Search results for "biofysiikka"
showing 9 items of 9 documents
Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs
2021
Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing tempera…
Chlorophyll a fluorescence illuminates a path connecting plant molecular biology to Earth-system science
2021
Remote sensing methods enable detection of solar-induced chlorophyll a fluorescence. However, to unleash the full potential of this signal, intensive cross-disciplinary work is required to harmonize biophysical and ecophysiological studies. For decades, the dynamic nature of chlorophyll a fluorescence (ChlaF) has provided insight into the biophysics and ecophysiology of the light reactions of photosynthesis from the subcellular to leaf scales. Recent advances in remote sensing methods enable detection of ChlaF induced by sunlight across a range of larger scales, from using instruments mounted on towers above plant canopies to Earth-orbiting satellites. This signal is referred to as solar-in…
Hidden and self-excited attractors in radiophysical and biophysical models
2017
One of the central tasks of investigation of dynamical systems is the problem of analysis of the steady (limiting) behavior of the system after the completion of transient processes, i.e., the problem of localization and analysis of attractors (bounded sets of states of the system to which the system tends after transient processes from close initial states). Transition of the system with initial conditions from the vicinity of stationary state to an attractor corresponds to the case of a self-excited attractor. However, there exist attractors of another type: hidden attractors are attractors with the basin of attraction which does not have intersection with a small neighborhoods of any equ…
Structural stability of DNA origami nanostructures under application-specific conditions
2018
With the introduction of the DNA origami technique, it became possible to rapidly synthesize almost arbitrarily shaped molecular nanostructures at nearly stoichiometric yields. The technique furthermore provides absolute addressability in the sub-nm range, rendering DNA origami nanostructures highly attractive substrates for the controlled arrangement of functional species such as proteins, dyes, and nanoparticles. Consequently, DNAorigami nanostructures have found applications in numerous areas of fundamental and applied research, ranging from drug delivery to biosensing to plasmonics to inorganic materials synthesis. Since many of those applications rely on structurally intact, well-defin…
Neural Mechanisms Underlying Human Auditory Evoked Responses Revealed By Human Neocortical Neurosolver
2022
Funding Information: This study was supported by National Institutes of Health (Grant Nos. NIBIB RO1 EB022889, NIMH RO1 MH106174). Publisher Copyright: © 2021, The Author(s). Auditory evoked fields (AEFs) are commonly studied, yet their underlying neural mechanisms remain poorly understood. Here, we used the biophysical modelling software Human Neocortical Neurosolver (HNN) whose foundation is a canonical neocortical circuit model to interpret the cell and network mechanisms contributing to macroscale AEFs elicited by a simple tone, measured with magnetoencephalography. We found that AEFs can be reproduced by activating the neocortical circuit through a layer specific sequence of feedforwar…
Ca-P-O thin film preparation, modification and characterisation
2011
Bioceramics are biocompatible ceramic materials, that interact with biological systems of the body to treat, strengthen or replace body functions. Most conventional bioceramics are oxide ceramics, glass ceramics and calcium phosphate ceramics. Among these calcium phosphates, synthetic hydroxyapatite has been extensively studied due to its biomimetic properties similar to that of natural bone. One approach to prepare synthetic hydroxyapatite is to first deposit amorphous Ca-P-O thin film and then by means of post deposition annealing initiate the formation of hydroxyapatite crystals to the film. In addition to the correct film composition and crystalline structure, other surface properties s…
Gap junctions and connexin hemichannels both contribute to the electrical properties of retinal pigment epithelium.
2022
Gap junctions are intercellular channels that permit the transfer of ions and small molecules between adjacent cells. These cellular junctions are particularly dense in the retinal pigment epithelium (RPE), and their contribution to many retinal diseases has been recognized. While gap junctions have been implicated in several aspects of RPE physiology, their role in shaping the electrical properties of these cells has not been characterized in mammals. The role of gap junctions in the electrical properties of the RPE is particularly important considering the growing appreciation of RPE as excitable cells containing various voltage-gated channels. We used a whole-cell patch clamp to measure …
Modeling of intracellular transport in realistic cell geometries
2018
The transport of molecules inside cells is a complex process, the characterization of which is important to gain full understanding of cellular processes. Understanding of intracellular transport is also important for medical applications, for example when analyzing transport of medicine inside cells. The intracellular environment is very complex, and at least the most crucial parts of this complexity must be accounted for to solve transport problems in cells. In this thesis the results of studies in modeling intracellular transport are presented. The aim of the work was to model intracellular transport of proteins and viral capsids in realistic cell environments. To this end, microscopic m…
Vierasmolekyylien sitoutumisen mallintaminen lipokaliiniproteiineissa
2008
Tässä työssä tutkittiin DigA16- ja 1KT7-proteiineja. Proteiineille suoritettiin klassisia MD-simulaatioita käyttämällä Orac4.0-ohjelmistoa. DigA16-proteiinin kokeellisesti mitattu rakenne täydennettiin tietokoneella ja kokonaisesta proteiinista simuloitiin kolmea eri rakennetta. 1KT7-proteiinin simulaation lähtörakenteena oli kokeellisesti mitattu rakenne, jota ei tarvinnut täydentää. Simulaatioita suoritettiin kutakin 10,751 nanosekunnin verran, joista 0,751 ns oli alustusta ja 10 ns simulointia 300 Kelvinissä. Tästä 10 ns vaiheesta kerättiin analysoitu data. Simulaation aikana kokonaisenergia kasvoi tasaisesti. Kasvu oli niin pientä, että sen voidaan katsoa johtuneen täysin MD-simulaatios…