scholarly journals Routes to cubic ice through heterogeneous nucleation

2021 ◽  
Vol 118 (13) ◽  
pp. e2025245118
Author(s):  
Michael Benedict Davies ◽  
Martin Fitzner ◽  
Angelos Michaelides
Keyword(s):  
Heterogeneous Nucleation ◽  
Physical Sciences ◽  
Water Contact ◽  
Lattice Match ◽  
Hexagonal Polytype ◽  
Computational Screening ◽  
Key Factor ◽  
Screening Study ◽  
Dynamics Simulations ◽  
And Control

The freezing of water into ice is one of the most important processes in the physical sciences. However, it is still not understood at the molecular level. In particular, the crystallization of cubic ice (Ic)—rather than the traditional hexagonal polytype (Ih)—has become an increasingly debated topic. Although evidence for Ic is thought to date back almost 400 y, it is only in the last year that pure Ic has been made in the laboratory, and these processes involved high-pressure ice phases. Since this demonstrates that pure Ic can form, the question naturally arises if Ic can be made from liquid water. With this in mind, we have performed a high-throughput computational screening study involving molecular dynamics simulations of nucleation on over 1,100 model substrates. From these simulations, we find that 1) many different substrates can promote the formation of pristine Ic; 2) Ic can be selectively nucleated for even the mildest supercooling; 3) the water contact layer’s resemblance to a face of ice is the key factor determining the polytype selectivity and nucleation temperature, independent of which polytype is promoted; and 4) substrate lattice match to ice is not indicative of the polytype obtained. Through this study, we have deepened understanding of the interplay of heterogeneous nucleation and ice I polytypism and suggest routes to Ic. More broadly, the substrate design methodology presented here combined with the insight gained can be used to understand and control polymorphism and stacking disorder in materials in general.

ACCESS TO AND CONTROL OVER LAND AS GENDERED: CONTEXTUALIZING WOMEN’S ACCESS AND OWNERSHIP RIGHTS OF LAND IN RURAL GHANA

2016 ◽  
Vol 45 (2) ◽  
pp. 28-48 ◽  
Author(s):  
Isaac Dery
Keyword(s):  
Thematic Analysis ◽  
Rural Women ◽  
Rural Poor ◽  
Rural Ghana ◽  
Secure Access ◽  
Key Factor ◽  
Access Rights ◽  
Ownership Rights ◽  
And Control ◽  
Relationship Of

Women’s access to and control over productive resources, including land, has increasingly been recognized in global discussions as a key factor in reducing poverty, ensuring food security and promoting gender equality. Indeed, this argument has been widely accepted by both feminists and development theorists since the 1980s. Based on qualitative research with 50 purposively selected men and women, this study explored the complexity of women’s access to and control over land within a specific relationship of contestations, negotiations, and manipulations with men. Data were analyzed using thematic analysis. While theoretically, participants showed that women’s [secure] access to and control over land has beneficial consequences to women themselves, households and the community at large, in principle, women's access and control status was premised in the traditional framework which largely deprives women, equal access and/or control over the land. The study indicates that even though land is the most revered resource and indeed, the dominant source of income for the rural poor, especially women, gender-erected discrimination and exclusion lie at the heart of many rural women in gaining access to land. This study argues that women's weak access rights and control over land continue to perpetuate the feminization of gender inequality–while men were reported to possess primary access and control over land as the heads of households, women were argued to have secondary rights due to their ‘stranger statuses’ in their husbands’ families. Overall, the degree of access to land among women was reported to be situated within two broad contexts–marriage and inheritance.

scholarly journals Tuning flavin environment to detect and control light-induced conformational switching in Drosophila cryptochrome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siddarth Chandrasekaran ◽  
Connor M. Schneps ◽  
Robert Dunleavy ◽  
Changfan Lin ◽  
Cristina C. DeOliveira ◽  
...  
Keyword(s):  
Side Reactions ◽  
Resonance Spectroscopy ◽  
Conformational Switching ◽  
Spin Resonance ◽  
Degradation Activity ◽  
Recognition Motifs ◽  
Cellular Turnover ◽  
Control Light ◽  
Dynamics Simulations ◽  
And Control

AbstractLight-induction of an anionic semiquinone (SQ) flavin radical in Drosophila cryptochrome (dCRY) alters the dCRY conformation to promote binding and degradation of the circadian clock protein Timeless (TIM). Specific peptide ligation with sortase A attaches a nitroxide spin-probe to the dCRY C-terminal tail (CTT) while avoiding deleterious side reactions. Pulse dipolar electron-spin resonance spectroscopy from the CTT nitroxide to the SQ shows that flavin photoreduction shifts the CTT ~1 nm and increases its motion, without causing full displacement from the protein. dCRY engineered to form the neutral SQ serves as a dark-state proxy to reveal that the CTT remains docked when the flavin ring is reduced but uncharged. Substitutions of flavin-proximal His378 promote CTT undocking in the dark or diminish undocking in the light, consistent with molecular dynamics simulations and TIM degradation activity. The His378 variants inform on recognition motifs for dCRY cellular turnover and strategies for developing optogenetic tools.

scholarly journals Origin and control of ionic hydration patterns in nanopores

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Miraslau L. Barabash ◽  
William A. T. Gibby ◽  
Carlo Guardiani ◽  
Alex Smolyanitsky ◽  
Dmitry G. Luchinsky ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Distribution Functions ◽  
Water Molecules ◽  
Surrounding Water ◽  
Ionic Hydration ◽  
Hydration Shells ◽  
Water Layers ◽  
Dynamics Simulations ◽  
And Control

AbstractIn order to permeate a nanopore, an ion must overcome a dehydration energy barrier caused by the redistribution of surrounding water molecules. The redistribution is inhomogeneous, anisotropic and strongly position-dependent, resulting in complex patterns that are routinely observed in molecular dynamics simulations. Here, we study the physical origin of these patterns and of how they can be predicted and controlled. We introduce an analytic model able to predict the patterns in a graphene nanopore in terms of experimentally accessible radial distribution functions, giving results that agree well with molecular dynamics simulations. The patterns are attributable to a complex interplay of ionic hydration shells with water layers adjacent to the graphene membrane and with the hydration cloud of the nanopore rim atoms, and we discuss ways of controlling them. Our findings pave the way to designing required transport properties into nanoionic devices by optimising the structure of the hydration patterns.

scholarly journals Diagnosis and Therapeutic Management of Liver Fibrosis by microRNA

2021 ◽  
Vol 22 (15) ◽  
pp. 8139
Author(s):  
Tomoko Tadokoro ◽  
Asahiro Morishita ◽  
Tsutomu Masaki
Keyword(s):  
Liver Fibrosis ◽  
Viral Infections ◽  
Primary Biliary Cholangitis ◽  
Medical Need ◽  
Key Factor ◽  
Complications Of Cirrhosis ◽  
And Control ◽  
Functional Rnas ◽  
Remarkable Progress ◽  
Made In

Remarkable progress has been made in the treatment and control of hepatitis B and C viral infections. However, fundamental treatments for diseases in which liver fibrosis is a key factor, such as cirrhosis, alcoholic/nonalcoholic steatohepatitis, autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis, are still under development and remain an unmet medical need. To solve this problem, it is essential to elucidate the pathogenesis of liver fibrosis in detail from a molecular and cellular perspective and to develop targeted therapeutic agents based on this information. Recently, microRNAs (miRNAs), functional RNAs of 22 nucleotides, have been shown to be involved in the pathogenesis of liver fibrosis. In addition, extracellular vesicles called “exosomes” have been attracting attention, and research is being conducted to establish noninvasive and extremely sensitive biomarkers using miRNAs in exosomes. In this review, we summarize miRNAs directly involved in liver fibrosis, miRNAs associated with diseases leading to liver fibrosis, and miRNAs related to complications of cirrhosis. We will also discuss the efficacy of each miRNA as a biomarker of liver fibrosis and pathology, and its potential application as a therapeutic agent.

Anti-Interference Optimal Design of Grain Combine Harvester Multiple Target Working Speed Control Model

2013 ◽  
Vol 753-755 ◽  
pp. 1382-1385
Author(s):  
Xin Wang ◽  
Han Fu ◽  
Du Chen ◽  
Shu Mao Wang
Keyword(s):  
Effective Means ◽  
Optimization Theory ◽  
Multiple Control ◽  
Power Cost ◽  
High Productivity ◽  
Key Factor ◽  
Objective Control ◽  
Combine Harvester ◽  
And Control ◽  
Measurement And Control

Harvesting speed is a key factor that influences working quality, utilization and harvest efficiency of the working process of grain combine harvester. In order to solve multi-objective control and poor anti-interference ability of measurement system in combine harvester, this paper uses optimization theory and error analysis theory to integrate analyze multi-source disturbance of data which is acquired in measurement and control system. The optimum working state control algorithm which proposes by this paper has better robust and anti-interference features, and what is more, it can be targeted by low yield loss, high productivity and low power cost. It provides theoretical basis and data support for the domestic agricultural harvesting machine, which also is an effective means to heighten the automatic level of the agricultural information technology. Keywords: Grain Combine harvester; Multiple control strategy; Anti-interference ability

scholarly journals Giving Birth With Epidural Analgesia: The Experience of First-Time Mothers

2012 ◽  
Vol 21 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Ryoko Hidaka ◽  
Lynn Clark Callister
Keyword(s):  
Pain Management ◽  
Epidural Analgesia ◽  
Epidural Administration ◽  
Birth Experience ◽  
Management Options ◽  
Key Factor ◽  
Qualitative Descriptive ◽  
And Control ◽  
First Time ◽  
Experiences Of Women

The purpose of our qualitative descriptive study was to describe the birth experiences of women using epidural analgesia for pain management. We interviewed nine primiparas who experienced vaginal births. Five themes emerged: (a) coping with pain, (b) finding epidural administration uneventful, (c) feeling relief having an epidural, (d) experiencing joy, and (e) having unsettled feelings of ambivalence. Although epidural analgesia was found to be effective for pain relief and may contribute to some women’s satisfaction with the birth experience, it does not guarantee a quality birth experience. In order to support and promote childbearing women’s decision making, we recommend improved education on the variety of available pain management options, including their risks and benefits. Fostering a sense of caring, connection, and control in women is a key factor to ensure positive birth experiences, regardless of pain management method.

scholarly journals Competences of teachers of natural-physical sciences. An analysis from the perception of the students

2020 ◽  
Vol 1674 (1) ◽  
pp. 012020
Author(s):  
R Prada-Núñez ◽  
E T Ayala ◽  
W R Avendaño-Castro
Keyword(s):  
Educational Institution ◽  
Evaluation Process ◽  
Future Research ◽  
Physical Sciences ◽  
Four Dimensions ◽  
State Tests ◽  
Need To Evaluate ◽  
The Subject ◽  
The One ◽  
And Control

Abstract This article arises as a proposal in view of the need to evaluate the scientific competences promoted by teachers of the subject of physics at the level of basic secondary and secondary technical education. A valid questionnaire was designed from the application of scalar analysis, factorial analysis and content analysis, which is composed of 49 items evaluated by means of a Likert scale with five levels of response. It was applied in a sample of 249 students enrolled in a public educational institution during 2019, characterized by their good results in the area of physics in state tests. The results allowed the identification of strengths in the four dimensions proposed by the Ministerio de Educación Nacional, Colombia (pedagogical, didactic, disciplinary and behavioural), in contrast with some weaknesses within which the evaluation process stands out as the one with the greatest impact, since the students state that this process is assumed by the teacher as a mechanism of pressure and control. When investigating the teachers in a complementary way, positions were determined that were totally opposite to those held by the students, then it is suggested for future research to consider both the students and the teachers as informants and a supervision of the students’ notes as the end of triangulating the results to refine the conclusions, on which future improvement plans will depend.

Study and Investigation of Energy Management Techniques Used in Electric/Hybrid Electric Vehicles

2021 ◽  
Vol 54 (4) ◽  
pp. 599-606
Author(s):  
Punyavathi Ramineni ◽  
Alagappan Pandian
Keyword(s):  
Energy Management ◽  
Electric Vehicles ◽  
Internal Combustion Engines ◽  
Hybrid Electric Vehicles ◽  
Vital Role ◽  
Combustion Engines ◽  
Key Factor ◽  
Hybrid Electric ◽  
And Control ◽  
Intelligent Controllers

Many pollution-related issues are raising due to the usage of conventional internal combustion engines (ICEs) vehicles. Electric Vehicles/ Hybrid electric vehicles (EVs/HEVs) are the finest solutions to overcome those problems associated with ICE-based vehicles. The EVs are introduced with a signal energy source (SES), which is not a successful attempt, especially during transient vehicles, driving, etc. Multiple energy sources (MES) EVs are introduced to attain better performance than the SES vehicles, which is obtained by combining two sources like battery/fuel cells, ultracapacitor. In this contest, energy management (EMNG) plays a vital role in sharing the load to the sources as per the EVs requirement. In the case of MES-based EVs, the controller always plays a significant role in the related EMNG system because it is the key factor in improving vehicle efficiency. In this article, a study has mainly been done related to several conventional, intelligent controllers and control algorithms to do the proper EMNG between sources present in the EV.

The Skew-Symmetric Property of the Newton-Euler Formulation for Constrained Multibody Systems

1996 ◽  
Author(s):  
Hong-Chin Lin ◽  
Tsung-Chieh Lin ◽  
KwangHae H. Yae
Keyword(s):  
Special Form ◽  
Multibody Systems ◽  
Large Scale ◽  
Computational Analysis ◽  
Necessary Condition ◽  
Large Scale Systems ◽  
Lagrange Formulation ◽  
Dynamics Simulations ◽  
And Control ◽  
Symmetric Property

Abstract This paper proposes a special form of the recursive Newton-Euler formulation that satisfies the skew-symmetric property, which is a necessary condition to ensure global convergence in a class of regressor-based identification and adaptive control (Slotine, 1987a & 1987b; Craig, 1987). For general multibody systems, such a special form has been developed in a reduced Euler-Lagrange formulation, but not in the Newton-Euler formulation, which has been very popular in the computational analysis of large scale systems. The paper successfully constructs a pair of inertia and Coriolis-centrifugal matrices for a “skew-symmetric” recursive Newton-Euler formulation, which can be used in both dynamics simulations and control applications.

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