Surface Hydroxylation-Induced Electrostatic Forces Thicken Water Films on Quartz.

Aqueous films on mineral surfaces control the physical, chemical, and biological transport processes in the atmosphere, soil, and rocks. Despite the importance of thin films for various research and engineering fields, there are still unanswered questions regarding the roles of the different forces affecting the nature of water films. One of these, the focus of this study, is the development of abnormally thick water films on quartz surfaces. In this study, we developed a density-functional-theory-based model to describe the time-dependent evolution of water films and identify the governing forces responsible for thickening films. We simulated the diffusion of water vapor from ambient air toward mineral surfaces and the formation and thickening of water films at various relative humidity values. Our model predicts an abnormal water film thickness on a hydroxylated quartz surface compared to a surface free of hydroxylation, which explains experimental observations. We further used the model to understand the key interaction forces at different stages of water film formation and thickening. Our model suggests that the attractive hydrogen bonding and van der Waals forces initiate a seed layer of water, and the electrostatic forces, generated by the hydroxylated and thus charged surface, lead to the thickening of water films. This generalizable model can provide insights into the peculiarities of water film development on various mineral surfaces.

Rapid Prediction of a Liquid Structure from a Single Molecular Configuration Using Deep Learning.

Molecular dynamics simulation is an indispensable tool for understanding the collective behavior of atoms and molecules and the phases they form. Statistical mechanics provides accurate routes for predicting macroscopic properties as time-averages over visited molecular configurations - microstates. However, to obtain convergence, we need a sufficiently long record of visited microstates, which translates to the high-computational cost of the molecular simulations. In this work, we show how to use a point cloud-based deep learning strategy to rapidly predict the structural properties of liquids from a single molecular configuration. We tested our approach using three homogeneous liquids with progressively more complex entities and interactions: Ar, NO, and H2O under varying pressure and temperature conditions within the liquid state domain. Our deep neural network architecture allows rapid insight into the liquid structure, here probed by the radial distribution function, and can be used with molecular/atomistic configurations generated by either simulation, first-principle, or experimental methods.

The analysis of factors increasing the odds for type 2 diabetes mellitus remission following re-do bariatric surgery after laparoscopic sleeve gastrectomy- cohort study.

INTRODUCTION: Metabolic/bariatric surgery is the only proven treatment for type 2 diabetes mellitus (T2D) with curative intent. However, in a number of patients, the surgery is not effective or they may experience a relapse. Those patients can be offered re-do bariatric surgery (RBS). PURPOSE: The study aimed to determine factors increasing the odds for T2D remission one year after RBS following primary laparoscopic sleeve gastrectomy. METHODS: A multicenter retrospective cohort study was conducted between January 2010 and January 2020, which included 12 bariatric centers in Poland. The study population was divided into groups: Group 1- patients with T2D remission after RBS (n = 28) and Group 2- patients without T2D remission after RBS (n = 49). T2D remission was defined as HBA1c < 6.0% without glucose-lowering pharmacotherapy and glycemia within normal range at time of follow-up that was completed 12 months after RBS. RESULTS: Fifty seven females and 20 males were included in the study. Patients who achieved BMI < 33 kg/m2 after RBS and those with %EBMIL > 60.7% had an increased chance of T2D remission (OR = 3.39, 95%CI = 1.28-8.95, p = 0.014 and OR = 12.48, 95%CI 2.67-58.42, p = 0.001, respectively). Time interval between primary LSG and RBS was significantly shorter in Group 1 than in Group 2 [1 (1-4) vs. 3 (2-4) years, p = 0.023]. CONCLUSIONS: Shorter time interval between LSG and RBS may ease remission of T2D in case of lack of remission after primary procedure. Significant excess weight loss seems to be the most crucial factor for T2D remission.

Concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in Human Serum and Adipose Tissues and Stimulatory Effect of Naphthalene in Adipogenesis in 3T3-L1 Cells.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most prevalent classes of environmental pollutants. Some evidence shows that PAHs could be involved in human obesity. However, little is known about the distribution patterns of PAHs in human adipose tissue (AT) and the role of PAHs on adipogenesis/lipogenesis. The aims of this pilot study were to determine concentrations of 16 PAHs defined as high-priority pollutants in the plasma and adipose tissue of French and Polish bariatric patients, as well as their correlation with body mass index (BMI), plasma and AT adipokines expression levels. We finally investigated the role of naphthalene on cell proliferation, viability, and differentiation in 3T3-L1 preadipocytes. The concentration of most PAHs was similar in the three types of AT and it was significantly higher in AT as compared to plasma, suggesting bioaccumulation. Polish patients had higher PAH levels in AT than French ones. Only the concentration of naphthalene in AT was positively correlated with the BMI and serum or adipose chemerin, adiponectin and resistin expression, in French but not in Polish patients, who had significantly higher BMIs. Moreover, naphthalene exposure increased the cell proliferation of 3T3-L1 preadipocytes and lipogenesis, and increased the expression of genes involved in adipogenesis after cell differentiation. Taken together, PAHs and more particularly naphthalene could be an obesogenic molecule and increase the risk of obesity.

Differences in Technical Aspects of Primary Sleeve Gastrectomy Prior to Redo Bariatric Surgery-A Multicenter Cohort Study (PROSS Study).

Background and Objectives: Although the technical simplicity of laparoscopic sleeve gastrectomy is relatively well understood, many parts of the procedure differ according to bariatric surgeons. These technical variations may impact postoperative weight loss or the treatment of comorbidities and lead to qualification for redo procedures. Materials and Methods: A multicenter, observational, retrospective study was conducted among patients undergoing revision procedures. Patients were divided into three groups based on the indications for revisional surgery (insufficient weight loss or obesity-related comorbidities treatment, weight regain and development of complications). Results: The median bougie size was 36 (32-40) with significant difference (p = 0.04). In 246 (51.57%) patients, the resection part of sleeve gastrectomy was started 4 cm from the pylorus without significant difference (p = 0.065). The number of stapler cartridges used during the SG procedure was six staplers in group C (p = 0.529). The number of procedures in which the staple line was reinforced was the highest in group A (29.63%) with a significant difference (0.002). Cruroplasty was performed in 13 patients (p = 0.549). Conclusions: There were no differences between indications to redo surgery in terms of primary surgery parameters such as the number of staplers used or the length from the pylorus to begin resection. The bougie size was smaller in the group of patients with weight regain. Patients who had revision for insufficient weight loss were significantly more likely to have had their staple line oversewn. A potential cause could be a difference in the size of the removed portion of the stomach, but it is difficult to draw unequivocal conclusions within the limitations of our study.

Chemical, technological, and sensory evaluation of the suitability of coconut by-products in white rolls.

BACKGROUND: Fortification of rolls, one of the most popular snacks for children and adults, with coconut by-products can be interesting in terms of both nutritional enrichment and reduction of food waste. Coconut by-products, such as residues from coconut milk (RCM) and coconut oil (RCO) extraction, are a valuable source of dietary fiber. In the study, coconut flours obtained from RCM and RCO were used (FCM and FCO, respectively) for supplementation of rolls; white wheat flour was replaced with FCM or FCO at levels of 6, 12, and 18 g per 100 g. RESULTS: The effect of the addition of the coconut by-products on the nutritional value, sensory evaluation, physical properties, and texture of rolls was determined after 24 and 72 h of storage. The research showed a positive effect of FCM and FCO on the roll yield, crumb moisture, and baking loss. The sensory evaluation revealed that the 12% addition of coconut residues yielded products with high overall acceptability (8 points on a 9-point scale). Compared with the control, a 12% addition of FCO or FCM contributed to an increase in proteins of 7.9% and 3.9% respectively and an increase in dietary fiber of 76% and 57% respectively. Despite the increase in the fat and protein contents, the energy value of the coconut rolls was significantly lower (244.6 kcal and 245.3 kcal for FCO and FCM respectively) than in the control wheat rolls (266.0 kcal). CONCLUSION: White rolls with coconut flours obtained after grinding residues from oil or coconut milk extraction significantly increased the nutritional value of the rolls. © 2021 Society of Chemical Industry.

Stinging Nettle (Urtica dioica L.) as a Functional Component in Durum Wheat Pasta Production: Impact on Chemical Composition, In Vitro Glycemic Index, and Quality Properties.

Stinging nettle (Urtica dioica L.) is a good source of biologically active compounds with proven beneficial health effects. This study aimed to investigate the effect of nettle herb supplementation on chemical composition, including the content of selected minerals and pigments, the in vitro glycemic response, and the cooking and sensory quality of extruded pasta. Tagliatelle-shaped pasta was produced under semi-technical scale by partial replacement of durum wheat semolina with 0, 1, 2, 3, 4, and 5% of lyophilized nettle. The partial substitution with freeze-dried nettle caused a statistically significant (p ≤ 0.05) increase in the content of minerals, especially calcium, iron, potassium, and magnesium in the products. The calcium content in the pasta fortified with 5%-addition of stinging nettle was 175.9 mg 100 g-1 and this concentration was 5.8 times higher than in the control sample. At the same time, high content of chlorophylls and carotenoids (237.58 µg g-1 and 13.35 µg g-1, respectively) was noticed. Enriching pasta with a 0-5% addition of stinging nettle resulted in a statistically significant (p ≤ 0.05) increase in the content of the total dietary fiber (TDF) (from 5.1 g 100 g-1 to 8.82 g 100 g-1) and the insoluble dietary fiber (IDF) (from 2.29 g 100 g-1 to 5.63 g 100 g-1). The lowest hydrolysis index of starch (HI = 17.49%) and the lowest glycemic index (GI = 49.31%) were noted for the pasta enriched with 3% nettle.

Temperature-dependence of the dielectric relaxation of water using non-polarizable water models.

Key physical and chemical properties of aqueous fluids are determined by the structure and dynamics of the hydrogen bond network of water but we lack adequate models for the linkages between hydrogen bonding and aqueous chemistry, particularly in non-ambient conditions or in confinement. Dielectric relaxation spectroscopy (DRS) provides a sensitive approach for probing water dynamics but sound interpretation of DRS data requires molecular simulation and associated computational methods capable of accurately representing aqueous fluids and their frequency dependent, complex permittivity. Here, we test the accuracy of dielectric spectra of bulk liquid water calculated from molecular dynamics simulations using 19 non-polarizable water models at 298 K. In contrast to prior studies, the simulation size, time-step and duration allow calculation of the dielectric function from 107-1012 Hz without assuming an analytical form. The accuracy of the prediction of the low-frequency (static) dielectric constant at room temperature is related to the water molecule dipole moment, specifically models with µ ≥ 2.4 D give ε(0) with a relative error lower than 5%. However, no water model tested can fully reproduce the complex dielectric spectra of water. For a subset of models, calculations of the dielectric response from -5 to 60 °C reproduces the experimental trend in water dynamics with temperature but the characteristic relaxation time is always underestimated. The calculated water dipole relaxation time and hydrogen-bond lifetime are both exponentially decaying functions of temperature, and exhibit a linear correlation very close to equality. The comparison provides new computational support for the concept that the Debye relaxation of liquid water is determined by the dynamics of the hydrogen-bond network, and that both are ensemble properties.

Legume flour as a natural colouring component in pasta production.

In recent years, natural food colouring components have been sought. The conducted study presents the possibility of using different legume flours as a colouring component in durum wheat semolina pasta. The impact of legume flours addition on chemical composition, cooking quality, and sensory properties of pasta was also investigated. The pasta was fortified with 0-20% of green pea, red lentil, and grass pea flours and was made using lamination technology. An increase in the amount of the legume flour caused a significant increase in the content of dietary fibre, ash, protein, and essential amino acids, including lysine. The addition of the legume flours changed the colour of the pasta samples. Most suitable colouring component of all the studied legume flours was the red lentil flour. The pasta with 20% addition of red lentil flour had the most intense colouring (ΔE = 11.31), highest level of consumer acceptance and were characterized by acceptable cooking losses (7.47% d.m.), appropriate weight increase index (2.44), and high firmness.

Functional outcomes after resections for low rectal tumors: comparison of Transanal with laparoscopic Total Mesorectal excision.

BACKGROUND: Aim of this study was to evaluate functional outcomes of transanal total mesorectal excision (TaTME) in comparison to conventional laparoscopic approach (LaTME) in terms of low anterior resection syndrome (LARS). METHODS: Forty-six patients who underwent total mesorectal excision for low rectal cancer between 2013 and 2017 were enrolled. Primary outcome was the severity of faecal incontinence, assessed both before the treatment and 6 months after ileostomy reversal. LARS score and Jorge-Wexner scale were utilized to analyze its severity. RESULTS: Twenty (87%) from TaTME and 21 (91%) from LaTME group developed LARS postoperatively. There were no significant differences between groups in terms of LARS occurrence (p = 0.63) and severity. The median Wexner score was comparable in both groups (8 [IQR: 4-12] vs 7 [3-11], p = 0.83). Univariate analysis revealed that postoperative complications were a risk factor for LARS development (p = 0.02). Perioperative outcomes, including operative time, blood loss and intraoperative adverse events did not differ significantly between groups either. Five TaTME patients developed postoperative complications, while there were morbidity 6 cases in LaTME group. Quality of mesorectal excision was comparable with 20 and 19 complete cases in TaTME and LaTME groups, respectively. CONCLUSIONS: TaTME provided comparable outcomes in terms of functional outcomes in comparison to LaTME for total mesorectal excision in low rectal cancers. Having said that, LARS prevalence is still high and requires further evaluation of the technique.

Rheological properties of milk-based desserts with the addition of oat gum and κ-carrageenan.

A growing interest in development of milk desserts with good nutritional and rheological properties can be observed. A good and stability rheological as well as nutritional properties of such desserts can be provided by applying suitably composed gum mixtures. In this work, the effect of 0.1% κ-carrageenan addition on the rheological properties of based-milk desserts with different oat gum concentrations (0.1, 0.3 and 0.5%) was investigated. All milk desserts tested in presented study showed a time dependent and shear-thinning flow behavior. The mechanical spectra were characterized by storage module (G') greater than loss module (G"), typical for viscoelastic materials such as gels and dispersions. The incorporation of 0.1% κ-carrageenan into milk dessert with different oat gum concentrations allows to obtain stronger gel structure compared to milk dessert with separate oat gum addition. It can be also observed that desserts systems with the 0.1% κ-carrageenan had more stable viscoelastic properties. Moreover, the use the κ-carrageenan addition caused an increase in consistency coefficient (K) and decreased in n-value for Ostwald de Waele rheological model. Combined addition of oat gum and carrageenan allows to obtain milk dessert with stronger texture. The hardness of milk desserts range from 0.32 to 0.49 N for desserts without κ-carrageenan addition and from 0.513 to 0.557 N for desserts with κ-carrageenan. The high synergistic effect of composed gum mixtures on rheological properties of milk dessert occurs at 0.1% oat gum and 0.1% κ-carrageenan concentration.

A quest for sphincter-saving surgery in ultralow rectal tumours-a single-centre cohort study.

INTRODUCTION: Despite the progress in the treatment of colorectal cancer, there is still no optimal strategy for tumours located adjacent to the anal sphincter. This study aims to evaluate oncological and functional results of surgery for rectal cancer in unfavourable locations in proximity to anal sphincters. MATERIALS AND METHODS: Patients with rectal cancer, which was either initially infiltrating the anal sphincter or located in the close proximity of the sphincter, were included in the study. Patients were submitted to extralevator abdominoperineal resection (APR), intersphincteric resection, or transanal total mesorectal excision (TaTME). Primary outcomes were perioperative data: operative time, blood loss, complications, length of stay (LOS), and 30-day mortality. Secondary outcomes were pathological quality of the specimens and functional outcome 6 months after defunctioning ileostomy closure. RESULTS: Among patients with cancer adjacent to the anal sphincter, 13 (25%) underwent APR, 14 (27%) patients were submitted to intersphincteric resection, and 25 (48%) patients were treated with the TaTME approach. Operative time was 240 (210-270 IQR) for APR, 212.5 (170-260 IQR) for intersphincteric resection, and 270 (240-330 IQR) for TaTME (p = 0.018). Perioperative morbidity was 31% for APR, 36% for intersphincteric resections, and 12% for the TaTME group (p = 0.181). Complete mesorectal excision was achieved in 92% of specimens in the TaTME group, 93% in intersphincteric resections, and 78% in the APR group (p = 0.72). Median circumferential resection margin in APR was 6 mm (4-7 IQR), in intersphincteric resections 7.5 mm (2.5-10 IQR), and in the TaTME group 4 mm (2.8-8 IQR). All patients after intersphincteric resections developed major low anterior resection syndrome (LARS). Four patients in the TaTME group developed minor LARS, and 21 had major LARS. CONCLUSION: Sphincter-saving rectal resections are a feasible alternative to APR with good clinical, pathological, and oncological outcomes. Intersphincteric resections and TaTME seem to be equal in terms of clinicopathological results. The functional outcome is yet to be investigated. TRIAL REGISTRATION: The study was retrospectively registered in Thai Clinical Trials Registry (23-07-2018, ID TCTR20180724001 ).

Stochastic Simulation of Isotopic Exchange Mechanisms for Fe(II)-Catalyzed Recrystallization of Goethite.

Understanding Fe(II)-catalyzed transformations of Fe(III)-(oxyhydr)oxides is critical for correctly interpreting stable isotopic distributions and for predicting the fate of metal ions in the environment. Recent Fe isotopic tracer experiments have shown that goethite undergoes rapid recrystallization without phase change when exposed to aqueous Fe(II). The proposed explanation is oxidation of sorbed Fe(II) and reductive Fe(II) release coupled 1:1 by electron conduction through crystallites. Given the availability of two tracer exchange data sets that explore pH and particle size effects (e.g., Handler et al. Environ. Sci. Technol. 2014 , 48 , 11302 - 11311 ; Joshi and Gorski Environ. Sci. Technol. 2016 , 50 , 7315 - 7324 ), we developed a stochastic simulation that exactly mimics these experiments, while imposing the 1:1 constraint. We find that all data can be represented by this model, and unifying mechanistic information emerges. At pH 7.5 a rapid initial exchange is followed by slower exchange, consistent with mixed surface- and diffusion-limited kinetics arising from prominent particle aggregation. At pH 5.0 where aggregation and net Fe(II) sorption are minimal, that exchange is quantitatively proportional to available particle surface area and the density of sorbed Fe(II) is more readily evident. Our analysis reveals a fundamental atom exchange rate of ∼10-5 Fe nm-2 s-1, commensurate with some of the reported reductive dissolution rates of goethite, suggesting Fe(II) release is the rate-limiting step in the conduction mechanism during recrystallization.

Potentiometric and electrokinetic signatures of iron(II) interactions with (α,γ)-Fe2O3.

The electrochemical signatures of Fe(II) interactions with iron(III) oxides are poorly understood, despite their importance in controlling the amount of mobilized iron. Here, we report the potentiometric titration of α,γ-Fe2O3 oxides exposed to Fe(II) ions. We monitored in situ surface and ζ potentials, the ratio of mobilized ferric to ferrous, and the periodically analyzed nanoparticle crystal structure using X-ray diffraction. Electrokinetic potential reveals weak but still noticeable specific sorption of Fe(II) to the oxide surface under acidic conditions, and pronounced adsorption under alkaline conditions that results in a surface potential reversal. By monitoring the aqueous iron(II/III) fraction, we found that the addition of Fe(II) ions produces platinum electrode response consistent with the iron solubility-activity curve. Although, XRD analysis showed no evidence of γ-Fe2O3 transformations along the titration pathway despite iron cycling between aqueous and solid reservoirs, the magnetite formation cannot be ruled out.

Probing the role of π interactions in the reactivity of oxygen species: a case of ethylzinc aryloxides with different dispositions of aromatic rings toward the metal center.

Ethylzinc derivatives of ortho-hydroxybiphenyl and 2,6-diphenylphenol that bear different nuclearity and dispositions of aromatic rings toward the metal center were synthesized and structurally characterized in the solid state and solution. This family of well-defined compounds was examined as a model system for the activation of dioxygen mediated by using complexes that feature lack of a redox-active metal center. Experimental and theoretical studies indicate an essential role in the oxygenation process of intramolecular interactions that involve aromatic subunits. Additionally, novel results for the oxygenation chemistry of alkylzinc compounds, including the isolation and structural characterization of the unique octanuclear aryloxide (hydroxide) compound Zn8 (OAr)8 (OH)6 (O2 ) with an encapsulated peroxide species, are presented.

Machine learning surrogates for surface complexation model of uranium sorption to oxides.

The safety assessments of the geological storage of spent nuclear fuel require understanding the underground radionuclide mobility in case of a leakage from multi-barrier canisters. Uranium, the most common radionuclide in non-reprocessed spent nuclear fuels, is immobile in reduced form (U(IV) and highly mobile in an oxidized state (U(VI)). The latter form is considered one of the most dangerous environmental threats in the safety assessments of spent nuclear fuel repositories. The sorption of uranium to mineral surfaces surrounding the repository limits their mobility. We quantify uranium sorption using surface complexation models (SCMs). Unfortunately, numerical SCM solvers often encounter convergence problems due to the complex nature of convoluted equations and correlations between model parameters. This study explored two machine learning surrogates for the 2-pK Triple Layer Model of uranium retention by oxide surfaces if released as U(IV) in the oxidizing conditions: random forest regressor and deep neural networks. Our surrogate models, particularly DNN, accurately reproduce SCM model predictions at a fraction of the computational cost without any convergence issues. The safety assessment of spent fuel repositories, specifically the migration of leaked radioactive waste, will benefit from having ultrafast AI/ML surrogates for the computationally expensive sorption models that can be easily incorporated into larger-scale contaminant migration models. One such model is presented here.

Surface potentials of (001), (012), (113) hematite (α-Fe2O3) crystal faces in aqueous solution.

Hematite (α-Fe2O3) is an important candidate electrode for energy system technologies such as photoelectrochemical water splitting. Conversion efficiency issues with this material are presently being addressed through nanostructuring, doping, and surface modification. However, key electrochemical properties of hematite/electrolyte interfaces remain poorly understood at a fundamental level, in particular those of crystallographically well-defined hematite faces likely present as interfacial components at the grain scale. We report a combined measurement and theory study that isolates and evaluates the equilibrium surface potentials of three nearly defect-free single crystal faces of hematite, titrated from pH 3 to 11.25. We link measured surface potentials with atomic-scale surface topology, namely the ratio and distributions of surface protonation-deprotonation site types expected from the bulk structure. The data reveal face-specific points of zero potential (PZP) relatable to points of zero net charge (PZC) that lie within a small pH window (8.35-8.85). Over the entire pH range the surface potentials show strong non-Nernstian charging at pH extremes separated by a wide central plateau in agreement with surface complexation modeling predictions, but with important face-specific distinctions. We introduce a new surface complexation model based on fitting the entire data set that depends primarily only on the proton affinities of two site types and the two associated electrical double layer capacitances. The data and model show that magnitudes of surface potential biases at the pH extremes are on the order of 100 mV, similar to the activation energy for electron hopping mobility. An energy band diagram for hematite crystallites with specific face expression and pH effects is proposed that could provide a baseline for understanding water splitting performance enhancement effects from nanostructuring, and guide morphology targets and pH for systematic improvements in efficiency.

Distance-dependent dielectric constant at the calcite/electrolyte interface: Implication for surface complexation modeling.

HYPOTHESIS: The electrical double layer formed at the mineral/electrolyte interface is often modeled using mean-field approaches based on a continuum description of the solvent whose dielectric constant is assumed to decrease monotonically with decreasing distance to the surface. In contrast, molecular simulations show that the solvent polarizability oscillates near the surface similar to the water density profile - as shown previously, for example, by Bonthuis et al. (D.J. Bonthuis, S. Gekle, R.R. Netz, Dielectric Profile of Interfacial Water and its Effect on Double-Layer Capacitance, Phys Rev Lett 107(16) (2011) 166102). We showed that molecular and mesoscale pictures agree by spatially averaging the dielectric constant obtained from molecular dynamics simulations over the distances relevant to the mean-field representation. In addition, the values of capacitances used to describe the electrical double layer in Surface Complexation Models (SCMs) of the mineral/electrolyte interface can be estimated using molecularly informed spatially averaged dielectric constants and positions of hydration layers. EXPERIMENTS: First, we used molecular dynamics simulations to model the calcite 101¯4/electrolyte interface. Next, by using atomistic trajectories, we calculated the distance-dependent static dielectric constant and water density in the direction normal to the. Finally, we applied spatial compartmentalization consistent with the model of parallel-plate capacitors connected in series to estimate SCM capacitances. FINDINGS: Computationally expensive simulations are required to determine the dielectric constant profile of interfacial water near the mineral surface. On the other hand, water density profiles are readily assessable from much shorter simulation trajectories. Our simulations confirmed that dielectric and water density oscillations at the interface are correlated. Here, we parametrized linear regression models to estimate the dielectric constant directly from the local water density. This is a significant computational shortcut compared to slowly converging calculations relying on total dipole moment fluctuations. The amplitude of the interfacial dielectric constant oscillation can exceed the dielectric constant of the bulk water, suggesting an ice-like frozen state, but only if there are no electrolyte ions. The interfacial accumulation of electrolyte ions causes a decrease in the dielectric constant due to the reduction of water density and re-orientation of water dipoles in ion hydration shells. Finally, we show how to use the computed dielectric properties to estimate SCM's capacitances.

Revisional bariatric procedures in the group of patients over 60 years of age: a multicenter cohort study (PROSS Study).

Introduction: The constantly increasing prevalence of obesity in the population and the lengthening of life expectancy affect the appearance of the problem of pathological obesity also in the elderly. At the same time, an increase in the number of bariatric procedures (also revisional) performed in elderly patients is observed. Aim: To assess the indications for revisional bariatric procedures along with the safety and postoperative results in the group of patients over 60 years of age. Material and methods: The study was conducted in 2019-2020 among patients undergoing revisional bariatric procedures in Polish bariatric centers. The data were obtained through a multicenter, observational retrospective study. Results: Our data consist of 55 (8.1%) patients older than 60 years of age who underwent revisional bariatric procedures. Revisional procedures in the group of patients over 60 years of age had fewer postoperative complications (16.4% vs. 23.1%, p < 0.05). Remission of type II diabetes or arterial hypertension was achieved to a lesser extent in patients operated on over the age of 60 (13% and 15%, respectively) compared to patients operated on under the age of 60 (47% and 34%, respectively; p < 0.05). Conclusions: Revisional bariatric procedures in the group of patients over 60 years of age do not cause an increased risk of postoperative complications or prolonged hospital stay. The possibility of achieving remission or improvement in the treatment of comorbidities in patients operated on over 60 years of age is relatively lower compared to a younger group.

Analysis of the risk factors for perioperative morbidity after laparoscopic revisional bariatric procedures: results from the multicenter Polish Revision Obesity Surgery Study.

BACKGROUND: The growing number of primary bariatric operations has led to an increase in demand for revision surgeries. Higher numbers of revisional operations are also observed in Poland, yet their safety and efficacy remain controversial because of a lack of current recommendations and guidelines. OBJECTIVE: To review risk factors influencing perioperative morbidity. METHODS: A retrospective study was conducted to analyze the results of surgical treatment among 12 Polish bariatric centers. Inclusion criteria were laparoscopic revisional bariatric surgeries and patients ≥18 years of age. The study included 795 patients, of whom 621 were female; the mean age was 47 years (range: 40-55 years). RESULTS: Perioperative morbidity occurred in 92 patients (11.6%) enrolled in the study, including 76 women (82.6%). The median age was 45 years (range: 39-54 years). Statistically significant risk factors in univariate logistic regression models for perioperative complications were the duration of obesity, revisional surgery after Roux-en-Y gastric bypass (RYGB) or adjustable gastric band (AGB), difference in body mass index before revisional surgery and the lowest achieved after primary surgery, and postoperative morbidity of the primary surgery as the cause for revisional bariatric surgery. These factors were included in the multivariate regression model. Revisional surgery after AGB (odds ratio [OR] = 2.18; 95% confidence interval [CI]: 1.28-3.69; P = .004), revisional surgery performed after RYGB (OR = 6.52; 95% CI: 1.98-21.49; P = .002), and revisions due to complication of the primary surgery (OR = 1.89; 95% CI: 1.06-3.34; P = .030) remained independent risk factors for perioperative morbidity. CONCLUSION: Revisional operations after RYGB or AGB and those performed because of postoperative morbidity after primary surgery as the main cause for revisional surgery were associated with a significantly increased risk of postoperative morbidity.