Cost-Effective Force Field Tailored for Solid-Phase Simulations of OLED Materials

A united atom force field is empirically derived by minimizing the difference between experimental and simulated crystal cells and melting temperatures for eight compounds representative of organic electronic materials used in OLEDs and other devices: biphenyl, carbazole, fluorene, 9,9′-(1,3-phenylene)bis(9H-carbazole)-1,3-bis(N-carbazolyl)benzene (mCP), 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (pCBP), phenazine, phenylcarbazole, and triphenylamine. The force field is verified against dispersion-corrected DFT calculations and shown to also successfully reproduce the crystal structure for two larger compounds employed as hosts in phosphorescent and thermally activated delayed fluorescence OLEDs: N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPD), and 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI). The good performances of the force field coupled to the large computational savings granted by the united atom approximation make it an ideal choice for the simulation of the morphology of emissive layers for OLED materials in crystalline or glassy phases.

Efficacy of an Internet-based, individually tailored smoking cessation program: A randomized trial

Introduction: Self-help computer-based programs are easily accessible and cost-effective interventions with a great recruitment potential. However, each program is different and results of meta-analyses may not apply to each new program; therefore, evaluations of new programs are warranted. The aim of this study was to assess the marginal efficacy of a computer-based, individually tailored program (the Coach) over and above the use of a comprehensive Internet smoking cessation website. Methods: A two-group randomized controlled trial was conducted. The control group only accessed the website, whereas the intervention group received the Coach in addition. Follow-up was conducted by e-mail after three and six months (self-administrated questionnaires). Of 1120 participants, 579 (51.7%) responded after three months and 436 (38.9%) after six months. The primary outcome was self-reported smoking abstinence over four weeks. Results: Counting dropouts as smokers, there were no statistically significant differences between intervention and control groups in smoking cessation rates after three months (20.2% vs. 17.5%, p¼0.25, odds ratio (OR)¼1.20) and six months (17% vs. 15.5%, p¼0.52, OR¼1.12). Excluding dropouts from the analysis, there were statistically significant differences after three months (42% vs. 31.6%, p¼0.01, OR¼1.57), but not after six months (46.1% vs. 37.8%, p¼0.081, OR¼1.41). The program also significantly increased motivation to quit after three months and self-efficacy after three and six months. Discussion: An individually tailored program delivered via the Internet and by e-mail in addition to a smoking cessation website did not significantly increase smoking cessation rates, but it increased motivation to quit and self-efficacy.

Producing computer-generated tailored written information for stroke patients and their carers: System development and preliminary evaluation

Purpose: The aim of this project was to design and evaluate a system that would produce tailored information for stroke patients and their carers, customised according to their informational needs, and facilitate communication between the patient and, health professional. Method: A human factors development approach was used to develop a computer system, which dynamically compiles stroke education booklets for patients and carers. Patients and carers are able to select the topics about which they wish to receive information, the amount of information they want, and the font size of the printed booklet. The system is designed so that the health professional interacts with it, thereby providing opportunities for communication between the health professional and patient/carer at a number of points in time. Results: Preliminary evaluation of the system by health professionals, patients and carers was positive. A randomised controlled trial that examines the effect of the system on patient and carer outcomes is underway. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Deterministic generation of tailored-optical-coherent-state superpositions

Pulsed coherent excitation of a two-level atom strongly coupled to a resonant cavity mode will create a superposition of two coherent states of opposite amplitudes in the field. By choosing proper parameters of interaction time and pulse shape the field after the pulse will be almost disentangled from the atom and can be efficiently outcoupled through cavity decay. The fidelity of the generation approaches unity if the atom-field coupling strength is much larger than the atomic and cavity decay rates. This implies a strong difference between even and odd output photon number counts. Alternatively, the coherence of the two generated field components can be proven by phase-dependent annihilation of the generated nonclassical superposition state by a second pulse.

Tailored conductivity in ion implanted polyetheretherketone

Ion implantation can be used to confer electrical conductivity upon conventional insulating polymers such as polyetheretherketone (PEEK). We have implanted PEEK films using three different types of ion implantation: conventional inert gas and metal ion implantation, and ion beam mixing. We have applied a number of analytical techniques to compare the chemical, structural and electrical properties of these films. The most effective means of increasing electrical conductivity appears to be via ion beam mixing of metals into the polymer, followed by metal ion implantation and finally, inert gas ion implantation. Our results suggest that in all cases, the conducting region corresponds to the implanted layer in the near surface to a depth of similar to750 Angstrom (ion beam mixed) to similar to5000 Angstrom (metal ion). This latter value is significantly higher than would be expected from a purely ballistic standpoint, and can only be attributed to thermal inter-diffusion. Our data also indicates that graphitic carbon is formed within the implant region by chain scission and subsequent cross-linking. All ion implanted samples retained their bulk mechanical properties, i.e. they remained flexible. The implant layers showed no signs of de-lamination. We believe this to be the first comparative study between different implantation techniques, and our results support the proposition that soft electronic circuitry and devices can be created by conductivity engineering with ion beams. (C) 2004 Elsevier B.V. All rights reserved.

Defenses against oxidative stress in Neisseria gonorrhoeae: A system tailored for a challenging environment

Neisseria gonorrhoeae is a host-adapted pathogen that colonizes primarily the human genitourinary tract. This bacterium encounters reactive oxygen and reactive nitrogen species as a consequence of localized inflammatory responses in the urethra of males and endocervix of females and also of the activity of commensal lactobacilli in the vaginal flora. This review describes recent advances in the understanding of defense systems against oxidative stress in N. gonorrhoeae and shows that while some of its defenses have similarities to the paradigm established with Escherichia coli, there are also some key differences. These differences include the presence of a defense system against superoxide based on manganese ions and a glutathione-dependent system for defense against nitric oxide which is under the control of a novel MerR-like transcriptional regulator. An understanding of the defenses against oxidative stress in N. gonorrhoeae and their regulation may provide new insights into the ways in which this bacterium survives challenges from polymorphonuclear leukocytes and urogenital epithelial cells.

Using epidemiological models to estimate the health effects of diet behaviour change: the example of tailored fruit and vegetable promotion

Objective: To explore the use of epidemiological modelling for the estimation of health effects of behaviour change interventions, using the example of computer-tailored nutrition education aimed at fruit and vegetable consumption in The Netherlands. Design: The effects of the intervention on changes in consumption were obtained from an earlier evaluation study. The effect on health outcomes was estimated using an epidemiological multi-state life table model. input data for the model consisted of relative risk estimates for cardiovascular disease and cancers, data on disease occurrence and mortality, and survey data on the consumption of fruits and vegetables. Results: if the computer-tailored nutrition education reached the entire adult population and the effects were sustained, it could result in a mortality decrease of 0.4 to 0.7% and save 72 to 115 life-years per 100000 persons aged 25 years or older. Healthy life expectancy is estimated to increase by 32.7 days for men and 25.3 days for women. The true effect is likely to lie between this theoretical maximum and zero effect, depending mostly on durability of behaviour change and reach of the intervention. Conclusion: Epidemiological models can be used to estimate the health impact of health promotion interventions.

Tailored laminin-332 alpha3 sequence is tethered through an enzymatic linker to a collagen scaffold to promote cellular adhesion

Surface modification techniques have been used to develop biomimetic scaffolds by incorporating cell adhesion peptides, which facilitates cell adhesion, migration and proliferation. In this study, we evaluated the cell adhesion properties of a tailored laminin-332 alpha3 chain tethered to a type I collagen scaffold using microbial transglutaminase (mTGase) by incorporating transglutaminase substrate peptide sequences containing either glutamine (peptide A: PPFLMLLKGSTREAQQIVM) or lysine (peptide B: PPFLMLLKGSTRKKKKG). The degree of cross-linking was studied by amino acid analysis following proteolytic digestion and the structural changes in the modified scaffold further investigated using Fourier transform infrared spectroscopy and atomic force microscopy. Fibroblasts were used to evaluate the cellular behaviour of the functionalized collagen scaffold. mTGase supports cell growth but tethering of peptide A and peptide B to the mTGase cross-linked collagen scaffold caused a significant increase in cell proliferation when compared with native and mTGase cross-linked collagen scaffolds. Both peptides enabled cell-spreading, attachment and normal actin cytoskeleton organization with slight increase in the cell proliferation was observed in peptide A when compared with the peptide B and mTGase cross-linked scaffold. An increase in the amount of epsilon(gamma-glutamyl) lysine isopeptide was observed in peptide A conjugated scaffolds when compared with peptide B conjugated scaffolds, mTGase cross-linked scaffold without peptide. Changes in D-spacing were observed in the cross-linked scaffolds with tethered peptides. These results demonstrate that mTGase can play a bifunctional role in both conjugation of the glutamine and lysine containing peptide sequences and also in the cross-linking of the collagen scaffold, thus providing a suitable substrate for cell growth.

In vitro characterization of a collagen scaffold enzymatically cross-linked with a tailored elastin-like polymer

Collagen, the main structural component of the extracellular matrix (ECM), provides tensile stiffness to different structures and organs against rupture. However, collagen tissue-engineered implants are hereto still lacking in mechanical strength. Attempts to create stiffer scaffolds have resulted in increased brittleness of the material, reducing the versatility of the original component. The hypothesis behind this research is that the introduction of an elastic element in the scaffold will enhance the mechanical properties of the collagen-based scaffolds, as elastin does in the ECM to prevent irreversible deformation. In this study, an elastin-like polymer (ELP) designed and synthesized using recombinant DNA methodology is used with the view to providing increased proteolytic resistance and increased functionality to the scaffolds by carrying specific sequences for microbial transglutaminase cross-linking, endothelial cell adhesion, and drug delivery. Evaluation of the effects that cross-linking ELP-collagen has on the physicochemical properties of the scaffold such as porosity, presence of cross-linking, thermal behavior, and mechanical strength demonstrated that the introduction of enzymatically resistant covalent bonds between collagen and ELP increases the mechanical strength of the scaffolds in a dose-dependent manner without significantly affecting the porosity or thermal properties of the original scaffold. Importantly, the scaffolds also showed selective behavior, in a dose (ELP)-dependent manner toward human umbilical vein endothelial cells and smooth muscle cells when compared to fibroblasts.