Moderate Hydration Research Articles

Probing structural features in potato starch granules at moderate hydration through the modelling of 1H->13C polarization transfer kinetics

The structural arrangement of starch polymers in presence of water is known to impact the functional properties of starchy products. In this study, the hydration of potato starch granules was investigated at the molecular level through various 1H->13C polarization transfer solid-state Nuclear Magnetic Resonance (ss-NMR) experiments. The impact of increasing the water content from 12.3 % to 45.9 % was assessed using 13C Cross Polarization Magic Angle Spinning (CPMAS), Variable Contact Time (VCT-CPMAS), Variable Spin Lock (VSL-CPMAS), and T One Rho QUEnching (TORQUE) NMR sequences. Of these, VCT-CPMAS proved to be the most promising. When applied with an optimal number of contact times, it enabled the application of several mathematical models that provided detailed insights into the structuring of protons in the hydrated potato starch granules. At low hydration (12.3 %), the models enabled various structural domains to be distinguished, which we suggest are associated with helical and amorphous structures. At moderate hydration (45.9 %), we tested two fitting models. Two pools of protons were revealed, corresponding to loosely ordered structures on the scale of tens of nanometers. These findings suggest varying water distribution during starch hydration and are likely to indicate variable hydration levels in the multilamellar amorphous structures of starch granules.

Lanthanide transport in angstrom-scale MoS2-based two-dimensional channels.

Rare earth elements (REEs), critical to modern industry, are difficult to separate and purify, given their similar physicochemical properties originating from the lanthanide contraction. Here, we systematically study the transport of lanthanide ions (Ln3+) in artificially confined angstrom-scale two-dimensional channels using MoS2-based building blocks in an aqueous environment. The results show that the uptake and permeability of Ln3+ assume a well-defined volcano shape peaked at Sm3+. This transport behavior is rooted from the tradeoff between the barrier for dehydration and the strength of interactions of lanthanide ions in the confinement channels, reminiscent of the Sabatier principle. Molecular dynamics simulations reveal that Sm3+, with moderate hydration free energy and intermediate affinity for channel interaction, exhibit the smallest dehydration degree, consequently resulting in the highest permeability. Our work not only highlights the distinct mass transport properties under extreme confinement but also demonstrates the potential of dialing confinement dimension and chemistry for greener REEs separation.

Ion and Water Dynamics in the Transition from Dry to Wet Conditions in Salt-Doped PEG.

The influence of the water content on ion and water transport mechanisms in polymer membranes under low to moderate hydration conditions remains poorly understood. In this study, we combine ion and water diffusivity (PFG-NMR) measurements with atomistic molecular dynamics simulations to better understand transport processes in hydrated salt-doped poly(ethylene glycol). Above the water percolation threshold, the experimental and simulated diffusivities are in good agreement with the free volume transport models. At low hydration levels, unlike dry systems, ion diffusion cannot be described by polymer segmental dynamics alone. We rationalize such observations by the interplay between ion-water and ion-polymer solvation of cations and between ion-water and cation-anion interactions for anions. Further, we demonstrate that a two-state model combining ion-water solvation and free volume transport can describe water dynamics across the entire hydration range of interest. Our findings provide a more encompassing analysis of ion and water transport in hydrated polyelectrolytes, specifically in the low hydration regime.

H2O budget and metamorphic re-equilibration in polycyclic rocks as recorded by garnet textures and chemistry

Massive dehydration is expected to occur during oceanic subduction. The situation is quite different during continental subduction, where often a large amount of crustal material has experienced a first orogenic cycle before the burial during the second subduction/collision cycle (rocks are therefore polycyclic). The amount and timing of dehydration and/or hydration episodes in polycyclic rocks strongly controls the extent of metamorphic re-equilibration during the second orogenic cycle. This study aims at estimating the fluid budget in polycyclic metapelites from the Muret Unit (Dora-Maira Massif, Western Alps). The excellent preservation, in a kilometre-scale low-strain domain, of pre-Alpine minerals and structures allows the comparison with the textures and structures observed in the pervasively foliated adjacent rocks. In the low-strain domain, the main foliation is pre-Alpine and defined by high-temperature minerals whereas the Alpine high-pressure overprint is static. Pre-Alpine garnet porphyroblasts were fractured and partially dissolved before the growth of the Alpine garnet over pre-Alpine garnet fragments. The preservation of the overall shape of the original pre-Alpine porphyroblasts suggests that pre-Alpine garnet crystals were pseudomorphically replaced by chlorite during the late Variscan retrogression. This process was likely triggered by an episode of fluid-rock interaction and moderate hydration (⁓ 1–2 wt% H2O) which is also responsible of the growth of metamorphic zircon at ~304 Ma. In the high-strain domain, the dominant fabric is Alpine and developed at high-pressure conditions. Despite the difference in the strain intensity, metapelites from both low- and high-strain domains developed the same peak Alpine assemblage garnet-chloritoid-glaucophane-muscovite-rutile in the presence of a free H2O phase at 21–22 kbar and 530–560 °C. Thermodynamic modelling indicates that after the peak pre-Alpine metamorphism, a minimum re-hydration of at least 1 wt% was needed in order to reach H2O-saturation during the Alpine cycle. Alpine garnet mainly sealed fractures and formed thin discontinuous overgrowth on the partially dissolved pre-Alpine garnet. Its growth occurred during the Alpine prograde to peak evolution, involving progressive consumption of chlorite and lawsonite and resulting in a prograde growth zoning. The preservation of the Alpine garnet growth zoning and the absence of complex compositional modifications suggest that the rock did not record massive pulses of fluid infiltration during subduction. Instead, the main fluid-rock interaction episode was limited and occurred before the Alpine re-equilibration during the late Variscan evolution.

The Relationship between Physical Activity and The Level of Physical Fitness of Pencak Silat Athletes

This study analyzed the relationship between macronutrient intake, hydration status, physical activity, and the physical fitness level of Pencak silat athletes in Banjarbaru. This analytical observational study used a cross-sectional design involving 30 pencak silat athletes selected using a total sampling technique. The research instruments included questionnaires, 24-hour food recall forms, a self-urine examination (PURI), a physical activity questionnaire, and a 12-minute running test. Data were analyzed using the Spearman Rank test. The results of this study indicated that most athletes had protein, fat, and carbohydrate deficiencies, moderate hydration status, and very light physical activity levels. It can be concluded that macronutrient intake, namely protein (p=0.264), fat (p=0.643), carbohydrates (p=0.101), and hydration status (p=0.264), had no association with the physical fitness levels of pencak silat athletes, while physical activity (p =0.010) had an association with the physical fitness level of Pencak silat athletes. Athletes are recommended to continue to pay attention to macronutrient intake and hydration status as needed because they also play an essential role in fitness apart from physical activity.

PALEOECOLOGICAL CONDITIONS AND CARBON ACCUMULATION IN GENESIS OF INUNDATED MIRE OF MID-RUSSIAN UPLAND

The aim is to study of influence of the ecological conditions on the carbon accumulation at the different stages of genesis of the inundated mire.
 Materials and methods. The macrofossil analysis and the degree of peat decomposition were studied by the microscopic method, the moisture content and the dry bulk density were studied by the gravimetric method. The ash content was determined by burning, the content of organic matter was calculated by the difference between the mass of dry peat and the ash content. The carbon content (%) in peat samples was calculated based on the dry bulk density, the organic matter content and the mass fraction of carbon for each volume of peat. The rate of vertical growth of peat and intensity of peat accumulation in periods of Holocene were calculated based on the results of radioactive dating.
 The parameters of surrounding landscapes during the mire genesis were characterized by the results of the palynology analysis and the estimation of fire activity. The intensity of fires in paleolandscapes was studied by the content of coal particles in each (1 cm3) sample of wet peat.
 Results. The genesis of the Podkosmovo mire is presented by 5 stages which were took place under the stable conditions of water-mineral nutrition. The carbon accumulation in the genesis proceeded at the rate of 45.7 g/m2/year on average. At the same time, the surrounding landscapes differed in the degree of afforestation and the intensity of anthropogenic press.
 Conclusion. The moderate hydration and nutrition with mineralized waters ensure the stability of the mire development and the intensity of carbon accumulation, despite the change of surrounding landscapes under the influence of climate or human. However, the active transformation of the surrounding landscapes can have a negative impact on the functioning of the mire and reduce the intensity of carbon accumulation.

The role of Tween 80 and SDS in the kinetics of semi-clathrate hydrates formation for carbon dioxide capture from flue gas

ABSTRACT The present study focuses on integrated experimental evaluation of a concentration effect in nonionic and anionic surfactants on semi-clathrate hydrates formation during the capture low-pressure carbon dioxide from the flue gas (N2 (83.13 mol.%)/CO2 (16.87 mol.%)). Semi-clathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable materials with phase changes due to their moderate hydrate formation conditions. The kinetics of CO2-N2-TBAB semi-clathrate hydrate formation was studied in the presence and absence of Tween-80 as a nonionic surfactant and sodium dodecyl sulfate (SDS) as an anionic one. The experiments were performed in a stirred batch reactor at a constant temperature of 273.55 K and an initial pressure of 2.1 MPa. 5.0 wt.% TBAB’s aqueous solutions were tested both in the absence of surfactants and in presence of Tween-80 and SDS at different concentrations (500, 1500, 3000 ppm). The separation factor and recovery for CO2 at low pressure were in situ controlled depending on the surfactant concentration. Adding 1500 ppm of Tween-80 provided optimal conditions for the СО2/N2 separation process; the separation factor was 9.5, the СО2 recovery was 53.1%.

Important Roles of Water Clusters Confined in a Nanospace as Revealed by a Synchrotron X-ray Diffraction Study

States of water molecules confined in a nanospace designed by montmorillonite (negatively charged silicate layer) and charge compensating benzylammonium were investigated. Caffeine was used as a probe because of its compatibility for the fine structure of the interlayer water. Powder synchrotron radiation X-ray diffraction (SXRD) and adsorption isotherms of the water vapor revealed a metastable structure of bimolecular water layers (2WLs) in the interlayer space. Water molecules readily penetrated to expand the interlayer space to 0.56 nm. The interlayer space did not increase further even in the presence of excess water. According to the isosteric heat of water, the expansion was limited because of moderate hydration as forming 2WLs. Caffeine molecules replaced a part of the water molecules in the 2WLs to expand the interlayer space to 0.65 nm. Time-resolved SXRD with an accumulation time of 500 ms revealed that the interlayer expansion reached a steady state within a few minutes. The caffeine intercalation proceeded, involving a change in the molecular orientation that increased the contact area of the caffeine molecules. The interlayer expansion was limited in all the solvents examined (mixtures of water with methanol, ethanol, acetone, and tetrahydrofuran), while the packing density of the incorporated caffeine was maximized in the absence of an organic solvent. The water molecules confined in the interlayer space acted as an actuator to accommodate a large quantity of amphiphilic molecules by adapting the nanostructure, which was achieved by releasing the confined water molecules.

Treating AGE in the ED: More ORT and Less IVF

Source: Poonai N, Powell EC, Schnadower D, et al. Variables associated with intravenous rehydration and hospitalization in children with acute gastroenteritis: a secondary analysis of 2 randomized clinical trials. JAMA Netw Open. 2021;4(4):e216433. doi:10.1001/jamanetworkopen.2021.6433Investigators from multiple institutions conducted a secondary analysis to identify factors associated with intravenous (IV) fluid administration and hospitalization in children with acute gastroenteritis (AGE). Data were obtained from 2 randomized controlled trials of probiotics in children with AGE-associated diarrhea. Participants were aged 3-48 months and had ≥3 watery stools in the preceding 24 hours of presentation to 1 of 16 emergency departments (EDs) in the US or Canada during the study period of 2013–2017. Demographics, clinical characteristics (eg, frequency of vomiting in the 24 hours pre-ED visit, previous health care visit for the same illness, duration of illness), and treatment received (eg, oral ondansetron, IV fluid administration) were collected from study participants. Dehydration was assessed using the Clinical Dehydration Scale, which is scored from 0-8 and categorized as no dehydration (0), mild to moderate dehydration (1-4), and severe dehydration (5-8).The primary outcomes for this study were: (1) IV rehydration, defined as any crystalloid administered through a peripheral IV line for the purposes of rehydration; and (2) hospitalization, defined as admission to an inpatient unit outside the ED. Investigators assessed the association between these outcomes and demographics, clinical characteristics, use of oral ondansetron, and dehydration scores. Multivariable models were created to test the independent association of these variables with outcomes.There were 1,846 participants included in analysis. The mean age of participants was 19.1 months, and 54.6% were boys. Overall, 13% of participants received IV rehydration, and 3.6% were hospitalized.In multivariable models, administration of oral ondansetron was associated with a significantly lower odds of IV rehydration (OR, 0.21; 95% CI, 0.13, 0.32) and hospitalization (OR, 0.44; 95% CI, 0.21, 0.89). Several variables were significantly associated with increased odds of IV rehydration, including mild to moderate hydration scores (OR, 8.73; 95% CI, 5.81, 13.13), severe dehydration scores (OR, 34.15; 95% CI, 13.45, 86.73), and a prior health care visit with IV rehydration (OR, 4.55; 95% CI, 1.32, 15.72). Several variables also were significantly associated with increased odds of hospitalization, including severe dehydration scores (OR, 53.45; 95% CI, 19.10, 149.57), a prior health care visit with IV rehydration (OR, 10.26; 95% CI, 3.11, 33.86), and duration of vomiting ≥48 hours (OR, 3.21; 95% CI, 1.37, 7.56).The investigators conclude that oral ondansetron use may reduce IV rehydration treatment and hospitalization in children with AGE.Dr Bechtel has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Children commonly present to EDs for evaluation of dehydration due to AGE.1 Despite guidelines recommending oral rehydration therapy (ORT), IV fluids frequently are administered to children with AGE in high-income countries such as the US.2 This likely is because parents of young children choose IV fluids over ORT when given a choice of rehydration therapy in the ED.3 It is important to note that meta-analysis has shown no clinically meaningful differences between ORT and IV fluids in terms of efficacy and safety.4 Furthermore, ondansetron for ORT will not mask illness more severe than AGE (See AAP Grand Rounds. 2010;23[5]:49.)5 Therefore, it would be helpful to know which children with AGE and dehydration likely will fail ORT and need IV fluids.The current authors found that mild to moderate hydration scores, severe dehydration scores, a prior health care visit with IV fluids, and vomiting ≥48 hours were associated with the need for IV fluids and hospitalization. More importantly, the use of oral ondansetron was associated with a reduced need for IV fluids and hospitalization, likely because it facilitated successful ORT. Future study is needed to determine if home use of ondansetron coupled with ORT would prevent an ED visit for dehydration from AGE in the first place.A limitation of the current study is that scores to assess dehydration and/or hydration status in children with AGE may be helpful only for children with moderate to severe dehydration in high-income settings.6 Thus, the applicability of the results of the current study to low- and medium-income countries may be limited.Administration of oral ondansetron to dehydrated children with AGE in the ED may reduce the likelihood for IV fluids and hospitalization.The higher rates of IV rehydration in US EDs as compared to those in Canada, without improved outcomes, may arise both from caregiver expectations and provider preferences.3 This is an opportunity in the US to decrease use of expensive health care resources.7

Influence of THF and THF/SDS on the Kinetics of CO2 Hydrate Formation Under Stirring

Hydrate-based gas separation is a potential technology for CO2 recovery and storage, and its products can be used for fire prevention and control in mines. Promoters are often employed to accelerate or moderate hydrate formation. In this study, experiments were performed to examine the effects of different concentrations of the thermodynamic promoter tetrahydrofuran (THF) and kinetic promoter sodium dodecyl sulphate (SDS) on CO2 hydrate formation under stirring. The results showed that THF significantly shortens the induction time of CO2 hydrates; however, because THF occupies a large cavity in the hydrate structure, it also reduces the gas absorption and hydrate formation rate. SDS has no obvious effect on the induction time of hydrates, but it can increase the gas storage density and hydrate formation rate. Using THF and SDS together consumed more CO2 than using THF alone or pure water. The peak gas consumption rate was 2.3 times that of the THF system. The hydrate formation efficiency was improved by including both THF and SDS, which maximized both the hydrate formation rate and total gas uptake.

Methoxy-Functionalized Glycerol-Based Aliphatic Polycarbonate: Organocatalytic Synthesis, Blood Compatibility, and Hydrolytic Property.

Polymers that are biocompatible and degradable are desired for tissue engineering approaches in the treatment of vascular diseases, especially for those involving small-diameter blood vessels. Herein, we report the compatibility of a newly developed glycerol-based aliphatic polycarbonate possessing simple methoxy side groups, named poly(5-methoxy-1,3-dioxan-2-one) (PMDO), with blood cells and plasma proteins as well as its susceptibility to hydrolysis. As a consequence of the organocatalytic ring-opening polymerization (ROP) of a methoxy-functionalized cyclic carbonate derived from glycerol, PMDO with a sufficiently high molecular weight (Mn 14 kg/mol) and a narrow distribution (D̵M 1.12) was obtained for evaluation as a bulk biomaterial. This study demonstrates for the first time the organocatalytic ROP of a glycerol-based cyclic carbonate in a controlled manner. Compared with the clinically applied aliphatic polycarbonate poly(trimethylene carbonate) (PTMC), PMDO inhibits platelet adhesion by 33% and denaturation of fibrinogen by 23%. Although the wettability of PMDO based on water contact angle was almost comparable to those of PTMC and poly(ethylene terephthalate), the reason for the inhibited platelet adhesion and protein denaturation appeared to be related to the presence of specific hydrated water formed in the hydrated polymer. The improved hydration of PMDO also enhanced the susceptibility to hydrolysis, with PMDO demonstrating a slightly higher hydrolytic property than PTMC. This simple glycerol-based aliphatic polycarbonate has the following benefits: bio-based characteristics of glycerol and improved blood compatibility and hydrolytic biodegradability stemming from moderate hydration of the methoxy side groups.

Tracking hydration status changes by bioimpedance spectroscopy in children on peritoneal dialysis.

This 6-month prospective longitudinal study investigates the association between hydration status changes using bioimpedance spectroscopy (BIS) and systolic blood pressure (SBP), pulse pressure (PP), and serum albumin (sAlb) changes in children on peritoneal dialysis (PD). Thirteen patients (median age: 12.58 years) were enrolled. Normal hydration, moderate hydration, severe overhydration, and dehydration were defined as -7% ≤ relative overhydration (Re-OH) < +7%, +7% ≤ Re-OH < +15%, Re-OH ≥ +15%, and Re-OH < -7%, respectively. Automated office blood pressure z-score, sAlb, and weight z-score were recorded. Fifty-two Re-OH measurements were recorded: three in five, four in five, five in two, and seven in one patient, respectively. SBP was higher and sAlb lower in cases with severe overhydration (9 readings) (p < 0.001, p < 0.001), but distribution of these parameters did not differ between normal hydration/dehydration (28 readings) and moderate overhydration (15 readings) cases. In patients with hydration status change, SBP and PP were higher while sAlb lower in cases with higher hydration status level (p = 0.026, p = 0.05, and p = 0.109, respectively). In all patients, visit-to-visit SBP, PP, and sAlb changes were correlated to Re-OH changes (rs = 0.693, p < 0.001; rs = 0.643, p < 0.001; rs = -0.444, p = 0.008, respectively) but not to weight changes (rs = 0.052, p = 0.754; rs = 0.034, p = 0.838; rs = -0.156, p = 0.378, respectively). Visit-to-visit Re-OH changes, which were >+4% or <-4%, were linearly correlated to SBP (r = 0.858, p < 0.001), PP (r = 0.757, p < 0.001), and sAlb (r = -0.699, p = 0.002) changes. In children on PD, longitudinal Re-OH changes are superior to weight changes in assessing volume-dependent variations of SBP, PP, and sAlb. Routine BIS application, rather than single BIS measurements, seems useful in the intra-patient monitoring of hydration status.

Weed infestation of soft spring wheat crops depending on the soil tillage system

The paper presents the results of the study on the influence of various tillage systems on the weed infestation of soft spring wheat of the Siberian Alliance variety. The study was carried out in a long-term stationary experiment (20152019) preceded by bare and green-manured fallow (rapeseed, melilot) in Kemerovo region. The soil of the experimental plot is classified as leached, medium-textured, medium-humus, heavy-loam chernozem. The following soil tillage systems were studied: deep moldboard, deep combined, minimum combined and minimum moldboard. Weather conditions during the research period were varied. Insufficient water supply during the first vegetation period of soft spring wheat (seedlings – leaf-tube formation) was noted in 2015-2017, with HTC (hydrothermal coefficient) being from 0.37 to 0.56. Excessive water content was observed in 2018 (HTC = 2.41) and moderate hydration – in 2019 (HTC = 1.12). Weed infestation was different in the conditions of each year. The impact of the soil tillage system on the number of weeds during the growing season of common spring wheat accounted for 21.6-90.4%, and their share in the total aboveground mass of the phytocenosis was 39.9-68.3%. The segetal flora in soft spring wheat crops is represented by monocotyledonous and dicotyledonous species with all the studied tillage systems. The highest density of weed vegetation during the tillering phase of soft spring wheat was recorded with deep moldboard soil tillage system (control). A reduction in weed infestation by 2.3 times compared to the control was noted with minimum moldboard soil tillage system preceded by bare fallow, 1.6 times – preceded by green-manured fallow with rapeseed, and 1.7 times – preceded by green-manured fallow with melilot. The same trend was observed in the proportion of weeds in the total aboveground mass of the phytocenosis during the wax ripeness phase of soft spring wheat with deep moldboard tillage system (4.3%), deep combined (3.9), minimum combined (4.1), minimum moldboard (2.6%).

Investigation of the kinetics of TBAB + carbon dioxide semiclathrate hydrate in presence of tween 80 as a cold storage material

Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, these materials could be used as a medium to store the cold energy in air conditioning systems. Semiclathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable phase change materials (PCMs), due to their moderate hydrate formation conditions. The kinetics of carbon dioxide - TBAB semiclathrate hydrate formation in presence and absence of tween 80 as a non-anionic surfactant is investigated in this research. The experiments were performed in a 169 cm3 stirred batch reactor at initial pressure of 3.2 MPa and isothermal condition of 276.15 K. Aqueous solutions of TBAB with concentrations of 0–15 wt% in presence and absence of tween 80 with concentrations of 500 and 1500 ppm are tested. The results revealed that utilization of TBAB with concentrations of 5–15 wt%, inhibits the kinetics of formed hydrates. By increasing the concentration of TBAB the amount and rate of gas uptake and storage capacity (SC) of formed hydrates decreases. Tween 80 with a concentration of 500 ppm presented a slight positive effect on the kinetics of hydrate formation in presence and absence of TBAB. While 1500 ppm of this additive inhibited the kinetics of formed hydrates.

Understanding hemicellulose-cellulose interactions in cellulose nanofibril-based composites

Plant-based polysaccharides (cellulose and hemicellulose) are a very interesting option for the preparation of sustainable composite materials to replace fossil plastics, but the optimum bonding mechanism between the hard and soft components is still not well known. In this work, composite films made of cellulose nanofibrils (CNF) and various modified and unmodified polysaccharides (galactoglucomannan, GGM; hydrolyzed and oxidized guar gum, GGhydHox; and guar gum grafted with polyethylene glycol, GG-g-PEG) were characterized from the nano- to macroscopic level to better understand how the interactions between the composite components at nano/microscale affect macroscopic mechanical properties, like toughness and strength. All the polysaccharides studied adsorbed well on CNF, although with different adsorption rates, as measured by quartz crystal microbalance with dissipation monitoring (QCM-D). Direct surface and friction force experiments using the colloidal probe technique revealed that the adsorbed polysaccharides provided repulsive forces–well described by a polyelectrolyte brush model – and a moderate reduction in friction between cellulose surfaces, which may prevent CNF aggregates during composite formation and, consequently, enhance the strength of dry films. High affinity for cellulose and moderate hydration were found to be important requirements for polysaccharides to improve the mechanical properties of CNF-based composites in wet conditions. The results of this work provide fundamental information on hemicellulose-cellulose interactions and can support the development of polysaccharide-based materials for different packaging and medical applications.

PROPOSED CO2 HYDRATE TECHNOLOGY APPLICATION FOR CARBON CAPTURE AND STORAGE IMPLEMENTATION IN INDONESIA

Carbon Capture and Sequestration (0r Storage)known as CCS needs to be implemented in various development activities in Indonesia including downstream oil and gas industry because the government of Indonesia has adopted the Paris Agreement on Greenhouse Gas Emissions Reduction. Various capture techniques have been developed for capturing CO2 from post combustion emission. One of the new approaches considered for capturing CO2 and hence reducing to atmospheric emissions is based on gas hydrate (crystallization) technology. The basis of the technology is the selective partition of the target component between the hydrate phase and the gaseous phase. It is expected that CO2 is preferentially trapped and encaged into the hydrate crystal phase compared to the other components. Previous study found that the gas/hydrate equilibrium pressure and temperature for the fl ue gas mixture in the range of 7.6 MPa and 11.0 MPa at 274 K and 277 K respectively, are inappropriate to the downstream oil and gas industrial reality because the operating cost will be expensive to compress the gas to the hydrate formation pressure. Suitable hydrate promoters including Tetrahydrofuran (THF) and Sodium Dodecyl Sulfate (SDS) can be used to achieve moderate hydrate formation pressure and energy consumption appropriate to the industrial reality. In the presence of THF and SDS about 62.3 Nm3/m3 CO2 hydrate can be formed at 30 bar pressure and 274 to 277 K temperature within around 15 minutes reaction time.Many experiments result indicates that continuous hydrates formation will be feasible for scale-up to industrial settings including downstream oil and gas industry emission reduction if the technology assures an optimal contact between gas and liquid phases plus the proper hydrate promoter. However, compared to current international carbon credit, the feasibility of onshore CO2 abatement cost in downstream oil and gas industry sensitively depends on the distance of CO2 hydrate pipeline transportation.

Coarse-grained model of nanoscale segregation, water diffusion, and proton transport in Nafion membranes.

We present a coarse-grained model of the acid form of Nafion membrane that explicitly includes proton transport. This model is based on a soft-core bead representation of the polymer implemented into the dissipative particle dynamics (DPD) simulation framework. The proton is introduced as a separate charged bead that forms dissociable Morse bonds with water beads. Morse bond formation and breakup artificially mimics the Grotthuss hopping mechanism of proton transport. The proposed DPD model is parameterized to account for the specifics of the conformations and flexibility of the Nafion backbone and sidechains; it treats electrostatic interactions in the smeared charge approximation. The simulation results qualitatively, and in many respects quantitatively, predict the specifics of nanoscale segregation in the hydrated Nafion membrane into hydrophobic and hydrophilic subphases, water diffusion, and proton mobility. As the hydration level increases, the hydrophilic subphase exhibits a percolation transition from a collection of isolated water clusters to a 3D network of pores filled with water embedded in the hydrophobic matrix. The segregated morphology is characterized in terms of the pore size distribution with the average size growing with hydration from ∼1 to ∼4 nm. Comparison of the predicted water diffusivity with the experimental data taken from different sources shows good agreement at high and moderate hydration and substantial deviation at low hydration, around and below the percolation threshold. This discrepancy is attributed to the dynamic percolation effects of formation and rupture of merging bridges between the water clusters, which become progressively important at low hydration, when the coarse-grained model is unable to mimic the fine structure of water network that includes singe molecule bridges. Selected simulations of water diffusion are performed for the alkali metal substituted membrane which demonstrate the effects of the counter-ions on membrane self-assembly and transport. The hydration dependence of the proton diffusivity reproduces semi-qualitatively the trend of the diverse experimental data, showing a sharp decrease around the percolation threshold. Overall, the proposed model opens up an opportunity to study self-assembly and water and proton transport in polyelectrolytes using computationally efficient DPD simulations, and, with further refinement, it may become a practical tool for theory informed design and optimization of perm-selective and ion-conducting membranes with improved properties.

Hydrophilic domain structure in polymer exchange membranes: Simulations of NMR spin diffusion experiments to address ability for model discrimination

ABSTRACTWe detail the development of a flexible simulation program (NMR_DIFFSIM) that solves the nuclear magnetic resonance (NMR) spin diffusion equation for arbitrary polymer architectures. The program was used to explore the proton (1H) NMR spin diffusion behavior predicted for a range of geometrical models describing polymer exchange membranes. These results were also directly compared with the NMR spin diffusion behavior predicted for more complex domain structures obtained from molecular dynamics (MD) simulations. The numerical implementation and capabilities of NMR_DIFFSIM were demonstrated by evaluating the experimental NMR spin diffusion behavior for the hydrophilic domain structure in sulfonated Diels‐Alder Poly(Phenylene) (SDAPP) polymer membranes. The impact of morphology variations as a function of sulfonation and hydration level on the resulting NMR spin diffusion behavior were determined. These simulations allowed us to critically address the ability of NMR spin diffusion to discriminate between different structural models, and to highlight the extremely high fidelity experimental data required to accomplish this. A direct comparison of experimental double‐quantum‐filtered 1H NMR spin diffusion in SDAPP membranes to the spin diffusion behavior predicted for MD‐proposed morphologies revealed excellent agreement, providing experimental support for the MD structures at low to moderate hydration levels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 62–78

DSC investigation of bovine hide collagen at varying degrees of crosslinking and humidities

Bovine hide collagen (nonCLC; non-CrossLinked Collagen) was analysed by differential scanning calorimetry (DSC) at different hydration degrees and compared with hide collagen samples crosslinked with glutaraldehyde (CLC-GA) and chromium(III) ions (CLC-Cr), respectively. Crosslinking and drying were confirmed to increase the denaturation temperature. Different regions were assigned, that reflect the variation of the influence of water on the denaturation temperature. Furthermore, at moderate hydration degrees, the enthalpies of non-crosslinked collagen increase compared to the fully hydrated state. This reflects a glue-like action of water in the range of 25% hydration. Crosslinking of bovine hide collagen decreases the enthalpy by 25% in the fully hydrated state, even at very low levels of crosslinking This can be explained by intensive effects of the crosslinking agent on the hydration network of the collagen molecules, assuming that the enthalpies are principally a result of hydrogen bonding. At very low water contents DSC peaks of CLC-Cr completely disappear. This could be explained by competition between hydroxosulfochromate(III) complexes and collagen for water.

Intensity of hydration changes the role of renin-angiotensin-aldosterone system blockers in contrast-induced nephropathy risk after coronary catheterisation in patients with chronic kidney disease.

Objective:This study evaluated the potential effect of hydration intensity on the role of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) on contrast-induced nephropathy in patients with renal insufficiency.Methods:All eligible patients were included and stratified according to hydration intensity defined as saline hydration volume to body weight tertiles: <10.21 mL/kg, 10.21 to <17.86 mL/kg, and ⩾17.86 mL/kg.Results:In total, 84 (6.7%) of 1254 patients developed contrast-induced nephropathy: 6.2% in the ACEI/ARB group versus 10.8% in the non-ACEI/ARB group (P=0.029), with an adjusted odds ratio (OR) of 0.89 (95% confidence interval (CI) 0.46–1.73, P=0.735). The incidence of contrast-induced nephropathy was lower in the ACEI/ARB group than in the non-ACEI/ARB group in the second tertile (P=0.031), while not significantly different in the first (P=0.701) and third (P=0.254) tertiles. ACEIs/ARBs were independently associated with a lower contrast-induced nephropathy risk (OR 0.26, 95% CI 0.09–0.74, P=0.012) and long-term all-cause death (hazard ratio 0.461, 95% CI 0.282–0.755, P=0.002) only in the second hydration volume to body weight tertile.Conclusion:The effects of ACEIs/ARBs on contrast-induced nephropathy risk vary according to saline hydration intensity in chronic kidney disease patients, and may further reduce contrast-induced nephropathy risk in patients administered moderate saline hydration.