Retention Aid Research Articles

Paper-based graphene oxide biosensor coupled with smartphone for the quantification of glucose in oral fluid.

Rapid, disposable, point-of-care (POC) oral fluid testing has gained considerable attention in recent years as saliva contains biomarker and components of the serum proteome that offer important information on both oral and systemic disease. Microfluidic paper-based analytical devices (μPADs) coupled with smartphone reflectance sensing systems have long been considered to be an effective POC tool for the diagnostics of biomarkers in oral fluid. However, the existing portable systems are limited by the poor color distribution in the detection area as well as not being universally applicable. Therefore, using the properties of nanomaterials to our advantage, we present a simple, universally applicable approach that features graphene oxide (GO) coated μPADs coupled with smartphone-based colorimetric detection for the direct quantification of glucose. An integrated portable system is used to implement the approach. Owing to the enhanced reagents absorptivity, reactive efficiency and homogeneity of color distribution from the deposition of GO, the glucose assay performance was improved. Also, by using a self-developed app, the glucose concentrations in physiological range can be automatically quantified. Finally, the approach is universally applicable as the modification of μPADs with GO can be achieved without the use of any linker, binder or retention aid, which avoids possible enzyme cross contamination. The system was first calibrated by standard glucose buffer solutions, and the limit of detection as well as the linear dynamic range were found to be 0.02mM and 0~1mM, respectively, which are appropriate for analyzing glucose concentrations in a clinically relevant range. Finally, the system was used for quantifying glucose concentrations in artificial saliva and the results obtained using our portable system showed reasonable agreement with the actual use concentrations. Thus, the utility of the system in sensitively quantifying glucose concentrations in a portable, and repeatable manner is demonstrated.

The wet strength of water- and foam-laid cellulose sheets prepared with polyamideamine-epichlorohydrin (PAE) resin

Abstract Some paper and paperboard grades require strength also when rewetted. The purpose of this study was to investigate the impact of web forming method, different foaming agents, polyamideamine-epichlorohydrin (PAE) wet strength resin, and retention aids on the strength development of hand sheets. Only a slight, if any, improvement in dry tensile strength due to PAE resin was observed. PAE improved the wet strength of the water-laid sheets, and the retention systems had a minor but positive impact. Although wet strength was lower at given PAE addition levels, the trend was similar with the sheets foam-laid with an anionic foaming agent, except at high PAE levels. With the non-ionic surfactant the maximum level of wet strength was reached already at a low PAE addition level and use of retention aids decreased wet strength. Such differences between the water- and foam-laid sheets are most likely due to the chemical interactions between PAE, foaming agents, and other additives.

Preparation and experimental dust suppression performance characterization of a novel guar gum-modification-based environmentally-friendly degradable dust suppressant

To address the coal dust pollution issue associated with coal mines and further improve the dust suppression performance of dust suppressants, the present study first uses Guar gum (GG), a widely available pollution-free natural polymer, as the main ingredient to produce modified Guar gum -GGTCS by chemically modifying its –OH functional group, followed by employing infrared spectroscopy and thermogravimetric analysis to characterize the chemical structure and thermal stability of GG and its modified product GGTCS; subsequently, the modified product GGTCS is used as the primary raw material, which is mixed with certain wetting and water retention agents so as to develop an environmentally-friendly degradable dust suppressant with decent dust suppression performance. The optimal formula for preparing this environmentally-friendly dust suppressant is determined as: 0.8% GGTCS +1.5% glycerol (GLY) + 0.1% sodium dodecyl benzene sulfonate (SDBS) + 0.02% fatty alcohol polyoxyethylene ether (AEO); the high-resolution Scanning Electron Microscopy (SEM) is employed to observe the solidified film on the coal powder surface before and after the treatment of dust suppressant. A digital display electronic universal testing machine is adopted to measure the maximum pressure the solidified film can withstand before being crushed (29 kPa), and a test is run to assess the degradability of the newly developed degradable dust suppressant. The test results indicate that the newly developed hybrid dust suppressant has decent water retention, hardening, cementing, anti-compression, and degradability characteristics, which can offer significant economic, environmental, and social benefits to the dust control field.

Study on the Preparation of Corn Starch Salt-resistant Water Retention Agent and Properties of Retention Agent Combined with Coal Gangue Pottery

Environmental protection agent is widely used in agriculture because of its ability to absorb water, water retention and salt resistance. In this study, Qinghai corn starch was used as raw material. A high absorbent resin was prepared using acrylic acid and acrylamide as monomer, N, N-methylene diacrylamide as cross-linking agent and ammonium persulfate as initiator for graft copolymerization. The Optimized experimental conditions as follows: monomer (acrylamide + acrylic) : Qinghai corn starch = 12 (mass ratio), acrylamide content was 12% (wt %).The concentration of the initiator was a/2. The absorption rate of the product reached 1548g/g, and the salt absorption rate was 96g/g (0.9 wt% KCl solution). Then on this basis, the water absorption rate of retention agent combined with coal gangue pottery is 1549g/g, and the salt absorption rate is 97g/g. The results showed that the water retention agent not only has good water retention and salt resistance, but also its water retention and salt resistance are not affected by the combination with Coal gangue pottery.

Cerium oxide immobilized paper matrices for bactericidal application

Cerium oxide (CeO2) nanoparticles (NPs) of diameter 20–100 nm have been successfully immobilized into the cellulose fiber matrices. The in situ synthesis was carried out using a single step hydrothermal technique at low temperature without the aid of linker, binder or retention aid. Paper matrices were immobilized with 0–6.5 wt% CeO2 and were investigated for their antibacterial activity against the Gram negative, E. coli, bacteria in the presence of visible light. It was observed that the paper matrix containing 6.5 wt% CeO2 inhibits 94% of E. coli growth after 9 h of exposure to visible light with an initial count of 576 × 104 CFU ml−1.

Preparation and Performance Analysis of Lignocellulose Water Retention Agent and Combination with Coal Gangue Ceramsite

Environmental friendly water retention agent has been widely used in agriculture, since its ability to absorb water, hold in water, resist salt. In this study, the water rentention agent was polymerized with using wood cellulose as raw material, acrylamide as monomer, N, N - methylene double acrylamide as crosslinking agent, ammonium persulfate as the initiator. The optimized technological conditions was obtained by the orthogonal experiments: the quality ratio of cellulose and acrylamide was in 1:6, ammonium persulfate was 1.5 wt%(of the total amount of cellulose and monomer), N, N - methylene double acrylamide 0.25 wt%(of the total amount of cellulose and monomer). The maximum water absorbency of water retention agent was 330.07g/g in distilled water and 117.48g/g in 0.9 wt% KCl solution. On the basis of this, using water retention agent as the coating for coal gangue ceramsite, and the maximum water absorbency of water retention agent was 332.15g/g in distilled water and 118.91g/g in 0.9wt% KCl solution. The results show that adopting above process not only can obtain good water retention agent, but also can enhance the water retention and salt resistance by using with ceramsite.

Book Review: Textbooks in Academic Libraries: Selection, Circulation, and Assessment

Do textbooks have a place in academic libraries? Nearly all of the nine chapters in this text begins by addressing this question. Long-standing concerns about the acquisition and inclusion of print textbooks in the library’s collection, including cost, frequency of replacement, etc., are cited in many of the case studies presented here. What is interesting is that this diverse group of institutions, representing both small and large private and public universities, all reached the same conclusion: the textbook reserve program aids in student recruitment, retention, and success.

Development of a fast and inexpensive method for detecting the main sediment sources in a river basin

The sediments are a key link to understand the dynamics of a water basin, since they are the main transport and retention agent of nutrients and contaminants. Therefore, a method to identify the main sediment sources and study their distribution through the basin over time without the need to use reference standards was developed.Water samples with suspended sediments were collected for one year from different sites of the Ludueña stream basin (Argentina). The sediments were deposited in fiberglass filters and their near infrared spectrum was measured. The data obtained were processed by bilinear and trilinear methods. Principal component analysis (PCA), multivariate curves resolution with alternating least squares (MCR-ALS) with and without trilinearity; and parallel factor analysis (PARAFAC) were applied. These algorithms allow identifying the three main sediment sources. The spectral loadings that characterize each source and the scores that reflect their distribution along the different sampling sites were obtained. It was concluded that the main contribution of sediments is given by the plant tissue developed by photosynthetic organisms that have a seasonal behavior. The remaining sources are characterized by being soil particles of the region under study (incorporated into the system by wind and rain) and the development of organisms with anoxygenic photosynthesis (their growth is favored due to the contribution of fluid discharges from anthropogenic activities).

Studies on Isolation, Modification, Characterization and Evaluation of Some Physicochemical Parameters of Potato Starch

Objectives: To isolate and modify starch using new and non-commonly used commercially available, cost-effective reagents and study the changes in functionality and physicochemical properties. Methods/Statistical Analysis: An outline and modification of the method: Addition of 100 mL of a 500 mL solution of 3.5 % hypochlorite (household bleach commonly known as hypo) in 2 L of water at interval of 1 min during grinding. Hypo substituted sodium metabisulphite, prevented browning and enhanced rasping and acted as bleach. Mucilage obtained by the modified method was nonsticky to starch cake. FT-IR results confirmed the direct formation of oxidized starch. Findings: Acetyl content (0.01-0.89 %) and DS (0.011-0.2) obtained by the modified method was in agreement with the approved DS by the Food and Drug Administration for food use. Proximate results showed that the isolated starch was rich in mineral content, fibre, fat and energy. Thermoplasticity of high temperature mercerized starch was revealed by SEM images. These properties will influence their use in composites and other applications where strength needs to be improved as documented. Mercerized starches as flocculants in water cleaning as ion changers or retention agents in the paper industry. The C=O absorption bands were observed at 1634, 1650, 1647 and 1646 cm-1 for mercerized starch. Bands observed at 1640, 1641, 1640, 1640 and 1642 cm-1 and 2932, 2926, 2920 and 2929 cm-1 and 1358, 1389, and 1385 cm-1 are assigned CO, C-H of methylene and -CH2 stretching vibrations in ester group due to acetylation. Results of these findings showed the application of hypo and vinegar for isolation and acetylation of starch respectively. Application/Improvements: The feasibility of the modified method for starch isolation and modification using readily available, cost effective and eco-friendly chemicals for obtainment of food and pharmaceutical grade starch. Keywords: Characterization, Modification, Potato, Starch, FT-IR, SEM

ApoB-100 Lipoprotein Complex Formation with Intima Proteoglycans as a Cause of Atherosclerosis and Its Possible Ex Vivo Evaluation as a Disease Biomarker.

Experimental and clinical data indicate that the initiation and progress of atherosclerosis and its clinical manifestations are first caused by circulating apoB-100 lipoproteins that enter and are retained in the arterial intima. Extracellular sulfated proteoglycans (PGs) of the intima are the retention agents. The PGs also initiate physical and biochemical lipoprotein degradation with the production of bioactive, lipid products that trigger an inflammatory response that leads to atherosclerosis. There are many simple methods for measuring abnormalities of circulating lipoproteins and their relation to atherosclerotic cardiovascular disease (ACVD). However, limited research aims to evaluate procedures that could report quantitatively about the contribution of the interaction of apoB-100 lipoprotein-arterial intima PGs to clinical manifestation of ACVD. In the present review we discuss observations indicating that simple ex vivo evaluation of the affinity of apoB-100 lipoproteins for arterial PGs and glycosaminoglycans (GAGs) can give an indication of its association with clinical manifestations of atherosclerosis. In addition, we discuss molecular and cellular aspects of the apoB-100 lipoproteins association with arterial PGs that are related to atherogenesis and that support the experimental framework behind the current “Response-to-Retention” hypothesis of atherosclerosis.

Influence of Cellulose Ethers on Fresh State Properties of Lime Mortars

Cellulose ethers (CEs) are widely used as viscosity enhancing, water retaining additives in cement based mortars. Nevertheless, studies about the effect of cellulose ethers on the properties of aerial lime-based mortars are very lack. The use of water retaining additives in lime mortars can influence not only their fresh state properties but also the pore structure and strength of hardened mortars. In this work, four different commercial cellulose ethers were added to lime mortars in order to test their influence on properties of mortars in the fresh state. Mortar rheological parameters (relative yield stress, consistency coefficient and fluidity index) were correlated with flow table tests, relative density measurements, water retention and air content in the mortars. It was found that CEs reduce the spread of lime mortars and increase air content in the mortars. The CEs are not so effective in water retention compared with other types of water retention agents. Most dosages of CEs change the behaviour of mortars from pseudoplastic to dilatant. In contrast to the effect of CEs in cement-based materials, their viscosity enhancing behavior in lime mortars is denied, due to the presence of large amounts of calcium hydroxide. From this point of view, the CEs are not so suitable to use as viscosity enhancing admixtures in lime mortars like derivatives of chitosan or guar gum.

Optimization of the Binder System for Improving Workability and Thermo-Mechanical Properties of Plastic Refractories

Plastic refractory properties were studied by synthesizing two different binders in the laboratory. Liquid phosphate binders from different sources, a sol-gel bonding system, organic plasticizers, water retention agent and deflocculating agent were optimally mixed using different techniques for binder synthesis. The stability of the thixotropic behaviour of the binders varied with different compositions and techniques. Plastic refractory products were manufactured in the laboratory with an identical raw material composition and particle size distribution. Plastic refractory products with different binders were characterized based on the workability index of green mass, bulk density, cold crushing strength, modulus of rupture and permanent linear change of fired samples at 850 °C and 1200 °C. Phase and micro-structure analysis was in line with the thermo-mechanical properties of end products. The plastic refractory prepared with Binder B-1 was found to be optimal in terms of workability and thermo-mechanical properties.

Fact or Fiction? Designing Stories for Active Learning Exercises

ABSTRACTStories can be employed in a variety of ways in college classrooms—such as in case studies, simulations, and problem-based learning (PBL) activities. Sometimes these stories are historically accurate, while in other instances they are fictional. What might be the benefits and challenges of using fictional narratives? This article draws upon data from student surveys and 15 years of teaching practice to consider the advantages and drawbacks of using fictional stories in PBL exercises. It finds that using fictional stories develops problem-solving and teamwork skills, promotes deep learning, enables the discussion of sensitive topics, and helps to build a community of learners. Also, the stories can be easily modified so as to meet learning objectives and enhance instructional flexibility. Moreover, the challenges of using fictional stories are manageable. Writing such narratives can be easier than imagined if professors fictionalize a case study with which they are familiar. Concerns about the acquisition of substantive knowledge can be addressed by discussing the similarities between fictional stories and real-world cases. Students report that the use of fictional narratives clarifies abstract concepts and aids in the long-term retention of course material. While this article focuses on PBL, its findings are pertinent to other forms of active learning.

Coding by hand or on the computer? Evaluating the effect of assessment mode on performance of students learning programming

Programming courses suffer from low retention rates, believed to be caused by difficulties in learning programming concepts. Another possibility relates to how programming ability is assessed. Although extensively used, pen-and-paper is arguably not the best way to assess a student’s programming ability. Although previous studies have chosen to implement lab exams as a replacement for pen-and-paper examinations, little consideration has been made to evaluate the extent of the exam mode effect in relation to the use of computers during summative assessment in programming courses, and to what degree this could affect the student’s performance. This study aims to answer to: Are there any differences in performance between students using a computer, compared to students using pen-and-paper during summative assessment of programming ability among novice programmers? This could aid teachers to better assess students’ programming ability in novice courses, which could in turn aid in student retention. An experimental approach has been applied. 20 students participated and were divided in two groups that were giving the same programming problems that was either solved and examined through pen-and-paper assessment or through computerised assessment. While some differences between the groups were noted, the overall results demonstrate no statistical significant difference between the groups in terms of performance.

The effect of guar gum and chitosan on fiber and fiber fine micromorphology in paper-process reconstituted tobacco pulp

To study the effect of guar gum and chitosan on the micromorphology of tobacco pulp and the retention mechanism of different retention aids by the MorFi Compact fiber analyzer, changes in the micromorphology of the tobacco pulp fibers and the fiber fines were studied by adding different dosages of guar gum and chitosan. The results indicated that the retention mechanisms of guar gum and chitosan on fibers and fiber fines were different. Addition chitosan, components of pulp intertwined to form a spatial reticular through the neutralization effect that consists of tobacco fiber bundles, fiber fines and fillers. The reticular size increased, fiber fines (especially those below the detection limit) and fillers bonded with chitosan to combined with fiber and fiber fines. Guar gum wrapped the fiber through “nucleation and growth” to achieve the retention effect. Microstructures of the handsheets were observed using SEM, and the change in the fiber curl rate was analyzed to verify the effects of mechanisms of two different retention aids.

Viscometric analysis of the hydration of a surface cross-linked EM-HEC polymer

Hydrophilic polymers are used in many different products and processes, in which they function, for example, as rheology control agents, steric stabilizers, water retention agents, or flocculants. When the application requires dissolution of polymer powders in water, this occurs through hydration of the hydrophilic chains, and is accompanied by an increase in solution viscosity through a combination of chain entanglement, hydrophobic interactions and hydrogen bonding. On a practical level, however, the addition of high molecular weight polymer powder to water can result in the formation of a surface gel layer leading to partial hydration and particle agglomeration, creating operational and formulation problems. One way of overcoming this is by chemically crosslinking hydroxyl groups on the particle surfaces, for example, by reaction with dialdehydes, such as glyoxal. This retards the initial hydration rate, thereby allowing more time for effective powder dispersion. The present study is concerned with factors affecting the hydration of a commercial non-ionic glyoxal-crosslinked methyl ethyl hydroxyethylcellulose, in the concentration range 0.15–0.5 wt%. Hydration kinetics have been determined by monitoring the increase in solution viscosity with time using low shear rotational viscometry. Experimental variables include polymer concentration, temperature, pH, the presence of anionic, cationic and non-ionic surfactants, and ionic strength (sodium chloride concentrations in the range 0–5 mol/L). In deionised water, the hydration process is shown to involve two kinetic steps, assigned to breakage of hemiacetal crosslinks and polymer hydration. The kinetic studies enabled the various stages in the overall hydration process to be analysed, and mechanistic implications and activation parameters to be assigned.

Novel biochar-impregnated calcium alginate beads with improved water holding and nutrient retention properties

Drought conditions and nutrients loss have serious impacts on soil quality as well as crop yields in agroecosystems. New techniques are needed to carry out effective soil water and nutrient conservation and fertilizer application tools. Here, calcium alginate (CA) beads impregnated with ball-milled biochar (BMB) were investigated as a new type of water/nutrients retention agent. Both CA and Ca-alginate/ball milled biochar composite (CA-BMB) beads showed high kinetic swelling ratios in KNO3 solution and low kinetic swelling ratios in water, indicating that CA-BMB beads have the potential to retain mineral nitrogen and nutrients by ion exchange. Pseudo-second-order kinetic model well-described the swelling kinetics of both beads in KNO3 solution. Over a range of temperatures, the characteristics of dehydration suggested that impregnation with BMB improved the water holding capacity and postponed the dehydration time of Ca-alginate. The cumulative swelling and release characteristics of water, K+, and NO3− indicated that CA-BMB beads have great potential as a soil amendment to improve its nutrient retention and water holding capacity.

Cellulose nanofibers from residues to improve linting and mechanical properties of recycled paper

The production of high filler-loaded recycled papers is often affected by high values of linting and low values of strength. In the first case, the accumulation of lint particles from paper’s surface on the printing blanket affects the quality of the printed paper and the pressroom’s productivity. In the second case, increasing the use of fillers and recycling cycles lead to poor paper strength. Cellulose nanofibers (CNFs) are receiving a great deal of attention due to their potential as a reinforcement aid for high filler-loaded papers through filler–fiber interaction and interfiber bonding. It is already proven that high quality CNFs can reduce linting, although their industrial application is limited by their high production cost. The objective of this research is, therefore, to quantify the effect of applying lower grade, more sustainable CNFs on linting phenomena and on the mechanical properties of recycled papers. Eucalyptus, pine and triticale residues were used as cellulose sources, and the CNFs were produced minimizing the chemical pretreatment before homogenization. Addition of 3 wt% of CNFs from pine residues into the recycled paper with 15.7 wt% of total filler reduced linting by 40% and increased tensile strength by 15.1%; further improvements on linting and mechanical properties were achieved at 5 wt%. Moreover, the increase in drainage time can be overcome by the addition of a retention aid, in this case a coagulant-cationic polyacrylamide-bentonite system, commonly used in paper mills.

Key role of anionic trash catching system on the efficiency of lignocellulose nanofibers in industrial recycled slurries

The processing of recycled paper into packaging materials is becoming one of the most important activities of paper mills. However, the use of recycled paper as a raw material causes an important increase of dissolved colloidal substances in industrial waters, known as anionic trash, which greatly increases water conductivity and cationic demand disturbing the function of commonly used retention agents (cationic starch, cationic polyacrylamides). On the other hand, several investigators showed that lignocellulosic nanofibers (LCNF) can be used as reinforcement in papermaking, but their retention can be affected by anionic trash. This work aims to study the technical viability of the application of triticale straw lignocellulose nanofibers in recycled fiber suspensions at industrial scale. For this purpose, a complex retention system of LCNF was proposed to improve the reinforcement efficiency of LCNF. Results show that, with the addition of only 1.5% (w/w) of LCNF, it is possible to fulfill the physical–mechanical requirements of the commercial test liner, and the addition of 4.5% of LCNF would allow the reduction of basis weight and additives or the development of applications with higher mechanical requirements.

Influence of Modified Carbon Fiber on Properties of Paper Based Friction Materials

The paper adopts modified carbon fiber with Meldrum's acid and silane coupling agent (KH-550), then add the modified carbon fiber to the paper based friction materials. The paper aims to explore the changes of modified carbon fiber in its surface structure and properties by electron microscopy and infrared spectral analysis, and the effect of anionic microparticle forming retention aid system comprised of lithium soapstone-cationic polyacrylamide (CPAM) on mechanical properties and retention of paper based friction materials. Compared with the addition of unmodified carbon fiber to paper based friction materials, the addition of modified carbon fiber with Meldrum's acid, silane coupling agent, Meldrum's acid and silane coupling agent enhance the tensile strength of paper based friction materials. The tensile index of paper based friction materials was separately enhanced by 64.87 %, 91.38 % and 28.88 %. Compared with the paper based friction materials without the anionic microparticle forming retention aid system, the basis weight of paper based friction materials increased by 13.97 %.