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1.
J Vis Exp ; (191)2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36688544

RESUMO

Ice on road surfaces can lead to a significant decrease in the friction coefficient, thus endangering driving safety. However, there are still no studies that provide exact friction coefficient values for pavements covered in ice, which is detrimental to both road design and the selection of winter road maintenance measures. Therefore, this article presents an experimental method to determine the friction coefficient of icy road surfaces in the winter. A British portable tester (BPT), also known as a pendulum friction coefficient meter, was employed for the experiment. The experiment was divided into the following five steps: the preparation of the equipment, the calculation and analysis of the snowfall, equipment calibration, friction coefficient determination, and data analysis. The accuracy of the final experiment is directly affected by the equipment accuracy, which is described in detail. Moreover, this article suggests a method for calculating the ice thickness for corresponding amounts of snowfall. The results illustrate that even patchy ice formed by very light snowfall may lead to a significant decrease in the friction coefficient of the pavement, thus endangering driving safety. Additionally, the friction coefficient is at its peak when the ice thickness reaches 5 mm, meaning protection measures should be taken to avoid the formation of such ice.


Assuntos
Condução de Veículo , Gelo , Fricção , Neve , Desenho de Equipamento
2.
Food Res Int ; 163: 112299, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36596202

RESUMO

Freeze denaturation of protein caused by ice crystals is the main motivation for the quality deterioration of surimi during circulation and storage. This investigation aimed to cryoprotect surimi by adding antifreeze peptides from Takifugu obscurus skin (TsAFP) which can inhibit ice recrystallization, and to elucidate regulating mechanism. The comprehensive results showed that 4% TsAFP, half dosage of commercial cryoprotectant, had good cryoprotection on surimi by reducing the moisture variation and maintaining protein solubility of surimi at macro level, as well as inhibiting the degeneration and structure changes of myofibrillar proteins at micro level. Meanwhile, TsAFP could directly bind to the structural cavity of myosin, inhibit protein freezing-induced oxidation, maintain the spatial structure of myosin and water retention ability to preserve the surimi quality. This study helped better comprehend the protective mechanisms of antifreeze peptides in frozen surimi and was expected to provide a promising cryoprotectant for low-sweetness and low-calorie surimi.


Assuntos
Crioprotetores , Gelo , Congelamento , Crioprotetores/farmacologia , Crioprotetores/química , Miosinas , Proteínas Anticongelantes
3.
Food Chem ; 408: 135202, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-36525728

RESUMO

Frozen storage technology has been widely used for the preservation of Aquatic products. However, ice crystals formation, lipid oxidation and protein denaturation still easily causes aquatic products deterioration. Cryoprotectants are a series of food additives that could efficiently prolong the shelf life and guarantee the acceptability of frozen aquatic products. This review comprehensively illustrated the mechanism of protein denaturation caused by the ice crystal formation and lipid oxidation. The cryoprotective mechanism of various kinds of antifreeze agents (saccharides, phosphates, antifreeze proteins and peptides) and these cryoprotective structure-activity relationship, application efficiency on the quality of aquatic products were also discussed. Moreover, the advantages and disadvantages of each cryoprotectant are also prospected. Compared with others, antifreeze peptides show higher commercial and application values. While, lots of scientific research works are still required to develop novel antifreeze agent as a versatile ingredient with commercial value, applicable in the aquatic products preservation industry.


Assuntos
Crioprotetores , Gelo , Crioprotetores/química , Congelamento , Aditivos Alimentares , Lipídeos , Proteínas Anticongelantes/química
4.
Food Chem ; 407: 135092, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-36502731

RESUMO

This study evaluated the effects of magnetic field-assisted immersion freezing (MIF) with different magnetic field intensities (0, 20, 40, 60, and 80 mT) on the freezing curves, ice crystal area, microstructure, and physicochemical properties of golden pompano (Trachinotus ovatus) muscle. The result showed that, compared with refrigerator freezing (RF) and immersion freezing (MIF-0), magnetic fields prolonged the freezing time. However, the centrifugal loss and cooking loss of MIF-20 were 23.55 % and 29.18 % lower than those of MIF-0 group, respectively (P < 0.05). Low field-nuclear magnetic resonance results showed that MIF-20 group exhibited more homogeneous of water distribution and higher water content, the T22 was 20.59 % shorter than of MIF-0 (P < 0.05). Microscopic observations confirmed that the MIF-20 group had the smallest and the most evenly distribution of ice crystals. Therefore, MIF at 20 mT intensity can effectively improve the muscle qualities of frozen golden pompano.


Assuntos
Gelo , Perciformes , Animais , Congelamento , Peixes , Músculos , Culinária
5.
Food Chem ; 407: 135139, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-36512908

RESUMO

In this work, the effects of different QPE addition on the freeze-thaw (F-T) stability of fish myofibrillar protein (MP) gels were revealed. During freezing process, QPE decreased the freezing point of MP gels and shortened the time to pass through the maximum-ice-crystal-formation zone. The occurrence of thermal hysteresis effect led to the formation of small ice crystals and alleviated the damage to MP gel network. The incorporation of 7.5% QPE also reduced the free water amount to 19.23% and improved the water holding capacity of MP gels. Furthermore, the incorporation of QPE decreased the carbonyl content of MP gels after F-T cycles and delayed the protein oxidation. Meanwhile, QPE addition maintained the stability of the tertiary structure of MP gels via stabilizing the microenvironment of tyrosine and tryptophan. Overall, QPE shows the potential as a new cryoprotectant to improve the F-T stability of MP gel products.


Assuntos
Chenopodium quinoa , Miofibrilas , Animais , Congelamento , Miofibrilas/química , Gelo/análise , Emulsões/química , Géis/química , Água/química , Proteínas de Peixes/análise
6.
Proc Natl Acad Sci U S A ; 120(1): e2214143120, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36574684

RESUMO

Due to its multifaceted impact in various applications, icing and ice dendrite growth has been the focus of numerous studies in the past. Dendrites on wetting (hydrophilic) and nonwetting (hydrophobic) surfaces are sharp, pointy, branching, and hairy. Here, we show a unique dendrite morphology on state-of-the-art micro/nanostructured oil-impregnated surfaces, which are commonly referred to as slippery liquid-infused porous surfaces or liquid-infused surfaces. Unlike the dendrites on traditional textured hydrophilic and hydrophobic surfaces, the dendrites on oil-impregnated surfaces are thick and lumpy without pattern. Our experiments show that the unique ice dendrite morphology on lubricant-infused surfaces is due to oil wicking into the porous dendritic network because of the capillary pressure imbalance between the surface texture and the dendrites. We characterized the shape complexity of the ice dendrites using fractal analysis. Experiments show that ice dendrites on textured oil-impregnated surfaces have lower fractal dimensions than those on traditional lotus leaf-inspired air-filled porous structures. Furthermore, we developed a regime map that can be used as a design guideline for micro/nanostructured oil-impregnated surfaces by capturing the complex effects of oil chemistry, oil viscosity, and wetting ridge volume on dendrite growth and morphology. The insights gained from this work inform strategies to reduce lubricant depletion, a major bottleneck for the transition of micro/nanostructured oil-impregnated surfaces from bench-top laboratory prototypes to industrial use. This work will assist the development of next-generation depletion-resistant lubricant-infused ice-repellent surfaces.


Assuntos
Excipientes , Gelo , Alimentos , Lubrificantes , Dendritos
7.
Ultrason Sonochem ; 92: 106259, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36502681

RESUMO

To improve the quality of cooked and frozen crayfish after repeated freeze-thaw cycles, the effects of alginate oligosaccharide (1 %, w/v) with ultrasound-assisted (40 W, 3 min) soaking (AUS) on the physicochemical properties were investigated. The AUS samples improved water-holding capacity with 19.47 % higher than the untreated samples. Low-field nuclear magnetic resonance confirmed that mobile water (T22) in the samples after 5 times of freeze-thaw cycles was reduced by 13.02 % and 29.34 % with AUS and without treatment, correspondingly; and with AUS and without treatment, average size of the ice crystals was around 90.26 µm2 and 113.73 µm2, and average diameter of the ice crystals was 5.83 µm and 8.14 µm, respectively; furthermore, it enhanced the solubility and zeta potential, lowered the surface hydrophobicity, reduced the particle size, and maintained the secondary and tertiary structures of myofibrillar protein (MP) after repeated freeze-thawing. Gel electrophoresis revealed that the AUS treatment mitigated the denaturation of MPs. Scanning electron microscopy revealed that the AUS treatment preserved the structure of the tissue. These findings demonstrated that the AUS treatment could enhance the water retention and physicochemical properties of protein within aquatic meat products during temperature fluctuations..


Assuntos
Astacoidea , Gelo , Animais , Congelamento , Proteínas , Água/química , Oligossacarídeos
8.
Sci Total Environ ; 861: 160708, 2023 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-36481160

RESUMO

Airborne mineral dust triggers ice formation in clouds and alters cloud microphysical properties by acting as ice-nucleating particles (INPs), potentially influencing weather and climate at regional and global scales. Anthropogenic pollution would modify natural mineral dust during the atmospheric transport process. However, the effects of anthropogenic pollution aging on the ice nucleation activity (INA) of mineral dust remain not well-understood. In this study, we investigated the immersion mode ice nucleation properties and particle chemical characterizations of collected size-resolved Asian dust samples (eight particle size classes ranging from 0.18 to 10.0 µm), and testified the chemical modification of aged dust particles via particle chemistry and morphology analyses including the mass concentrations of particulate matter, the water-soluble ion concentrations, the mental element concentrations, and single-particle morphology. The mass fraction of Ca2+ in element Ca and the mean relative mass proportions of supermicron Ca2+ increased by 67.0 % and 3.5-11.2 % in aged Asian dust particles, respectively, suggesting the occurrence of heterogeneous reactions. On the other hand, the total INP concentrations (total NINP) and total ice nucleation active site densities (total ns(T)) were consistent between aged and normal dust particles (0.62-1.18 times) without a statistically significant difference. And the NINP and ns(T) of chemically aged supermicron dust (1.0-10.0 µm) in each particle size class were nearly equal to or slightly higher than those of normal Asian dust, which were 0.70-2.45 times and 0.64-4.34 times at -18 °C, respectively. These results reveal that anthropogenic air pollution does not notably change the INP concentrations and does not impair the INA of Asian dust. Our work provides direct observational evidence and clarifies the non-suppression effect of anthropogenic air pollution on the INA of East Asian dust, advancing the understanding of the ice nucleation of airborne aged mineral dust.


Assuntos
Poeira , Gelo , Humanos , Poeira/análise , Minerais , Tempo (Meteorologia) , Observação
9.
Environ Pollut ; 318: 120905, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36549445

RESUMO

Concern over microplastics has grown tremendously, and they have been found in all environmental compartments; yet, much remains unknown regarding their impact on a variety of human-consuming food products. Here, we contribute to ongoing research by screening the 15 most popular commercial brands of packaged food ice cubes in Mexico City for microplastics. Microplastics were detected in 100% of the samples evaluated, with concentrations ranging from 19 ± 4 to 178 ± 78 L-1. There was a significant difference in the microplastic concentration across samples. The mean microplastic concentration was 79 ± 47 L-1, and the main types were polypropylene, polyethylene, polyvinyl alcohol, tygon polymer, sealing ring gardena 2824 large, polyamide 6, and cellophane. Moreover, microplastics that are fibrous (87%), non-colored (54%), and less than 300 µm in size (63%), were found to be more prevalent. The SEM-EDX analysis showed heterogeneous structural and morphological characteristics of microplastics, as well as traces of Si, S, Ti, Ca, Al, and Na. Furthermore, we estimate that ice cube consumption in Mexico City can result in the inadvertent ingestion of 4.9 × 102 ± 3.4 × 102-1 × 104 ± 7.2 × 103 microplastics annually. The findings of the study revealed that microplastics were identified in ice cubes and can be conveyed to humans, stressing the need of managing and eradicating such contamination from our food.


Assuntos
Microplásticos , Poluentes Químicos da Água , Humanos , Plásticos/análise , Gelo/análise , Monitoramento Ambiental , Poluentes Químicos da Água/análise
10.
J Colloid Interface Sci ; 634: 757-768, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36565618

RESUMO

Time-resolved structural investigations of crystallization of water in lipid/protein/salt mesophases at cryogenic temperatures are significant for comprehension of ice nanocrystal nucleation kinetics in lipid membranous systems and can lead to a better understanding of how to experimentally retard the ice formation that obstructs the protein crystal structure determination. Here, we present a time-resolved synchrotron microfocus X-ray diffraction (TR-XRD) study based on ∼40,000 frames that revealed the dynamics of water-to-ice crystallization in a lipid/protein/salt mesophase subjected to cryostream cooling at 100 K. The monoolein/hemoglobin/salt/water system was chosen as a model composition related to protein-loaded lipid cubic phases (LCP) broadly used for the crystallization of proteins. Under confinement in the nanoscale geometry, metastable short-living cubic ice (Ic) rapidly crystallized well before the formation of hexagonal ice (Ih). The detected early nanocrystalline states of water-to-ice transformation in multicomponent systems are relevant to a broad spectrum of technologies and understanding of natural phenomena, including crystallization, physics of water nanoconfinement, and rational design of anti-freezing and cryopreservation systems.


Assuntos
Gelo , Água , Cristalização , Transição de Fase , Água/química , Temperatura Baixa
11.
Food Res Int ; 162(Pt B): 112116, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36461350

RESUMO

Synchrotron X-rays micro-computed tomography was applied to visualize and quantify 3D ice crystal changes into a model sponge cake after freezing and subsequent frozen storage. Model sponge cake samples were submitted to two different freezing rates (fast: 17.2 °C min-1 and slow: 0.3 °C min-1), then stored at constant and fluctuating temperatures over a two weeks period. 3D images were acquired at frozen state thanks to a thermostated cell (CellStat) and processed using a grey level based segmentation method. Image analysis revealed that the ice volume fraction is conserved during storage but ice crystal size and location change whatever the freezing rate and the storage conditions. Maximum local thicknesses increase both inside (from 20 µm to 50 µm) and outside (from 47 µm to 70 µm) the matrix during the fourteen days storage period. Both specific surface areas between starch and ice (SSAice/starch) and between air and ice (SSAair/ice) also evolve with storage duration: SSAice/starch decreases up to - 30 % while SSAair/ice increases up to + 13 % depending on the freezing rates and the storage conditions. These results highlighted that, during storage, ice crystals evolve according to two different mechanisms depending on the freezing rate: fast freezing leads to a local redistribution of water both within the starch matrix and within the pores, while slow freezing results in both local redistribution within the starch matrix and water migration towards the pores. In addition, stable storage temperatures favor local water redistribution whereas water migration from the starch matrix towards the pores was greater in the case of fluctuating storage temperatures. This study shows that freezing and frozen storage conditions have a synergistic effect on the microstructure evolution of sponge cake due to recrystallization phenomena.


Assuntos
Gelo , Síncrotrons , Microtomografia por Raio-X , Congelamento , Raios X , Amido , Água
12.
Med Oncol ; 40(1): 58, 2022 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-36562896

RESUMO

Oral cryotherapy (OC) is a common preventive treatment of oral mucositis (OM) and is recommended in international guidelines. Ice and air OC have previously been shown to result in temperature reductions of 8.1-12.9 °C, and 14.5 °C, respectively, in healthy volunteers. However, no direct comparison between these two modalities has been performed. The primary aim was to investigate the tolerability and side effects of air OC using an intra-oral air-cooling (IOAC) device compared with ice OC. The secondary aim was to evaluate the temperature reduction in the mouth for the two respective methods. Cross-over study with randomization to order of treatment, in 15 healthy volunteers. We evaluated the self-reported intensity, frequency, and discomfort for 13 pre-defined side effects used in previous studies. All participants were able to complete both OC sessions, although one participant required reduced airflow in the air OC arm. The subjects reported more discomfort from being cold, having sensitive teeth, and numbness in the ice OC group, while they reported more discomfort from swallowing when subjected to air OC. No significant difference in the median temperature reduction was detected in the two modalities, except for the dorsal posterior part of the tongue where temperature reduction was larger in the ice OC group. We found that oral cooling using a new IOAC device was tolerated and seems to be safe in healthy volunteers.


Assuntos
Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Estomatite , Humanos , Gelo , Estudos Cross-Over , Voluntários Saudáveis , Estomatite/prevenção & controle , Crioterapia/efeitos adversos
13.
Sci Bull (Beijing) ; 67(5): 537-546, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36546175

RESUMO

Lake ice thickness (LIT) is important for regional hydroclimate systems, lake ecosystems, and human activities on the ice, and is thought to be highly susceptible to global warming. However, the spatiotemporal variability in LIT is largely unknown due to the difficulty in deriving in situ measurements and the lack of an effective remote sensing platform. Despite intensive development and applications of lake ice models driven by general circulation model output, evaluation of the global LIT is mostly based on assumed "ideal" lakes in each grid cell of the climate forcing data. A method for calculating the actual global LIT is therefore urgently needed. Here we use satellite altimetry to retrieve ice thickness for 16 large lakes in the Northern Hemisphere (Lake Baikal, Great Slave Lake, and others) with an accuracy of ∼0.2 m for almost three decades. We then develop a 1-D lake ice model driven primarily by remotely sensed data and cross-validated with the altimetric LIT to provide a robust means of estimating LIT for lakes larger than 50 km2 across the Northern Hemisphere. Mean LIT (annual maximum ice thickness) for 1313 simulated lakes and reservoirs covering ∼840,000 km2 for 2003-2018 is 0.63 ± 0.02 m, corresponding to ∼485 Gt of water. LIT changes are projected for 2071-2099 under RCPs 2.6, 6.0, and 8.5, showing that the mean LIT could decrease by ∼0.35 m under the worst concentration pathway and the associated lower ice road availability could have a significant impact on socio-economic activities.


Assuntos
Gelo , Lagos , Humanos , Gelo/análise , Ecossistema , Clima , Aquecimento Global
14.
Biomolecules ; 12(12)2022 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-36551237

RESUMO

The internal architecture of tissue-like constructs is fundamental to their structural and biological functions. Here, we introduce a simple and robust method to fabricate cryogels based on derivatized extracellular matrix (ECM) macromolecules with porosity arranged according to the typical Benninghoff zonal architecture of articular cartilage. To obtain this arcade-like structure, the technique used the growth of ice crystals from copper pins at cryogenic temperatures. The directional cryogel formation enabled the organized growth of ice crystals over a large distance (>4 mm). The compositional properties were achieved by forming double networks (DNs) of hyaluronic acid and collagen derivatives (MeHA and CollGTA, respectively), which also served to improve the mechanical properties of the otherwise weak collagen scaffolds. Compositionally biomimetic and more resilient MeHA-CollGTA DNs (Young's modulus ≈ 200 kilopascals) were therefore produced. The technique presented expands the fabrication methods available for providing ECM macromolecules with architectural elements mimicking cartilage complexity.


Assuntos
Cartilagem Articular , Ácido Hialurônico , Ácido Hialurônico/química , Criogéis/química , Tecidos Suporte/química , Engenharia Tecidual/métodos , Congelamento , Gelo , Colágeno
15.
J Phys Chem B ; 126(50): 10637-10645, 2022 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-36513495

RESUMO

Antifreeze glycoproteins (AFGPs) are a special kind of antifreeze proteins with strong flexibility. Whether their antifreeze activity is achieved by reversibly or irreversibly binding to ice is widely debated, and the molecular mechanism of irreversible binding remains unclear. In this work, the antifreeze mechanism of the smallest AFGP isoform, AFGP8, is investigated at the atomic level. The results indicate that AFGP8 can bind to ice both reversibly through its hydrophobic methyl groups (peptide binding) and irreversibly through its hydrophilic disaccharide moieties (saccharide binding). Although peptide binding occurs faster than saccharide binding, free-energy calculations indicate that the latter is energetically more favorable. In saccharide binding, at least one disaccharide moiety is frozen in the grown ice, resulting in irreversible binding, while the other moieties significantly perturb the water hydrogen-bonding network, thus inhibiting ice growth more effectively. The present study reveals the coexistence of reversible and irreversible bindings of AFGP8, both contributing to the inhibition of ice growth and further provides molecular mechanism of irreversible binding.


Assuntos
Gelo , Água , Água/química , Proteínas Anticongelantes/química , Dissacarídeos , Peptídeos
16.
Nature ; 612(7939): 363-366, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36477136

Assuntos
Gelo , Astros Celestes
17.
Artigo em Inglês | MEDLINE | ID: mdl-36554969

RESUMO

Alpine lakes play a significant role in improving watershed ecology, adjusting water storage, and managing regional water resources. They are also a valuable freshwater reservoir, flood storage, and species gene pool in Central Asia. This article validated the accuracy of the CryoSat-2 footprints altimetry dataset for the Lake Bosten and Lake Issyk-Kul ranges. The time series for the surface elevations of the Central Asian alpine lakes Karakul and Chatyrkul were established, based on footprints altimetry data. The lake hydrological drivers were analyzed using remote sensing meteorological reanalysis data of the lake basins. The following main conclusions were reached. The CryoSat-2 footprints altimetry dataset has high confidence in lake surface elevation monitoring. Compared with Hydroweb monitoring results, the agreement between the monitoring results in the range between Lake Bosten and Lake Issyk-Kul are 0.96 and 0.84. The surface elevation of Lake Karakul shows an overall increasing trend with a variation rate of +7.7 cm/yr from 2010 to 2020, which has a positive correlation with the temperature in the basin. This indicates that the increased temperature, which results in the increased snow and ice meltwater in the basin, is the main driving force of the increased lake evolution. The lake surface elevation of Lake Chatyrkul shows an overall decreasing trend, with a variation rate of -9.9 cm/yr from 2010 to 2020, which has a negative correlation with the temperature in the basin. This suggests that Lake Chatyrkul is poorly recharged by snow and ice meltwater. The main driving force of its evolution is the increased evaporative output of the lake due to the increase in temperature. These conclusions prove that temperature and alpine glacial variability within the lake basin play an important role in lake surface elevation variations in alpine regions of Central Asia.


Assuntos
Lagos , Tecnologia de Sensoriamento Remoto , Gelo , Temperatura , Monitoramento Ambiental/métodos
18.
J Phys Chem A ; 126(51): 9699-9708, 2022 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-36534075

RESUMO

Since the observation of the first sulfur-containing molecule, carbon monosulfide (CS), in the interstellar medium (ISM) half a century ago, sulfur-bearing species have attracted great attention from the astrochemistry, astrobiology, and planetary geology communities. Nevertheless, it is still not clear in which forms most of the sulfur resides in molecular clouds, an unsolved problem referred to as "sulfur depletion". Reported herein is the formation of thioformic acid (HCOSH)─the simplest thioacid─in interstellar ice analogues containing carbon monoxide (CO) and hydrogen sulfide (H2S) at 5 K. Utilizing single photoionization reflectron time-of-flight mass spectrometry and isotopically labeled molecules, thioformic acid molecules were selectively photoionized in the temperature-programmed desorption phase. These studies unravel a key reaction pathway to thioformic acid, an organic molecule recently detected toward the giant molecular cloud G+0.693-0.027 and the hot core G31.41+0.31, thus shedding light on interstellar sulfur chemistry.


Assuntos
Gelo , Gelo/análise , Análise Espectral , Espectrometria de Massas , Temperatura
19.
Astrobiology ; 22(12): 1400-1413, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36475963

RESUMO

The interstellar objects 1I/'Oumuamua and 2I/Borisov confirm the long-held expectation that bodies from one stellar system will be carried to another, allowing, in principle, interstellar panspermia. Life might be transferred between stellar systems, depending on the nature of the bodies and how they escaped their systems. 2I/Borisov appears to be a comet, with no more likelihood of carrying life than Solar System comets. In contrast, the nature of 1I/'Oumuamua has been difficult to determine. We review various hypotheses for its origin, including ejection of N2 ice from the surface of an exo-Pluto, formation in a molecular cloud by freezing of H2, and a derelict solar sail of alien construction. Of these, the N2 ice fragment hypothesis is uniquely falsifiable, plausible, and completely consistent with all observations. The possibility of interstellar panspermia would be made more probable if 'Oumuamua originated on a dwarf planet rather than a comet, although substantial challenges to transfer of life would remain. Of proposed mechanisms for interstellar panspermia, transfer of life via rocky meteoroids is perhaps less improbable.


Assuntos
Gelo , Abelhas , Animais
20.
In Vitro Cell Dev Biol Anim ; 58(10): 867-876, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36515806

RESUMO

Insect cell lines are an invaluable resource that facilitate various fundamental and applied research programs. Genetically engineered insect cell lines, in particular, serve as a platform through which the function of heterologously expressed proteins can be studied. However, a barrier to more widespread utilization and distribution of insect cell lines, genetically modified or not, is the technical and operational challenge associated with traditional cryopreservation methods, including their dependence on the use of liquid nitrogen facilities, animal or human serum products, and relatively high concentrations of permeating cryoprotectants (e.g., DMSO). Recent innovations in cryopreservation technologies have produced reagents with improved abilities to effectively preserve mammalian cell lines for long periods in regular laboratory deep freezers without using serum products, but their effectiveness in preserving genetically engineered insect cell lines has not yet been evaluated. In this study, we engineered Sf9 cells to express a dopamine receptor and used them as a model for evaluating the efficacy of a novel cryopreservation medium product, C80EZ®-INSECT, in not only preserving cell viability and proliferation efficiency but also maintaining the insect cell line's "functionality" after storage at -80°C. We found that the engineered Sf9 cells frozen using C80EZ®-INSECT with 5% DMSO alone and stored at -80°C for 6 mo displayed higher viability and growth rates than cells frozen using traditional fetal bovine serum (FBS)-based cryopreservation media with 10% DMSO that were stored at -80°C or in liquid nitrogen for the same period of time. We also found that after 6 mo of storage at -80°C or in liquid nitrogen the cells retained a responsiveness to dopamine comparable to that of the initial cell line, regardless of the cryopreservation reagent used. These results suggest that, due to the unique characteristics of C80EZ®-INSECT in preventing ice recrystallization and reducing ice crystal size and cellular apoptosis during cryostorage procedures, it is an effective cryopreservation reagent for genetically engineered Sf9 cells, and it practically eliminates the need for liquid nitrogen-based storage facilities and FBS-based cryopreservation formulations, as well as reduces the use of permeating cryoprotectants.


Assuntos
Dimetil Sulfóxido , Gelo , Humanos , Animais , Dimetil Sulfóxido/farmacologia , Dimetil Sulfóxido/química , Criopreservação/métodos , Crioprotetores/farmacologia , Sobrevivência Celular , Nitrogênio , Mamíferos
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