Search results for "bioengineering"
showing 10 items of 1963 documents
A robust forward-displacement analysis of spherical parallel robots
2009
The forward-displacement analysis of spherical parallel robots (SPRs) is revisited. A robust approach, based on the input–output (I/O) equation of spherical four-bar linkages, is proposed. In this approach, the closed-loop kinematic chain of a SPR is partitioned into two four-bar spherical chains, whose I/O equations are at the core of the analysis reported here. These equations lead to a trigonometric equation in the joint angles, which is solved semigraphically to obtain the joint variables for the determination of the moving plate orientation. Examples are included to demonstrate the application of the method.
Developments in the use of baculoviruses for the surface display of complex eukaryotic proteins
2001
The ability to couple genotype to phenotype has proven to be of immense value in systems such as phage display and has allowed genes encoding novel functions to be selected directly from complex libraries. However, the complexity of many eukaryotic proteins places a severe constraint on successful display in Escherichia coli. This restriction could be resolved if a eukaryotic virus could be similarly engineered for display purposes. Preliminary data have suggested that the baculovirus Autographa californica, a multiple nuclear polyhedrosis virus (AcMNPV) is a candidate for eukaryotic virus display because the insertion of peptides into the native virus coat protein, or the expression of for…
Bacterial sensors based on biosilica immobilization for label-free OWLS detection
2013
In the last years, a new group of enzymes, the so-called silicateins, have been identified and characterized, which form the axial filaments of the spicules of the siliceous sponges, consisting of not only amorphous silica among others. These enzymes are able to catalyze the polycondensation and deposition of silica at mild conditions. Silicateins can be expressed in Escherichia coli. The recombinant proteins are expressed on the surface of the cell wall and are able to catalyze the formation of a polysilicate net around the bacterial cells providing the possibility for further attachment to the surface of SiO2 containing sensor chips. With this mild immobilization process it is now possibl…
Design characteristics, primary stability and risk of fracture of orthodontic mini-implants: Pilot scan electron microscope and mechanical studies
2013
Objectives: Orthodontic mini-implants (OMIs) are increasingly used in orthodontics but can fail for various reasons. This study investigates the effects of OMI design characteristics on the mechanical properties in artificial bone. Material and Methods: Twelve self-drilling OMIs (2 small, 6 medium, 4 large) from 8 manufacturers were tested for their primary stability in simulated medium-high cancellous bone and the risk to fracture in high-density methacrylate blocks. For the assessments of the maximum insertion torque (IT) and torsional fracture (TF) 5 of each OMI were used and for the pull-out strength (POS) 10. The OMIs were inserted with a torque screwdriver (12 sec/360°) until the bott…
Functionality of endothelial cells on silk fibroin nets: Comparative study of micro- and nanometric fibre size
2007
Biomimetic material design, such as mimicking nanostructured components of the extracellular matrix, is an actual challenge for biomaterial research with a high impact on tissue engineering and regenerative medicine. Thus, understanding the cellular response at the cell biological and molecular level and the consequences of various chemically or physically modified biomaterials is highly important. In the present study we assessed the response of human umbilical vein endothelial cells (HUVEC) and outgrowth endothelial cells (OEC) from endothelial progenitor cells to different variants of nanofibrous silk fibroin nets in comparison to microfibrous silk fibroin scaffolds with regard to cellul…
NanoBioInterface: a multidisciplinary challenge
2009
Nanotechnologies are being applied to many fields of science and engineering and represent a broad spectrum of methods, some of which have been known for a long time. However, the public interest as well as the promotion of this topic by funding agencies has led in some cases to a simple renaming of
Radiation-Engineered Functional Nanoparticles in Aqueous Systems.
2015
Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic rout…
Cultivation of primmorphs from the marine sponge Suberites domuncula: morphogenetic potential of silicon and iron.
2002
Abstract Marine demosponges (phylum Porifera) are rich sources for potent bioactive compounds. With the establishment of the primmorph system from sponges, especially from Suberites domuncula , the technology to cultivate sponge cells in vitro improved considerably. This progress was possible after the elucidation that sponges are provided with characteristic metazoan cell adhesion receptors and extracellular matrix molecules which allow their cells a positioning in a complex organization pattern. This review summarizes recent data on the cultivation of sponges in aquaria and—with main emphasis—of primmorphs in vitro. It is outlined that silicon and Fe(+++) contribute substantially to the f…
<p>Isolation and Functions of Extracellular Vesicles Derived from Parasites: The Promise of a New Era in Immunotherapy, Vaccination, and Diagno…
2020
Experimental and epidemiological evidence shows that parasites, particularly helminths, play a central role in balancing the host immunity. It was demonstrated that parasites can modulate immune responses via their excretory/secretory (ES) and some specific proteins. Extracellular vesicles (EVs) are nano-scale particles that are released from eukaryotic and prokaryotic cells. EVs in parasitological studies have been mostly employed for immunotherapy of autoimmune diseases, vaccination, and diagnosis. EVs can carry virulence factors and play a central role in the development of parasites in host cells. These molecules can manipulate the immune responses through transcriptional changes. Moreo…
Anisotropic chemical etching of semipolar \{10\bar {1}\bar {1}\}\mbox {/} \{10\bar {1}{+}1\} ZnO crystallographic planes: polarity versus dangling bo…
2009
ZnO thin films grown by metal?organic vapor phase epitaxy along the nonpolar direction and exhibiting semipolar facets have been chemically etched with HCl. In order to get an insight into the influence of the ZnO wurtzite structure in the chemical reactivity of the material, Kelvin probe microscopy and convergent beam electron diffraction have been employed to unambiguously determine the absolute polarity of the facets, showing that facets are unstable upon etching in an HCl solution and transform into planes. In contrast, facets undergo homogeneous chemical etching perpendicular to the initial crystallographic plane. The observed etching behavior has been explained in terms of surface oxy…