mass yields, it is necessary to further analyze the influence of the HTC parameters or hydrothermal co-carbonization with other biomass should be taken into concern. The results showed that HTC could be an efficient method to improve the combustion properties of PL biomass.
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•Raw corn silk as novel adsorbent for copper and zinc has been investigated.•Adsorption process of metal is favorable and occurs under monolayer surface.•The involvement of ...complexation and ion – exchange binding mechanisms is confirmed.•Adsorption process is feasible, spontaneous and endothermic.•Adsorbent can be efficiently regenerated and reused.
In this study the novel biosorbent – raw corn silk (CS) was investigated for Cu2+ and Zn2+ removal from aqueous solutions. The physical and chemical properties of CS were determined by SEM – EDX and ATR – FTIR techniques. The SEM micrographs revealed that surface morphology of CS is suitable for metal adsorption, while FTIR analysis confirmed presence of various active groups (OH, CO, COC, CC and amide II) which could interact with metal ions. The adsorption experiments were performed in batch system. Experimental data were fitted by pseudo – first order and pseudo – second order kinetic models as well as Langmuir and Freundlich isotherm models. Biosorption of the both metals follow pseudo second-order kinetic model. The best fitting adsorption model is Langmuir model and the maximum biosorption capacities (qmax) for Cu2+ and Zn2+ at 313K and pH 5.0 were 15.35mg g−1 and 13.98mgg−1, respectively. The thermodynamic parameters such as Gibbs free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were studied at different metal concentration and three temperatures. According to thermodynamic study, the biosorption process for both metals is feasible, endothermic and spontaneous. According to thermodynamic study, the biosorption process for both metals is feasible, endothermic and spontaneous. Ion – exchange is the dominant mechanism in adsorption of Cu2+ and Zn2+ on the CS with a certain degree of complexation. Desorption study was performed in three adsorption/desorption cycles with diluted nitric acid. Results show that after metal adsorption CS can be efficiently recovered and reused for new adsorption process. Obtained results indicated that corn silk could be used as efficient novel biosorbent for Cu2+ and Zn2+ removal from water samples.
Pulsed laser ablation in liquids (PLAL) is an approach for the direct synthesis of nanoparticles from the bulk material. In the present work, silver and gold nanoparticles (NPs) were synthesized ...using the PLAL technique, and obtained water colloid suspensions were characterized by TEM–EDX, ICP-OES, UV–VIS, and DLS methods. On the other hand, Laser-Induced Breakdown Spectroscopy (LIBS) is a well-recognized and versatile analytical technique for the element analysis of solid samples. However, obtaining improved spectral intensity and detection sensitivity are still great challenging tasks, especially for an alternative and cost-effective LIBS setup based on TEA CO
2
laser. Considering these demands, this work aimed to investigate a promising approach to signal enhancement based on the deposition of noble NPs on the plastic sample. The effect of NPS on the enhancement of the LIBS signal has been investigated. LIBS experiments were carried out in air at atmospheric pressure and obtained spectra with a high signal-to-background (SBR) ratio. This study shows that signal enhancement can be achieved followed by the lower limits of detection by increasing the ablation amount rate.
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