Development and characterization of a biocompatible OH-modified copolymer based on polyurethane

Different polyurethanes were synthesized by varying the diol as well as the diisocyanate components and chain extenders. Polyurethanes with OH-groups were obtained by photo- and thermoinitiation of the radical polymerization of hydroxy alkyl acrylates in the presence of the polyurethanes. The polymers were evaluated with respect to their biocompatibility by measuring the cell spreading, the rates of DNA- and protein synthesis and the swelling behaviour. The differences in the surfaces and the bulks between the selected basic polyurethane and the functionalized modification were determined and characterized by XPS, FTIR-ATR and ¹³C-FT-NMR-spectroscopy. The mechanical data of Tecoflex EG 60D® and Pellethane 2363–80AE® were compared with the data of the synthesized polyurethanes.     

SO(3) nonlinear σ model for a spiral phase in the spin-fermion model

Starting from a doped spin-fermion model for the CuO₂ planes in high-T_c superconductors, we derive an effective continuum theory for the spin degrees of freedom by means of a gradient expansion. We assume an incommmensurate, spiral configuration for the spins. Extending our previous treatment of a planar spiral, we allow for three-dimensional fluctuations of the spin fields, which are described by an S0(3) matrix order parameter. The continuum limit is obtained by a systematic expansion in powers of a short distance cutoff. The occurring infinite series is summed to all orders using a combinatorial method which exploits the constraint obeyed by the S0(3) order parameter. The resulting continuum theory is given by an S0(3) quantum nonlinear model, where the influence of doping is contained in the fermionic susceptibilities that enter into the coupling constants of the model.     

Theory, simulation, experimentation: an integrated approach toteaching digital control systems

This paper discusses the approach adopted by the authors for teaching an undergraduate course (lecture and laboratory) in digital controls. Theoretical material is developed in the lecture concerning the application of direct digital control (DDC) to an analog bench-scale system consisting of a DC motor and tachometer. A simulation of the closed-loop control system with embedded digital controller is developed and run by the students using the TUTSIM dynamic simulation language. Finally, students perform a laboratory experiment in which they write a program to control the actual system using a personal computer and inexpensive interface card. The combination of hands-on experience and computer simulation with the more traditional, theoretical lecture material provides a well-rounded learning experience that better prepares the students to implement digital control systems in the real world     

Perturbations Involving nu1 of NCCN

From high-resolution infrared spectra of 14N12C12C14N, 14N13C13C14N, and 15N12C12C15N, we find that the levels 1000(0)0(0), 1000(0)1(1), 1000(0)2(0,2), and 1000(0)3(1,3) have very pronounced perturbations. Our analysis shows that these perturbations are due to a vibrational resonance among the levels 1000(0)0(0), 0102(0)2(0), and 0102(0)2(2) in the one case, and equivalent levels with one or more additional quanta of nu5 in the other three cases. The resonance constant for the perturbation involving nu1 is 0.25 cm-1. It has the dependence on v5 and l5 that is expected for the sextic potential constant, K124455, although it seems too large for such a high-order constant. The Deltal (or Deltak) = 2 interaction between, for instance, 1000(0)0(0) and 0102(0)2(2e) is shown to be primarily due to the l-type resonance mixing of the 0102(0)2(0) and 0102(0)2(2e) states. The resonance is nearly "turned off" for the 1000(0)2(0,2) and 1000(0)3(1,3) states of 14N13C13C14N because there are no level crossings between the interacting states and the band centers are too far away to have an obvious effect, although careful analysis shows that the perturbation can be seen in their effective centrifugal distortion constants. The spectrum of 15N12C12C15N shows level crossings only in the case of the 1000(0)1(1), 1000(0)2(0,2), and 1000(0)3(1,3) states. Copyright 1999 Academic Press.     

Changes in proton currents in murine microglia induced by cytoskeletal disruptive agents

The sera of 385 buffaloes of different age and sex, collected from the various areas of the Khoozestan province, Iran, were tested by the IFA test, from April 1995 to February 1996. The results indicated 8.8% (34 out of 385) buffaloes had anti-Toxoplasma gondii antibodies titered 1:16 and more. The infection rate of buffaloes under the age of a year, above a year female, and male were 10.8%, 4.7%, 12.1%, and 5.3%, respectively.     

Functionalization of silicone rubber for the covalent immobilization of fibronectin

Surface modification techniques were employed in order to provide functionalized silicone rubber with enhanced cytocompatibility. Acrylic acid (AAc), methacrylic acid (MAAc) and glycidylmethacrylate (GMA) were graft-co-polymerized onto the surface of silicone induced by an argon plasma and thermal initiation. The polymerizations were carried out in solution, in the case of acrylic acid a vapor phase graft-co-polymerization subsequent to argon plasma activation was carried out as well. Human fibronectin (hFn), which acts as a cell adhesion mediator for fibroblasts, was immobilized by making use of the generated carboxylic or epoxy groups, respectively. Surface analysis was accomplished by means of X-ray photoelectron spectroscopy (XPS), infrared spectroscopy in attenuated total reflection mode (IR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic contact angle measurements using the Wilhelmy-plate method. The amount of immobilized active hFn was semiquantified by enzyme-linked immunosorbent assay (ELISA) using a structure-specific antibody against the cell-binding domain of hFn. In vitro testing showed a remarkable difference between surfaces exposing adsorbed-only and surfaces with covalently immobilized hFn. © 2001 Kluwer Academic Publishers     

The chorioallantoic membrane of the chick embryo as a simple model for the study of the angiogenic and inflammatory response to biomaterials

Angiogenesis is essential in wound healing and a common feature in chronic inflammation which is crucially involved in the biological response to biomaterials. A useful system to evaluate the angiogenic activity and the inflammatory potency of various agents is the chorioallantoic membrane (CAM) of the chick embryo. Here we examined its response to different biomaterials. Smooth materials such as PVC or the polyurethane Tecoflex® either unmodified or modified by an OH- or N(CH₃) ₃ ⁺ -end group (HEMA or MAPTAC) inhibited angiogenesis and did not induce the formation of granulation tissue. The anti-angiogenic effects of PVC, Tecoflex® and its HEMA modification, however, were only seen at an early stage of development. In contrast, the MAPTAC modified Tecoflex>® inhibited angiogenesis over the whole time. Rough materials, e.g. filter paper or a collagen/elastin membrane, stimulated angiogenesis and induced the formation of inflammatory tissue. Histological analysis revealed that the filter material was homogeneously populated with cells consisiting mainly of macrophages, fibroblasts and endothelial cells. The collagen/elastin membrane was only partially infiltrated with cells. Among those also clusters of granulocytes were present pointing to an acute inflammatory process. These data show that the angiogenic activity and inflammatory response of biomaterials strongly depend on the chemical composition and the physical structure of the material. The CAM assay appears to be a useful tool for studying biocompatibility. © 2001 Kluwer Academic Publishers     

Therapeutic alliance: Early indicators, course, and outcome.

Investigated therapeutic alliance (TA) for 32 outpatients (aged 20–57 yrs) in psychotherapy. Ss completed the SCL-90 (Revised) prior to and following 14–71 (median 29) psychotherapy sessions. Sessions were videotaped; a 15-min segment of each session was rated on the Therapeutic Alliance Rating Scale of C. R. Marmar et al (1985). Findings supported hypotheses that (1) Ss' positive and negative contributions to the TA in the 1st session would predict the maintenance of the TA throughout treatment and (2) among Ss who achieve significant change, positive contributions to the TA would be greater in the later phases of therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The case of the omitted inventor

What happens when an inventor who made a very small contribution to an invention is left off a patent? Can a company charged with infringement obtain a license from the omitted inventor and so scot free? That was the question before the court in the recent case of Ethicon v. U.S. Surgical. The answer the court gave was yes. The case involved surgical instruments, known as trocars, used to perform minimally invasive abdominal surgery. Ethicon obtained an exclusive license to a patent of Dr. InBae Yoon to an improved trocar (a “safety trocar”) that was less likely to damage internal organs during the initial puncturing of the abdominal wall. Ethicon sold more than $300 million worth of instruments covered by the patent and paid Yoon more than $15 million in royalties. In 1989, Ethicon sued Surgical for infringement of two of the 55 claims of Yoon's patent. As is standard, Surgical took Yoon's deposition and asked about the origin of the invention. In that process, the name of Mr. Choi came up, but Yoon denied that he was an inventor of any of the claims of the patent. Surgical contacted Choi and was told a different story; namely, that Choi was an inventor of at least some parts of the patent. Based on this representation, Surgical took a license from Choi retroactive to the date of issuance of the patent. Surgical paid Choi $300000 for the license and promised to pay an additional $1 million if Surgical prevailed over Ethicon in the lawsuit     

Where did the U.S. patent laws come from?

Where did the U.S. patent laws come from? One answer is from from the greed of English kings and queens. To raise money for themselves and their friends, the kings and queens of England adopted a policy of granting monopolies called “letters patents” for everyday goods such as vinegar, wine, salt, paper, oil, bottles, you name it. The crown sold these letters patents to brokers (or gave them to friends and supporters), who in turn sold them to particular companies interested in trading in the various goods. Over the years the U.S. Congress has enacted a series of comprehensive Patent Statutes, the first of which went into effect in 1790 and the most recent of which was enacted in 1952. Congress has also regularly fine-tuned the Patent Statutes in major and minor ways to respond to perceived needs in the country's continuing efforts to encourage innovation and thus grow the economy. Various stages of U.S. patent law can be identified in this process of legislating rewards for innovation. Initially, before 1836, U.S. patents were granted without examination, as is still done in some parts of the world. This left the issue of patent validity solely to the courts, which was unsatisfactory for a growing economy. In response, Congress created the Patent Office in 1836 and directed that Office to conduct a thorough examination of the prior art before a patent was issued. The Patent Office also was charged with resolving disputes between rival inventors and disseminating the technical information contained in patents to the public