scholarly journals Enzyme kinetics modelling approach to evaluate the impact of high CO2 and super-atmospheric O2 concentrations on respiration rate of pomegranate arils

2017 ◽  
Vol 15 (4) ◽  
pp. 608-616 ◽  
Author(s):  
Zinash A. Belay ◽  
Oluwafemi J. Caleb ◽  
Umezuruike Linus Opara
Keyword(s):  
Enzyme Kinetics ◽  
Respiration Rate ◽  
High Co2 ◽  
Kinetics Modelling ◽  
The Impact ◽  
Pomegranate Arils ◽  
Modelling Approach

scholarly journals Selecting pH cut-offs for the safe verification of nasogastric feeding tube placement: a decision analytical modelling approach

BMJ Open ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. e018128 ◽  
Author(s):  
Melody Zhifang Ni ◽  
Jeremy R Huddy ◽  
Oliver H Priest ◽  
Sisse Olsen ◽  
Lawrence D Phillips ◽  
...  
Keyword(s):  
Care Pathway ◽  
Feeding Tube ◽  
Tube Placement ◽  
X Rays ◽  
Clinical Environment ◽  
Nasogastric Feeding ◽  
Relative Safety ◽  
Checking Procedure ◽  
The Impact ◽  
Modelling Approach

ObjectivesThe existing British National Patient Safety Agency (NPSA) safety guideline recommends testing the pH of nasogastric (NG) tube aspirates. Feeding is considered safe if a pH of 5.5 or lower has been observed; otherwise chest X-rays are recommended. Our previous research found that at 5.5, the pH test lacks sensitivity towards oesophageal placements, a major risk identified by feeding experts. The aim of this research is to use a decision analytic modelling approach to systematically assess the safety of the pH test under cut-offs 1–9.Materials and methodsWe mapped out the care pathway according to the existing safety guideline where the pH test is used as a first-line test, followed by chest x-rays. Decision outcomes were scored on a 0–100 scale in terms of safety. Sensitivities and specificities of the pH test at each cut-off were extracted from our previous research. Aggregating outcome scores and probabilities resulted in weighted scores which enabled an analysis of the relative safety of the checking procedure under various pH cut-offs.ResultsThe pH test was the safest under cut-off 5 when there was ≥30% of NG tube misplacements. Under cut-off 5, respiratory feeding was excluded; oesophageal feeding was kept to a minimum to balance the need of chest X-rays for patients with a pH higher than 5. Routine chest X-rays were less safe than the pH test while to feed all without safety checks was the most risky.DiscussionThe safety of the current checking procedure is sensitive to the choice of pH cut-offs, the impact of feeding delays, the accuracy of the pH in the oesophagus, as well as the extent of tube misplacements.ConclusionsThe pH test with 5 as the cut-off was the safest overall. It is important to understand the local clinical environment so that appropriate choice of pH cut-offs can be made to maximise safety and to minimise the use of chest X-rays.Trial registration numberISRCTN11170249; Pre-results.

scholarly journals Key Factors for Activated Carbon Adsorption of Pharmaceutical Compounds from Wastewaters: A Multivariate Modelling Approach

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 166
Author(s):  
Rui M. C. Viegas ◽  
Ana S. Mestre ◽  
Elsa Mesquita ◽  
Miguel Machuqueiro ◽  
Marta A. Andrade ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Activated Carbons ◽  
Univariate Analysis ◽  
Pharmaceutical Compounds ◽  
Pls Regression ◽  
Short Term ◽  
Latent Structures ◽  
The Impact ◽  
Inorganic Matrix ◽  
Modelling Approach

Projection to Latent Structures (PLS) regression, a generalization of multiple linear regression, is used to model two datasets (40 observed data points each) of adsorption removal of three pharmaceutical compounds (PhCs), of different therapeutic classes and physical–chemical properties (carbamazepine, diclofenac, and sulfamethoxazole), from six real secondary effluents collected from wastewater treatment plants onto different powdered activated carbons (PACs). For the PLS regression, 25 descriptors were considered: 7 descriptors related to the PhCs properties, 10 descriptors related to the wastewaters properties (8 related to the organic matrix and 2 to the inorganic matrix), and 8 descriptors related to the PACs properties. This modelling approach showed good descriptive capability, showing that hydrophobic PhC-PAC interactions play the major role in the adsorption process, with the solvation energy and log Kow being the most suitable descriptors. The results also stress the importance of the competition effects of water dissolved organic matter (DOM), namely of its slightly hydrophobic compounds impacting the adsorption capacity or its charged hydrophilic compounds impacting the short-term adsorption, while the water inorganic matrix only appears to impact PAC adsorption capacity and not the short-term adsorption. For the pool of PACs tested, the results point to the BET area as a good descriptor of the PAC capacity, while the short-term adsorption kinetics appears to be better related to its supermicropore volume and density. The improvement in these PAC properties should be regarded as a way of refining their performance. The correlations obtained, involving the impact of water, PhC and PAC-related descriptors, show the existence of complex interactions that a univariate analysis is not sufficient to describe.

Predicting the Effects of Overloads on Fatigue Crack Growth in an Al-SiC MMC Using a Computational Model

2004 ◽  
Vol 126 (2) ◽  
pp. 172-178
Author(s):  
M. S. Bruzzi ◽  
P. E. McHugh
Keyword(s):  
Crack Growth ◽  
Growth Curves ◽  
Cyclic Stress ◽  
Crack Growth Behavior ◽  
Matrix Composites ◽  
Modeling Approach ◽  
Sic Particles ◽  
The Impact ◽  
Modelling Approach ◽  
Fatigue Modeling

A defect tolerant approach to fatigue modeling for constant amplitude loading was developed by Bruzzi and McHugh (2002) and applied to two metal matrix composites: (1) a forged 2124 Al reinforced with 17 percent SiC particles and (2) a cast 359 Al reinforced with 20 percent SiC particles MMC in Bruzzi and McHugh (2003). In reality, however, engineering components are invariably subjected to varying cyclic stress amplitudes. In order to investigate the suitability of extending the fatigue modelling approach developed to variable amplitude loading, the effects of single and periodic peak tensile overloads are investigated in this work for the case of the Al 2124 MMC. The effects of overloads in causing significant changes to the level of closure in the wake of the crack tip, following the overload, in addition to changes in the nominally applied stress amplitude are firstly discussed in an overview. The quantification of the effects of overloads by use of experimental “resistance to crack growth curves” and the extension of the fatigue modeling approach to account for these effects are then described and investigated. Finally the predicted results of the impact of overloads on the short crack growth behavior of the Al 2124 MMC are presented and discussed. The extension of the fatigue modeling approach to account for the effects of overloads provides an additional means of validating the modelling approach developed by Bruzzi and McHugh (2002, 2003).

How dry was the LGM? A Biosphere-Hydrosphere modelling approach for the paleo-lake Chew Bahir and Omo-River catchment in southern Ethiopia

2021 ◽  
Author(s):  
Markus L. Fischer ◽  
Felix Bachofer ◽  
Martin H. Trauth ◽  
Annett Junginger
Keyword(s):  
Land Cover ◽  
Environmental Data ◽  
Boosted Regression Trees ◽  
Lapse Rate ◽  
Southern Ethiopia ◽  
Lake Turkana ◽  
Ethiopian Highlands ◽  
Omo River ◽  
The Impact ◽  
Modelling Approach

<p>The formation of the East African Rift System led to the emergence of large topographical contrasts in southern Ethiopia. This extreme topography is in turn responsible for an extreme gradient in the distribution of precipitation between the dry lowlands (~500 mm a<sup>-1</sup>) in the surrounding of Lake Turkana and the moist western Ethiopian Highlands (~2,000 mm a<sup>-1</sup>). As a consequence, the prevailing vegetation is fractionated into a complex mosaic that includes desert scrubland along the Lake Turkana shore, woodlands and wooded grasslands in the Omo-River lowlands and the paleo-lake Chew Bahir catchment, afro-montane forests of the Ethiopian Highlands, and afro-alpine heath in most elevated parts. During the past 25 ka, southern Ethiopia has been exposed to significant climate changes, from a dry and cold Last Glacial Maximum (LGM, 25-18 ka BP) to the African Humid Period (AHP, 15-5 ka BP), and back to present-day dry conditions. These shifts in temperature and precipitation may have affected the vegetation pattern and landscape in the area, but environmental data especially from LGM times are rare. This is because in times of a dry climate the paleo-lake Chew Bahir was dried up and hence the climate record in lake sediments was interrupted.</p><p>In this study, we investigate the hydrological conditions during the LGM using a previously-developed lake balance model (LBM) for southern Ethiopia, which is now coupled with a new predictive vegetation model (PVM) to better understand the biosphere-hydrosphere interactions and thus possible precipitation thresholds. The PVM is based on the method of boosted regression trees using elevation and monthly precipitation as input to predict land-cover, tree-cover and vegetation greenness for a ~1 km grid covering the Omo-River, paleo-lake Chew Bahir, Lake Chamo and Lake Abaya catchments. We linked the PVM and the resulting land surface parameters with the LBM to model the impact of a changing land-cover to the actual evaporation. Furthermore, we used the glycerol dialkyl glycerol tetraethers (GDGT) based paleo-temperature and tropical lapse rate reconstructions from Mount Kenya to consider the orographic temperature distribution in southern Ethiopia during the LGM. Using both, we simulated different precipitation amounts from 100% to 50% compared to the modern-day multi-annual averages and their effect on vegetation and lake levels of paleo-lake Chew Bahir. Our biosphere-hydrosphere modelling approach suggests 25 to 30% lower moisture availability during the LGM compared to the modern conditions and provides a high-resolution spatial reconstruction of the potential prevailing vegetation in the southern Ethiopian region.</p>

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