Initial Mass Research Articles

A Machine Learning Algorithm using Clinical and Demographic Data for All-Cause Preterm Birth Prediction.

Preterm birth remains the predominant cause of perinatal mortality throughout the United States and the world, with well-documented racial and socioeconomic disparities. To develop and validate a predictive algorithm for all-cause preterm birth using clinical, demographic, and laboratory data using machine learning. We performed a cohort study of pregnant individuals delivering at a single institution using prospectively collected information on clinical conditions, patient demographics, laboratory data, and health care utilization. Our primary outcome was all-cause preterm birth before 37 weeks. The dataset was randomly divided into a derivation cohort (70%) and a separate validation cohort (30%). Predictor variables were selected amongst 33 that had been previously identified in the literature (directed machine learning). In the derivation cohort, both statistical (logistic regression) and machine learning (XG-Boost) models were used to derive the best fit (C-Statistic) and then validated using the validation cohort. We measured model discrimination with the C-Statistic and assessed the model performance and calibration of the model to determine whether the model provided clinical decision-making benefits. The cohort includes a total of 12,440 deliveries among 12,071 individuals. Preterm birth occurred in 2,037 births (16.4%). The derivation cohort consisted of 8,708 (70%) and the validation cohort consisted of 3,732 (30%). XG-Boost was chosen due to the robustness of the model and the ability to deal with missing data and collinearity between predictor variables. The top five predictor variables identified as drivers of preterm birth, by feature importance metric, were multiple gestation, number of emergency department visits in the year prior to the index pregnancy, initial unknown body mass index, gravidity, and prior preterm delivery. Test performance characteristics were similar between the two populations (derivation cohort area under the curve [AUC] = 0.70 vs. validation cohort AUC = 0.63). Clinical, demographic, and laboratory information can be useful to predict all-cause preterm birth with moderate precision. · Machine learning can be used to create models to predict preterm birth.. · In our model, all-cause preterm birth can be predicted with moderate precision.. · Clinical, demographic, and laboratory information can be useful to predict all-cause preterm birth..

The big-bang started from nothing: Not the initially hot cosmic matter, but a positive vacuum pressure made the universe explode!

Mankind all over its past epochs did ask the question, how this huge and materially impressive universe could ever have started its existence. The standard dogmatic answer presently given by the majority of modern cosmologists is: By the Big-Bang! - i.e. that initial explosion of the central highly condensed world matter system! But why - it could be asked - should this system have exploded at all? Perhaps this popular BB-hypothesis of a general and global cosmic explosion creating the world is especially suggestive just in these days of wars and weapons all around. Nevertheless to declare such an initial event as the begin of the universe unexpectedly turns out to be extremely hard to explain when based on purely physical grounds. Though it is easy to envisage a granate explosion causing matter to fly apart in all directions from the center of the explosion, but as a total surprise it is extremely hard to explain which physically operating forces or pressures might be responsible to drive the initially highly compacted cosmic matter agglomeration apart of each other. If the explosion forces are imagined as due to acting thermal pressure forces of normal massive matter, then the needed pressures cannot be due to the extremely high temperatures of the condensed matter, because the thermal energy of relativistically hot matter, as relativity theory tells us, will act as an additional source of gravity, i.e. making matter even "heavier"! Hence this just impedes the initial mass agglomeration to explode and fly apart. As we shall show in the following article the explosive BB- event can only physically be explained, if the necessary pressure is not conventionally realized by the temperature of the gravitating matter, but to the contrary by the immaterial cosmic vacuum. In fact - as we shall demonstrate here - without a cosmic vacuum pressure, the so-called Big-Bang never at all could have happened. Certainly vacuum pressure up to the present days of cosmology still is a fully speculative subject, but it will become evident in the following article, that without this highly speculative, physically handable quantity a primordial Big-Bang would not have happened at all.

The impact of convective criteria on the properties of massive stars

Context. Libraries of stellar models computed with either the Ledoux or the Schwarzschild criterion to determine the sizes of convective regions are available in the literature. It is still not clear, however, which of these two criteria should be used, although many works have been devoted to that question in the past. Aims. In the framework of the evolution of single rotating stars, we study the differences between models computed with Ledoux and Schwarzschild criteria on the internal structure, evolutionary track in the Hertzsprung–Russell diagram (HRD), lifetimes, evolution of the surface abundances and velocities, and masses of the He and CO cores. We investigate the consequences on the nature of the supernova (SN) progenitors and the type of SN events, as well as on the stellar yields of light elements. We also study the impact on the outputs of population synthesis models. Methods. Models with initial masses between 7 and 120 M⊙ at solar metallicity (Z = 0.014) and with an initial rotation equal to 0 or 0.4 times the critical velocity at the zero-age main sequence were computed with either the Schwarzschild or the Ledoux criterion until the end of the C-burning phase. Results. Models with initial masses between 15 and 32 M⊙ computed with the Schwarzschild criterion show larger intermediate convective zones attached to the H-burning shell than models computed with the Ledoux criterion. Their CO cores and outer convective zones in the red supergiant (RSG) phase are also smaller. This impacts many outputs of stars during the core He-burning phase. Schwarzschild models have smaller CO cores and outer convective zones in the RSG phase, and their blue-to-red supergiant ratio is much higher than for Ledoux models. They also produce longer crossings of the Hertzsprung gap and favour blue loops. The upper luminosity of RSGs is little affected by the change in the convective criterion. The maximum luminosity of RSG progenitors for type II-P SN events is lowered from 5.2 to 4.95 when the Ledoux criterion is used instead of the Schwarzschild criterion in non-rotating models. The Schwarzschild criterion predicts longer-lasting, less nitrogen-enriched, and faster-rotating Cepheids. Rotational mixing tends to decrease the differences between Schwarzschild and Ledoux models. Conclusions. The results of this paper can be used as first guidelines to set up observational programs that may help to distinguish between these two model families.

Growth characteristics of early-stage (IA) lung adenocarcinoma and its value in predicting lymph node metastasis

BackgroundWe aim to compare the differences in growth characteristics between part-solid and solid lung adenocarcinoma, and to investigate the value of volume doubling time (VDT) or mass doubling time (MDT) in predicting lymph node (LN) metastasis and preoperative evaluation in patients of early-stage (IA) non-small cell lung cancer (NSCLC).MethodWe reviewed 8,653 cases of surgically resected stage IA lung adenocarcinoma between 2018 and 2022, with two follow-up visits at least 3 months apart, comparing diameter, volume, and mass growth of pSN and SN. VDT and MDT calculations for nodules with a volume change of at least 25%. Univariable or multivariable analysis was used to identify the risk factors. The area under the curve (AUC) for the receiver operating characteristic (ROC) curves was used to evaluate the diagnostic value.ResultsA total of 144 patients were included 114 with solid nodules (SN) and 25 with part-solid nodules (pSN). During the follow-up period, the mean VDTt and MDTt of SN were shorter than those of pSN, 337 vs. 541 days (p = 0.005), 298 vs. 458 days (p = 0.018), respectively. Without considering the ground-glass component, the mean VDTc and MDTc of SN were shorter than the solid component of pSN, 337 vs. 498 days (p = 0.004) and 298 vs. 453 days (p = 0.003), respectively. 27 nodules were clinically and pathologically diagnosed as N1/N2. Logistic regression identified initial diameter (p < 0.001), consolidation increase (p = 0.019), volume increase (p = 0.020), mass increase (p = 0.021), VDTt (p = 0.002), and MDTt (p = 0.004) were independent factors for LN metastasis. The ROC curves showed that the AUC for VDTt was 0.860 (95% CI, 0.778–0.943; p < 0.001) and for MDTt was 0.848 (95% CI, 0.759–0.936; p < 0.001).ConclusionsOur study showed significant differences in the growth characteristics of pSN and SN, and the application of VDT and MDT could be a valid predictor LN metastasis in patients with early-stage NSCLC.

Effective electronic waste valorization via microwave-assisted pyrolysis: investigation of graphite susceptor and feedstock quantity on pyrolysis using experimental and polynomial regression techniques.

Waste printed circuit board (WPCB) was subjected to microwave-assisted pyrolysis (MAP) to investigate the energy and pyrolysis products. In MAP, pyrolysis experiments were conducted, and the effects of WPCB to graphite mass ratio on three-phase product yields and their compositions were analyzed. In addition, the role of the initial WPCB mass (10, 55, and 100 g) and susceptor loading (2, 22, and 38 g) on the quality of product yield was also evaluated. By using design of experiments, the effects of graphite susceptor addition and WPCB feedstock quantity was investigated. A significant liquid yield of 38.2 wt.% was achieved at 38g of graphite and 100g of WPCB. Several other operating parameters, including average heating rate, pyrolysis time, microwave energy consumption, specific microwave power used, and product yields, were optimized for the MAP of WPCB. Pyrolysis index (PI) was calculated at the blending of fixed quantity WPCB (100g) and various graphite quantities in the following order: 2g (21) > 20g (20.4) > 38g (19.5). The PI improved by increasing the WPCB quantity (10, 55, and 100g) with a fixed quantity of graphite. This work proposes the product formation and new reaction pathways of the condensable compounds. GC-MS of the liquid fraction from the MAP of WPCBs without susceptor resulted in the generation of phenolic with 46.1% relative composition. The addition of graphite susceptor aided in the formation of phenolic and the relative composition of phenolics was found to be 83.6%. The area percent of phenol increased from 42.8% (without susceptor) to 78.6% (with susceptor). Without a susceptor, cyclopentadiene derivative was observed in a very high composition (~ 31 area %).

SUNRISE: The rich molecular inventory of high-redshift dusty galaxies revealed by broadband spectral line surveys

Understanding the nature of high-redshift dusty galaxies requires a comprehensive view of their interstellar medium (ISM) and molecular complexity. However, the molecular ISM at high redshifts is commonly studied using only a few species beyond 12C16O, limiting our understanding. In this paper, we present the results of deep 3 mm spectral line surveys using the NOrthern Extended Millimeter Array (NOEMA) targeting two strongly lensed dusty galaxies observed when the Universe was less than 1.8 Gyr old: APM 08279+5255, a quasar at redshift z = 3.911, and NCv1.143 (H-ATLAS J125632.7+233625), a z = 3.565 starburst galaxy. The spectral line surveys cover rest-frame frequencies from about 330 to 550 GHz for both galaxies. We report the detection of 38 and 25 emission lines in APM 08279+5255 and NCv1.143, respectively. These lines originate from 17 species, namely CO, 13CO, C18O, CN, CCH, HCN, HCO+, HNC, CS, C34S, H2O, H3O+, NO, N2H+, CH, c-C3H2, and the vibrationally excited HCN and neutral carbon. The spectra reveal the chemical richness and the complexity of the physical properties of the ISM. By comparing the spectra of the two sources and combining the analysis of the molecular gas excitation, we find that the physical properties and the chemical imprints of the ISM are different: the molecular gas is more excited in APM 08279+5255, which exhibits higher molecular gas temperatures and densities compared to NCv1.143; the molecular abundances in APM 08279+5255 are akin to the values of local active galactic nuclei (AGN), showing boosted relative abundances of the dense gas tracers that might be related to high-temperature chemistry and/or the X-ray-dominated regions, while NCv1.143 more closely resembles local starburst galaxies. The most significant differences between the two sources are found in H2O: the 448 GHz ortho-H2O(423 − 330) line is significantly brighter in APM 08279+5255, which is likely linked to the intense far-infrared radiation from the dust powered by AGN. Our astrochemical model suggests that, at such high column densities, far-ultraviolet radiation is less important in regulating the ISM, while cosmic rays (and/or X-rays and shocks) are the key players in shaping the molecular abundances and the initial conditions of star formation. Both our observed CO isotopologs line ratios and the derived extreme ISM conditions (high gas temperatures, densities, and cosmic-ray ionization rates) suggest the presence of a top-heavy stellar initial mass function. From the ∼330–550 GHz continuum, we also find evidence of nonthermal millimeter flux excess in APM 08279+5255 that might be related to the central supermassive black hole. Such deep spectral line surveys open a new window into the physics and chemistry of the ISM and the radiation field of galaxies in the early Universe.

Variation of the High-mass Slope of the Stellar Initial Mass Function: Theory Meets Observations

We present observational evidence of a correlation between the high-mass slope of the stellar initial mass function (IMF) in young star clusters and their stellar surface density, σ *. When the high-mass end of the IMF is described by a power law of the form , the value of Γ is seen to decrease weakly with increasing σ *, following a relation. We also present a model that can explain these observations. The model is based on the idea that the coalescence of protostellar cores in a protocluster-forming clump is more efficient in high-density environments where cores are more closely packed. The efficiency of the coalescence process is calculated as a function of the parental clump properties, in particular the relation between its mass and radius as well as its core formation efficiency. The main result of this model is that the increased efficiency of the coalescence process leads to shallower slopes of the IMF, in agreement with the observations of young clusters, and the observations are best reproduced with compact protocluster-forming clumps. These results have significant implications for the shape of the IMF in different Galactic and extragalactic environments and have very important consequences for galactic evolution.

Probing the Low-mass End of Core-collapse Supernovae Using a Sample of Strongly-stripped Calcium-rich Type IIb Supernovae from the Zwicky Transient Facility

The fate of stars in the zero-age main-sequence (ZAMS) range ≈8–12 M ⊙ is unclear. They could evolve to form white dwarfs or explode as electron-capture supernovae (SNe) or iron core-collapse SNe (CCSNe). Even though the initial mass function indicates that this mass range should account for over 40% of all CCSN progenitors, few have been observationally confirmed, likely due to the faintness and rapid evolution of some of these transients. In this paper, we present a sample of nine Ca-rich/O-poor Type IIb SNe detected by the Zwicky Transient Facility with progenitors likely in this mass range. These sources have a [Ca ii] λ λ7291, 7324/[O i] λ λ6300, 6364 flux ratio of ≳2 in their nebular spectra. Comparing the measured [O i] luminosity (≲1039 erg s−1) and derived oxygen mass (≈0.01 M ⊙) with theoretical models, we infer that the progenitor ZAMS mass for these explosions is less than 12 M ⊙. The ejecta properties (M ej ≲ 1 M ⊙ and E kin ∼ 1050 erg) are also consistent. The low ejecta mass of these sources indicates a class of strongly-stripped SNe that is a transition between the regular stripped-envelope SNe and ultra-stripped SNe. The progenitor could be stripped by a main-sequence companion and result in the formation of a neutron star−main sequence binary. Such binaries have been suggested to be progenitors of neutron star−white dwarf systems that could merge within a Hubble time and be detectable with LISA.

Mechanical cleaning of food soil from a solid surface: A tribological perspective

In this work, a tribological approach was used to distinguish the synergistic effects of mechanical removal and chemical removal (i.e. dissolution) of a layer of representative food soil from a solid surface, using a tribometer, Mini Traction Machine (MTM). Gravimetric and wear measurements of the soil were used to calculate the cleaning rates of burnt tomato puree on a stainless-steel disc, and the corresponding frictional characteristics offers insight of the mechanical removal. The cleaning due to soil dissolution (chemical removal) was quantified by UV–Vis measurements. The overall cleaning rates of food soil featured a linear reduction in mass over time, with a scaled removal rate k = 0.0046 s−1 (5 N applied force and 100 mm s−1 relative velocity), for most cases studied. It was observed that the cleaning rate can be improved with an increasing mechanical load or speed (50% from 1 to 2.5 N and 13% from 50 to 100 mm s−1), but is independent of the initial mass. UV–Vis measurements show that by increasing the load or speed the removal of chunks of burnt tomato puree was enhanced more than removal attributed to dissolution. Similar values of cleaning rates for most experimental parameters were extracted from both the gravimetric and wear measurements. Adhesion and cohesion measurements of the burnt tomato puree were conducted with a micromanipulator. It was found that adhesion forces are higher than cohesion for short soaking times, but for longer times the adhesion forces became weaker and with the additional shear rate in the MTM cleaning experiment, adhesion failure was observed in many cases by the end of the experiment. Indentation measurements showed the change in mechanical properties of the food foulant with a few minutes of soaking in water.

Black hole growths in gamma-ray bursts driven by the Blandford–Znajek mechanism

ABSTRACT The Blandford–Znajek (BZ) mechanism in stellar-mass black hole (BH) hyperaccretion systems is generally considered to power gamma-ray bursts (GRBs). Based on observational GRB data, we use the BZ mechanism driven by the BH hyperaccretion disc to investigate the evolution of the BH mass and spin after the jets break out from the progenitors. We find that the BH growths are almost independent of initial BH masses. Meanwhile, the BH growths will be more efficient with smaller initial spin parameters. We conclude that (i) the BZ mechanism is efficient for triggering BH growths for only 1 of 206 typical long-duration GRBs; (ii) the mean BH mass growths of ultra-long GRBs are marginal for all 7 samples collected; (iii) for the short-duration GRBs, the results that BHs show minimal growths is consistent with the mass supply limitation in the scenario of compact object mergers.

Measuring the initial-final mass relation using wide double white dwarf binaries from Gaia DR3

ABSTRACT The initial-final mass relation (IFMR) maps the masses of main-sequence stars to their white dwarf descendants. The most common approach to measure the IFMR has been to use white dwarfs in clusters. However, it has been shown that wide double white dwarfs can also be used to measure the IFMR using a Bayesian approach. We have observed a large sample of 90 Gaia double white dwarfs using FORS2 on the VLT. Considering 52 DA + DA, DA + DC, and DC + DC pairs, we applied our extended Bayesian framework to probe the IFMR in exquisite detail. Our monotonic IFMR is well constrained by our observations for initial masses of 1–5 M⊙, with the range of 1–4 M⊙ mostly constrained to a precision of 0.03 M⊙ or better. We add an important extension to the framework, using a Bayesian mixture-model to determine the IFMR robustly in the presence of systems departing from single star evolution. We find a large but uncertain outlier fraction of 59 ± 21 per cent, with outlier systems requiring an additional $0.70_{-0.22}^{+0.40}$ Gyr uncertainty in their cooling age differences. However, we find that this fraction is dominated by a few systems with massive components near 0.9 M⊙, where we are most sensitive to outliers, but are also able to establish four systems as merger candidates.

Metagenomic domain substitution for the high-throughput modification of nonribosomal peptides.

The modular nature of nonribosomal peptide biosynthesis has driven efforts to generate peptide analogs by substituting amino acid-specifying domains within nonribosomal peptide synthetase (NRPS) enzymes. Rational NRPS engineering has increasingly focused on finding evolutionarily favored recombination sites for domain substitution. Here we present an alternative evolution-inspired approach that involves large-scale diversification and screening. By amplifying amino acid-specifying domains en masse from soil metagenomic DNA, we substitute more than 1,000 unique domains into a pyoverdine NRPS. Initial fluorescence and mass spectrometry screens followed by sequencing reveal more than 100 functional domain substitutions, collectively yielding 16 distinct pyoverdines as major products. This metagenomic approach does not require the high success rates demanded by rational NRPS engineering but instead enables the exploration of large numbers of substitutions in parallel. This opens possibilities for the discovery and production of nonribosomal peptides with diverse biological activities.

The Golden meteorite fall: Fireball trajectory, orbit, and meteorite characterization

AbstractThe Golden (British Columbia, Canada) meteorite fall occurred on October 4, 2021 at 0534 UT with the first recovered fragment (1.3 kg) landing on an occupied bed. The associated fireball was recorded by numerous cameras permitting reconstruction of its trajectory and orbit. The fireball entered the atmosphere at a 54° angle from the horizontal at a speed of 18 km s−1. The fireball reached a peak brightness of −14, having first become luminous at a height of &gt;84 km and ending at 18 km altitude. Analysis of the infrasonic record of the bolide produced an estimated mass of kg while modeling of the fireball light curve suggests an initial mass near 70 kg. The fireball experienced a major flare near 31 km altitude where more than half its mass was lost in the form of dust and gram‐sized fragments under a dynamic pressure of 3.3 MPa. The strength and fragmentation behavior of the fireball were similar to those reported for other meteorite‐producing fireballs (Borovička et al., 2020). Seven days after the fireball occurred, an additional 0.9 kg fragment was recovered during the second day of dedicated searching guided by initial trajectory and dark flight calculations. Additional searching in the fall and spring of 2021–2022 located no additional fragments. The meteorite is an unbrecciated, low‐shock (S2) ordinary chondrite of intermediate composition, typed as an L/LL5 with a grain density of ~3530 k gm−3, an average bulk density of 3150 kg m−3 and calculated porosity of ~10%. From noble gas measurements, the cosmic ray exposure age is 25 ± 4 Ma while gas retention ages are all &gt;2 Ga. Short‐lived radionuclides and noble gas measurements of the pre‐atmospheric size overlap with estimates from infrasound and light curve modeling producing a preferred pre‐atmospheric mass of 70–200 kg. The orbit of Golden has a high inclination (23.5°) and is consistent with delivery from the inner main belt. The highest probability (60%) of an origin is from the Hungaria group. We propose that Golden may originate among the background S‐type asteroids found interspersed in the Hungaria region. The current collection of 18 L/LL—chondrite orbits shows a strong preference for origins in the inner main belt, suggesting multiple parent bodies may be required to explain the diversity in CRE ages and shock states.

Body content and mineral requirements of dairy goats in early lactation

This study aimed to evaluate the dynamics mobilization of body macrominerals and estimate dairy goats' maintenance and lactation requirements at the beginning of lactation. Fifty-one goats were slaughtered to estimate the body macromineral of the animals. Three goats (baseline) and forty-eight goats, with an initial body mass of 57.19 ± 8.4 kg, were assigned to a completely randomized design in eight weeks of lactation. Six goats were slaughtered per week. The intake of dry matter and minerals presented a quadratic behavior (P < 0.05) as the lactation advanced, except for the Mg intake. Milk yield and minerals were affected throughout the 56 days of lactation. Macrominerals decreased linearly in the empty body weight (EBW) (P < 0.05) with the advance in lactation. The weeks of lactation affected only the maintenance requirement of Mg (P = 0.021) and Na (P = 0.017). When analyzing lactation requirements, macrominerals decreased (P < 0.05) over the 56 days of lactation. However, only the total P and K requirements were not affected (P > 0.05). In conclusion, dairy goats in early lactation mobilize on average 12.1 ± 0.3 g Ca, 5.7 ± 0.2 g P, 0.9 ± 0.1 g Mg, 9.1 ± 0.2 g K, and 3.4 ± 0.1 g Na from EBW/day. cc

The merger of hard binaries in globular clusters as the primary channel for the formation of second-generation stars

ABSTRACT We have recently presented observational evidence which suggests that the origin of the second-generation (G2) stars in globular clusters (GCs) is due to the binary-mediated collision of primordial (G1) low-mass main-sequence (MS) stars. This mechanism avoids both the mass budget problem and the need of external gas for dilution. Here, we report on another piece of evidence supporting this scenario: (1) the fraction of MS binaries is proportional to the fraction of G1 stars in GCs and, at the same time, (2) the smaller the fraction of G1 stars is, the more deficient binaries of higher mass ratio (q&amp;gt;0.7) are. They are, on average, harder than their smaller mass-ratio counterparts due to higher binding energy at a given primary mass. Then (2) implies that (1) is due to the merging/collisions of hard binaries rather than to their disruption. These new results complemented by the present-day data on binaries lead to the following conclusions: (i) the mass-ratio distribution of binaries, particularly short-period ones, with low-mass primaries, MP &amp;lt; 1.5 M⊙, is strongly peaked close to q=1.0, whereas (ii) dynamical processes at high stellar density tend to destroy softer binaries and make hard (nearly) twin binaries to become even harder and favour their mergers and collisions. G2 stars formed this way gain mass that virtually doubles the primary one, 2MP, at which the number of G1 stars is approximately five times smaller than at MP according to the slope of a Milky Way-like initial mass function at MMS &amp;lt; 1.0 M⊙.

The first analysis of three long-period low mass-ratio contact binaries

ABSTRACT The photometric and spectroscopic studies of three contact binaries, ASASSN-V J052036.28+144711.0, ASASSN-V J064846.22+241709.9, and ASASSN-V J073441.02+555833.0 were performed for the first time. The periods of all the three targets are longer than 0.5 d, and we discovered that their mass ratios are all smaller than 0.25. So, they are long-period low mass-ratio contact binaries. ASASSN-V J052036.28+144711.0 and ASASSN-V J064846.22+241709.9 are medium contact binaries. ASASSN-V J073441.02+555833.0 is a deep contact binary, which is also the only one existing O’Connell effect. We attached a dark spot on its secondary component for a better fit of light curves featuring asymmetry. From orbital period analysis, two of the three targets are believed to demonstrate a secular period increase, while one shows no long-term variation. We employed the spectral subtraction approach to investigate the LAMOST spectra, while all of the three binaries show no H α emission line, implying no chromospheric activity. Their initial masses, current average densities, and mass transfer rates between the two components were calculated. We obtained that the three targets are stable for the moment.

Some Unmodified Household Adsorbents for the Adsorption of Benzalkonium Chloride-A Kinetic and Thermodynamic Case Study for Commercially Available Paper.

The extensive use of biocide surfactant benzalkonium chloride (BAC) during the SARS-CoV-2 pandemic has led to the buildup of this hazardous chemical in waste, surface and groundwater. e The study aims to elucidate whether various low-cost household materials are suitable, in their unmodified and untreated form, to effectively adsorb BAC from its aqueous solutions.. Additionally, if a proper adsorbent is identified, a description of the kinetics and thermodynamics of the process is also targeted. From among the five tested materials, a commercially available white household paper towel was chosen to best satisfy the criteria of low price, large availability, and standardization degree, as well as high adsorption capacity within a fairly short time window needed until equilibrium. Batch experiments were carried out with a commercial mixture of BAC-12 and BAC-14 within a temperature range of 18-45 degrees Celsius, and a 25-100 mg/g BAC/adsorbent initial mass ratio range, respectively. The overall process follows a pseudo-second-order kinetic law, with an apparent activation energy of 73.35 KJ/mole. Both the Langmuir and the Redlich-Peterson isotherms describe the equilibrium data at 298 K well, with a Gibbs free energy of -20.64 KJ/mole. These findings are in agreement with previous reports and suggest a hybrid but chemisorption-dominated process.

The metallicity dependence of the stellar initial mass function

ABSTRACT During star formation, dust plays the crucial role of coupling gas to stellar radiation fields, allowing radiation feedback to influence gas fragmentation and thus the stellar initial mass function (IMF). Variations in dust abundance therefore provide a potential avenue by which variation in galaxy metallicity might affect the IMF. In this paper, we present a series of radiation-magnetohydrodynamic simulations in which we vary the metallicity and thus the dust abundance from 1 per cent of solar to 3× solar, spanning the range from the lowest metallicity dwarfs to the most metal-rich early-type galaxies (ETGs) found in the local Universe. We design the simulations to keep all dimensionless parameters constant so that the interaction between feedback and star-forming environments of varying surface density and metallicity is the only factor capable of breaking the symmetry between the simulations and modifying the IMF, allowing us to isolate and understand the effects of each environmental parameter cleanly. We find that shifts in the IMF with varying metallicity at a fixed surface density are smaller than the shifts in varying surface density at a fixed surface metallicity. We also find that metallicity-induced IMF variations are too small to explain the mass-to-light ratio shifts seen in the ETGs. We therefore conclude that metallicity variations are much less important than variations in surface density in driving changes in the IMF and that the latter rather than the former are most likely responsible for the IMF variations found in ETGs.

Considering the Single and Binary Origins of the Type IIP SN 2017eaw

Current population synthesis modeling suggests that 30%–50% of Type II supernovae originate from binary progenitors; however, the identification of a binary progenitor is challenging. One indicator of a binary progenitor is that the surrounding stellar population is too old to contain a massive single star. Measurements of the progenitor mass of SN 2017eaw are starkly divided between observations made temporally close to core collapse, which show a progenitor mass of 13–15 M ⊙ (final helium-core mass MHe,core=4.4–6.0M⊙ —which is a more informative property than initial mass) and those from the stellar population surrounding the SN, which find M ≤ 10.8 M ⊙ ( MHe,core≤3.4M⊙ ). In this paper, we reanalyze the surrounding stellar population with improved astrometry and photometry, finding a median age of 16.8−1.0+3.2 Myr for all stars younger than 50 Myr ( MHe,core=4.7M⊙ ) and 85.9−6.5+3.2 Myr for stars younger than 150 Myr. 16.8 Myr is now consistent with the helium-core mass range derived from the temporally near-explosion observations for single stars. Applying the combined constraints to population synthesis models, we determine that the probability of the progenitor of SN 2017eaw being an initially single star is 65% compared to 35% for prior binary interaction. 85.9 Myr is inconsistent with any formation scenarios. We demonstrate that combining progenitor age constraints with helium-core mass estimates from red supergiant SED modeling, late-time spectra, and indirectly from light-curve modeling can help to differentiate single and binary progenitor scenarios and provide a framework for the application of this technique to future observations.

Effects of hydroxy methionine zinc on growth performance, immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii)

This study aimed to evaluate the effects of varying zinc (Zn) levels on the growth performance, non-specific immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii (P. clarkii)). Adopting hydroxy methionine zinc (Zn-MHA) as the Zn source, 180 healthy crayfish with an initial body mass of 6.50 ± 0.05 g were randomly divided into the following five groups: X1 (control group) and groups X2, X3, X4, and X5, which were fed the basal feed supplemented with Zn-MHA with 0, 15, 30, 60, and 90 mg kg−1, respectively. The results indicated that following the addition of various concentrations of Zn-MHA to the diet, the following was observed: Specific growth rate (SGR), weight gain rate (WGR), total protein (TP), total cholesterol (TC), the activities of alkaline phosphatase (AKP), phenoloxidase (PO), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) and catalase (CAT), the expression of CTL, GPX, and CuZn-SOD genes demonstrated a trend of rising and then declining—with a maximum value in group X4—which was significantly higher than that in group X1 (P < 0.05). Zn deposition in the intestine and hepatopancreas, the activity of GSH-PX, and the expression of GSH-PX were increased, exhibiting the highest value in group X5. The malonaldehyde (MDA) content was significantly reduced, with the lowest value in group X4, and the MDA content of the Zn-MHA addition groups were significantly lower than the control group (P < 0.05). In the analysis of the intestinal microbiota of P. clarkii, the number of operational taxonomic units in group X4 was the highest, and the richness and diversity indexes of groups X3 and X4 were significantly higher than those in group X1 (P < 0.05). Meanwhile, the dietary addition of Zn-MHA decreased and increased the relative abundance of Proteobacteria and Tenericutes, respectively. These findings indicate that supplementation of dietary Zn-MHA at an optimum dose of 60 mg kg−1 may effectively improve growth performance, immune response, antioxidant capacity, and intestinal microbiota richness and species diversity in crayfish.