1,388 research outputs found
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Direct iminization of PEEK
Semi-crystalline poly(ether ketone)s are important high-temperature engineering thermoplastics, but are difficult to characterize at the molecular level because of their insolubility in conventional organic solvents. Here we report that polymers of this type, including PEEK, react cleanly at high temperatures with low-volatility aralkyl amines to afford stable, noncrystalline poly(ether-imine)s, which are readily soluble in solvents such as chloroform, THF and DMF and so characterizable by conventional size-exclusion chromatography
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Synthesis, x-ray structure and anion binding properties of a cryptand-like hybrid calixpyrrole
The novel cryptand in/out-3, containing two tripyrrolemethane units briged by three 1,3- diisopropylidenbenzene arms was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid state X-ray structure of the free cryptand 3 was also determined
Rhamnogalacturonase B from Aspergillus aculeatus Is a Rhamnogalacturonan [alpha]-L-Rhamnopyranosyl-(1->4)-[alpha]-D-Galactopyranosyluronide Lyase
One-step syntheses of very large cage-type molecules from aromatic sub-units
Polycondensation of a trifunctional, ketone-activated fluoroarene
with bis- or tris-phenoxides under pseudo-high
dilution conditions affords a series of very large macropolycyclic
aromatic ether ketones; isolation and characterisation
of these materials by NMR, MALDI-TOF MS and,
for one example (after reduction of the carbonyl groups to
methylene linkages) by X-ray crystallography, confirms that
polycondensations which would normally lead to highly
branched or cross-linked polymers can also give rise to large,
closed-network molecules
Diffusive hidden Markov model characterization of DNA looping dynamics in tethered particle experiments
In many biochemical processes, proteins bound to DNA at distant sites are
brought into close proximity by loops in the underlying DNA. For example, the
function of some gene-regulatory proteins depends on such DNA looping
interactions. We present a new technique for characterizing the kinetics of
loop formation in vitro, as observed using the tethered particle method, and
apply it to experimental data on looping induced by lambda repressor. Our
method uses a modified (diffusive) hidden Markov analysis that directly
incorporates the Brownian motion of the observed tethered bead. We compare
looping lifetimes found with our method (which we find are consistent over a
range of sampling frequencies) to those obtained via the traditional
threshold-crossing analysis (which can vary depending on how the raw data are
filtered in the time domain). Our method does not involve any time filtering
and can detect sudden changes in looping behavior. For example, we show how our
method can identify transitions between long-lived, kinetically distinct states
that would otherwise be difficult to discern
Reporting and design elements of audit and feedback interventions: a secondary review
BACKGROUND: Audit and feedback (A&F) is a frequently used intervention aiming to support implementation of research evidence into clinical practice with positive, yet variable, effects. Our understanding of effective A&F has been limited by poor reporting and intervention heterogeneity. Our objective was to describe the extent of these issues. METHODS: Using a secondary review of A&F interventions and a consensus-based process to identify modifiable A&F elements, we examined intervention descriptions in 140 trials of A&F to quantify reporting limitations and describe the interventions. RESULTS: We identified 17 modifiable A&F intervention elements; 14 were examined to quantify reporting limitations and all 17 were used to describe the interventions. Clear reporting of the elements ranged from 56% to 97% with a median of 89%. There was considerable variation in A&F interventions with 51% for individual providers only, 92% targeting behaviour change and 79% targeting processes of care, 64% performed by the provider group and 81% reporting aggregate patient data. CONCLUSIONS: Our process identified 17 A&F design elements, demonstrated gaps in reporting and helped understand the degree of variation in A&F interventions
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Supramolecular approach to new inkjet printing inks
Electronically complementary, low molecular weight polymers that self-assemble through tunable π−π stacking interactions to form extended supramolecular polymer networks have been developed for inkjet printing applications and successfully deposited using three different printing techniques. Sequential overprinting of the complementary components results in supramolecular network formation through complexation of π-electron rich pyrenyl or perylenyl chain-ends in one component with π-electron deficient naphthalene diimide residues in a chain-folding polyimide. The complementary π−π stacked polymer blends generate strongly colored materials as a result of charge-transfer absorption bands in the visible spectrum, potentially negating the need for pigments or dyes in the ink formulation. Indeed, the final color of the deposited material can be tailored by varying the end-groups of the π-electron rich polymer component. Piezoelectric printing techniques were employed in a proof of concept study to allow characterization of the materials deposited, and a thermal inkjet printer adapted with imaging software enabled in situ analysis of the ink drops as they formed and of their physical properties. Finally, continuous inkjet printing allowed greater volumes of material to be deposited, on a variety of different substrate surfaces, and demonstrated the utility and versatility of this novel type of ink for industrial applications
Intergenerational equity in municipal accounting: New Zealand 1910s
Accounting for fixed assets by municipalities has been discussed in the accounting history literature previously. This paper addresses two issues related to accounting for fixed assets not previously discussed; the influence of the principle of intergenerational equity on local government accounting, and the influence of users of accounting information in accounting policy making in government accounting. The paper identifies that users of accounting information have had significant influence in a debate on government accounting policy, and that the principle of intergenerational equity was given a position of high importance in the debate, but not an unchallengeable position. The motivation of the users of accounting information to engage in the debates is identified as a form of civic duty, which is consistent with the ethical imperative in ensuring intergenerational equity
Focused cardiac ultrasound screening for rheumatic heart disease by briefl y trained health workers: a study of diagnostic accuracy
Background Echocardiographic screening for rheumatic heart disease (RHD) can identify individuals with subclinical
disease who could benefi t from antibiotic prophylaxis. However, most settings have inadequate resources to
implement conventional echocardiography and require a feasible, accurate screening method. We aimed to investigate
the accuracy of screening by non-expert operators using focused cardiac ultrasound (FoCUS).
Methods In this prospective study of diagnostic accuracy, we recruited schoolchildren aged 5 to 15 years in Fiji to
undergo two blinded tests. The index test was a FoCUS assessment of mitral and aortic regurgitation, performed by
nurses after an 8-week training programme. The reference standard was the diagnosis of RHD by a paediatric
cardiologist, based on a standard echocardiogram performed by a skilled echocardiographer. The primary outcome
was the accuracy of the index test with use of the most sensitive criteria (any regurgitation).
Findings We included 2004 children in the study. The index tests were done between September, 2012, and
September, 2013, by seven nurses in eight schools in Fiji. The diagnostic accuracy of the screening test (area under
receiver operator characteristic curve) was 0·89 (95% CI 0·83–0·94). When the primary cut-off point (any
regurgitation) was used for analysis, sensitivity was 84·2% (72·1–92·5) and specifi city was 85·6% (83·9–87·1). The
sensitivity of individual nurses ranged from 66·7% to 100% and specifi city 74·0% to 93·7%.
Interpretation Screening by briefl y trained nurses using FoCUS was accurate for the diagnosis of RHD. Refi nements
to training and screening test methods should be studied in a range of settings, and in parallel with investigations of
the long-term clinical and cost-eff ectiveness of screening for RHD
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