Smart Surfaces with Tunable Wettability

21st Century Surface Science - a Handbook ◽

10.5772/intechopen.92426 ◽

2020 ◽

Author(s):

Meenaxi Sharma ◽

Krishnacharya Khare

Keyword(s):

Mechanical Strain ◽

Surface Wettability ◽

External Stimulus ◽

Primary Role ◽

Complete Wetting ◽

Smart Surfaces ◽

Responsive Surfaces ◽

The Right ◽

External Stimuli

Modification of surface wettability (ranging from complete wetting to complete non-wetting) of various surfaces is often required in many applications. Conventionally, it is done using a coating of suitable materials as per the requirement. In this approach, the old coating needs to be replaced every time by a new appropriate one. Alternatively, smart responsive surfaces can show tunable wettability with external stimulus. Electric field, temperature, light, pH, mechanical strain, etc. can be effectively used as external stimuli, and a suitable coating can be incorporated, which responses to the respective stimulus. These surfaces can be used to tune the surface wettability to any extent based on the magnitude of the stimulus. The primary role of the external stimulus is to vary the liquid-solid interfacial energy, which subsequently changes the surface wettability. The biggest advantage of this approach is that the surface wettability can be reversibly tuned. Each of the techniques mentioned above has many advantages along with certain limitations, and the combination of advantages and limitations helps users to choose the right technique for their work. Many recent studies have used this approach to quantify the tuning of the surface wettability and have also demonstrated its potential in various applications.

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Smart Bionic Surfaces with Switchable Wettability and Applications

Journal of Bionic Engineering ◽

10.1007/s42235-021-0038-7 ◽

2021 ◽

Vol 18 (3) ◽

pp. 473-500

Author(s):

Shuyi Li ◽

Yuyan Fan ◽

Yan Liu ◽

Shichao Niu ◽

Zhiwu Han ◽

...

Keyword(s):

Hot Spot ◽

Surface Wettability ◽

Future Perspective ◽

Geometrical Structures ◽

Physical Stimulation ◽

Water Separation ◽

Practical Applications ◽

Smart Surfaces ◽

Recent Developments ◽

External Stimuli

AbstractIn order to satisfy the needs of different applications and more complex intelligent devices, smart control of surface wettability will be necessary and desirable, which gradually become a hot spot and focus in the field of interface wetting. Herein, we review interfacial wetting states related to switchable wettability on superwettable materials, including several classical wetting models and liquid adhesive behaviors based on the surface of natural creatures with special wettability. This review mainly focuses on the recent developments of the smart surfaces with switchable wettability and the corresponding regulatory mechanisms under external stimuli, which is mainly governed by the transformation of surface chemical composition and geometrical structures. Among that, various external stimuli such as physical stimulation (temperature, light, electric, magnetic, mechanical stress), chemical stimulation (pH, ion, solvent) and dual or multi-triggered stimulation have been sought out to realize the regulation of surface wettability. Moreover, we also summarize the applications of smart surfaces in different fields, such as oil/water separation, programmable transportation, anti-biofouling, detection and delivery, smart soft robotic etc. Furthermore, current limitations and future perspective in the development of smart wetting surfaces are also given. This review aims to offer deep insights into the recent developments and responsive mechanisms in smart biomimetic surfaces with switchable wettability under external various stimuli, so as to provide a guidance for the design of smart surfaces and expand the scope of both fundamental research and practical applications.

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Primary Role of Mitochondria and Calcium Ions in the Induction of Reactive Oxygen Species by External Stimuli such as Triorganotins

Toxicology in Vitro ◽

10.1016/s0887-2333(98)00034-4 ◽

1998 ◽

Vol 12 (5) ◽

pp. 551-556 ◽

Cited By ~ 9

Author(s):

E. Corsini ◽

B. Viviani ◽

M. Marinovich ◽

C.Lodovico Galli

Keyword(s):

Reactive Oxygen Species ◽

Calcium Ions ◽

Reactive Oxygen ◽

Primary Role ◽

Oxygen Species ◽

External Stimuli

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Stimuli-responsive surfaces for switchable wettability and adhesion

Journal of The Royal Society Interface ◽

10.1098/rsif.2021.0162 ◽

2021 ◽

Vol 18 (179) ◽

pp. 20210162

Author(s):

Chang Li ◽

Ming Li ◽

Zhongshi Ni ◽

Qingwen Guan ◽

Bamber R. K. Blackman ◽

...

Keyword(s):

Contact Angles ◽

Smart Devices ◽

Stimuli Responsive ◽

Liquid Transport ◽

Adhesion Properties ◽

Smart Surfaces ◽

Biological Surfaces ◽

Responsive Surfaces ◽

Rose Petal ◽

External Stimuli

Diverse unique surfaces exist in nature, e.g. lotus leaf, rose petal and rice leaf. They show similar contact angles but different adhesion properties. According to the different wettability and adhesion characteristics, this review reclassifies different contact states of droplets on surfaces. Inspired by the biological surfaces, smart artificial surfaces have been developed which respond to external stimuli and consequently switch between different states. Responsive surfaces driven by various stimuli, e.g. stretching, magnetic, photo, electric, temperature, humidity and pH, are discussed. Studies reporting on either atmospheric or underwater environments are discussed. The application of tailoring surface wettability and adhesion includes microfluidics/droplet manipulation, liquid transport and harvesting, water energy harvesting and flexible smart devices. Particular attention is placed on the horizontal comparison of smart surfaces with the same stimuli. Finally, the current challenges and future prospects in this field are also identified.

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Development of the new “DIV” rail fastening system

10.5592/co/cetra.2020.984 ◽

2021 ◽

Author(s):

Stjepan Lakušić ◽

Ivo Haladin ◽

Mate Ivančev ◽

Maja Baniček ◽

Janko Košćak

Keyword(s):

Railway Track ◽

Primary Role ◽

Noise And Vibration ◽

Rail Vehicles ◽

Vehicle Load ◽

The Right ◽

The University ◽

Research Centres ◽

Design Construction

The primary role of the rail fastening system is to position and fasten the rails to sleepers and transfer the vehicle load from the rails to the track substructure. The type and characteristics of the fastening system are usually chosen depending on the required elasticity of the track, the design load, and the type of rail. The rail fastening system has also a significant effect on the emission of noise and vibration that occurs during the operation of rail vehicles, so the right choice of fastening system contributes to noise and vibration mitigation. Worldwide, there are many types of rail fastening systems, which differ in design, construction and technical characteristics. The most used rail fastening systems are W-clip, E-clip, Nabla clip, etc. Various types of fastenings are a result of effort of both independent institutions, rail equipment manufacturers and a significant number of research centres of the developed railway authorities. When optimizing the railway track, it is necessary to choose the right properties of the fastening system, which will ensure safe and reliable operation of railway vehicles with a minimum of noise and vibration emission. The characteristics of the fastening clip and the rail pad have the greatest influence on the mechanical behaviour of the fastening system. The Faculty of Civil Engineering of the University of Zagreb cooperates with DIV d.o.o., a manufacturer of railway equipment, on an R&D project “Development of the elastic fastening system DIV”. With the aim of developing a new fastening system, this paper primarily analyses the properties of existing fastening systems. A meaningful evaluation of the rail fastening systems requires the understanding of the geometry, materials, mechanical properties and the utilisation of the clip and the rail pad. The new fastening system should meet the requirements defined in the standards EN 13146 and EN 13481.

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Revisiting the role of the judiciary in enforcing the state’s duty to provide access to the minimum core content of socio-economic rights in South Africa and Kenya

Journal of Comparative Law in Africa ◽

10.47348/jcla/v7/i2a3 ◽

2020 ◽

Vol 7 (2) ◽

pp. 60-89

Author(s):

Justice Alfred Mavedzenge

Keyword(s):

South Africa ◽

Separation Of Powers ◽

The State ◽

Primary Role ◽

Economic Rights ◽

Core Content ◽

Secondary Role ◽

International Obligation ◽

The Right

Although the realisation of the full scope of each socio-economic right is meant to be achieved progressively, Kenya and South Africa have an international obligation to immediately provide vulnerable persons with access to the minimum core of each of these rights. As revealed (again) by the COVID-19 pandemic, the two states are in violation of this obligation as millions of people in both countries are living in abject poverty, without access to the bare necessities. Attempts to enforce the government’s minimum core obligations have failed at least three times in South Africa, and the Court of Appeal in Kenya has hesitated to enforce these obligations. Relying on the doctrinal review of jurisprudence from both countries and international law, this article proposes that, in order to enforce the minimum core obligations without violating the separation of powers doctrine, the judiciary must be perceived to have a primary role and a secondary role. The primary role of the court must be to enforce meaningful engagement between the state and the rights bearers in determining the quantitative aspects of the minimum core content of each right. Once the state has developed this core content, the court can review its reasonableness by measuring it against the qualitative minimum standards imposed by the right. In circumstances of urgent need, where the state has failed to develop a reasonable quantitative minimum core content and rights bearers are in danger of suffering irreparable harm, the court should invoke its secondary role which entails setting the quantitative minimum core content to be provided by the state as a temporary measure.

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A mental number line in human newborns

10.1101/159335 ◽

2017 ◽

Cited By ~ 3

Author(s):

Rosa Rugani ◽

Marco Lunghi ◽

Elisa Di Giorgio ◽

Lucia Regolin ◽

Beatrice Dalla Barba ◽

...

Keyword(s):

Social Interactions ◽

Number Line ◽

Mental Number Line ◽

Neural Systems ◽

Cultural Learning ◽

Primary Role ◽

Human Adults ◽

The Right ◽

The Brain

ABSTRACTIn the 19th century Francis Galton first reported that humans represent numbers on a mental number line with smaller numbers on the left and larger numbers on the right. It has been suggested that this orientation emerges as a result of reading/writing habits for both words or numbers. Recent evidence in animals and infants in the first months of life has challenged the primary role of language in determining the left-to-right direction of spatial-numerical association, SNA. However, the possibility that SNA is learnt by early exposure to caregivers’ directional biases is still open. Here we show that 55-hour-old newborns, once habituated to a number (i.e., 12), spontaneously associated a smaller number (i.e., 4) with the left side and a larger number (i.e., 36) with the right side of space. Moreover, SNA in neonates was not absolute but relative. The same number (i.e., 12) was associated with the left side whenever the previously experienced number was larger (i.e., 36), but with the right side whenever the number was smaller (i.e., 4). Control on continuous physical variables showed that the effect was specific of discrete magnitudes. Hence, soon after birth humans associate smaller numbers with the left space and larger numbers with the right space. These results constitute strong evidence that in our species SNA originates from pre-linguistic and biologically precursors in the brain.SIGNIFICANCE STATEMENTFor human adults, the representation of number and space is profoundly intertwined. Humans represent numbers on a left to right oriented Mental Number Line (MNL), with small numbers located on the left and larger ones on the right. How do these connections arise? Do we learn to associate numbers with space throughout cultural learning and social interactions or is this association rooted in the biology of the human brain? We showed that neonates spontaneously associate numbers with space. After being habituated to a certain number, neonates associated a smaller number with the left and a larger number with the right side. This evidence demonstrates that a predisposition to map numbers onto space is rooted in human neural systems.

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