871 research outputs found
Biofunctionalized Patterned Polymer Brushes via Thiol-Ene Coupling for the Control of Cell Adhesion and the Formation of Cell Arrays
Thiolâene
radical coupling is increasingly used for the
biofunctionalization of biomaterials. Thiolâene chemistry presents
interesting features that are particularly attractive for platforms
requiring specific reactions with peptides or proteins and the patterning
of cells, such as reactivity in physiological conditions and photoactivation.
In this work, we synthesized alkene-functionalized (allyl and norbornene
residues) antifouling polymer brushes (based on polyÂ(oligoethylene
glycol methacrylate)) and studied thiolâene coupling with a
series of thiols including cell adhesive peptides RGD and REDV. The
adhesion of umbilical
vein endothelial cells (HUVECs) to these interfaces was studied and
highlighted the absence of specific integrin engagement to REDV, in
contrast to the high level of cell spreading observed on RGD-functionalized
polymer brushes. This revealed that α<sub>4</sub>ÎČ<sub>1</sub> integrins (binding to REDV sequences) are not sufficient
on their own to sustain HUVEC spreading, in contrast to α<sub>v</sub>ÎČ<sub>3</sub> and α<sub>5</sub>ÎČ<sub>1</sub> integrins. In addition, we photopatterned peptides at the surface
of polyÂ(oligoethylene glycol methacrylate) (POEGMA) brushes and characterized
the quality of the resulting arrays by epifluorescence microscopy
and atomic force microscopy (AFM). This allowed the formation of cell
patterns and demonstrated the potential of thiolâene based
photopatterning for the design of cell microarrays
Modulation of Thiol-Ene Coupling by the Molecular Environment of Polymer Backbones for Hydrogel Formation and Cell Encapsulation
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A multi-wavelength analysis of active regions and sunspots by comparison of automatic detection algorithms
YesThe launch of the Solar Dynamics Observatory (SDO) in early 2010 has provided the solar
physics community with the most detailed view of the Sun to date. However, this presents new
challenges for the analysis of solar data. Currently,
SDO sends over 1 terabyte of data per day back to Earth and methods for fast and reliable analysis are
more important than ever. This article details four algorithms developed separately at the Universities
of Bradford and Glasgow, the
Royal Observatory of Belgium and Trinity College Dublin for the purposes of automated detection of
solar active regions (ARs) and sunspots at different levels of the solar atmosphere
Communications and sensing of illumination contributions in a power led lighting system
Abstract â In recent years, LED technology emerged as a prime candidate for the future illumination light source, due to high energy efficiency and long life time. In addition, LEDs offer a superior flexibility in terms of colors and shapes, which leads to a potentially infinite variety of available light patterns. In order to create these patterns via easy user interaction, we need to sense the local light contribution of each LED. This measurement could be enabled through tagging of the light of each LED with unique embedded IDs. To this end, we propose a new modulation and multiple access scheme, named as codetime division multiple access- pulse position modulation (CTDMA-PPM): a form of PPM which is keyed according to a spreading sequence, and in which the duty cycle is subject to pulse width modulation (PWM) according to the required lighting setting. Our scheme considers illumination constraints in addition to the communication requirements and, to our best knowledge, it has not been addressed by other optical modulation methods. Based on the proposed modulation method and multiple access schemes, we develop a system structure, which includes illumination sources, a sensor receiver and a control system. Illumination sources illuminate the environment and transmit information, simultaneously. According to our theoretical analysis, this system structure could support a number of luminaries equal to the size of the CDMA codebook times the dimming range. I
Peptide Cross-Linked Poly(2-oxazoline) as a Sensor Material for the Detection of Proteases with a Quartz Crystal Microbalance
Inflammatory conditions are frequently accompanied by increased levels of active proteases, and there is rising interest in methods for their detection to monitor inflammation in a point of care setting. In this work, new sensor materials for disposable single-step protease biosensors based on poly(2-oxazoline) hydrogels cross-linked with a protease-specific cleavable peptide are described. The performance of the sensor material was assessed targeting the detection of matrix metalloproteinase-9 (MMP-9), a protease that has been shown to be an indicator of inflammation in multiple sclerosis and other inflammatory conditions. Films of the hydrogel were formed on gold-coated quartz crystals using thiolâene click chemistry, and the cross-link density was optimized. The degradation rate of the hydrogel was monitored using a quartz crystal microbalance (QCM) and showed a strong dependence on the MMP-9 concentration. A concentration range of 0â160 nM of MMP-9 was investigated, and a lower limit of detection of 10 nM MMP-9 was determined
Multiple Projection Optical Diffusion Tomography with Plane Wave Illumination
We describe a new data collection scheme for optical diffusion tomography in
which plane wave illumination is combined with multiple projections in the slab
imaging geometry. Multiple projection measurements are performed by rotating
the slab around the sample. The advantage of the proposed method is that the
measured data can be much more easily fitted into the dynamic range of most
commonly used detectors. At the same time, multiple projections improve image
quality by mutually interchanging the depth and transverse directions, and the
scanned (detection) and integrated (illumination) surfaces. Inversion methods
are derived for image reconstructions with extremely large data sets. Numerical
simulations are performed for fixed and rotated slabs
Determination of ochratoxin a in baby foods by ELISA and HPLC
Ochratoxin A, is a well-known nephrotoxic, hepatotoxic and carcinogenic mycotoxin, produced by some species of mould genera such as Aspergillus spp. and Penicillium spp. under various environmental conditions, such as moisture and temperature. The main sources of Ochratoxin A intake for humans are cereals and cereal derived products, when they are consumed in large quantities, as in the case of breakfast cereals and cereal based baby foods principally consumed by babies. In this study, a total of 150 samples (50 infant formulas, 50 follow-on formulas, and 50 cereal based supplementary foods for infants and children) were obtained randomly from various supermarkets and pharmacies in Istanbul, and 52 out of 150 (34.7%) analysed samples were contaminated with Ochratoxin A. None of the examined baby food samples were above the Turkish Food Codex maximum limit of Ochratoxin A in baby, infant, and young children foods (0.5 ÎŒg kgâ1). These results reinforce the idea of strict and routine quality controls and good hygiene practices have to be performed in every step of production to minimize the potential risk of Ochratoxin A contamination
Diffusion of particles moving with constant speed
The propagation of light in a scattering medium is described as the motion of
a special kind of a Brownian particle on which the fluctuating forces act only
perpendicular to its velocity. This enforces strictly and dynamically the
constraint of constant speed of the photon in the medium. A Fokker-Planck
equation is derived for the probability distribution in the phase space
assuming the transverse fluctuating force to be a white noise. Analytic
expressions for the moments of the displacement along with an
approximate expression for the marginal probability distribution function
are obtained. Exact numerical solutions for the phase space
probability distribution for various geometries are presented. The results show
that the velocity distribution randomizes in a time of about eight times the
mean free time () only after which the diffusion approximation becomes
valid. This factor of eight is a well known experimental fact. A persistence
exponent of is calculated for this process in two dimensions
by studying the survival probability of the particle in a semi-infinite medium.
The case of a stochastic amplifying medium is also discussed.Comment: 9 pages, 9 figures(Submitted to Phys. Rev. E
Processing of weather radar raw IQ-data towards the identification and correction of wind turbine interference â Project RIWER: Removing the Influence of Wind Park Echoes in Weather Radar Measurements
In recent years, the fast construction, expansion and repowering
of wind parks have been a major source of concern for the weather radar
community and meteorological services. Among others because wind turbines
are extremely tall, reflective, and moving objects, which make them a source
of interference that is hard to distinguish from meteorological echoes and
therefore difficult to filter and even more difficult to correct.
Polarimetric C-Band Doppler weather radar measurements enable us to analyse
and understand the impact of wind turbine interference on meteorological
weather radar echoes and to build up knowledge. The main idea is to analyse
the raw IQ-data in order to quantify the behaviour of wind turbine
interference with meteorological scattering. As a first step in this
direction, this paper will focus on the derivation and analysis of radar
moments such as Reflectivity (Z), Differential Reflectivity (ZDR),
Differential Propagation Phase (PHIDP), Mean Doppler Velocity (V), and
Correlation Coefficient (RHOHV). We will consider two cases: (i)Â events with
precipitation, and (ii)Â events without precipitation, in order to understand
and model the impact of wind turbine interference (WTI). For this purpose,
weather radar measurements from Deutscher Wetterdienst (DWD), recorded under
the aegis of the project RIWER (Removing the Influence of Wind Park Echoes
in Weather Radar Measurements), are presented, analysed and discussed in
detail.</p
BISTATIC SCATTERING CHARACTERISTICS OF A WIND PARK TURBINE DERIVED FROM AN UAV-MOUNTED RECEIVER RECORDING C-BAND WEATHER RADAR SIGNALS
As a result of increasing use of wind energy as a sustainable source of electricity, large Wind Parks with numerous Wind Turbines have been constructed. Wind turbines are extremely tall objects consisting of stationary and moving parts. The presence of wind turbines in the vicinity of weather radar systems can significantly impact their performance, leading to false alarms and errors in radar measurements. Accurate weather forecasting is challenging in this circumstance. Large Radar Cross Section (RCS) of wind turbines results in interference, also known asWind Turbine Clutter (WTC) orWind Turbine Interference (WTI), within and beyond the radar main beam, Multipath Interference (MPI), and phenomena referred to as âshadowing effectsâ behind the wind turbines. These effects vary significantly in both time and space as a result of various wind turbine operations and meteorological conditions. It can often be difficult to distinguish wind turbine returns from weather-like signals. For the assessment of WTC or WTI, it is essential to understand the scattering properties of these wind turbines. In this paper, the bistatic scattering characteristics of a wind park turbine using a Unmanned Aerial Vehicle (UAV)-mounted receiver recording C-band weather radar signals were investigated by determining the average received power (PRxAvg (θs)) and RCS of wind turbine as a function of the scattering angle. For this purpose, the measurements and data provided by the German Meteorological Service (DWD, DeutscherWetterdienst) were utilised. The average received power as a function of scattering angle (θs) was calculated by using I-Q (In-phase and Quadrature) signals. Forward, back and side scattering of the calculated average received power were analysed separately. Moreover, Front-to-Back ratio, Front-to-Right side ratio and Front-to-Left side ratio were calculated and compared using forward, back and side scatter values. RCS values were also calculated depending on the scattering angle (θs) of the wind turbine
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