Relaxation properties of the ice cover

The aim of this work was to generalize the known data and conduct experiments to determine the relaxation properties of ice in the ice cover under short-term (no more than 1 min.) loading. The problem lies in the fact that when one is solving applied problems of ice engineering, ice is often considered as an elastic isotropic material, and its stress-strain state (SSS) is studied in terms of the theory of bending of elastic plates. This does not allow performing theoretical calculations when resonant flexural gravity waves (IGW) are excited by moving loads, because under these conditions, the deflections of the ice increase to infinity and the known solutions become unusable. In fact, ice clearly manifests the properties of a quasi-isotropic medium, and the relationship between stresses and deformations is of a viscoelastic nature. It is noted in the work that, depending on the mode in which external loads act on the ice cover, its inelastic properties affect the nature of its behavior in different ways, while the viscoelastic properties of the ice cover are well described by the linear models of Maxwell or Kelvin-Voigt inelastic continuous media. The experimental material is duly processed and analysis is carried out of the results of experimental studies performed in the field by loading the ice cover with balanced loads using a specially made loading device, which was a frame with three supports. The design of the device made it possible to load the ice cover with balanced loads, which made it possible to exclude the influence of false elasticity of water on the results of experiments. For the rheological models of ice behavior indicated, the most probable ranges of changes in the relaxation times of stresses and deformations of the ice cover in the ice conditions considered are given. The results obtained can be used in theoretical studies of ice engineering problems.

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Theory of Structural and Secondary Relaxation in Amorphous Drugs under Compression

Pharmaceutics ◽

10.3390/pharmaceutics12020177 ◽

2020 ◽

Vol 12 (2) ◽

pp. 177 ◽

Cited By ~ 2

Author(s):

Anh D. Phan ◽

Katsunori Wakabayashi

Keyword(s):

Single Molecule ◽

Nearest Neighbor ◽

Theoretical Calculations ◽

Relaxation Times ◽

Experimental Studies ◽

Quantitative Agreement ◽

External Pressure ◽

Drug Formulation ◽

Small Displacement ◽

Amorphous Drugs

Compression effects on alpha and beta relaxation process of amorphous drugs are theoretically investigated by developing the elastically collective nonlinear Langevin equation theory. We describe the structural relaxation as a coupling between local and nonlocal activated process. Meanwhile, the secondary beta process is mainly governed by the nearest-neighbor interactions of a molecule. This assumption implies the beta relaxation acts as a precursor of the alpha relaxation. When external pressure is applied, a small displacement of a molecule is additionally exerted by a pressure-induced mechanical work in the dynamic free energy, which quantifies interactions between a molecule with its nearest neighbors. The local dynamics has more restriction and it induces stronger effects of collective motions on single-molecule dynamics. Thus, the alpha and beta relaxation times are significantly slowed down with increasing compression. We apply this approach to determine the temperature and pressure dependence of the alpha and beta relaxation time for curcumin, glibenclamide, and indomethacin, and compare numerical results with prior experimental studies. Both qualitative and quantitative agreement between theoretical calculations and experiments validate our assumptions and reveal their limitations. Our approach would pave the way for the development of the drug formulation process.

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Influence of working bodies of technical means on injury and quality of seed of grain crops

Naukovij žurnal «Tehnìka ta energetika» ◽

10.31548/machenergy2020.03.049 ◽

2020 ◽

Vol 11 (3) ◽

pp. 49-54

Author(s):

D. A. Derevianko ◽

◽

V. M. Polishchuk ◽

O. D. Derevianko ◽

◽

...

Keyword(s):

Technological Process ◽

Theoretical Calculations ◽

Structural Parameters ◽

Experimental Studies ◽

Grain Crops ◽

Transportation Process ◽

Working Bodies ◽

The Relationship ◽

Harmful Effects

Theoretical calculations and experimental studies show that during the technological process of transporting seeds by technical means, in particular ladle conveyors, macro- and especially microtrauma of grains occurs, which affects a decrease in quality indicators. Analysis of the studies shows that the structural parameters of the working bodies, the biological and physico-mechanical properties of the kernels, as well as the material for the manufacture or coating of the working elements, affect the trauma and quality of the seeds. Experimental data showed that microtrauma of winter wheat grains before transportation was in the range of 22,9- 23,5%, and after completion of the transportation process was 45,3-46,4%, that is, doubled. Further studies to improve the quality of seeds of grain crops, reduce the harmful effects of microorganisms on caryopsis and reduce macro- and microtrauma should be carried out in the relationship and the complex of biological and physico-mechanical features of the entire technological process.

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The Impact of Sea Ice on Cruise Tourism on Svalbard

ARCTIC ◽

10.14430/arctic68320 ◽

2019 ◽

Vol 72 (2) ◽

pp. 151-165 ◽

Cited By ~ 4

Author(s):

Marta Bystrowska

Keyword(s):

Sea Ice ◽

Ice Cover ◽

The Arctic ◽

Cruise Industry ◽

Cruise Tourism ◽

Ice Conditions ◽

Arctic Climate Change ◽

The Impact ◽

The Relationship ◽

Method Approach

This paper explores the relationship between sea ice conditions and cruise tourism activities in the Arctic Archipelago of Svalbard. It analyzes how cruise tourism planning and organization depend on sea ice conditions and to what extent Arctic climate change influences tourism. A mixed-method approach, including sea ice analysis and interviews with 13 cruise tourism stakeholders, was applied to grasp the complexity of Svalbard’s cruise tourism. The outcomes show that cruise traffic depends on the sea ice cover, but only to some extent. Other factors, such as a location’s attractiveness or sailing regulations also influence cruise itineraries around Svalbard. Sea ice conditions are in general considered favorable for cruising around Svalbard, and sea ice is a not a decisive factor in cruise planning and organization. The sea ice cover around Svalbard is decreasing; thus, high annual and inter-annual unpredictability of sea ice poses challenges for cruise operations around Svalbard. Flexibility in itineraries, plus good cooperation and management help the cruise industry adjust to any challenges arising from uncertain sea ice conditions. However, issues of overcrowding and decreased attractiveness due to disappearing ice are more and more visible and may challenge the development of cruise tourism around Svalbard in the future.

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Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

10.26434/chemrxiv.5717950 ◽

2017 ◽

Author(s):

Haibo Ge ◽

Lei Pan ◽

Piaoping Tang ◽

Ke Yang ◽

Mian Wang ◽

...

Keyword(s):

Bond Activation ◽

Theoretical Calculations ◽

Experimental Studies ◽

Bond Functionalization ◽

Aliphatic Ketones ◽

Site Selectivity ◽

Mechanistic Investigation ◽

Palladium Catalyzed ◽

Metal Catalyzed ◽

Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp3 carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp3)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp3)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.

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Potential Role of Inflammation in Associations between Particulate Matter and Heart Failure

Current Pharmaceutical Design ◽

10.2174/1381612824666180110150550 ◽

2018 ◽

Vol 24 (3) ◽

pp. 341-358 ◽

Cited By ~ 7

Author(s):

Xiaotong Ji ◽

Yingying Zhang ◽

Guangke Li ◽

Nan Sang

Keyword(s):

Heart Failure ◽

Particulate Matter ◽

Inflammatory Response ◽

Heart Diseases ◽

Experimental Studies ◽

Epidemiological Studies ◽

Inflammatory Mechanism ◽

High Concentrations ◽

Future Work ◽

The Relationship

Recently, numerous studies have found that particulate matter (PM) exposure is correlated with increased hospitalization and mortality from heart failure (HF). In addition to problems with circulation, HF patients often display high expression of cytokines in the failing heart. Thus, as a recurring heart problem, HF is thought to be a disorder characterized in part by the inflammatory response. In this review, we intend to discuss the relationship between PM exposure and HF that is based on inflammatory mechanism and to provide a comprehensive, updated evaluation of the related studies. Epidemiological studies on PM-induced heart diseases are focused on high concentrations of PM, high pollutant load exposure in winter, or susceptible groups with heart diseases, etc. Furthermore, it appears that the relationship between fine or ultrafine PM and HF is stronger than that between HF and coarse PM. However, fewer studies paid attention to PM components. As for experimental studies, it is worth noting that coarse PM may indirectly promote the inflammatory response in the heart through systematic circulation of cytokines produced primarily in the lungs, while ultrafine PM and its components can enter circulation and further induce inflammation directly in the heart. In terms of PM exposure and enhanced inflammation during the pathogenesis of HF, this article reviews the following mechanisms: hemodynamics, oxidative stress, Toll-like receptors (TLRs) and epigenetic regulation. However, many problems are still unsolved, and future work will be needed to clarify the complex biologic mechanisms and to identify the specific components of PM responsible for adverse effects on heart health.

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Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

Annals of Glaciology ◽

10.1017/s0260305500012143 ◽

1997 ◽

Vol 24 ◽

pp. 181-185 ◽

Cited By ~ 3

Author(s):

Katsuhisa Kawashima ◽

Tomomi Yamada

Keyword(s):

Experimental Studies ◽

Ice Formation ◽

Compression Tests ◽

Densification Rate ◽

Overburden Pressure ◽

Proportionality Constant ◽

Wet Snow ◽

Water Saturated ◽

The Relationship ◽

Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

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Application of intelligent orienteering based on Internet of things

EURASIP Journal on Wireless Communications and Networking ◽

10.1186/s13638-020-01814-1 ◽

2020 ◽

Vol 2020 (1) ◽

Author(s):

Donghui Zhang ◽

Ruijie Liu

Keyword(s):

Internet Of Things ◽

Network Architecture ◽

Emergency Services ◽

Simulation Experiment ◽

Experimental Studies ◽

Signal Stability ◽

Anchor Nodes ◽

Set Up ◽

The Relationship ◽

The Internet Of Things

Abstract Orienteering has gradually changed from a professional sport to a civilian sport. Especially in recent years, orienteering has been widely popularized. Many colleges and universities in China have also set up this course. With the improvement of people’s living conditions, orienteering has really become a leisure sport in modern people’s life. The reduced difficulty of sports enables more people to participate, but it also exposes a series of problems. As the existing positioning technology is relatively backward, the progress in personnel tracking, emergency services, and other aspects is slow. To solve these problems, a new intelligent orienteering application system is developed based on the Internet of things. ZigBee network architecture is adopted in the system. ZigBee is the mainstream scheme in the current wireless sensor network technology, which has many advantages such as convenient carrying, low power consumption, and signal stability. Due to the complex communication environment in mobile signal, the collected information is processed by signal amplification and signal anti-interference technology. By adding anti-interference devices, video isolators and other devices, the signal is guaranteed to the maximum extent. In order to verify the actual effect of this system, through a number of experimental studies including the relationship between error and traffic radius and the relationship between coverage and the number of anchor nodes, the data shows that the scheme studied in this paper has a greater improvement in comprehensive performance than the traditional scheme, significantly improving the accuracy and coverage. Especially the coverage is close to 100% in the simulation experiment. This research has achieved good results and can be widely used in orienteering training and competition.

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The Relationships Between Serum DHEA-S and AMH Levels in Infertile Women: A Retrospective Cross-Sectional Study

Journal of Clinical Medicine ◽

10.3390/jcm10061211 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1211

Author(s):

Li-Te Lin ◽

Kuan-Hao Tsui

Keyword(s):

Generalized Linear Models ◽

Large Scale ◽

Linear Models ◽

Positive Association ◽

Cross Sectional Study ◽

Dehydroepiandrosterone Sulphate ◽

Sectional Study ◽

Cross Sectional ◽

Infertile Women ◽

The Relationship

The relationship between serum dehydroepiandrosterone sulphate (DHEA-S) and anti-Mullerian hormone (AMH) levels has not been fully established. Therefore, we performed a large-scale cross-sectional study to investigate the association between serum DHEA-S and AMH levels. The study included a total of 2155 infertile women aged 20 to 46 years who were divided into four quartile groups (Q1 to Q4) based on serum DHEA-S levels. We found that there was a weak positive association between serum DHEA-S and AMH levels in infertile women (r = 0.190, p < 0.001). After adjusting for potential confounders, serum DHEA-S levels positively correlated with serum AMH levels in infertile women (β = 0.103, p < 0.001). Infertile women in the highest DHEA-S quartile category (Q4) showed significantly higher serum AMH levels (p < 0.001) compared with women in the lowest DHEA-S quartile category (Q1). The serum AMH levels significantly increased across increasing DHEA-S quartile categories in infertile women (p = 0.014) using generalized linear models after adjustment for potential confounders. Our data show that serum DHEA-S levels are positively associated with serum AMH levels.

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Relationship between Cycling Infrastructure and Transportation Cycling in a Small Urban Area

Future Transportation ◽

10.3390/futuretransp1010007 ◽

2021 ◽

Vol 1 (1) ◽

pp. 99-112

Author(s):

Richard Larouche ◽

Nimesh Patel ◽

Jennifer L. Copeland

Keyword(s):

Generalized Linear Models ◽

Qualitative Data ◽

Linear Models ◽

The Other ◽

Small City ◽

The Road ◽

The Past ◽

Low Prevalence ◽

The Relationship

The role of infrastructure in encouraging transportation cycling in smaller cities with a low prevalence of cycling remains unclear. To investigate the relationship between the presence of infrastructure and transportation cycling in a small city (Lethbridge, AB, Canada), we interviewed 246 adults along a recently-constructed bicycle boulevard and two comparison streets with no recent changes in cycling infrastructure. One comparison street had a separate multi-use path and the other had no cycling infrastructure. Questions addressed time spent cycling in the past week and 2 years prior and potential socio-demographic and psychosocial correlates of cycling, including safety concerns. Finally, we asked participants what could be done to make cycling safer and more attractive. We examined predictors of cycling using gender-stratified generalized linear models. Women interviewed along the street with a separate path reported cycling more than women on the other streets. A more favorable attitude towards cycling and greater habit strength were associated with more cycling in both men and women. Qualitative data revealed generally positive views about the bicycle boulevard, a need for education about sharing the road and for better cycling infrastructure in general. Our results suggest that, even in smaller cities, cycling infrastructure may encourage cycling, especially among women.

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The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction

Structural Chemistry ◽

10.1007/s11224-021-01805-y ◽

2021 ◽

Author(s):

Ibon Alkorta ◽

José Elguero

Keyword(s):

Linear Models ◽

Theoretical Calculations ◽

Computational Method ◽

Basis Set ◽

Free Energies ◽

Nitrogen And Phosphorus ◽

Atom Pairs ◽

Leaving Groups ◽

First Time ◽

Nitrogen Phosphorus

AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.

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