Zeta potentials of PDMS surfaces modified with poly(ethylene glycol) by physisorption.

Controlling zeta potential of PDMS surface coated with a layer of PEG is important for electroosmosis and electrophoresis in PDMS made microfluidic chips. Here, zeta potentials of PDMS surfaces modified by simple physisorption of PEG of different concentrations in phosphate buffer solutions, pure water, and PEG solution were reported. Coating PEG on PDMS surfaces was achieved by immersing a PDMS layer into the PEG solution for 10 min and then taking it out and placing it in an oven at 80℃ for 10 h. To avoid damaging the PEG layer on the PDMS surface, an induction current method was employed for zeta potential measurement. Zeta potentials of PEG modified PDMS in electrolyte solutions were measured. The results show that 2.5% PEG can effectively modify PDMS surface with positive zeta potential value in phosphate buffer solutions, pure water and 10% PEG solution. Further increase in PEG solution beyond 5% for surface modification has no obvious effect on zeta potential change.

Short communication: Hypernatremia in diarrheic calves associated with oral electrolyte administration in water and milk replacer in absence of access to water.

A major goal in treatment of calves with diarrhea is to restore hydration and to correct metabolic acidosis. This can be achieved by the administration of oral electrolyte solutions (OES). However, the composition of OES products and the administration protocols in practice vary widely, which can potentially compromise the efficacy and safety of these treatments. In particular, administration of OES in milk replacer (MR) and the absence of water supply in young calves are not unusual and these conditions could compromise calf health. In this light, the objective of this study was to evaluate the efficacy and safety of OES administered in MR and in water without access to water. Forty-five male Holstein calves (16.6 ± 1.6 d of age and 45.4 ± 2.2 kg at arrival) were purchased from a collection center located in the Netherlands. After arrival, calves went through an adaptation period of 4 d. Calves that developed diarrhea within 6 d after the end of the adaptation period were enrolled in the study, and the remaining calves were sold after being weaned. Upon morning detection of abnormal fecal scores (d 1 starting point), calves were blocked based on initial BW. Within each block, calves were randomly assigned to 1 of 2 treatments, including a control consisting of a small dose of whey (CON; n = 12) and an OES treatment (OES; n = 14). Treatments were blinded to the farm staff by randomly assigning a letter to each treatment. Treatments were simultaneously administered for 4 d in MR (2.5 L at 0800 and 1730 h) and in water (3 L at 1300 and 2200 h). Calves had no supplemental access to plain water. Blood samples were taken at 0600 h for 4 d, and fecal scores (0 = normal; 1 = watery feces) were assessed daily at 0900 h for 15 consecutive days. Additionally, skin turgor and degree of enophthalmos were assessed at 1000 h from d 1 to 4 using a 3-level scoring system. Calves fed OES had a higher prevalence of diarrhea on d 3, 4, and 5 as well as higher prevalence of delayed skin turgor and increased degree of enophthalmos over the 4 monitoring days. Diarrhea duration was longer in calves receiving OES than in calves receiving CON (4.2 d vs. 2.1 d, respectively). The OES treatment resulted in hypernatremia (serum Na+ >145 mmol/L) within 48 h after the first OES administration. Hypernatremia was linked with higher serum Cl- and urea concentrations and thus higher serum osmolarity in OES calves compared with CON calves. Administered under these conditions, OES resulted in various degrees of hypernatremia and a delayed recovery from diarrhea, thus defeating the purpose of OES administration.

Temperature Compensation for Conductivity-Based Phase Fraction Measurements with Wire-Mesh Sensors in Gas-Liquid Flows of Dilute Aqueous Solutions.

Wire-mesh sensors are well-established scientific instruments for measuring the spatio-temporal phase distribution of two-phase flows based on different electrical conductivities of the phases. Presently, these instruments are also applied in industrial processes and need to cope with dynamic operating conditions increasingly. However, since the quantification of phase fractions is achieved by normalizing signals with respect to a separately recorded reference measurement, the results are sensitive to temperature differences in any application. Therefore, the present study aims at proposing a method to compensate temperature effects in the data processing procedure. Firstly, a general approach is theoretically derived from the underlying measurement principle and compensation procedures for the electrical conductivity from literature models. Additionally, a novel semi-empirical model is developed on the basis of electrochemical fundamentals. Experimental investigations are performed using a single-phase water loop with adjustable fluid temperature in order to verify the theoretical approach for wire-mesh sensor applications and to compare the different compensation models by means of real data. Finally, the preferred model is used to demonstrate the effect of temperature compensation with selected sets of experimental two-phase data from a previous study. The results are discussed in detail and show that temperature effects need to be handled carefully-not merely in industrial applications, but particularly in laboratory experiments.

Electric Double Layers with Surface Charge Regulation Using Density Functional Theory.

Surprisingly, the local structure of electrolyte solutions in electric double layers is primarily determined by the solvent. This is initially unexpected as the solvent is usually a neutral species and not a subject to dominant Coulombic interactions. Part of the solvent dominance in determining the local structure is simply due to the much larger number of solvent molecules in a typical electrolyte solution.The dominant local packing of solvent then creates a space left for the charged species. Our classical density functional theory work demonstrates that the solvent structural effect strongly couples to the surface chemistry, which governs the charge and potential. In this article we address some outstanding questions relating double layer modeling. Firstly, we address the role of ion-ion correlations that go beyond mean field correlations. Secondly we consider the effects of a density dependent dielectric constant which is crucial in the description of a electrolyte-vapor interface.

Effects of different solutions consumed during exercise on cognitive function of male college soccer players.

Background/Objectives: The present study aimed to investigate the effects of three solutions, i.e. carbohydrate-electrolyte-solution (CES), carbohydrate-electrolyte-protein-solution (CEPS), and placebo (PLA), on cognitive function of college soccer players. METHODS: Sixteen male college soccer players completed three main trials in a randomized cross-over study design. In each main trial, participants completed 90 min Loughborough Intermittent Shuttle Test (LIST) protocol and consumed one of three solutions. The cognitive function tests were performed; blood glucose and lactate concentrations, and several subjective measurements were also recorded in each trial. RESULTS: Compared with pre-exercise level, the accuracy of Rapid Visual Information Processing test (RVIPT) and the response time in Visual Search Test (VST, complex level) after LIST improved in CES and CEPS trials, but not in PLA trial. However, the accuracy of VST (complex level) decreased in both CES and CEPS trials, compared with PLA trial. CEPS consumption improved accuracy in VST (simple level), compared with CES consumption. Blood glucose concentrations were well maintained in CEPS trial, but not in CES and PLA trials. CONCLUSION: It seems that both CES and CEPS consumption show certain benefits on some aspects of cognitive function in male college soccer players in Hong Kong. However, these effects may be specific to the cognitive domain tested.

Comparison of oral, intravenous, and subcutaneous fluid therapy for resuscitation of calves with diarrhea.

Neonatal diarrhea remains the primary cause of mortality in dairy calves around the world, and optimal treatment protocols are needed. The main goals of therapy are to restore hydration and electrolyte concentrations, correct strong ion (metabolic) acidemia, and provide nutritional support. Administration of oral electrolyte solutions (OES) has long been the primary method used to treat neonatal diarrhea in humans and calves because OES are capable of addressing each of the primary goals of therapy. In calves with moderate dehydration, we hypothesized that oral electrolytes would be as good as or better than small volumes of intravenous (IV) or subcutaneous (SC) fluids. Therefore, the main goal of this study was to compare the ability of a commercially available oral electrolyte solution (OES) administered alone or in combination with hypertonic saline with small volumes of IV or SC fluid therapy to resuscitate calves with diarrhea. Thirty-three Holstein calves from 5 to 14 d of age were utilized in this clinical trial. Diarrhea and dehydration were induced by adding sucrose to the milk replacer. In addition, hydrochlorothiazide and spironolactone were given orally and furosemide intramuscularly. Depression status, clinical hydration scores, fecal consistency, and body weight were recorded at regular intervals. Treatment began when calves had severe diarrhea and had a decrease in plasma volume of at least 10%. Calves were randomly assigned to 1 of 4 treatment groups of 8 to 9 calves per group: (1) OES; (2) OES with hypertonic saline (4 mL/kg, IV); (3) IV fluids (lactated Ringer's, 2 L); or (4) SC fluids (lactated Ringer's, 2 L). Treatments were given at 0 and 12 h. Changes in plasma volume, blood pH, electrolyte levels, and physical examination scores were determined before therapy and again at 1, 2, 4, 8, and 12 h after each treatment. All 4 treatments were ultimately successful in improving hydration as well as increasing blood pH; however, animals in both groups that received OES had much faster resuscitation than those in either the IV or SC fluid group. In conclusion, oral electrolyte products remain the gold standard for resuscitating diarrheic calves with moderate dehydration and acidemia and will likely perform better than small volumes of IV lactated Ringer's solution. Subcutaneous fluids by themselves are a poor treatment option and should be only be used as supportive therapy following the initial correction of hypovolemia and metabolic acidosis.

Role of Carboxyl and Amine Termination on a Boron-Doped Diamond Solution Gate Field Effect Transistor (SGFET) for pH Sensing.

In this paper, we report on the effect of carboxyl- and amine terminations on a boron-doped diamond surface (BDD) in relation to pH sensitivity. Carboxyl termination was achieved by anodization oxidation in Carmody buffer solution (pH 7). The carboxyl-terminated diamond surface was exposed to nitrogen radicals to generate an amine-terminated surface. The pH sensitivity of the carboxyl- and amine-terminated surfaces was measured from pH 2 to pH 12. The pH sensitivities of the carboxyl-terminated surface at low and high pH are 45 and 3 mV/pH, respectively. The pH sensitivity after amine termination is significantly higher—the pH sensitivities at low and high pH are 65 and 24 mV/pH, respectively. We find that the negatively-charged surface properties of the carboxyl-terminated surface due to ionization of ⁻COOH causes very low pH detection in the high pH region (pH 7⁻12). In the case of the amine-terminated surface, the surface properties are interchangeable in both acidic and basic solutions; therefore, we observed pH detection at both low and high pH regions. The results presented here may provide molecular-level understanding of surface properties with charged ions in pH solutions. The understanding of these surface terminations on BDD substrate may be useful to design diamond-based biosensors.

Aqueous solution interactions with sex hormone-binding globulin and estradiol: a theoretical investigation.

Sex hormone-binding globulin (SHBG) is a binding protein that regulates the availability of steroid hormones in the plasma. Although best known as a steroid carrier, recent studies have associated SHBG in modulating behavioral aspects related to sexual receptivity. Among steroids, estradiol (17ß-estradiol, oestradiol or E2), documented as the most active endogenous female hormone, exerts important physiological roles in both reproductive and non-reproductive functions. In this framework, we employed molecular dynamics (MD) and docking techniques for quantifying the interaction energy between a complex aqueous solution, composed by different salts, SHBG and E2. As glucose concentration resembles measured levels in diabetes, special emphasis was devoted to analyzing the interaction energy between this carbohydrate, SHBG and E2 molecules. The calculations revealed remarkable interaction energy between glucose and SHBG surface. Surprisingly, a movement of solute components toward SHBG was observed, yielding clusters surrounding the protein. The high energy and short distance between glucose and SHBG suggests a possible scenario in favor of a detainment state between the sugar and the protein. In this context, we found that glucose clustering does not insert modification on binding site area nor over binding energy SHBG-E2 complex, in spite of protein superficial area increment. The calculations also point to a more pronounced interaction between E2 and glucose, considering the hormone immersed in the solution. In summary, our findings contribute to a better comprehension of both SHBG and E2 interplay with aqueous solution components.

An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor.

A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2-10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.

A metered intake of milk following exercise and thermal dehydration restores whole-body net fluid balance better than a carbohydrate-electrolyte solution or water in healthy young men.

Appropriate rehydration and nutrient intake in recovery is a key component of exercise performance. This study investigated whether the recovery of body net fluid balance (NFB) following exercise and thermal dehydration to -2 % of body mass (BM) was enhanced by a metered rate of ingestion of milk (M) compared with a carbohydrate-electrolyte solution (CE) or water (W). In randomised order, seven active men (aged 26·2 (sd 6·1) years) undertook exercise and thermal dehydration to -2 % of BM on three occasions. A metered replacement volume of M, CE or W equivalent to 150 % of the BM loss was then consumed within 2-3 h. NFB was subsequently measured for 5 h from commencement of rehydration. A higher overall NFB in M than CE (P=0·001) and W (P=0·006) was observed, with no difference between CE and W (P=0·69). After 5 h, NFB in M remained positive (+117 (sd 122) ml) compared with basal, and it was greater than W (-539 (sd 390) ml, P=0·011) but not CE (-381 (sd 460) ml, P=0·077, d=1·6). Plasma osmolality (Posm) and K remained elevated above basal in M compared with CE and W. The change in Posm was associated with circulating pre-provasopressin (r s 0·348, P<0·001), a biomarker of arginine vasopressin, but could not account fully for the augmented NFB in M compared with CE and W. These data suggest that a metered approach to fluid ingestion acts in synergy with the nutrient composition of M in the restoration of NFB following exercise and thermal dehydration.

Extended Debye-Hückel theory for studying the electrostatic solvation energy.

The electrostatic part of the solvation energy has been studied by using extended Debye-Hückel (DH) theories. Specifically, our molecular Debye-Hückel theory [J. Chem. Phys. 2011, 135, 104104] and its simplified version, an energy-scaled Debye-Hückel theory, were applied to electrolytes with strong electrostatic coupling. Our theories provide a practical methodology for calculating the electrostatic solvation free energies, and the accuracy was verified for atomic and diatomic charged solutes.

The development of pediatric fluid resuscitation: an interview with Dr. Frederic A. 'Fritz' Berry.

Dr. Frederic A. 'Fritz' Berry (1935), Professor Emeritus of Anesthesiology and Pediatrics at the University of Virginia, has played a pioneering role in the development of pediatric anesthesiology through training generations of anesthesiologists. He identifies his early advocacy of balanced electrolyte solution for perioperative fluid resuscitation as his defining contribution. Based on his clinical experiences, he pushed to extend the advances in adult fluid resuscitation into pediatric practice. He imparted these and other insights to his colleagues although textbooks, book chapters, original journal publications, and decades of Refresher Course Lectures at the American Society of Anesthesiologists' annual meetings. A model educator, clinician, and researcher, he shaped the careers of hundreds of physicians-in-training while advancing the field of pediatric anesthesiology.

Rehydration post-transport: duration of oral fluid therapy on behavior, biochemical measures of hydration, and health of neonatal dairy calves.

The objective of this study was to determine the impact of 0, 1, 2, or 3 d of oral electrolyte solutions (OES) following transport on calf behavior, biochemical measures of hydration, and subsequent health. Two cohorts of 60 Holstein bull calves ~3 to 7 d of age were included in this experiment. Calves (n = 30/treatment) were randomized to 1 of 4 treatments on arrival at a calf-raising facility: (1) 1-d OES, (2) 2-d OES, (3) 3-d OES, or (4) no OES (control). Calves were evaluated for signs of arthritis, depression, dehydration, diarrhea, fever, navel inflammation, and respiratory disease on arrival (day 0) and 1, 2, 3, and 7 d after arrival. Blood was obtained following each examination to assess biochemical measures of hydration, including serum electrolytes, glucose, hematocrit, lactate, pH, and serum total protein (STP). Calves were fitted with 3D accelerometers attached to the right hind leg along the metatarsus bone to continuously measure lying time. Linear regression models with Gaussian or Poisson link functions were used to test differences between treatments in blood parameters, as well as disease frequency and behavior, respectively. Calves spent the most time lying immediately post-transport (day 0); however, there was no effect of OES treatment on lying time. On arrival, 90% (95% CI: 84.6% to 95.4%) of calves had mild to moderate dehydration, and there was no significant difference in hydration status across treatments. Mildly dehydrated calves that received 1- and 2-d OES had higher STP concentration compared to the control. Moderately dehydrated calves that received 3- vs. 1-d OES had higher (101.4 vs. 93.7 mmol/L, respectively; P = 0.01) glucose concentration, and 3- vs. 2-d OES (101.4 vs. 96.2, respectively; P = 0.07) calves tended to have higher glucose concentration. The prevalence of failed transfer of passive immunity (STP < 5.1 g/dL) and hypoglycemia (glucose < 4.95 mmol/L) was 26.7% (18.6% to 34.7%) and 76.5% (68.7% to 84.2%), respectively. The frequency of moderate dehydration was lower for calves that received 2-d OES compared to the control (count ratio: 0.4; 0.2% to 0.8%; P = 0.009). These results underline the need for more research on rehydration strategies to help inform calf processing protocols. Future research should investigate preconditioning strategies to minimize the impact of marketing and transport on dairy calves. Continued nutritional-based research is also needed to better support calves' recovery post-transport.

Most male calves are sold and transported from the dairy farm soon after birth. Typically, calves are transported without access to milk and/or water, and they often arrive at calf-raising facilities with varying degrees of dehydration. This study provided calves with 0 (control), 1, 2, or 3 consecutive days of oral electrolyte solutions following transportation and assessed calf behavior, biomarkers of hydration, and subsequent health post-transport. Most calves were dehydrated and hypoglycemic (low blood glucose levels) on arrival at the calf-raising facility. Calves spent the most time lying immediately post-transport; however, electrolytes did not impact total lying time, the number of lying bouts, or lying bout duration. Providing calves with electrolytes for 2 d improved moderate dehydration (assessed via skin tent test) compared to the control. These results suggest that providing calves with 2 consecutive days of electrolytes following transportation can improve hydration status; however, more research is needed to mitigate dehydration prior to arrival at calf-raising facilities.

Sugar-free menthol candy drops improve the palatability and bowel cleansing effect of polyethylene glycol electrolyte solution.

BACKGROUND: Colon preparations are generally poorly tolerated. OBJECTIVE: To study the efficacy of sugar-free candy drops in improving palatability and tolerability of polyethylene glycol electrolyte solution (PEG-E). DESIGN: Single-blind, randomized, controlled trial. SETTING: University medical center. PATIENTS: Ambulatory patients scheduled for elective colonoscopy. INTERVENTION: Menthol candy drops. Patients were randomly assigned to split-dose, 4-L, PEG-E ± cough drops. Palatability was assessed on a linear scale of 1 to 5 (1 = disgusting; 5 = tasty). Quality of preparation, remaining unconsumed volume, and side effects were secondary outcomes. MAIN OUTCOME MEASUREMENTS: Palatability and tolerability of PEG-E. RESULTS: A total of 99 patients were enrolled (50 control group, 49 candy drops-added group). The mean (± standard deviation) palatability score was significantly better in candy drop users versus controls (3.9 ± 0.7 vs 2.8 ± 1.2, respectively; P < .001) as were the preparations scored as excellent (63.3% vs 34% of controls; P = .004). Side effects were similar except for nausea (24.5% candy drops vs 44% controls; P = .04). The amount of unconsumed PEG-E was not different between candy drop and control groups (128 [± 361 mL] versus 69 [± 194 mL], respectively; P = .32) but was significantly lower in excellent grade preparations versus other grades (31 [± 103 mL] versus 162 [± 384 mL], respectively; P = .024). On multivariate logistic regression, an excellent preparation was associated with candy drops (odds ratio [OR] 3.3, 95% confidence interval [CI], 1.4-7.8; P = .006) and smaller unconsumed volume of same-day PEG-E [OR 0.996, 95% CI, 0.992-1.000; P = .044). LIMITATIONS: Single-center study. CONCLUSION: Sugar-free menthol candy drops are a safe and effective addition to split-dose PEG-E, resulting in improved tolerability and patient compliance, which appears to translate into improved bowel cleansing. ( CLINICAL TRIAL REGISTRATION NUMBER: NCT01541683.).

Nonlinear dielectric decrement of electrolyte solutions: An effective medium approach.

HYPOTHESIS: The dielectric constant of an electrolyte solution, which determines electrostatic interactions between colloids and interfaces, depends nonlinearly on the salinity and also on the type of salt. The linear decrement at dilute solutions is due to the reduced polarizability in the hydration shell around an ion. However, the full hydration volume cannot explain the experimental solubility, which indicates the hydration volume should decrease at high salinity. Volume reduction of the hydration shell is supposed to weaken dielectric decrement and thus should be relevant to the nonlinear decrement. SIMULATIONS: According to the effective medium theory for the permittivity of heterogeneous media, we derive an equation which relates the dielectric constant with the dielectric cavities created by the hydrated cations and anions, and the effect of partial dehydration at high salinity is taken into account. FINDINGS: Analysis of experiments on monovalent electrolytes suggests that weakened dielectric decrement at high salinity originates primarily from the partial dehydration. Furthermore, the onset volume fraction of the partial dehydration is found to be salt-specific, and is correlated with the solvation free energy. Our results suggest that while the reduced polarizability of the hydration shell determines the linear dielectric decrement at low salinity, ion-specific tendency of dehydration is responsible for nonlinear dielectric decrement at high salinity.

Oral rehydration beverages for treating exercise-associated dehydration: a systematic review.Part I: carbohydrate-electrolyte solutions.

OBJECTIVE: Exercise-associated dehydration is a common problem, especially at sporting events. Although there are recommendations to drink a certain volume per kg body mass lost after exercise, there is no clear guidance about the type of rehydration beverage. The aim of this systematic review is to assess the effectiveness of carbohydrate-electrolyte solutions as a rehydration solution for exercise-associated dehydration. DATA SOURCES: Medline (via the PubMed interface), Embase and the Cochrane Library were searched for relevant studies. The search is up to date until June 2022. STUDY SELECTION: Controlled trials involving adults and children were included if dehydration was the result of physical exercise and if drinking carbohydrate-electrolyte solutions, of any percentage carbohydrate, was compared with drinking water. All languages were included as long as an English abstract was available. DATA EXTRACTION: Data on study design, study population, interventions, outcome measures and study limitations were extracted from each included article. Certainty was assessed using GRADE. DATA SYNTHESIS: Out of 3485 screened articles, 19 studies were included that assessed carbohydrate-electrolyte solutions (0% - 9% carbohydrate) compared with water. Although there is variability amongst the identified studies, drinking 0-3.9% and, especially, 4-9% carbohydrate-electrolyte (CE) solution may be effective for rehydration. CONCLUSIONS: A potential beneficial effect of drinking CE drinks compared with water was seen for many of the reviewed outcomes. Commercial CE drinks (ideally 4-9% CE drinks or alternatively 0-3.9% CE drinks) could be suggested for rehydration in persons with exercise associated dehydration when whole foods are not available.

Enteral hydration in cows: Comparison between continuous flow and bolus administration.

BACKGROUND: Enteral hydration in cattle is most commonly performed as a bolus (B) via the ororuminal route, although continuous flow (CF) administration via the nasoesophageal route represents a viable alternative. Currently, no study has compared the effectiveness of these two methods. This study aimed to compare the efficiency of enteral hydration using CF and B to correct water, electrolyte and acid-base imbalances in cows. METHODS: Protocols for the induction of dehydration were applied twice to eight healthy cows, with an interval of 1 week. In a crossover design, two types of enteral hydration were performed using the same electrolyte solution and volume equal to 12% of bodyweight (BW): CF (10 mL/kg/h, between 0 and 12 hours) and B (6% BW, twice, at 0 and 6 hours). Clinical and blood variables were determined at -24, 0, 6, 12 and 24 hours and compared using repeated-measures ANOVA. RESULTS: Induced moderate dehydration and hypochloremic metabolic alkalosis were corrected after 12 hours using the two hydration methods, with no differences observed between the methods. LIMITATIONS: The study was conducted with induced rather than natural imbalances, so the findings should be interpreted cautiously. CONCLUSION: Enteral CF hydration is as effective as B hydration in reversing dehydration and correcting electrolyte and acid-base imbalances.

Molecular Dynamics Investigation of Hyaluronan in Biolubrication.

Aqueous solution of strongly hydrophilic biopolymers is known to exhibit excellent lubrication properties in biological systems, such as the synovial fluid in human joints. Several mechanisms have been proposed on the biolubrication of joints, such as the boundary lubrication and the fluid exudation lubrication. In these models, mechanical properties of synovial fluid containing biopolymers are essential. To examine the role of such biopolymers in lubrication, a series of molecular dynamics simulations with an all-atom classical force field model were conducted for aqueous solutions of hyaluronan (hyaluronic acid, HA) under constant shear. After equilibrating the system, the Lees-Edwards boundary condition was imposed, with which a steady state of uniform shear flow was realized. Comparison of HA systems with hydrocarbon (pentadecane, PD) solutions of similar mass concentration indicates that the viscosity of HA solutions is slightly larger in general than that of PDs, due to the strong hydration of HA molecules. Effects of added electrolyte (NaCl) were also discussed in terms of hydration. These findings suggest the role of HA in biolubirication as a load-supporting component, with its flexible character and strong hydration structure.

Fluorine-Terminated Polycrystalline Diamond Solution-Gate Field-Effect Transistor Sensor with Smaller Amount of Unexpectedly Generated Fluorocarbon Film Fabricated by Fluorine Gas Treatment.

In this study, a partially fluorine-terminated solution-gate field-effect transistor sensor with a smaller amount of unexpectedly generated fluorohydrocarbon film on a polycrystalline diamond channel is described. A conventional method utilizing inductively coupled plasma with fluorocarbon gas leads the hydrogen-terminated diamond to transfer to a partially fluorine-terminated diamond (C-F diamond); an unexpected fluorohydrocarbon film is formed on the surface of the diamond. To overcome this issue, we newly applied fluorine gas for the fluoridation of the diamond. Analytical results of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry suggest that the fluorocarbon film does not exist or only a smaller amount of fluorocarbon film exists on the diamond surface. Conversely, the C-F diamond fabricated by the conventional method of inductively coupled plasma with a perfluoropropane gas (C3F8 gas) source possesses a certain amount of fluorocarbon film on its surface. The C-F diamond with a smaller amount of unexpectedly generated fluorohydrocarbon film possesses nearly ideal drain-source-voltage vs. gate-source-current characteristics, corresponding to metal-oxide-silicon semiconductor field-effect transistor theory. The results indicate that the fluorine gas (F2 gas) treatment proposed in this study effectively fabricates a C-F diamond sensor without unexpected semiconductor damage.

Electrification of water interface.

The surface charge of a water interface determines many fundamental processes in physical chemistry and interface science, and it has been intensively studied for over a hundred years. We summarize experimental methods to characterize the surface charge densities developed so far: electrokinetics, double-layer force measurements, potentiometric titration, surface-sensitive nonlinear spectroscopy, and surface-sensitive mass spectrometry. Then, we elucidate physical ion adsorption and chemical electrification as examples of electrification mechanisms. In the end, novel effects on surface electrification are discussed in detail. We believe that this clear overview of state of the art in a charged water interface will surely help the fundamental progress of physics and chemistry at interfaces in the future.