Magnetic freezing is nowadays established as a commercial reality mainly oriented towards the food market. According to advertisements, magnetic freezing is able to generate tiny ice crystals ...throughout the frozen product, prevent cell destruction, and preserve the quality of fresh food intact after thawing. If all these advantages were true, magnetic freezing would represent a significant advance in freezing technology, not only for food preservation, but also for cryopreservation of biological specimens such as cells, tissues, and organs. Magnetic fields (MFs) are supposed to act directly on water by orientating, vibrating, and/or spinning molecules to prevent them from clustering and, thus, to promote supercooling. However, many doubts exist about the real effects of MFs on freezing and the science behind the potential mechanisms involved. To provide a basis for extending the understanding of magnetic freezing, this paper presents a critical review of the materials published in the literature up to now, including both patents and experimental results. After examining the information available, it was not possible to discern whether MFs have an appreciable effect on supercooling, freezing kinetics, ice crystals, quality, and/or viability of the frozen products. Experiments described in the literature frequently fail to identify and/or control all the factors that can play a role in magnetic freezing. Moreover, many of the comparisons between magnetic and conventional freezing are not correctly designed to draw valid conclusions, and wide ranges of MF intensities and frequencies are unexplored. Therefore, more rigorous experimentation and further evidence are needed to confirm or reject the efficacy of MFs in improving the quality of frozen products.
Since the early 2000s, electromagnetic freezers have been sold all over the world. According to the manufacturers, the oscillating magnetic fields (OMFs) applied by these devices are capable of ...avoiding ice damage in frozen foods. To assess the effectiveness of OMFs in preserving food quality, we froze crab sticks in a commercial electromagnetic freezer, both with (<2 mT, 6–59 Hz) and without OMF application. Crab sticks were also frozen in a conventional freezer, both with static- and forced-air conditions, to compare electromagnetic freezing with conventional methods. After 24 h and 1, 3, 6, 9, and 12 months of storage, we did not find any effect of the OMFs on the drip loss, water-holding capacity, toughness, and whiteness of the crab sticks frozen in the electromagnetic device. Moreover, no advantage of electromagnetic freezing over air-blast freezing was detected at the conditions tested. More experiments at larger magnetic field strength and wider frequency ranges are needed to have a complete view of the potential effects of OMFs on food freezing.
•Crab sticks were frozen in both an electromagnetic and a conventional freezer.•Several quality attributes were assessed after 0–12 months of frozen storage.•Electromagnetic freezing failed to retain the quality of fresh crab sticks unaltered.•Oscillating magnetic fields produced no effect on the quality of the frozen samples.•No advantage of electromagnetic freezing over air-blast freezing was observed.
Abstract Galactic X-ray sources are diverse, ranging from active M dwarfs to compact object binaries, and everything in between. The X-ray landscape of today is rich, with point source catalogs such ...as those from XMM-Newton, Chandra, and Swift, each with ≳10 5 sources and growing. Furthermore, X-ray astronomy is on the verge of being transformed through data releases from the all-sky SRG/eROSITA survey. Many X-ray sources can be associated with an optical counterpart, which in the era of Gaia, can be determined to be Galactic or extragalactic through parallax and proper motion information. Here, I present a simple diagram—the “X-ray Main Sequence,” which distinguishes between compact objects and active stars based on their optical color and X-ray-to-optical flux ratio ( F X / F opt ). As a proof of concept, I present optical spectroscopy of six exotic accreting WDs discovered using the X-ray Main Sequence as applied to the XMM-Newton catalog. Looking ahead to surveys of the near future, I additionally present SDSS-V optical spectroscopy of new systems discovered using the X-ray Main Sequence as applied to the SRG/eROSITA eFEDS catalog.
A number of novel freezing systems have been developed that claim to improve the quality of frozen foods by enhancing supercooling in the food prior to ice nucleation and consequently controlling ice ...crystal formation. One of these is the Cells Alive System (CAS) produced by ABI of Japan, which applies oscillating magnetic fields (OMF) during freezing. This study was carried out to investigate what effect applying OMF (0.04 to 0.53 mT) during freezing had on the freezing characteristics of pork loin samples when compared to freezing under the same conditions without OMF. Overall, the results of this study clearly indicate that freezing under the OMF conditions used in these experiments had no significant effect on the freezing characteristics of pork, in comparison with freezing under the same conditions without OMF.
Previous papers in the literature show no agreement on the effects of static magnetic fields (SMFs) on water supercooling and freezing kinetics. Hypothetical effects of the SMF orientation and the ...presence of ions in the sample are also unclear. To shed light on this matter, we froze 10-mL pure water samples and 0.9% NaCl solutions subjected or not to the SMFs generated by two magnets. We found that the relative position of the magnet poles affected the magnetic field orientation, strength, and the spatial magnetic gradients established throughout the sample. Thus, the SMF strength ranged from 107 to 359 mT when unlike magnet poles faced each other whereas it ranged from 0 to 241 mT when like magnet poles were next to each other. At both conditions, we did not detect any effect of the SMFs on the time at which nucleation occurred, the extent of supercooling, and the phase transition and total freezing times in both pure water and 0.9% NaCl solutions. More experiments, under well-characterized SMFs, should be performed to definitively evaluate the ability of SMFs in improving food freezing.
•The relative position of the magnet poles affected the SMF orientation and strength.•Significant spatial magnetic gradients were established throughout the samples.•Magnetic gradients were in the 107–359 mT and 0–241 mT range in SMF-A and SMF-R samples.•SMFs produced no effect on supercooling and freezing kinetics of water and 0.9% NaCl solutions.•An accurate SMF characterization is needed to assess the effect of SMFs on freezing.
A Sun-like star orbiting a black hole El-Badry, Kareem; Rix, Hans-Walter; Quataert, Eliot ...
Monthly notices of the Royal Astronomical Society,
01/2023, Letnik:
518, Številka:
1
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We report discovery of a bright, nearby ($G = 13.8;\, \, d = 480\, \rm pc$) Sun-like star orbiting a dark object. We identified the system as a black hole candidate via its astrometric ...orbital solution from the Gaia mission. Radial velocities validated and refined the Gaia solution, and spectroscopy ruled out significant light contributions from another star. Joint modelling of radial velocities and astrometry constrains the companion mass of $M_2 = 9.62\pm 0.18\, \mathrm{M}_{\odot }$. The spectroscopic orbit alone sets a minimum companion mass of $M_2\gt 5\, \mathrm{M}_{\odot }$; if the companion were a $5\, \mathrm{M}_{\odot }$ star, it would be 500 times more luminous than the entire system. These constraints are insensitive to the mass of the luminous star, which appears as a slowly rotating G dwarf ($T_{\rm eff}=5850\, \rm K$, log g = 4.5, $M=0.93\, \mathrm{M}_{\odot }$), with near-solar metallicity ($\rm Fe/H = -0.2$) and an unremarkable abundance pattern. We find no plausible astrophysical scenario that can explain the orbit and does not involve a black hole. The orbital period, Porb = 185.6 d, is longer than that of any known stellar-mass black hole binary. The system’s modest eccentricity (e = 0.45), high metallicity, and thin-disc Galactic orbit suggest that it was born in the Milky Way disc with at most a weak natal kick. How the system formed is uncertain. Common envelope evolution can only produce the system’s wide orbit under extreme and likely unphysical assumptions. Formation models involving triples or dynamical assembly in an open cluster may be more promising. This is the nearest known black hole by a factor of 3, and its discovery suggests the existence of a sizable population of dormant black holes in binaries. Future Gaia releases will likely facilitate the discovery of dozens more.
Describe the histological findings of minimally ultrasound-guided invasive autopsies in deceased patients with severe SARS-CoV-2 and compare the diagnostic yield with open autopsies.
Observational ...post-mortem cohort study. Minimally invasive ultrasound-guided autopsies were performed in fourteen deceased patients with a confirmed diagnosis of SARS-CoV-2 pneumonia. Histological and clinical findings of lung, kidney, and liver tissue are described and contrasted with those previously reported in the literature.
Single-center COVID-19 reference center in Mexico City.
Fourteen minimally invasive autopsies revealed a gross correlation with open autopsies reports: 1) Lung histology was characterized mainly by early diffuse alveolar damage (12/13). Despite low lung compliances and prolonged mechanical ventilation, the fibrotic phase was rarely observed (2/13). 2) Kidney histopathology demonstrated acute tubular injury (12/13), interstitial nephritis (11/13), and glomerulitis (11/13) as the predominant features 3) Liver histology was characterized by neutrophilic inflammation in all of the cases, as well as hepatic necrosis (8/14) despite minimal alterations in liver function testing. Hepatic steatosis was observed in most cases (12/14). SARS-CoV-2 positivity was widely observed throughout the immunohistochemical analysis. However, endothelitis and micro thrombosis, two of the hallmark features of the disease, were not observed.
Our data represents the largest minimally invasive, ultrasound-guided autopsy report. We demonstrate a gross histological correlation with large open autopsy cohorts. However, this approach might overlook major histologic features of the disease, such as endothelitis and micro-thrombosis. Whether this represents sampling bias is unclear.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We apply a conventional accretion disk model to the FU Ori–type objects HBC 722 and Gaia 17bpi. Our base model is a steady-state, thin Keplerian disk featuring a modified Shakura–Sunyaev ...temperature profile, with each annulus radiating as an area-weighted spectrum given by a NextGen atmosphere at the appropriate temperature. We explore departures from the standard model by altering the temperature distribution in the innermost region of the disk to account for “boundary region”–like effects. We consider the overall spectral energy distribution as well as medium- and high-resolution spectra in evaluating best-fit models to the data. Parameter degeneracies are studied via a Markov Chain Monte Carlo parameter estimation technique. Allowing all parameters to vary, we find accretion rates for HBC 722 of
M
̇
=
10
−
4.90
M
⊙
yr
−
1
−
0.40
+
0.99
dex
and for Gaia 17bpi of
M
̇
=
10
−
6.70
M
⊙
yr
−
1
−
0.36
+
0.46
dex
;
the corresponding maximum disk temperatures are
7100
−
500
+
300
K and
7900
−
400
+
900
K, respectively. While the accretion rate of HBC 722 is on the same order as other FU Ori–type objects, Gaia 17bpi has a lower rate than previously reported as typical, commensurate with its lower luminosity. Alternate models that fix some disk or stellar parameters are also presented, with tighter confidence intervals on the remaining fitted parameters. In order to improve upon the somewhat large credible intervals for the
M
̇
values, and to make progress on boundary layer characterization, flux-calibrated ultraviolet spectroscopy is needed.
Several studies in the literature suggest that the frequency of weak oscillating magnetic fields (OMFs) significantly affects supercooling and freezing kinetics, although the effects described by ...different authors are apparently contradictory. To shed light on this matter, we froze pure water samples and 0.9% NaCl solutions in a 0.8-mT magnetic field at different frequencies (20, 50, 200, and 2000 Hz). Moreover, experiments with no OMF application were also performed to act as controls. Our results show that the application of a 0.8-mT OMF at frequencies between 20 Hz and 2000 Hz during freezing has no effect on the parameters that characterize either supercooling (time at which nucleation occurred and extent of supercooling achieved at the sample center) or freezing kinetics (precooling, phase transition, and tempering times), both in pure water and 0.9% NaCl solutions. More research is needed to elucidate all the factors that could affect OMF-assisted freezing.
•The effect of the frequency of weak oscillating magnetic fields (OMFs) on freezing was evaluated.•Freezing curves of pure water and 0.9% NaCl solutions in a 0.8-mT OMF at 20–2000 Hz were compared to those obtained with no OMF application.•The application of a 0.8-mT OMF at 20–2000 Hz did not affect supercooling.•The application of a 0.8-mT OMF at 20–2000 Hz did not affect freezing kinetics.
Environmental studies on coastal dune systems are faced with a considerable cost barrier due to the cost of the instrumentation and sensory equipment required for data collection. These systems play ...an important role in coastal areas as a protection against erosion and as providers of stability to coastal sedimentary deposits. The DIY (
) approach to data acquisition can reduce the cost of these environmental studies. In this paper, a low-cost DIY wireless wind data acquisition system is presented which reduces the cost barrier inherent to these types of studies. The system is deployed for the analysis of the foredune of Maspalomas, an arid dune field situated on the south coast of Gran Canaria (Canary Islands, Spain), for the specific purpose of studying the dynamics of a dune type (
), which is typical of this environment. The results obtained can be of interest for the study of these coastal environments at both the local level, for the management of this particular dune field, and at the general level for other similar dune fields around the world.
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