254 research outputs found
Electrostatically Directed Self-Assembly of Ultrathin Supramolecular Polymer Microcapsules.
Supramolecular self-assembly offers routes to challenging architectures on the molecular and macroscopic scale. Coupled with microfluidics it has been used to make microcapsules-where a 2D sheet is shaped in 3D, encapsulating the volume within. In this paper, a versatile methodology to direct the accumulation of capsule-forming components to the droplet interface using electrostatic interactions is described. In this approach, charged copolymers are selectively partitioned to the microdroplet interface by a complementary charged surfactant for subsequent supramolecular cross-linking via cucurbit[8]uril. This dynamic assembly process is employed to selectively form both hollow, ultrathin microcapsules and solid microparticles from a single solution. The ability to dictate the distribution of a mixture of charged copolymers within the microdroplet, as demonstrated by the single-step fabrication of distinct core-shell microcapsules, gives access to a new generation of innovative self-assembled constructs.This work was supported by the Engineering Physical Sciences Research Council, Institutional Sponsorship 2012-University of Cambridge EP/K503496/1, and the Translational Grant EP/H046593/1; Y.Z. and R.P. were also funded from the Starting Investigator grant ASPiRe (No. 240629) from the European Research Council and the Isaac Newton Trust research grant No. 13.7(c). A.S. was supported by the Nano Doctoral Training Centre (NanoDTC).This is the final version of the article. It first appeared from Wiley at http://dx.doi.org/10.1002/adfm.20150107
Anomalous Behavior of Ru for Catalytic Oxidation: A Theoretical Study of the Catalytic Reaction CO + 1/2 O_2 --> CO_2
Recent experiments revealed an anomalous dependence of carbon monoxide
oxidation at Ru(0001) on oxygen pressure and a particularly high reaction rate.
Below we report density functional theory calculations of the energetics and
reaction pathways of the speculated mechanism. We will show that the
exceptionally high rate is actuated by a weakly but nevertheless well bound
(1x1) oxygen adsorbate layer. Furthermore it is found that reactions via
scattering of gas-phase CO at the oxygen covered surface may play an important
role. Our analysis reveals, however, that reactions via adsorbed CO molecules
(the so-called Langmuir-Hinshelwood mechanism) dominate.Comment: 5 pages, 4 figures, Phys. Rev. Letters, Feb. 1997, in prin
Neuromuscular Electrical Stimulation for Intermittent Claudication (NESIC): multicentre, randomized controlled trial
\ua9 The Author(s) 2023. Published by Oxford University Press on behalf of BJS Society Ltd. METHODS: This was an open, multicentre, randomized controlled trial. Patients with intermittent claudication attending vascular surgery outpatient clinics were randomized (1:1) to receive either neuromuscular electrical stimulation (NMES) or not in addition to local standard care available at study centres (best medical therapy alone or plus supervised exercise therapy (SET)). The objective of this trial was to investigate the clinical efficacy of an NMES device in addition to local standard care in improving walking distances in patients with claudication. The primary outcome was change in absolute walking distance, measured by a standardized treadmill test at 3 months. Secondary outcomes included intermittent claudication (IC) distance, adherence, quality of life, and haemodynamic changes. RESULTS: Of 200 participants randomized, 160 were included in the primary analysis (intention to treat, Tobit regression model). The square root of absolute walking distance was analysed (due to a right-skewed distribution) and, although adjunctive NMES improved it at 3 months, no statistically significant effect was observed. SET as local standard care seemed to improve distance compared to best medical therapy at 3 months (3.29 units; 95 per cent c.i., 1.77 to 4.82; P < 0.001). Adjunctive NMES improved distance in mild claudication (2.88 units; 95 per cent c.i., 0.51 to 5.25; P = 0.02) compared to local standard care at 3 months. No serious adverse events relating to the device were reported. CONCLUSION: Supervised exercise therapy is effective and NMES may provide further benefit in mild IC.This trial was supported by a grant from the Efficacy and Mechanism Evaluation Program, a Medical Research Council and National Institute for Health and Care Research partnership. Trial registration: ISRCTN18242823.Patients with intermittent claudication experience pain in their legs during walking or exercise which ends with rest. This severely impairs physical activity and quality of life. Treatment for such patients typically involves best medical therapy, which includes exercise advice. This study aimed to determine whether a neuromuscular electrical stimulation device improved the walking distance of patients with intermittent claudication compared to local standard care available (which may include supervised exercise therapy) in a trial. Supervised exercise improved walking distances but there was no difference in those that received a device in this patient group
Adiabatic population transfer via multiple intermediate states
This paper discusses a generalization of stimulated Raman adiabatic passage
(STIRAP) in which the single intermediate state is replaced by intermediate
states. Each of these states is connected to the initial state \state{i} with
a coupling proportional to the pump pulse and to the final state \state{f}
with a coupling proportional to the Stokes pulse, thus forming a parallel
multi- system. It is shown that the dark (trapped) state exists only
when the ratio between each pump coupling and the respective Stokes coupling is
the same for all intermediate states. We derive the conditions for existence of
a more general adiabatic-transfer state which includes transient contributions
from the intermediate states but still transfers the population from state
\state{i} to state \state{f} in the adiabatic limit. We present various
numerical examples for success and failure of multi- STIRAP which
illustrate the analytic predictions. Our results suggest that in the general
case of arbitrary couplings, it is most appropriate to tune the pump and Stokes
lasers either just below or just above all intermediate states.Comment: 14 pages, two-column revtex style, 10 figure
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Online dietary intake estimation : Reproducibility and validity of the Food4Me food frequency questionnaire against a 4-day weighed food record
©Rosalind Fallaize, Hannah Forster, Anna L Macready, Marianne C Walsh, John C Mathers, Lorraine Brennan, Eileen R Gibney, Michael J Gibney, Julie A Lovegrove. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 11.08.2014. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on http://www.jmir.org/, as well as this copyright and license information must be included.Background: Advances in nutritional assessment are continuing to embrace developments in computer technology. The online Food4Me food frequency questionnaire (FFQ) was created as an electronic system for the collection of nutrient intake data. To ensure its accuracy in assessing both nutrient and food group intake, further validation against data obtained using a reliable, but independent, instrument and assessment of its reproducibility are required. Objective: The aim was to assess the reproducibility and validity of the Food4Me FFQ against a 4-day weighed food record (WFR). Methods: Reproducibility of the Food4Me FFQ was assessed using test-retest methodology by asking participants to complete the FFQ on 2 occasions 4 weeks apart. To assess the validity of the Food4Me FFQ against the 4-day WFR, half the participants were also asked to complete a 4-day WFR 1 week after the first administration of the Food4Me FFQ. Level of agreement between nutrient and food group intakes estimated by the repeated Food4Me FFQ and the Food4Me FFQ and 4-day WFR were evaluated using Bland-Altman methodology and classification into quartiles of daily intake. Crude unadjusted correlation coefficients were also calculated for nutrient and food group intakes. Results: In total, 100 people participated in the assessment of reproducibility (mean age 32, SD 12 years), and 49 of these (mean age 27, SD 8 years) also took part in the assessment of validity. Crude unadjusted correlations for repeated Food4Me FFQ ranged from .65 (vitamin D) to .90 (alcohol). The mean cross-classification into "exact agreement plus adjacent" was 92% for both nutrient and food group intakes, and Bland-Altman plots showed good agreement for energy-adjusted macronutrient intakes. Agreement between the Food4Me FFQ and 4-day WFR varied, with crude unadjusted correlations ranging from .23 (vitamin D) to .65 (protein, % total energy) for nutrient intakes and .11 (soups, sauces and miscellaneous foods) to .73 (yogurts) for food group intake. The mean cross-classification into "exact agreement plus adjacent" was 80% and 78% for nutrient and food group intake, respectively. There were no significant differences between energy intakes estimated using the Food4Me FFQ and 4-day WFR, and Bland-Altman plots showed good agreement for both energy and energy-controlled nutrient intakes. Conclusions: The results demonstrate that the online Food4Me FFQ is reproducible for assessing nutrient and food group intake and has moderate agreement with the 4-day WFR for assessing energy and energy-adjusted nutrient intakes. The Food4Me FFQ is a suitable online tool for assessing dietary intake in healthy adults.Peer reviewedFinal Published versio
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A Call to Improve Methods for Estimating Tree Biomass for Regional and National Assessments
Tree biomass is typically estimated using statistical models. This review highlights five limitations of most tree biomass models, which include the following: (1) biomass data are costly to collect and alternative sampling methods are used; (2) belowground data and models are generally lacking; (3) models are often developed from small and geographically limited data sets; (4) simplistic model forms and predictor variables are used; and (5) variation is commonly averaged or grouped rather than accounted for. The consequences of these limitations are highlighted and discussed. Several recommendations for future efforts are presented including the following: (1) collection of field measurements of tree biomass using consistent protocols; (2) compilation of existing data; (3) continued evaluation and improvement of existing models; (4) exploration of new models; and (5) adoption of state-of-the-art analytical and statistical techniques. Given the increasing importance of accurately estimating forest biomass, there is a critical need to understand, evaluate, and improve current tree biomass prediction methods.Keywords: forest biomass, statistical equations, tree measurementsKeywords: forest biomass, statistical equations, tree measurement
Designing a spoken dialogue interface to an intelligent cognitive assistant for people with dementia
Intelligent cognitive assistants support people who need help performing everyday tasks by detecting when problems occur and providing tailored and context-sensitive assistance. Spoken dialogue interfaces allow users to interact with intelligent cognitive assistants while focusing on the task at hand. In order to establish\ud
requirements for voice interfaces to intelligent cognitive assistants, we conducted three focus groups with people with dementia, carers, and older people without a diagnosis of dementia. Analysis of the focus group data showed that voice and interaction style should be chosen based on the preferences of the user, not those of the carer. For people with dementia, the intelligent cognitive assistant should act like a patient,encouraging guide, while for older people without dementia, assistance should be to the point and not patronising. The intelligent cognitive assistant should be able to adapt to cognitive decline
Effects of zilpaterol hydrochloride and zinc methionine on growth performance and carcass characteristics of beef bulls
Sixty beef bulls with a body weight (BW) of 314.79 16.2 kg were used to evaluate the effects of zilpaterol hydrochloride (ZH) and zinc methionine (ZM) on growth performance and carcass characteristics. The experimental design was a randomized complete block, with a factorial 22 arrangement of treatments (ZH: 0 and 0.15 mg kg 1 BW; ZM: 0 and 80 mg kg 1 dry matter). The ZH increased (PB0.05) the final BW, average daily gain, feed conversion, carcass yield and longissimus dorsi area. Bulls fed ZH plus ZM had less (PB0.01) backfat thickness and intramuscular fat (IMF) compared with those fed ZH or ZM alone. The ZH increased (PB0.02) the meat crude protein content and cooking loss. It is therefore concluded that ZH increases growth performance, carcass yield, longissimus dorsi area, and meat crude protein. The interaction of ZM and ZH did not present additional advantages. The reason for the reduction in backfat thickness and IMF by ZH plus ZM is unclear, and implies that our knowledge of b-agonistic adrenergic substances and their interactions with minerals is incomplete
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