Swelling of latex particles—towards a solution of the riddle

The assumption that during emulsion polymerization, the monomer molecules simply diffuse through the aqueous phase into the latex particles is a commonplace. However, there are experimental hints that this might not be that easy. Here, simulation results are discussed based on Fick’s diffusion laws regarding the swelling of latex particles. The results of quantitative application of these laws for swelling of latex particles allow the conclusion that the instantaneous replenishment of the consumed monomer during emulsion polymerization requires a close contact between the monomer and the polymer particles

Towards a consistent mechanism of emulsion polymerization—new experimental details

The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the ‘classical’ batch ab initio emulsion polymerization of styrene revealed astonishing facts. The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water system. These monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low-molecular-weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters)

Introgression between Pinus taeda L. and Pinus echinata Mill

Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003

Genetic Analysis of a Disease Resistance Gene from Loblolly Pine

Rapid advances in molecular genetics provide great opportunities for studies of host defense mechanisms. Examination of plant responses to disease at the cellular and molecular level permits both discovery of changes in gene expression in the tissues attacked by pathogens, and identification of genetic components involved in the interaction between host and pathogens. Expression of specific proteins, which is one type of defense mechanism, may offer the host a weapon to protect it from invasion of pathogenic attack. Recently, we have isolated a novel antimicrobial protein gene (PtAMP) from loblolly pine during our gene screening effort. Studies of molecular characterization show that the PtAMP gene shares limited similarity with previously reported antimicrobial proteins in the amino acid sequences, but it contains some common features, e.g. DNA sequences and protein structure, with those antimicrobial proteins. The function of this novel antimicrobial gene has been analyzed at the in vitro and in vivo levels. Antimicrobial assay data showed that the purified PtAMP protein has strong inhibitory activities against a variety of pathogenic bacteria and fungi. Furthermore, the gene for the PtAMP was transferred into the tobacco genome via Agrobacterium-mediated transformation. Ectopic expression of the PtAMP protein in transgenic tobacco plants confers resistance to bacterial and fungal phytopathogens. Our data suggest that the PtAMP gene has the potential through genetic manipulation to protect plants from a wide range of plant pathogens. Analysis of its function provides further understanding of plant defense mechanisms in loblolly pine.Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003

Experiencing neutropenia: Quality of life interviews with adult cancer patients

BACKGROUND: Neutropenia is a common toxicity in chemotherapy but detailed information about how neutropenia is associated with changes in patients' quality of life is not readily available. This prospective study interviewed patients with grade 4 neutropenia to provide qualitative information on patients' experience of developing and coping with grade 4 neutropenia during a cycle of chemotherapy. METHODS: A sample of 34 patients who developed grade 4 neutropenia during the first cycle of chemotherapy completed a total of 100 structured clinical interviews. Interviews were transcribed, and 2 raters inductively developed 5 broad categories comprising 80 specific complaint domains nominated by patients. Thirty-five patient-nominated problems were mentioned in 5% or more of the interviews. RESULTS: Fatigue was the most common physical symptom. Interference in daily routine, negative self-evaluation, negative emotion, and social isolation were other common complaints associated with neutropenia. CONCLUSION: Neutropenia is associated with a number of negative experiences among cancer patients undergoing chemotherapy, and these negative experiences have an adverse effect on the patient's quality of life. Oncology nurses can play a key role in helping patients manage adverse effects to maintain their quality of life

Lebenslanges Lernen und Wissenschaftliche Weiterbildung an der Universität Rostock: Problemfelder und Lösungsansätze

Auf der Suche nach Antworten auf die Frage, welche Probleme einem Engagement von ca. 90 % der Hochschullehrerinnen und Hochschullehrer der Universität Rostock sowie deren wissenschaftlicher Mitarbeiterinnen und Mitarbeiter im Lebenslangen Lernen (LLL) und in der Wissenschaftlichen Weiterbildung möglicherweise entgegenstehen, liefert das vorliegende Arbeitspapier erste Erklärungsansätze. Insbesondere erweist sich der geringe Stellenwert der Wissenschaftlichen Weiterbildung an der Universität Rostock – aber vermutlich auch an den meisten anderen deutschen Universitäten – als problematisch, der sich einerseits darin zeigt, dass Landesregierung und Universitätsleitung die Einhaltung des Weiterbildungsauftrags nicht nachdrücklich einfordern und andererseits in der mangelnden Akzeptanz von Weiterbildung als Aufgabe von Professorinnen und Professoren. Aus deren Sicht sind dafür v.a. die beschränkten Ressourcen der Universität verantwortlich: neben Forschung und Lehre im grundständigen Studium lässt die knappe Ausstattung der Lehrstühle kaum zusätzliche Aktivitäten in der Wissenschaftlichen Weiterbildung zu. Überdies fehlen attraktive Anreize für ein Weiterbildungsengagement von Hochschullehrenden in der Weiterbildung. Dass trotz dieser wenig weiterbildungsförderlichen Umstände dennoch rund 10 % der Hochschullehrerinnen und Hochschullehrer in der Wissenschaftlichen Weiterbildung der Universität Rostock aktiv sind, ist sicher auch dem hohen Engagement der Mitarbeiterinnen und Mitarbeiter dieses Bereichs zu verdanken. Wie die Untersuchung von Maaß et al. (2013) zeigte, entstehen neue weiterbildende Studiengänge und Zertifikatskurse i.d.R. erst durch die Initiative des Bereichs Wissenschaftliche Weiterbildung und die kontinuierliche Begleitung des Entstehungsprozesses

Quantifying serum antibody in bird fanciers' hypersensitivity pneumonitis

BACKGROUND: Detecting serum antibody against inhaled antigens is an important diagnostic adjunct for hypersensitivity pneumonitis (HP). We sought to validate a quantitative fluorimetric assay testing serum from bird fanciers. METHODS: Antibody activity was assessed in bird fanciers and control subjects using various avian antigens and serological methods, and the titer was compared with symptoms of HP. RESULTS: IgG antibody against pigeon serum antigens, quantified by fluorimetry, provided a good discriminator of disease. Levels below 10 mg/L were insignificant, and increasing titers were associated with disease. The assay was unaffected by total IgG, autoantibodies and antibody to dietary hen's egg antigens. Antigens from pigeon serum seem sufficient to recognize immune sensitivity to most common pet avian species. Decreasing antibody titers confirmed antigen avoidance. CONCLUSION: Increasing antibody titer reflected the likelihood of HP, and decreasing titers confirmed antigen avoidance. Quantifying antibody was rapid and the increased sensitivity will improve the rate of false-negative reporting and obviate the need for invasive diagnostic procedures. Automated fluorimetry provides a method for the international standardization of HP serology thereby improving quality control and improving its suitability as a diagnostic adjunct