Preparation and characterization of hydroxyapatite from eggshell

Hydroxyapatite (HAp) was successfully produced by using recycled eggshell. The observed phases of the synthesised materials were dependent on the mechanochemical activation method (ball milling and attrition milling). The structures of the HAp were characterized by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. Attrition milling proved to be more efficient than ball milling, as resulted nanosize, homogenous HAp even after milling.     

Multidimensional Vascularized Polymers using Degradable Sacrificial Templates

Complex multidimensional vascular polymers are created, enabled by sacrificial template materials of 0D to 3D. Sacrificial material consisting of the commodity biopolymer poly(lactic acid) is treated with a tin catalyst to accelerate thermal depolymerization, and formed into sacrificial templates across multiple dimensions and spanning several orders of magnitude in scale: spheres (0D), fibers (1D), sheets (2D), and 3D printed. Templates are embedded in a thermosetting polymer and removed using a thermal treatment process, vaporization of sacrificial components (VaSC), leaving behind an inverse replica. The effectiveness of VaSC is verified both ex situ and in situ, and the resulting structures are validated via flow rate testing. The VaSC platform is expanded to create vascular and porous architectures across a wide range of size and geometry, allowing engineering applications to take advantage of vascular designs optimized by biology.     

Investigation of the thermoformability of various D-Lactide content poly(lactic acid) films by ball burst test

In this article, we investigated the thermoformability of poly(lactic acid) (PLA) films with various D -Lactide contents and therefore different crystallization properties, performing tensile and ball burst tests at various temperatures and testing rates. We found that the behavior of the PLA films tested above the glass transition temperature significantly differs due to the difference in D -Lactide content, and thus crystallinity. During tensile testing, elevated temperatures and mechanical stress caused the crystallization temperature to decrease and thus highly induced crystallization. At the same time, as testing speed was increased, the ability of the polymer to crystallize decreased. In ball burst tests, the PLA films crystallized more than during tensile testing. We described the differences found between tensile testing and ball burst testing, which latter better represents the conditions of thermoforming through inducing biaxial deformation.     

Terminal Phase Components of the Clotting Cascade in Patients with End-Stage Renal Disease Undergoing Hemodiafiltration or Hemodialysis Treatment

Hemostasis disorder in patients with end-stage renal disease (ESRD) is frequently associated with bleeding diathesis but it may also manifest in thrombotic complications. Analysis of individual coagulation and fibrinolytic factors may shed light on the background of this paradox situation. Here we explored components essential for fibrin formation/stabilization in ESRD patients being on maintenance hemodiafiltration (HDF) or hemodialysis (HD). Pre-dialysis fibrinogen, factor XIII (FXIII) antigen concentrations and FXIII activity were elevated, while α₂-plasmin inhibitor (α₂PI) activity decreased. The inflammatory status, as characterized by C-reactive protein (CRP) was a key determinant of fibrinogen concentration, but not of FXIII and α₂PI levels. During a 4-h course of HDF or HD, fibrinogen concentration and FXIII levels gradually elevated. When compensated for the change in plasma water, i.e., normalized for plasma albumin concentration, only FXIII elevation remained significant. There was no difference between HDF and HD treatments. Individual HDF treatment did not influence α₂PI activity, however after normalization it decreased significantly. HD treatment had a different effect, α₂PI activities became elevated but the elevation disappeared after normalization. Elevated fibrinogen and FXIII levels in ESRD patients might contribute to the increased thrombosis risk, while decreased α₂PI activity might be associated with elevated fibrinolytic potential.     

Plastic Properties of a Mg-Al-Ca Alloy Reinforced with Short Saffil Fibers

AX41 magnesium alloy was reinforced with short Saffil fibers using squeeze cast technology. Samples of the composite were deformed in compression at elevated temperatures. The work hardening rate as a function of the flow stress in the matrix was investigated. A model taking into account two hardening and two softening processes was used for analyzing of experimental curves. Parameters of the model follow different temperature dependences. Possible hardening and softening processes are discussed.     

Light-harvesting bio-nanomaterial using porous silicon and photosynthetic reaction center

ABSTRACT: Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by scanning electron microscopy and atomic force microscopy. The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon-based electronics and biological redox systems.     

An electrically controlled quantum dot based spin current injector

We present a proposal for a fully electrically controllable quantum dot based spin current injector. The device consists of a quantum dot that is strongly coupled to a ferromagnetic electrode on one side and weakly coupled to a nonmagnetic electrode on the other side. The presence of the ferromagnetic electrode results in an exchange field that splits the dot level. We show that this exchange-induced splitting can lead to almost full spin polarization of the current flowing through the device. Moreover, we also demonstrate that the sign of polarization can be changed by the gate or the bias voltage within a switching time in the nanosecond range. Thus, the proposed device can operate as an electrically controlled, rapidly switchable spin current source, which can be realized in various state-of-the-art nanostructures.