1,237 research outputs found
Self‐Assembled Monolayers of Carbohydrate Derivatives on Gold Surfaces
Self‐assembled monolayers (SAMs) presenting carbohydrates (glycans) have been widely prepared on gold surfaces to mimic the carbohydrate surfaces that are involved in molecular recognition phenomena in living cells. The binding affinity of carbohydrate immbolized on SAM surfaces to various carbohydrate‐binding proteins (such as lectins) can be studied by optical, electrochemical, piezoelectrical and thermal sensing techniques. The lectins present on the surface of pathogens (e.g., bacteria or viruses) can be used as targets for capturing onto carbohydrates immobilized on SAM surfaces. The immobilized carbohydrates can also be used for detecting different types of disease biomarkers present in bodily fluids. Synergistic properties of carbohydrate SAMs and gold nanoparticles can be used for vaccine preparation and drug delivery. By studying different types of glycans, their properties, and the behavior toward recognition of specific pathogens and biomarkers, we can develop not only new therapeutics but also enhance the diagnostic strategies of various diseases. In this chapter, we discuss carbohydrate‐terminated SAMs and their common preparation strategies. Next, we focus on roles of different components of SAMs, characterization techniques, and applications
Structure and Applications of Gold in Nanoporous Form
Nanoporous gold (np-Au) has many interesting and useful properties that make it a material of interest for use in many technological applications. Its biocompatible nature and ability to serve as a support for self-assembled monolayers of alkanethiols and their derivative make it a suitable support for the immobilization of carbohydrates, enzymes, proteins, and DNA. Its chemically inert, physically robust and conductive high-surface area makes it useful for the design of electrochemistry-based chemical/bio-sensors and reactors. Furthermore, it is also used as solid support for organic molecular synthesis and biomolecules separation. Its enhanced optical property has application in design of plasmonics-based sensitive biosensors. In fact, np-Au is one of the few materials that can be used as a transducer for both optical and electrochemical biosensing. Due to the presence of low-coordination surface sites, np-Au shows remarkable catalytic activity for oxidation of molecules like carbon monoxide and methanol. Owing to the importance of np-Au, in this chapter we will highlight different strategies of fabrication of np-Au and its emerging applications based on its unique properties
Multiple coating thicknesses for sampling of organic pollutants – linear regressions confirm equilibrium even in challenging environmental media
Recommended from our members
Detonation spreading in fine TATBs
A test has been devised that permits rapid evaluation of the detonation-spreading (or corner-turning) properties of detonations in insensitive high explosives. The test utilizes a copper witness plate as the medium to capture performance data. Dent depth and shape in the copper are used as quantitative measures of the detonation output and spreading behavior. The merits of the test are that it is easy to perform with no dynamic instrumentation, and the test requires only a few grams of experimental explosive materials
HIV testing in Europe: Evaluating the impact, added value, relevance and usability of the European centre for disease prevention and control (ECDC)’s 2010 HIV testing guidance
Background: An evaluation of the 2010 ECDC guidance on HIV testing, conducted in October 2015–January 2016, assessed its impact, added value, relevance and usability and the need for updated guidance. Methods: Data sources were two surveys: one for the primary target audience (health policymakers and decision makers, national programme managers and ECDC official contact points in the European Union/ European Economic Area (EU/EEA) countries and one for a broader target audience (clinicians, civil society organisations and international public health agencies); two moderated focus group discussions (17 participants each); webpage access data; a literature citation review; and an expert consultation (18 participants) to discuss the evaluation findings. Results: Twenty-three of 28 primary target audience and 31 of 51 broader target audience respondents indicated the guidance was the most relevant when compared with other international guidance. Primary target audience respondents in 11 of 23 countries reported that they had used the guidance in development, monitoring and/or evaluation of their national HIV testing policy, guidelines, programme and/or strategy, and 29 of 51 of the broader target audience respondents reported having used the guidance in their work. Both the primary and broader target audience considered it important or very important to have an EU/EEA-level HIV testing guidance (23/28 and 46/51, respectively). Conclusion: The guidance has been widely used to develop policies, guidelines, programmes and strategies in the EU/EEA and should be regularly updated due to continuous developments in the field in order to continue to serve as an important reference guidance in the region
A Phase-Field Model of Spiral Dendritic Growth
Domains of condensed-phase monolayers of chiral molecules exhibit a variety
of interesting nonequilibrium structures when formed via pressurization. To
model these domain patterns, we add a complex field describing the tilt degree
of freedom to an (anisotropic) complex-phase-field solidification model. The
resulting formalism allows for the inclusion of (in general, non-reflection
symmetric) interactions between the tilt, the solid-liquid interface, and the
bond orientation. Simulations demonstrate the ability of the model to exhibit
spiral dendritic growth.Comment: text plus Four postscript figure file
The Shapes of Flux Domains in the Intermediate State of Type-I Superconductors
In the intermediate state of a thin type-I superconductor magnetic flux
penetrates in a disordered set of highly branched and fingered macroscopic
domains. To understand these shapes, we study in detail a recently proposed
"current-loop" (CL) model that models the intermediate state as a collection of
tense current ribbons flowing along the superconducting-normal interfaces and
subject to the constraint of global flux conservation. The validity of this
model is tested through a detailed reanalysis of Landau's original conformal
mapping treatment of the laminar state, in which the superconductor-normal
interfaces are flared within the slab, and of a closely-related straight-lamina
model. A simplified dynamical model is described that elucidates the nature of
possible shape instabilities of flux stripes and stripe arrays, and numerical
studies of the highly nonlinear regime of those instabilities demonstrate
patterns like those seen experimentally. Of particular interest is the buckling
instability commonly seen in the intermediate state. The free-boundary approach
further allows for a calculation of the elastic properties of the laminar
state, which closely resembles that of smectic liquid crystals. We suggest
several new experiments to explore of flux domain shape instabilities,
including an Eckhaus instability induced by changing the out-of-plane magnetic
field, and an analog of the Helfrich-Hurault instability of smectics induced by
an in-plane field.Comment: 23 pages, 22 bitmapped postscript figures, RevTex 3.0, submitted to
Phys. Rev. B. Higher resolution figures may be obtained by contacting the
author
A Pilot Study of Postoperative Animal Welfare as a Guidance Tool in the Development of a Kidney Autotransplantation Model With Extended Warm Ischemia
Background:
This pilot study aimed to maintain acceptable animal welfare in the development of a porcine autotransplantation model with severe and incremental renal ischemic injury, a model for usage in future intervention studies. Secondary aims were to develop and test methods to collect blood and urine without the need to restrain or use sedative and avoid transportation to optimize welfare of the pig.
Methods:
Kidneys from 7 female pigs were subjected to incremental durations of warm ischemia (WI) 30, 45, or 75 minutes by left renal artery and vein clamping. After static cold storage, contralateral nephrectomy was performed, and the injured graft was autotransplanted and animals observed for 14 days. Animal welfare was assessed and recorded using a structured scoring sheet before and 4 days after the kidney autotransplantation. Furthermore, blood samples were drawn daily the first week and every second day the following week using a semi-central venous catheter. An ostomy bag around the genitals was tested for urine collection. Measured glomerular filtration rate was calculated using renal clearance of chromium-51-labeled ethylenediamine tetraacetic acid on day 14.
Results:
None of the 7 animals died during the follow-up. The animal welfare was moderately affected when applying 75 minutes of WI (n = 2), and for that reason WI was not further increased. Pigs with lower WI had no observed welfare issues. With 75 minutes of WI peak, plasma creatinine was 1486 and 1317 µmol/L, reached on day 4. Lowest glomerular filtration rate levels were observed in the pigs with 75 minutes of WI.
Conclusions:
WI up to 75 minutes caused the intended severely impaired renal function without significantly compromising animal welfare. Blood and urine was collected postoperatively without sedation of the pigs or use of a metabolic cage.</p
Topography and instability of monolayers near domain boundaries
We theoretically study the topography of a biphasic surfactant monolayer in
the vicinity of domain boundaries. The differing elastic properties of the two
phases generally lead to a nonflat topography of ``mesas'', where domains of
one phase are elevated with respect to the other phase. The mesas are steep but
low, having heights of up to 10 nm. As the monolayer is laterally compressed,
the mesas develop overhangs and eventually become unstable at a surface tension
of about K(dc)^2 (dc being the difference in spontaneous curvature and K a
bending modulus). In addition, the boundary is found to undergo a
topography-induced rippling instability upon compression, if its line tension
is smaller than about K(dc). The effect of diffuse boundaries on these features
and the topographic behavior near a critical point are also examined. We
discuss the relevance of our findings to several experimental observations
related to surfactant monolayers: (i) small topographic features recently found
near domain boundaries; (ii) folding behavior observed in mixed phospholipid
monolayers and model lung surfactants; (iii) roughening of domain boundaries
seen under lateral compression; (iv) the absence of biphasic structures in
tensionless surfactant films.Comment: 17 pages, 9 figures, using RevTeX and epsf, submitted to Phys Rev
- …