Search results for "Stimuli"
showing 10 items of 123 documents
Fabrication of Single Cylindrical Au-Coated Nanopores with Non-Homogeneous Fixed Charge Distribution Exhibiting High Current Rectifications
2014
We have designed and characterized a cylindrical nanopore that exhibits high electrochemical current rectification ratios at low and intermediate electrolyte concentrations. For this purpose, the track-etched single cylindrical nanopore in polymer membrane is coated with a gold (Au) layer via electroless plating technique. Then, a non-homogeneous fixed charge distribution inside the Au-coated nanopore is obtained by incorporating thiol-terminated uncharged poly(N-isopropylacrylamide) (PNIPAM) chains in series to poly(4-vinyl pyridine) (PVP) chains, which are positively charged at acidic pH values. The functionalization reaction is checked by measuring the current–voltage (I–V) curves prior …
Stimuli-Responsive Y-Shaped Polymer Brushes Based on Junction-Point-Reactive Block Copolymers
2012
Reversibly responsive, thin or ultrathin polymer fi lms, often referred to as “smart surfaces”, can alter their properties upon application of external stimuli. [ 1 , 2 ] One particular application fi eld represents the engineering of nanostructured fi lms mimicking cell membranes. [ 3 , 4 ] Such materials offer application potential for sensors, textiles, construction materials, and smart coatings due to a rapid change in surface energy and morphology. [ 5–7 ] The surface response can be triggered by various external stimuli such as light, temperature, electrical potential, mechanical force, magnetic fi eld, pH change, or selective solvent treatment. [ 1 , 8–12 ] A variety of different thi…
Multi-stimuli responsive polymers – the all-in-one talents
2014
Stimuli-responsive polymers have gained increasing attention, which is attributed to the manifold applications they can be used for. Several years' intensive research was invested in stimuli-responsive polymers. Their stimuli-responsiveness led not only to novel responsive groups, which enabled the translation of an external physical impact into a change of a material property, but also to polymers that are equipped with more than one responsive group. The integration of several responsive moieties within one polymer yields smart polymers exhibiting complex responsive behaviour of the polymers. This review summarises recent developments in the area of multi-stimuli responsive polymers, layi…
A clickable NHC–Au(i)-complex for the preparation of stimulus-responsive metallopeptide amphiphiles
2018
We report the synthesis of an alkyne functionalised NHC-Au(i)-complex which is conjugated with amphiphilic oligopeptides using a copper(i) catalysed cycloaddition. The resulting Au(i)-metalloamphiphiles are shown to self-assemble into charge-regulated stimulus-responsive supramolecular polymers in water via a weakly cooperative polymerisation mechanism.
Probing the Folding of Peptide–Polymer Conjugates Using the π-Dimerization of Viologen End-Groups
2020
The synthesis of a foldable viologen-functionalized peptide–polymer conjugate is presented. The ABA-type triblock conjugate with a PEG polymer was capped with a FHFHF pentapeptide sequence and further modified with a viologen building block at both chain ends. The pH-responsive peptide domains fold into an intermediate structure inducing close proximity of the viologen units, which upon a reduction step form π-dimers of the radical cation. Overall the intramolecular folding and intermolecular self-assembly process leads to the formation of supramolecular nanorods. Mixing of viologen-peptide–polymer conjugates with unfunctionalized conjugates leads to crosslinking of the nanorods and hydroge…
Differences in Chromatic Sensitivity Estimated Using Static and Dynamic Colour Stimuli
2017
Abstract The current study reports on a novel computerised colour vision test employing static and dynamic stimuli. The aim of the study was to assess if static and dynamic stimuli result in comparable chromatic discrimination thresholds when participant’s age is taken into account. Participants (n = 20) were 21 to 77 years old, had normal colour vision and no history of any eye disease. They all participated in two sessions estimating chromatic sensitivity with static and dynamic stimuli, respectively, with six directions in colour space varying either along the red-green (RG) or yellow- blue (YB) directions. We found no significant differences in chromatic thresholds along a tritan axis o…
Optimal inter-stimulus interval for interpolated twitch technique when using double pulse stimulation
2013
Interpolated twitch technique is a method frequently used to assess voluntary activa- tion. This method uses electrically evoked twitch superimposed on the voluntary activi- ty and its comparison with the twitch in rested muscle i.e. control twitch, to evaluate completeness of muscle activation. The purpose of this study was to investigate the ef- fect of interval in paired stimulation on control twitch in young and elderly individuals with bent and flexed knee positions. Supramaximal electrical stimulation consisted of one single stimulus and eight paired stimulation with intervals from 5 to 40ms, with increments of 5ms. In evoked twitches normalized peak torque amplitude (NPT), time to pe…
3D nanoscale ordered architectures in thin films for organic electronics
2011
Order in molecular thin films is of fundamental importance to gain and exploit a series of properties in nanotechnology. In this contest, engineering 2D supramolecular and molecular superstructures is of particular interest. They offer great possibilities for several applications whose achievement also allows for new theoretical approaches and nanoscale laws [1]. A natural extension of 2D nanopatterning concerns the attainment of a 3D nanoscale control in molecular films [2]. This question is complex to challenge and it is of ultimate importance in emerging fields like organic and hybrid photovoltaics, organic thin film transistors and sensors as well as plastic electronics. For example, th…
Latvijas augsto tehnoloģiju uzņēmumus stimulējošie faktori ieiešanai ārvalstu tirgos
2015
Bakalaura darba tēma ir „Latvijas augsto tehnoloģiju uzņēmumus stimulējošie faktori ieiešanai ārvalstu tirgos”, ar mērķi noskaidrot kādi faktori mudina Latvijas augsto tehnoloģiju uzņēmumus internacionalizēt savu darbību. Darbus izstrādāts trīs daļas. Pirmajā daļā apskatīta internacionalizācija un tās stimulu teorētiskais aspekts, kā arī augsto tehnoloģiju uzņēmumu raksturojošas pazīmes. Tai seko augsto tehnoloģiju industrijas apskats Eiropā un Latvijā. Trešajā daļā veikta pētījuma gaitā aptaujāto Latvijas augsto tehnoloģiju uzņēmumu sniegto rezultātu analīze, secinot, ka iekšējie faktori ir primārie internacionalizācijas stimuli, no kuriem iespēja palielināt peļņu un uzņēmuma sniegtā produ…
Automatic auditory and somatosensory brain responses in relation to cognitive abilities and physical fitness in older adults
2017
AbstractIn normal ageing, structural and functional changes in the brain lead to an altered processing of sensory stimuli and to changes in cognitive functions. The link between changes in sensory processing and cognition is not well understood, but physical fitness is suggested to be beneficial for both. We recorded event-related potentials to somatosensory and auditory stimuli in a passive change detection paradigm from 81 older and 38 young women and investigated their associations with cognitive performance. In older adults also associations to physical fitness were studied. The somatosensory mismatch response was attenuated in older adults and it associated with executive functions. So…