Molar mass-dependent profiles of functional groups and carbohydrates in kraft lignin

Technical lignins are complex, irregular, polyphenolic compounds obtained in large quantities as by-products of the pulp and paper industries or according to current biorefinery setups. The availability of kraft lignin is increasing due to larger scale retrieval from process liquors, which opens new possibilities for further refining or new applications of such lignins. In the present study, sequential ultrafiltration of kraft lignin was performed to fractionate the lignin and to elucidate molar mass-dependent changes in lignin structure. Two industrial black liquors and three precipitated lignins were fractionated, and their functional groups were determined, providing molar mass-dependent profiles. Interrelations between structural parameters and functional groups, the molecular weight ranges, and the different lignin sources are discussed. This will help to establish structure-property-application relationships (SPARs) for technical lignins which are required for any future large-scale application.     

Half order plus time delay (HOPTD) models to tune PI controllers

Methods based on the first‐order plus time delay (FOPTD) model are very popular for tuning proportional‐integral (PI) controllers. The FOPTD model‐based methods are simple and their utility has been proved with many successful applications to a wide range of processes in practice. However, even for some overdamped processes where the FOPTD model seems to be applied successfully, these empirical FOPTD model‐based methods can fail to provide stable tuning results. To remove these drawbacks, a PI controller tuning method based on half‐order plus time delay (HOPTD) model is proposed. Because FOPTD model‐based methods can be applied to higher order processes, the proposed HOPTD model‐based method can be applied to higher order processes as well. It does not require any additional process information compared to the FOPTD model‐based method and hence can be used for overdamped processes in practice, complementing the traditional FOPTD model‐based methods. © 2016 American Institute of Chemical Engineers AIChE J, 63: 601–609, 2017     

Modeling the dynamics of tamponade multicomponent gases during retina reattachment surgery

Vitrectomy and pneumatic retinopexy are common surgical procedures used to treat retinal detachment. To reattach the retina, gases are used to inflate the vitreous space allowing the retina to attach by surface tension and buoyancy forces that are superior to the location of the bubble. These procedures require the injection of either a pure tamponade gas, such as C₃F₈ or SF₆, or mixtures of these gases with air. The location of the retinal detachment, the anatomical spread of the retinal defect, and the length of time the defect has persisted, will determine the suggested volume and duration of the gas bubble to allow reattachment. After inflation, the gases are slowly absorbed by the blood allowing the vitreous to be refilled by aqueous. We have developed a model of the mass transfer dynamics of tamponade gases during pneumatic retinopexy or pars plana vitrectomy procedures. The model predicts the expansion and persistence of intraocular gases (C₃F₈, SF₆), oxygen, nitrogen, and carbon dioxide, as well as the intraocular pressure. The model was validated using published literature in rabbits and humans. In addition to correlating the mass transfer dynamics by surface area, permeability, and partial pressure driving forces, the mass transfer dynamics are affected by the percentage of the tamponade gases. Rates were also correlated with the physical properties of the tamponade and blood gases. The model gave accurate predictions in humans. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3651–3662, 2017     

Numerical simulation of solvent and water assisted electrical heating of oil sands including aquathermolysis and thermal cracking reactions

Simulations of bitumen recovery using solvent‐ and water‐assisted electrical heating of oil sands are presented to evaluate the process and to study gas generation. Aquathermolysis and thermal cracking and dissolution of acid‐gases in water are included. Steam‐assisted gravity drainage (SAGD) is also simulated for comparison. Results show that gas generation negatively impacts SAGD. However, in electrical heating dissolution of gases into solvent weakens their negative impact. Results indicate that SAGD generates a larger gas volume than electrical heating. In both processes, methane is found to be the major species in the produced gas and H₂S concentration can reach high values. While the effect of acid–gas solubility in water on oil recovery is not evident its effect on generated gas volume is significant. Simulation results demonstrate that electrical heating is more energy efficient than SAGD. These results find application in design of experiments and pilot and field‐scale implementation of the process. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4243–4258, 2017     

Analogy between adsorption and sorption:An elementary mechanistic approach.I.Monolayer adsorption and sorption without solvent cluster formation

The elementary mechanistic model of adsorption and sorption is based on a simple hypothesis:the adsorption sites are uniformly distributed on the surface of the pore walls in the adsorbent,the sorption sites are uniformly distributed in the volume of the polymer.In this first paper we will analyze the simple case where one solute mol-ecule is only allowed to occupy a single adsorption or sorption site.A common elementary occupation law of the free sites is assumed:the differential increase of the number of the adsorbed/sorbed molecules is proportional to the differential increase of the activity of the solute and the concentration of the free(non-occupied)sites in the solid.The proportionality coefficient is called affinity coefficient depending on the solid/solute couple and on the temperature and independent of the concentration of the solute.In adsorption the concentration of the free sites is a surface concentration on the pore walls and in sorption it is expressed by the molarity.The simple mono-layer adsorption law of Jovanovi?is obtained:n=n0(1?e?KP)where n is the number of moles adsorbed when the pressure is P. n0is the total number of adsorption sites and K the affinity coefficient for adsorption.The sorption law writes:a= 1k? ?1??]+1?rk ln?1+1r?1??]where?,r and k hold respectively for the volume fraction of the solvent in the polymer,for the ratio of the molar volumes of the solvent to the elementary polymer chain containing one single adsorption site and for the sorption affinity coefficient.The confrontation of these equations to experimental isotherms is satisfactory in comparison with the classical Langmuir and Flory-Huggins equations:the best results are obtained for adsorption of vapors on a 5A zeolite and for all analyzed sorption results.     

Effect of betaine supplementation on cycling sprint performance

Purpose

To examine the effect of betaine supplementation on cycling sprint performance.

Methods

Sixteen recreationally active subjects (7 females and 9 males) completed three sprint tests, each consisting of four 12 sec efforts against a resistance equal to 5.5% of body weight; efforts were separated by 2.5 min of cycling at zero resistance. Test one established baseline; test two and three were preceded by seven days of daily consumption of 591 ml of a carbohydrate-electrolyte beverage as a placebo or a carbohydrate-electrolyte beverage containing 0.42% betaine (approximately 2.5 grams of betaine a day); half the beverage was consumed in the morning and the other half in the afternoon. We used a double blind random order cross-over design; there was a 3 wk washout between trials two and three. Average and maximum peak and mean power were analyzed with one-way repeated measures ANOVA and, where indicated, a Student Newman-Keuls.

Results

Compared to baseline, betaine ingestion increased average peak power (6.4%; p < 0.001), maximum peak power (5.7%; p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%; p = 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly increased average peak power (3.4%; p = 0.026), maximum peak power max (3.8%; p = 0.007), average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for all subjects combined. There were no differences between the placebo and baseline trials.

Conclusions

One week of betaine ingestion improved cycling sprint power in recreationally active males and females.     

Food group intake patterns and nutrient intake vary across low-income Hispanic and African American preschool children in Atlanta: a cross sectional study

ABSTRACT: BACKGROUND: The food group intake patterns of low income Hispanic and African American preschool children are not well documented. The aim of this study was to perform a food group intake analysis of low income minority preschool children and evaluate how macronutrient and micronutrient intake compares to Dietary Reference Intakes (DRI). METHODS: A cross sectional study design using three-day food diaries analyzed by dietary analysis software (Nutrient Database System for Research) was used. Children were recruited from well-child clinics at Children's Healthcare of Atlanta at Hughes Spalding and North Dekalb Grady Satellite Clinic, Atlanta, GA. Low-income, African American and Hispanic preschool age children (n = 291) were enrolled. A total of 105 completed the 3-day food diaries were returned and analyzed. Chi-squared tests were used to assess demographic variables. The mean percentage of intake per day of specific food groups and sub-groups were obtained (servings of given food group/total daily servings). Food intake data and proportion of children meeting DRIs for macro- and micronutrients were stratified by race/ethnicity, nutritional status, and caloric intake, and were compared using t-tests. Regression models controlling for age, BMI and sex were obtained to assess the effect of total caloric intake upon the proportional intake of each studied food group. RESULTS: The mean age of African American children was 2.24 [PLUS-MINUS SIGN] 1.07 years and Hispanic children 2.84 [PLUS-MINUS SIGN] 1.12 years. African Americans consumed more kcal/kg/day than Hispanics (124.7 [PLUS-MINUS SIGN] 51 vs. 96.9 [PLUS-MINUS SIGN] 33, p < 0.05). Hispanics consumed more fruits (22.0 [PLUS-MINUS SIGN] 10.7% vs. 14.7 [PLUS-MINUS SIGN] 13.7%, p < 0.05), while African Americans consumed more grains (25.7 [PLUS-MINUS SIGN] 7.8% vs. 18.1 [PLUS-MINUS SIGN] 6.4%, p < 0.05), meats (20.7 [PLUS-MINUS SIGN] 9.0% vs. 15.4 [PLUS-MINUS SIGN] 6.1%, p < 0.05), fats (9.8 [PLUS-MINUS SIGN] 5.4% vs. 7.0 [PLUS-MINUS SIGN] 5.8%, p < 0.05), sweet drinks (58.7 [PLUS-MINUS SIGN] 17.1% vs. 41.3 [PLUS-MINUS SIGN] 14.8%, p < 0.05) and low-fat dairy products (39.5 [PLUS-MINUS SIGN] 19.3% vs. 28.9 [PLUS-MINUS SIGN] 12.6%, p < 0.05). Among Hispanics, the proportional intake of fruits, fats and grains varied by total caloric intake, while no difference by total caloric intake was found for the dietary patterns of African Americans. Micronutrient intake also differed significantly between African American and Hispanic children. CONCLUSIONS: Food group intake patterns among low-income children differ by ethnic group. There is a need for more research to guide program design and target nutritional interventions for this population.     

Developments in and practical guidelines for tip-enhanced Raman spectroscopy

This feature review provides an overview of the state-of the art and recent developments in tip-enhanced Raman spectroscopy (TERS), in-depth information about the different available types of instruments including their (dis-)advantages and capabilities as well as a short glance at a number of samples that have recently been investigated using TERS. Issues concerning the progression of TERS from point spectroscopy to an imaging technique are discussed, as well as problems arising from background and contamination signals. This review is concluded with a short TERS 'user guideline', trying to aid researchers new in the field to properly align and test their own TERS setups. Finally, a short outlook is given and some critical issues are raised that need to be solved by the community sooner or later, in order to promote TERS towards a 'push-button' operation.     

Aligned carbon nanotubes sandwiched in epitaxial NbC film for enhanced superconductivity

Highly aligned carbon nanotube (CNT) ribbons were sandwiched in epitaxial superconducting NbC films by a chemical solution deposition method. The incorporation of aligned long CNTs into NbC film enhances the normal-state conductivity and improves the superconducting properties of the assembly.