Simple and efficient generation in vitro of nested deletions and inversions: Tn5 intramolecular transposition

We have exploited the intramolecular transposition preference of the Tn 5 in vitro transposition system to test its effectiveness as a tool for generation of nested families of deletions and inversions. A synthetic transposon was constructed containing an ori, an ampicillin resistance (Ampr) gene, a multi-cloning site (MCS) and two hyperactive end sequences. The donor DNA that adjoins the transposon contains a kanamycin resistance (Kanr) gene. Any Amprreplicating plasmid that has undergone a transposition event (Kans) will be targeted primarily to any insert in the MCS. Two different size targets were tested in the in vitro system. Synthetic transposon plasmids containing either target were incubated in the presence of purified transposase (Tnp) protein and transformed. Transposition frequencies (Ampr/Kans) for both targets were found to be 30-50%, of which >95% occur within the target sequence, in an apparently random manner. By a conservative estimate 10(5) or more deletions/inversions within a given segment of DNA can be expected from a single one-step 20 microl transposition reaction. These nested deletions can be used for structure-function analysis of proteins and for sequence analysis. The inversions provide nested sequencing templates of the opposite strand from the deletions.     

Structural studies on sucrose monolaurate

Conclusion A product corresponding to sucrose monolaurate was prepared by the alcoholysis of methyl laurate with sucrose. This product appears to be a mixture, with the principal component having the lauroyl radical at the 6-position of the glucose portion. Presented in part at the XIVth International Congress of Pure id Applied Chemistry, Zurich, July 21–27, 1955.     

Capacitance tomography sensor without CMOS switches

Usually, CMOS switches are used to select excitation and detection electrodes in electrical capacitance tomography (ECT) systems. However, these switches cause charge injection or coupling leakage problems. An ECT sensor is described which does not use any switches directly connected to the measurement electrodes. The potentials on the electrodes are digitally controlled and the excitation field of the sensor is totally flexible. Experimental results show that the circuit performs well as either an excitation or a detection channel     

Studies of Hie Effect of Powder Moisture Content on Drug Release from Hard Gelatin Capsules

The in vitro dissolution of model formulations from hard gelatin capsules containing drug: diluent powder mixtures at different moisture levels has been studied. The capsules were filled to a constant porosity of 50%. to contain either sodium barbitone or barbitone in 50:50 mixture with lactose or maize starch, the latter at one of three moisture levels. In addition, capsules containing drug alone were examined. The wettability and polarity indeces of the individual powders and binary mixtures, as well as the permeability and liquid penetration rates of powder beds were also determined.

The presence of either excipient was found to modify the time for 50% drug dissolution (t₅₀) compared with drug alone for all formulations examined, apart from the sodium barbitone: lactose capsules. The rate of drug dissolution was also dependent on the initial powder moisture content for the drug:starch formulations. Open storage of capsules at 20^%/75%. R.lt. generally increased t₅₀figures.

The findings are discussed in terms of the nature of the surfaces of the powder particles, moisture sorption phenomena and factors such as powder bed permeability and water penetitration lates.     

Graduate nursing education: developmental disabilities and special health care needs

As children and adults with developmental disabilities and special health care needs are integrated into home, school, and community life, nurses are being required to provide leadership, advocacy, and training in community settings to a much greater extent than in the past. To assess the school and community need for formal graduate preparation for nurses who work with individuals with developmental disabilities and/or special health care needs, 25 nurses in leadership positions representing urban and rural health agencies throughout Minnesota took part in a 5-hour focus group discussion. Analysis of data summarized from this process shows five features of the recommended curriculum necessary for advanced practitioners in this specialty area: (a) discipline-specific core competencies, (b) discipline-specific specialty competencies, (c) genetic competencies not specific to nursing but necessary to function in nursing roles, (d) interdisciplinary and intradisciplinary learning experiences, and (e) clinical experiences with preceptors. The authors recommend the development of interdisciplinary graduate programs designed to prepare nurses to assume leadership roles in school health, public health, home health care, and systems management that will affect public policy and, ultimately, promote change in the systems charged with responsibility to serve this population.     

Experimental and first-principles studies of BiVO4/BiV1-xMnxO4-y n-n+ homojunction for efficient charge carrier separation in sunlight induced water splitting

Though bismuth vanadate (BiVO₄) is extensively used as a photoactive material, its performance in harnessing solar energy is limited by ineffective separation of photo-excited charge carriers. We demonstrate here a concept of n-n⁺ homojunction of BiVO₄/BiV_1-xMn_xO_4-y, which improves its charge separation efficiency. Using first-principles theoretical calculations, we determine the effect of Mn substitution on oxygen vacancy formation energies and associated changes in the electronic structure of BiVO₄. Showing that Mn substitution pushes the Fermi level of BiVO₄ towards its conduction band, we predict that the associated enhanced bending of bands at the homojunction (BiVO₄/BiV_1-xMn_xO_4-y) facilitates efficient separation of charge carriers. With Mott-Schottky experiments, we verify the increased band bending at the n-n⁺ homojunction, and show that the maximum photocurrent density measured in a sample with n-n⁺ homojunction is ten times higher than that obtained of the pristine sample. Secondly, Mn substitution in BiVO₄ also reduces the oxygen vacancy formation energy, promoting higher concentration of O-vacancies, further enhancing the photoelectrochemical response.