1,481 research outputs found
Exploring the cellular accumulation of metal complexes
Transition metal complexes offer great potential as diagnostic and therapeutic agents, and a growing number of biological applications have been explored. To be effective, these complexes must reach their intended target inside the cell. Here we review the cellular accumulation of metal complexes, including their uptake, localization, and efflux. Metal complexes are taken up inside cells through various mechanisms, including passive diffusion and entry through organic and metal transporters. Emphasis is placed on the methods used to examine cellular accumulation, to identify the mechanism(s) of uptake, and to monitor possible efflux. Conjugation strategies that have been employed to improve the cellular uptake characteristics of metal complexes are also described
Development of resins for composites by resin transfer molding
Designed to cover a wide range of resin technology and to meet the near-term and long-term needs of the aircraft industry, this research has three objectives: to produce resin transfer molding (RES) resins with improved processability, to produce prepreg systems with high toughness and service temperature, and to produce new resin systems. Progress on reaching the objectives is reported
Greater osteoblast and endothelial cell adhesion on nanostructured polyethylene and titanium
Mostly due to desirable mechanical properties (such as high durability and low wear), certain synthetic polymers (such as polyethylene) and metals (such as titanium) have found numerous applications in the medical device arena from orthopedics to the vasculature, yet frequently, they do not proactively encourage desirable cell responses. In an effort to improve the efficacy of such traditional materials for various implant applications, this study used electron beam evaporation to create nanostructured surface features that mimic those of natural tissue on polyethylene and titanium. For other materials, it has been shown that the creation of nanorough surfaces increases surface energy leading to greater select protein (such as vitronectin and fibronectin) interactions to increase specific cell adhesion. Here, osteoblast (bone forming cells) and endothelial cell (cells that line the vasculature) adhesion was determined on nanostructured compared to conventional, nano-smooth polyethylene and titanium. Results demonstrated that nanorough surfaces created by electron beam evaporation increased the adhesion of both cells markedly better than conventional smooth surfaces. In summary, this study provided evidence that electron beam evaporation can modify implant surfaces (specifically, polyethylene and titanium) to have nanostructured surface features to improve osteoblast and endothelial cell adhesion. Since the adhesion of anchorage dependent cells (such as osteoblasts and endothelial cells) is a prerequisite for their long-term functions, this study suggests that electron beam evaporation should be further studied for improving materials for various biomedical applications
Polarization transfer in scattering using the Super BigBite Spectrometer
The effects of multi-photon-exchange and other higher-order QED corrections
on elastic electron-proton scattering have been a subject of high experimental
and theoretical interest since the polarization transfer measurements of the
proton electromagnetic form factor ratio at large momentum
transfer conclusively established the strong decrease of this ratio with
for GeV. This result is incompatible with previous
extractions of this quantity from cross section measurements using the
Rosenbluth Separation technique. Much experimental attention has been focused
on extracting the two-photon exchange (TPE) effect through the unpolarized
cross section ratio, but polarization transfer in polarized elastic
scattering can also reveal evidence of hard two-photon exchange. Furthermore,
it has a different sensitivity to the generalized TPE form factors, meaning
that measurements provide new information that cannot be gleaned from
unpolarized scattering alone. Both -dependence of polarization
transfer at fixed , and deviations between electron-proton and
positron-proton scattering are key signatures of hard TPE. A polarized positron
beam at Jefferson Lab would present a unique opportunity to make the first
measurement of positron polarization transfer, and comparison with
electron-scattering data would place valuable constraints on hard TPE. Here, we
propose a measurement program in Hall A that combines the Super BigBite
Spectrometer for measuring recoil proton polarization, with a non-magnetic
calorimetric detector for triggering on elastically scattered positrons. Though
the reduced beam current of the positron beam will restrict the kinematic
reach, this measurement will have very small systematic uncertainties, making
it a clean probe of TPE.Comment: 6 pages, 3 figures. Contribution to the EPJA topical issue, "An
Experimental Program with Positron Beams at Jefferson Lab." arXiv admin note:
substantial text overlap with arXiv:2007.15081, arXiv:1906.0941
Anterior segment photography - An evaluation of the various techniques and films
This paper investigates some of the various methods of photographing the anterior segment of the eye. It deals with slit lamp photography, macrophotography, and hand-held photography and points out the advantages and disadvantages of each. Various films including color negative, color slide, and infra-red film were also employed in order to determine the benefits of each. The Hentor slit lamp is dealt with in particular in order to develop photographic attachments for it. This paper also explains why ocular photography is important and how to do it
Biomechanical Evaluation of a Mandibular Spanning Plate Technique Compared to Standard Plating Techniques to Treat Mandibular Symphyseal Fractures
Purpose. The purpose of this study is to compare the biomechanical behavior of the spanning reconstruction plate compared to standard plating techniques for mandibular symphyseal fractures. Materials and Methods. Twenty-five human mandible replicas were used. Five unaltered synthetic mandibles were used as controls. Four experimental groups of different reconstruction techniques with five in each group were tested. Each synthetic mandible was subjected to a splaying force applied to the mandibular angle by a mechanical testing unit until the construct failed. Peak load and stiffness were recorded. The peak load and stiffness were analyzed using ANOVA and the Tukey test at a confidence level of 95% (P<0.05). Results. The two parallel plates’ group showed statistically significant lower values for peak load and stiffness compared to all other groups. No statistically significant difference was found for peak load and stiffness between the control (C) group, lag screw (LS) group, and the spanning plate (SP1) group. Conclusions. The spanning reconstruction plate technique for fixation of mandibular symphyseal fractures showed similar mechanical behavior to the lag screw technique when subjected to splaying forces between the mandibular gonial angles and may be considered as an alternative technique when increased reconstructive strength is needed
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