Application of aerosol‐spray deposition for determination of fine structure of barley starch using atomic force microscopy

Starch samples extracted from barley cultivars with varying AM concentrations were imaged by AFM using intermittent contact mode. Two different deposition methods were used: a simple solution drop and an aerosol spray deposition. Using the drop deposition method, starch appeared mainly as small particles and aggregated globules, with average heights of 1.8 ± 0.2, 2.7 ± 0.7, and 5.5 ± 1.0 nm, for starch solutions containing increased (38%), normal (25.8%), and undetectable (0%) AM, respectively. The aerosol spray deposition method allowed analysis of individual biopolymer chains of AM and biopolymer fibrils of AP. The image of normal starch showed individual AM chains with an average height of 0.8 ± 0.2 nm, and an average contour length of 178 ± 127 nm. For increased AM starch, the height of individual AM chains was similar to normal starch, but the average contour length was shorter (140 ± 70 nm). All barley starches showed fibril bundles of AP with average heights of 1.9 to 2.9 nm and lengths in the micron size range.     

Using the internet to assist smoking prevention and cessation in schools: A randomized, controlled trial.

Objective: To evaluate the impact of a classroom-based, Web-assisted tobacco intervention addressing smoking prevention and cessation with adolescents. Design: A two-group randomized control trial with 1,402 male and female students in grades 9 through 11 from 14 secondary schools in Toronto, Canada. Participants were randomly assigned to a tailored Web-assisted tobacco intervention or an interactive control condition task conducted during a single classroom session with e-mail follow-up. The cornerstone of the intervention was a five-stage interactive Web site called the Smoking Zine (http://www.smokingzine.org) integrated into a program that included a paper-based journal, a small group form of motivational interviewing, and tailored e-mails. Main Outcome Measure: Resistance to smoking, behavioral intentions to smoke, and cigarette use were assessed at baseline, postintervention, and three- and six-month follow-up. Multilevel logistic growth modeling was used to assess the effect of the intervention on change over time. Results: The integrated Smoking Zine program helped smokers significantly reduce the likelihood of having high intentions to smoke and increased their likelihood of high resistance to continued cigarette use at 6 months. The intervention also significantly reduced the likelihood of heavy cigarette use adoption by nonsmokers during the study period. Conclusion: The Smoking Zine intervention provided cessation motivation for smokers most resistant to quitting at baseline and prevented nonsmoking adolescents from becoming heavy smokers at 6 months. By providing an accessible and attractive method of engaging young people in smoking prevention and cessation, this interactive and integrated program provides a novel vehicle for school- and population-level health promotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fabrication and characterization of Ti-Ba-Ca-Cu-O superconducting films on LaAlO3 substrates

A multi-step process is used to fabricate Tl₂Ba₂Ca₁Cu₂O₈ films on (100) LaA10₃ substrates. Submicron thick precursor films of Ba-Ca-Cu-O are rf magnetron sputter deposited from a single target. Film stoichiometry is measured by ion beam backscattering spectroscopy. Deficiencies of the alkaline earths that are found in the precursor films are then compensated for by the addition of appropriate CaF₂ and/or BaF₂ films onto the surface of the precursor film. Post deposition annealing of the films is then done in an atmosphere of thallium oxide and oxygen in order to form the superconducting phases. The annealed films are examined using x-ray diffraction (XRD), an ac inductance technique, and critical current in an external magnetic field. XRD shows the c-axis length of the superconducting phase to increase as the overall film stoichiometry approaches 2212. The transition widths measured by inductive coupling weakly correlate with 77 K critical current measurements. Our best critical current results are 1.5*10⁶ amps/ cm² for a film measured at 4 K in an 8 T magnetic field (parallel to the films' c-axis).     

In vitro assessment of the biological activity of basic fibroblast growth factor released from various polymers and biomatrices

The kinetics of controlled release of basic fibroblast growth factor (bFGF) from polymers (sutures, polycarbonate, Hydron, and Elvax), biopolymers (alginate), and biomatrices (lens capsules), and conditions for storage of bFGF (temperature, plastic type, heparin) were evaluated in vitro. Tissue culture proliferation bioassays with 3T3 fibroblasts, showed that only lens capsules with bFGF had a sustained release of bFGF for up to three weeks. The other materials released all of the 'bound' bFGF with two hours or produced an inflammatory response in vivo. Therefore, the lens tissue had the most potential for controlled long-term delivery of bFGF in vivo. These studies emphasise the importance of in vitro analysis of release kinetics of growth factors from a range of materials as a basis for potential in vivo applications.     

Mode of action of site-directed irreversible folate analogue inhibitors of thymidylate synthase

5,8-Dideazafolate analogues are tight binding but not irreversible inhibitors of thymidylate synthase (TS). However, when a chloroacetyl (ClAc) group is substituted at the N10-position of 2-desamino-2-methyl-5,8-dideazafolate (DMDDF), the resulting compound, ClAc-DMDDF, although still a reversible inhibitor (KI = 3.4 x 10(-3) M), gradually inactivates thyA-TS irreversibly at a rate of 0.37 min-1. The corresponding iodoacetyl derivative alkylated the enzyme somewhat slower (k3 = 0.15 min-1 ) than ClAc-DMDDF but was bound more tightly (KI = 1.4 x 10(-5) M), resulting in a second-order rate constant (k3/KI) of inactivation that was 100-fold greater than that of ClAc-DMDDF. A tryptic digest of the ClAc-DMDDF-inactivated enzyme yielded a peptide on HPLC, which revealed that cysteine-146, the residue at the active site that is intimately involved in the catalytic process, had reacted with ClAc-DMDDF to form a covalent bond. This derivative was confirmed indirectly by Edman analysis and more directly by mass spectrometry. Deoxyuridine 5'-monophosphate, a substrate in the catalytic reaction, protected against inactivation. Similar to previously described Lactobacillus casei TS inhibition studies with sulfhydryl reagents [Galivan, J., Noonan, J., and Maley, F. (1977) Arch. Biochem. Biophys. 184, 336-345], the kinetics of inhibition suggested that complete inhibition occurs on reaction of only one of the two active site cysteines, although sequence and amino acid analysis revealed that iodoacetate and ClAc-DMDDF had reacted with both active site cysteines. These studies demonstrate that a sulfhydryl reactive compound that is directed to the folate binding site of TS may diffuse to the active site cysteine, and form a covalent bond with this residue. How this inhibition comes about is suggested in a stereoscopic view of the ligand when modeled to the known crystal structure of Escherichia coli TS.     

A generic algorithm for one-dimensional homotopic compaction

One-dimensional homotopic compaction problems model the task of VLSI layout compaction with automatic jog insertion. They have the following form: given a routable layout, find a layout of minimum width reachable by a continuous motion of layout components that displaces each rigid component horizontally and preserves routability. We define a configuration space for this problem, and prove that if routability is characterized bycut conditions, then the set of reachable configurations is a closed, convex polyhedron. We also present a polynomial-time algorithm that finds the constraints defining this polyhedron and solves them to produce an optimal configuration. A homotopic router can recover the compacted layout from this configuration. We illustrate our strategy in thesketch model of VLSI layout, where it yields a compaction algorithm with worst-case running timeO(N ⁴) on input of sizeN.     

Testing homotopic routability under polygonal wiring rules

Ahomotopic routability problem asks whether a VLSI layout can be made legal by applying continuous deformations (homotopies) to its wires. This paper presents an optimally efficient algorithm for deciding homotopic routability under polygonal and grid-based wiring rules. The algorithm runs in timeO(N logN) and spaceO(N), whereN is the number of line segments composing the input.This research was supported in part by a Mathematical Sciences Postdoctoral Research Fellowship from the National Science Foundation, Grant DMS-8705835.     

Neosporosis and bovine abortion in Scotland

Serum samples were collected over a two-year period from aborting cows and their fetuses from throughout Scotland; 465 maternal sera were examined using an immunofluorescent antibody test for IgG antibody to Neospora caninum and 547 fetal sera were examined for IgM and IgG antibody to the parasite; 355 of the maternal sera were paired with their respective fetal samples. The maternal titres ranged from 1/8 to 1/16,384, with 59 per cent (275) having titres of 1/128 or 1/256. Of the 547 fetal sera, 9.9 per cent had IgM titres equal to or greater than 1/64, 11.2 per cent had IgG titres equal to or greater than 1/64 and 15.9 per cent had IgM and/or IgG titres equal to or greater than 1/64. It is concluded that a fetal IgM or IgG titre of 1/64 or more is evidence of fetal exposure to N caninum but that the examination of maternal sera is less reliable on an individual basis, although valuable for indicating the degree of infection in a herd. Although fetal seropositivity does not necessarily provide proof that N caninum was the cause of death in a given case, the observation that 15.9 per cent of aborted fetuses had antibody to the parasite shows that vertical transmission from dam to fetus is relatively common and may be an important cause of fetal loss in cattle in Scotland.