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- Donald, Rob, et al.
(author)
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Forewarning of hypotensive events using a Bayesian artificial neural network in neurocritical care
- 2019
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In: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 33:1, s. 39-51
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Journal article (peer-reviewed)abstract
- Traumatically brain injured (TBI) patients are at risk from secondary insults. Arterial hypotension, critically low blood pressure, is one of the most dangerous secondary insults and is related to poor outcome in patients. The overall aim of this study was to get proof of the concept that advanced statistical techniques (machine learning) are methods that are able to provide early warning of impending hypotensive events before they occur during neuro-critical care. A Bayesian artificial neural network (BANN) model predicting episodes of hypotension was developed using data from 104 patients selected from the BrainIT multi-center database. Arterial hypotension events were recorded and defined using the Edinburgh University Secondary Insult Grades (EUSIG) physiological adverse event scoring system. The BANN was trained on a random selection of 50% of the available patients (n = 52) and validated on the remaining cohort. A multi-center prospective pilot study (Phase 1, n = 30) was then conducted with the system running live in the clinical environment, followed by a second validation pilot study (Phase 2, n = 49). From these prospectively collected data, a final evaluation study was done on 69 of these patients with 10 patients excluded from the Phase 2 study because of insufficient or invalid data. Each data collection phase was a prospective non-interventional observational study conducted in a live clinical setting to test the data collection systems and the model performance. No prediction information was available to the clinical teams during a patient's stay in the ICU. The final cohort (n = 69), using a decision threshold of 0.4, and including false positive checks, gave a sensitivity of 39.3% (95% CI 32.9-46.1) and a specificity of 91.5% (95% CI 89.0-93.7). Using a decision threshold of 0.3, and false positive correction, gave a sensitivity of 46.6% (95% CI 40.1-53.2) and specificity of 85.6% (95% CI 82.3-88.8). With a decision threshold of 0.3, > 15min warning of patient instability can be achieved. We have shown, using advanced machine learning techniques running in a live neuro-critical care environment, that it would be possible to give neurointensive teams early warning of potential hypotensive events before they emerge, allowing closer monitoring and earlier clinical assessment in an attempt to prevent the onset of hypotension. The multi-centre clinical infrastructure developed to support the clinical studies provides a solid base for further collaborative research on data quality, false positive correction and the display of early warning data in a clinical setting.
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- Köhnke, Tobias, 1978, et al.
(author)
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Nanoreinforced xylan-cellulose composite foams by freeze-casting
- 2012
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In: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 14:7, s. 1864-1869
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Journal article (peer-reviewed)abstract
- Structured biofoams have been prepared from the readily available renewable biopolymer xylan by employing an ice-templating technique, where the pore morphology of the material can be controlled by the solidification conditions and the molecular structure of the polysaccharide. Furthermore, reinforcement of these biodegradable foams using cellulose nanocrystals shows potential for strongly improved mechanical properties.
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| 12. |
- Stell, A., et al.
(author)
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Supporting clinical trials to predict adverse events in the brain trauma domain
- 2012
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In: IEEE Symposium on Computer-Based Medical Systems. - 9781467320511 ; , s. 6266380-
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Conference paper (peer-reviewed)abstract
- There are many serious and acute physiological conditions about which we have incomplete medical knowledge. To address this and develop effective treatments it is often the case that a wealth of clinical data is required for collection, analysis and feedback. Whilst such data often exists it is typically held in a variety of different formats and locations. This paper describes the EU FP7-funded Avert-IT project (www.avert-it.org), which has developed an integrated, real-time physiological data infrastructure (ICUnet) to address the specific issue of prediction of hypotensive events in the brain trauma domain. This system has been used to support a major multi-centre clinical trial. In this paper, the implementation and application of the ICUnet system is described, followed by the design and results of the clinical trial.
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- Goetz, L. A., et al.
(author)
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Preparation of Microwave-Assisted Polymer-Grafted Softwood Kraft Pulp Fibers. Enhanced Water Absorbency
- 2011
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 119:1, s. 387-395
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Journal article (peer-reviewed)abstract
- A wood pulp cellulose-based hydrogel material was prepared with poly(methyl vinyl ether-co-maleic acid) (PMVEMA), polyethylene glycol (PEG), and softwood ECF kraft pulp via microwave and thermal esterification and compared via hydrogel absorption and retention of water and 0.10M NaCl. The microwave initiated reaction time was optimized to 105 s at 1600 W based on maximum water absorption of 96 g/g of the 49% PMVEMA pulp hydrogels. The influence of reaction variables such as pulp fiber size and the weight ratios of PMVEMA to pulp were investigated. The maximum water absorbency of the milled pulp fibers microwave initiated products was 151 g/g, whereas the maximum water absorbency of the milled pulp fibers thermally initiated hydrogels was 198 g/g. In addition, the microwave initiated hydrogels retained a maximum of 67% of absorbed water after centrifugation at 770 rpm for 10 min, whereas the thermally initiated hydrogels retained a maximum of 49% of water absorbed. Fourier transform infrared spectroscopy (FTIR) was used to confirm the esterification of the PMVEMA with the pulp cellulose. Microwave initiated crosslinking successfully produced a pulp hydrogel with a shorter reaction time and comparable or improved water absorption and retention properties when compared with the traditional thermally crosslinked pulp hydrogel system.
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| 17. |
- Kosa, M., et al.
(author)
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Pyrolysis oils from CO2 precipitated Kraft lignin
- 2011
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In: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 13:11, s. 3196-3202
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Journal article (peer-reviewed)abstract
- A common goal in present and future forestry, biofuels and biomaterials practices, is the need to valorize lignocellulose processes to maximize value and optimize autonomic economy. Consequently, a key focus of modern biorefining is the on-site utilization of all residual materials generating products of the highest possible value. The LignoBoost process, recently demonstrated on the pilot-scale at Kraft pulp mills, injects CO(2) into pulping liquors which results in a lower solution pH and thereby precipitates lignin. The present paper compares and evaluates the pyrolysis of pulping liquor lignins precipitated by sulfuric acid (pH 3) and the aforementioned CO(2) method (pH 10.5 and 9.5). The CO(2) based process yielded lignin that showed superior pyrolysis properties including low gas formation and increased bio-oil yields, close to 40%, consisting primarily of low (similar to 150 g mol(-1)) molecular weight compounds. Subsequent NMR analysis showed that the oils exhibit favorable changes in functionalities, e. g. loss of aromatic and gain in aliphatic carbon percentages as well as decrease in carboxyl and methoxyl (oxygen containing) groups. Moreover, NMR results further confirmed previously hypothesized lignin pyrolysis reactions, while at the same time showed the potential of CO(2) precipitated lignin for pyrolysis and subsequent liquid biofuel production.
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| 18. |
- Köhnke, Tobias, 1978, et al.
(author)
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Ice templated and cross-linked xylan/nanocrystalline cellulose hydrogels
- 2014
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 100, s. 24-30
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Journal article (peer-reviewed)abstract
- Structured xylan-based hydrogels, reinforced with cellulose nanocrystals (CNCs), have successfully been prepared from water suspensions by cross-linking during freeze-casting. In order to induce cross-linking during the solidification/sublimation operation, xylan was first oxidized using sodium periodate to introduce dialdehydes. The oxidized xylan was then mixed with CNCs after which the suspension was frozen unidirectionally in order to control the ice crystal formation and by that the pore morphology of the material. Finally the ice crystal templates were removed by freeze-drying. During the freeze-casting process hemiacetal bonds are formed between the aldehyde groups and hydroxyl groups, either on other xylan molecules or on CNCs, which cross-links the system. The proposed cross-linking reaction was confirmed by using cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy. The pore morphology of the obtained materials was analyzed by scanning electron microscopy (SEM). The materials were also tested for compressive strength properties, both in dry and water swollen state. All together this study describes a novel combined freeze-casting/cross-linking process which enables fabrication of nanoreinforced biopolymer-based hydrogels with controlled porosity and 3-D architecture.
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| 19. |
- Nagy, M., et al.
(author)
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Characterization of CO2 precipitated Kraft lignin to promote its utilization
- 2010
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In: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 12:1, s. 31-34
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Journal article (peer-reviewed)abstract
- Converting pulp mills into forest biorefineries to produce biopower and biomaterials can decrease their environmental impact and increase feasibility at the same time. One of the key challenges to reach this goal is the recovery of lignin from process streams for subsequent utilization in a variety of innovative green processes. This study examines the fundamental chemical structure of lignin recovered from Kraft pulping streams by an acid precipitation/washing methodology. Functional group analysis and molecular weight profiles were determined by NMR and SEC with promising results for future conversions; such as low hydroxyl (oxygen) contents and low molecular weights (similar to 3000 g mol(-1)).
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| 20. |
- Neumann, JO, et al.
(author)
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The use of hyperventilation theraphy after traumatic brain injury in Europe : an analysis of the BrainIT database
- 2008
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In: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 34:9, s. 1676-1682
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Journal article (peer-reviewed)abstract
- Objective To assess the use of hyperventilation and the adherence to Brain Trauma Foundation-Guidelines (BTF-G) after traumatic brain injury (TBI). Setting Twenty-two European centers are participating in the BrainIT initiative. Design Retrospective analysis of monitoring data. Patients and participants One hundred and fifty-one patients with a known time of trauma and at least one recorded arterial blood–gas (ABG) analysis. Measurements and results A total number of 7,703 ABGs, representing 2,269 ventilation episodes(VE) were included in the analysis. Related minute-by-minute ICP data were taken from a 30 min time window around each ABG collection. Data are given as mean with standard deviation. (1) Patients without elevated intracranial pressure (ICP) (\20 mmHg) manifested a statistically significant higher PaCO2(36 ± 5.7 mmHg) in comparison to patients with elevated ICP(C20 mmHg; PaCO2:34 ± 5.4 mmHg, P\0.001). (2) Intensified forced hyperventilation(PaCO2 B 25 mmHg) in the absence of elevated ICP was found in only 49VE (2%). (3) Early prophylactic hyperventilation (\24 h after TBI;PaCO2 B 35 mmHg,ICP\20 mmHg) was used in 1,224VE (54%). (4) During forced hyperventilation(PaCO2 B 30 mmHg), simultaneous monitoring of brain tissue pO2 or SjvO2 was used in only 204 VE (9%). Conclusion While overall adherence to current BTF-Gseems to be the rule, its recommendations on early prophylactic hyperventilation as well as the use of additional cerebral oxygenation monitoring during forced hyperventilation are not followed in this sample of European TBI centers. Descriptor Neurotrauma
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| 22. |
- Pu, Y., et al.
(author)
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Investigation into nanocellulosics versus acacia reinforced acrylic films
- 2007
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In: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368. ; 38:3, s. 360-366
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Journal article (peer-reviewed)abstract
- Three closely related cellulosic acrylic latex films were prepared employing acacia pulp fibers, cellulose whiskers and nanocellulose balls and their respective strength properties were determined. Cellulose whisker reinforced composites had enhanced strength properties compared to the acacia pulp and nanoball composites. AFM analysis indicated that the cellulose whisker reinforced composite exhibited decreased surface roughness. Published by Elsevier Ltd.
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| 23. |
- Saxena, A., et al.
(author)
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Novel nanocellulosic xylan composite film
- 2009
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In: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368. ; 40:8, s. 727-730
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Journal article (peer-reviewed)abstract
- Nanocellulosic-xylan films were prepared employing oat spelt xylan, cellulose whiskers and a plasticizer. The mechanical properties of the films were evaluated using tensile testing under controlled temperature and humidity conditions. The tensile data showed that the addition of sulfonated cellulose whiskers lead to a substantial improvement in strength properties. Addition of 7 wt% of sulfonated whiskers increased the tensile energy absorption of xylan films by 445% and the tensile strength of the film by 141%. Furthermore, films to which 7% cellulose whiskers were added showed that nanocellulose whiskers produced with sulfuric acid (sulfonated whiskers) were significantly better at increasing film strength than cellulose whiskers produced by hydrochloric acid hydrolysis of cellulosic fibers. (C) 2009 Elsevier Ltd. All rights reserved.
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| 24. |
- Saxena, A., et al.
(author)
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Water transmission barrier properties of biodegradable films based on cellulosic whiskers and xylan
- 2009
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 78:2, s. 357-360
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Journal article (peer-reviewed)abstract
- The reinforcement of natural biopolymers with cellulosic whiskers has been shown to be beneficial for physical strength properties including xylan films. This study examines the water transmission properties of xylan films reinforced with cellulosic whiskers prepared from kraft pulp hydrolyzed with sulfuric acid. Measurements of water transmission rate (WVTR) were accomplished by a modification of wet cup method described by ASTM E 96-95. The results showed that films prepared by xylan reinforced by 10% sulfonated whiskers exhibited a 74% reduction in specific water transmission properties with respect to xylan film and a 362% improvement with respect to xylan films reinforced with 10% softwood kraft fibers. (C) 2009 Elsevier Ltd. All rights reserved.
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| 25. |
- Shaw, M, et al.
(author)
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The brain monitoring with information technology (BrainIT) collaborative network : data validation results
- 2009
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In: Acta Neurochirurgica Supplements. - Vienna : Springer Vienna. - 9783211855775 - 9783211855782 ; , s. 217-221
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Book chapter (other academic/artistic)abstract
- Background The BrainIT group works collaboratively on developing standards for collection and analyses of data from brain injured patients towards providing a more efficient infrastructure for assessing new health technology. Materials and methods Over a 2 year period, core dataset data (grouped by nine categories) were collected from 200 head-injured patients by local nursing staff. Data were uploaded by the BrainIT web and random samples of received data were selected automatically by computer for validation by data validation (DV) research nurse staff against gold standard sources held in the local centre. Validated data was compared with original data sent and percentage error rates calculated by data category. Findings Comparisons, 19,461, were made in proportion to the size of the data received with the largest number checked in laboratory data (5,667) and the least in the surgery data (567). Error rates were generally less than or equal to 6%, the exception being the surgery data class where an unacceptably high error rate of 34% was found. Conclusions The BrainIT core dataset (with the exception of the surgery classification) is feasible and accurate to collect. The surgery classification needs to be revised.
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