Application of a microcoil probe head in NMR analysis of chemicals related to the chemical weapons convention

A 1.7-mm microcoil probe head was tested in the analysis of organophosphorus compounds related to the Chemical Weapons Convention. The microcoil probe head demonstrated a high mass sensitivity in the detection of traces of organophosphorus compounds in samples. Methylphosphonic acid, the common secondary degradation product of sarin, soman, and VX, was detected at level 50 ng (0.52 nmol) from a 30-microL water sample using proton-observed experiments. Direct phosphorus observation of methylphosphonic acid with (31)P{(1)H} NMR experiment was feasible at the 400-ng (4.17 nmol) level. Application of the microcoil probe head in the spiked sample analysis was studied with a test water sample containing 2-10 microg/mL of three organophosphorus compounds. High-quality (1)H NMR, (31)P{(1)H} NMR, 2D (1)H-(31)P fast-HMQC, and 2D TOCSY spectra were obtained in 3 h from the concentrated 1.7-mm NMR sample prepared from 1 mL of the water solution. Furthermore, a 2D (1)H-(13)C fast-HMQC spectrum with sufficient quality was possible to measure in 5 h. The microcoil probe head demonstrated a considerable sensitivity improvement and reduction of measurement times for the NMR spectroscopy in identification of chemicals related to the Chemical Weapons Convention.     

Zn2+ complexes of di- and tri-nucleating azacrown ligands as base-moiety-selective cleaving agents of RNA 3',5'-phosphodiester bonds: binding to guanine base

The ability of the dinuclear Zn2+ complex of 1,4-bis[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(1)) to promote the cleavage of the phosphodiester bond of dinucleoside-3',5'-monophosphates that contain a guanine base has been studied over a narrow pH range from pH 5.8 to 7.2 at 90 degrees C. Comparative measurements have been carried out by using the trinuclear Zn2+ complex of 1,3,5-tris[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(2)) as a cleaving agent and guanylyl-3',5'-guanosine (5'-GpG-3') as a substrate. The strength of the interaction between the cleaving agent and the starting material has been elucidated by UV spectrophotometric titrations. The speciation and binding mode have been clarified by potentiometric titrations with hydrolytically stable 2'-O-methylguanylyl-3',5'-guanosine and 1H NMR spectroscopic measurements with guanylyl-3',5'-guanosine. The results show that the guanine base is able to serve as a site for anchoring for the Zn2+-azacrown moieties of the cleaving agents L(1) and L(2), analogously to uracil base. The interaction is, however, weaker than with the uracil base and, hence, only the 5'-GpG-3' site (in addition to 5'-GpU-3' and 5'-UpG-3' sites) is able to markedly modulate the phosphodiester cleavage by the Zn2+ complexes of di- and trinucleating azacrown ligands containing an ether oxygen as a potential H-bond-acceptor site.     

In vivo degradation of poly(DTE carbonate) membranes. Analysis of the tissue reactions and mechanical properties

Different bioabsorbable polymers and their co-polymers have been used to construct an optimal material for guided bone regeneration applications. Our aim was to evaluate a novel bioabsorbable material in a soft tissue environment. In this study, a poly(DTE carbonate) membrane (0.2–0.3 mm) was implanted into 20 NZW rabbits’ subcutaneous pouches for 6, 12, 24 and 52 weeks. The material was evaluated by means of histological reactions to the material and mechanical properties of the membrane. Based on this study, it can be concluded that poly(DTE carbonate) elicited a very modest foreign body reaction in the soft tissues. This reaction was uniform throughout the study. Varying amounts of calcification was seen in the fibrous capsule surrounding the implant. The number of calcified bodies did not correlate to healing time.     

Unsteady Flow Simulation and Erosion Assessment in a Ditch Network of a Drained Peatland Forest Catchment in Eastern Finland

We developed and applied a computational model for simulating unsteady flow in a drainage network of a boreal forested peatland site. The input to the model was the hourly runoff produced by a hydrological model. The simulations of the flow in the ditch network were performed using an iterative procedure for solving the Saint-Venant equations that govern the flow in each of the network channels. These equations were solved separately for each ditch branch, and the flow depths at the junctions were corrected using the method of characteristics. The model was applied to the drainage network of a peatland catchment in Eastern Finland over a period of 15 months. Because flow resistance in the ditches depended strongly on flow conditions, flow resistance (Manning’s n) was introduced as a function of discharge. The model was calibrated and validated against field data and the simulation results were further applied to assess erosion risk. The highest risk of erosion occurred during long lasting flows induced by snowmelt at ditch sections with a steep slope and a large upstream area. These model results can aid in the design and siting of water protection measures within the drained area.     

Shared Gaze in Collaborative Visual Search

ABSTRACT

Collaboration improves efficiency, avoids duplication of efforts, improves goal-awareness, and makes working generally more pleasurable. While collaboration is desirable, it introduces additional costs because of the required coordination. In this article, we study how visual search is affected by gaze-sharing collaboration. There is evidence that pairs of visual searchers using gaze-only sharing are more efficient than single searchers. We extend this result by investigating if groups of three searchers are more efficient, and if and how the groups of searchers develop their search strategy. We conducted an experiment to understand how the collaboration develops when groups of one to three participants perform a visual search task by collaborating with shared gaze. The task was to state if the target was present among distractors. Our results show that users are able to develop an efficient search and division-of-labor strategy when the only collaboration method is gaze-sharing.     

Social interaction and reflection for behaviour change

This article introduces the theme issue on social interaction and reflection for behaviour change. A large body of research exists on systems designed to help users in changing their behaviours, for instance, to exercise more regularly or to reduce energy consumption. Increasingly, these systems focus on multiple users, often to encourage open-ended reflection rather than prescribing a particular course of action. As background for this theme issue, this article presents a literature review on behaviour change support systems that focus on social interaction and reflection. The review highlights five key approaches amongst these systems: social traces, social support, collective use, reflection-in-action, and reflection-on-action. Each approach offers unique benefits, but also challenges for the design of behaviour change support systems. We highlight how the articles in this theme issue contribute to our current understanding of these five approaches, and beyond that, set out some broad directions for future work.     

Drying of foam-formed mats from virgin pine fibers

The purpose of this work was to select an efficient drying technique for drying of highly porous thick fiber foam mats with minimum impact on their structure after forming and drainage. Thick fiber mats were produced from wood fibers using foam-forming technology and dried using several different drying methods. The mixture of pine fibers and surfactant (foaming agent) in water was blended using a high-speed blender. After fiber foam generation, a sample mold was filled with wet fiber foam, and after drainage, drying experiments were performed. For comparison, experiments were carried out in an oven, an impingement dryer assisted with a vacuum, and a combined impingement-infrared dryer. At low moisture contents, through-air drying experiments were also carried out. Drying curves, temperature profiles, and shrinkage were measured from the produced mat structures. The most promising drying technique in this study was the combined impingement-infrared drying, used until the fiber mat became permeable, followed by through-air drying until the desired final moisture content was achieved.     

Hydrolysis behaviour of crosslinked poly(ester anhydride) networks prepared from functionalised poly(ε-caprolactone) precursors

Biodegradable poly(ester anhydride) networks based on functionalised poly(ε-caprolactone) precursors with different hydrophobicities, molecular weights and architectures were synthesised. Networks that were prepared from the star-shaped precursors clearly showed higher gel contents and crosslinking densities than the networks that were prepared from the linear precursors. Functionalising with different alkenylsuccinic anhydrides and/or varying the molecular weight of the precursor, the thermal properties, surface hydrophobicity and erosion of the crosslinked networks were widely tailored. The dissolution behaviour of the networks changed dramatically as the molecular weight of the precursor increased from 2000 to 4000 g/mol or the alkenyl chain of the alkenylsuccinic anhydride increased from 8 to 18 carbons. The networks that were prepared from the lower molecular weight precursors, without an alkenyl chain or with an 8 carbon alkenyl chain, lost their mass in a few days, whereas the networks that were prepared from higher molecular weight precursors or contained a hydrophobic 18 carbon alkenyl chain did not show any mass loss over a period of 8 weeks.