Modifier Concentration Research Articles

EFFECTS OF WASTE CROSSED-LINKED POLYETHYLENE ELECTRICAL WASTE COATING ON THE PROPERTIES OF BITUMEN

The high cost of construction materials and increased axle loads has motivated researchers to seek alternative cost-effective materials for road construction. Studies on the use of waste thermoplastic polyethylene material to improve bitumen properties have been investigated. However, few studies on the use of thermoset polyethylene (cross-linked polyethylene) to modify bitumen have been carried out. This research investigated the use of waste cross-linked polyethylene (XLPE) cable coating on bitumen properties. An FTIR analysis carried out on waste XLPE cable coating revealed that it is predominantly composed of XLPE material. A comparative study carried out on the bitumen properties revealed that the modifier had a decreasing effect on its penetration and ductility but, had an increasing effect on softening point and specific gravity; Hence, a considerable improvement in the temperature susceptibility and stability of the bitumen. The short-term ageing analysis carried out revealed that the modified bitumen can withstand short-term ageing requirements at 2% and 4% by weight of pure bitumen. FTIR analysis carried out on the pure and modified bitumen revealed that changes observed in bitumen properties with increasing modifier content were a result of physical changes and not chemical changes. A one-way ANOVA carried out on the properties of various bitumen content revealed that the modifier had a significant effect on the properties of pure bitumen with increasing bitumen content. The regression models developed properly described the relationship between the modifier content and the bitumen properties as they expressed very good R2 values.

A chiral metal-organic framework synthesized by the mixture of chiral and non-chiral organic ligands for enantioseparation of drugs by open-tubular capillary electrochromatography

A chiral metal-organic framework L-Histidine-Zeolitic imidazolate framework-67 (L-His-ZIF-67) was synthesized by the mixture of chiral organic ligand L-histidine and non-chiral organic ligand 2-methylimidazole directly, and to the author's knowledge, the chiral L-His-ZIF-67 coated capillary column we prepared has still not been reported to date in the field of capillary electrophoresis. This chiral metal-organic frameworks material was used as the chiral stationary phase for enantioseparation of drugs by open-tubular capillary electrochromatography. The separation conditions such as pH value, buffer concentration and proportion of organic modifier were optimized. Under optimal conditions, the established enantioseparation system achieved good separation effect, and the resolution of five chiral drugs: esmolol (7.93), nefopam (3.03), salbutamol (2.42), scopolamine (1.08) and sotalol (0.81). In addition, the chiral recognition mechanism of L-His-ZIF-67 was elucidated by a series of mechanism experiments, and the specific interaction force was preliminarily speculated.

Application of a new electrochemical sensor for voltammetric determination of p-nitrophenol and betulin

A highly sensitive electrochemical sensor based on a Surface Active Modifier (SAM) consisting of Taunit-M carbon nanotubes and mesoporous carbon (NanoTechCenter LLC, Tambov, Russia) is developed for the voltammetric determination of betulin and p-nitrophenol. The effect of the modifier concentration on the electrode surface on the analytical signal of betulin was studied, and a method for modifying the surface of the SAM graphite electrode was developed. The developed method is easy to use, fast, stable, sensitive, and cost-effective procedure, which can be used to detect these analytes in real samples. Voltammograms of p-nitrophenol were obtained for the first time on the developed modified electrochemical sensor and the dependence of the height of its analytical signal on the pH of a phosphate buffer thus obtained was studied in a wide pH range from 4 to 12, a background electrolyte with optimal pH was also chosen. Proceeding from the calibration dependences of the height of the betulin analytical signal on the concentration obtained for various background electrolytes with different pH and cation-anion composition, a background electrolyte with the maximum sensitivity of the analytical signal was selected on a modified electrochemical sensor. Study of cyclic voltammograms was carried out to understand the electrode processes, exhibiting a pronounced peak of anodic oxidation observed in a potential range from 0.7 to 0.9 V. However, there was no peak in the cathodic direction which indicates the irreversible nature of the electrode process. When determining the nature of currents, the Semerano criterion equal to 1.6 was calculated, which indicates the absence of the contribution of the diffusion component of the current. Verification of the correctness of the voltammetric method for determining betulin on a new electrochemical sensor was carried out using the «spike-test» method. The data obtained show that the voltammetric determination of betulin can be carried out with a measurement error not exceeding 15%. The proposed modified electrodes were compared with previously known electrodes for the determination of pentacyclic triterpenoids and pesticides at concentrations of 0.5 × 10–3 – 8.0 × 10–3 mg/dm3.

THE EFFECT OF CARBON AND NEGATIVE TEMPERATURE ON THE PHYSICAL, MECHANICAL AND OPERATIONAL PROPERTIES OF AUSTENITIC HIGH-MANGANESE STEEL

Purpose. It consists in determining the influence of carbon and manganese, concentrations of modifiers, test temperatures on the physical and mechanical properties and wear resistance of austenitic highmanganese steel Г13Л.
 Research methods. Determination of impact viscosity was carried out on the MK-30A pendulum probe, microhardness – on the PMT-3 device. The hydrostatic weighing method was used to determine the density. Microstructural analysis and study of non-metallic inclusions were carried out using metallographic and electron microscopes. Corrosion resistance was determined in a model environment with pH9, which corresponded to the production conditions of beneficiation processes of ferrous and non-ferrous metallurgy.
 Results. It was established that the best indicators of the properties of steel 110Г13Л are provided at average values of carbon and manganese concentrations within the standard. For parts that work under low shock loads, it is advisable to use austenitic wear-resistant steels with lower manganese concentrations and higher carbon concentrations within the standard chemical composition.
 Scientific novelty. New dependences on carbon influence, structural modification, non-metallic inclusions, and physical and mechanical properties of high-manganese steel were clarified and obtained. The strength limit of steel increases monotonically with increasing carbon content, and the dependences describing changes in plasticity, impact toughness, and hardness are extreme in nature.
 Practical value. A rational method of modification to improve the operational characteristics of steels is proposed. The influence of the test temperature on the impact toughness of steel with changes in carbon concentrations was studied, as the main indicator of the reliability of machine parts at low temperatures.

Selective Hydrogenation of Acetylene over Pd-Co/C Catalysts: The Modifying Effect of Cobalt

Novel bimetallic Pd-Co catalysts supported on the carbon material Sibunit were synthesized by an incipient wetness impregnation method and used for ethylene production by selective acetylene hydrogenation. It has been established that an increase in the Pd:Co molar ratio from 1:0 to 1:2 in 0.5%Pd-Co/C catalysts, treated in hydrogen at 500 °C, leads to an increase in the ethylene selectivity from 60 to 67% (T = 45 °C). The selectivity does not change with a further increase in the modifier concentration. The catalysts were investigated by TPR-H2, XRD, TEM HR, EDS, and XPS methods. It was shown that palladium and cobalt in the 0.5%Pd-Co/C samples form Pd(1−x)Cox phases of solid solutions with different compositions depending on the Pd:Co ratio. The cobalt concentration in the Pd-Co particles increases with an increase in the Pd:Co ratio up to 1:2 and then remains at a constant level. In addition, monometallic Co particles were present in the samples with the Pd:Co ratio higher then 1:2. The optimal combination of catalytic properties (the ethylene yield is 62–63%) is typical for catalysts with a Pd:Co molar ratio of 1:2–1:4. which is mainly due to the presence of bimetallic particles containing ~41–43% by at. of cobalt.

INCREASING OF THE CORROSION RESISTANCE OF FIBERGLASS PLASTIC REINFORCEMENT THROUGH MODIFICATION OF THE POLYMER BINDER

The issue of increasing the corrosion resistance of composite reinforcement, based on glass fiber and epoxy anhydride binder, is considered. The proposed samples of composite reinforcement were manufactured by needle extrusion technology. Glass fibers were evenly distributed in the channels and impregnated with a polymer binder based on epoxy resin. The amount of phenolic modifier in the polymer binder, according to the technological mode of obtaining composite reinforcement, was brought up to 5%. With a further increase in the content of the modifier, the degree of conversion of epoxy groups was no more than 70%, which sharply reduced the operational characteristics of the material. The overall ratio of polymer binder and glass reinforcement in the composite was ~ 60÷40. It was established that at low concentrations of the polymer modifier (up to 5 wt. parts), the processes of ordering and chemical grafting lead to compaction of the molecular grouping in the system, which in our case is characteristic of phenolic resins of the novolach and resol types. At the same time, under the conditions of the production technology, internal stresses in materials of this type increase sharply, which leads to the formation of surface defects (microcracks). At the tip of a crack or defect, sodium ions or other cations under the action of water undergo hydrolysis to form metal hydroxide, which, in turn, causes hydrolysis of siloxane bonds, thus weakening the mesh structure of silicon dioxide. The experimental activation energy was identified with the activation energy of sodium ion diffusion in the glass mass. But the plastic deformation of the glass in the region before the crack is very small, and instead of a uniform distribution of stress, the material cracks along the weakened centers The obtained data indicate that the action of the alkaline environment causes an increased loss of mass of the composite, both for the unmodified and for those modified with traditional phenolic resins. In turn, this ensures a high degree of penetration of alkalis into the volume of the material, access to reinforced fibers with their subsequent damage. To increase the corrosion resistance of composite reinforcement based on an epoxy anhydride binder, it is advisable to use a reactive sulfur-containing phenolic modifier. Its action is based on the ability to maintain the permissible monolithicity of fiberglass in the alkaline environment of concrete, the modulus of elasticity and necessary strength. Keywords: composite polymer reinforcement, fiberglass, alkaline environment, phenolic modifier.

Effect of Adding LDPE Bags on Rutting and Stripping Behaviour of Asphalt Mix

Disposal or incineration of waste low-density polyethylene (LDPE) bags is a major problem, as it causes pollution. The pavement over time gets deteriorated by vehicular traffic, which mostly results in rutting and other distresses. This research is based on the performance evaluation of hot mix asphalt (HMA) modified with LDPE. Aggregates National Highway Authority Pakistan (NHA) gradation B, bitumen grade 60/70 and waste LDPE bags from the dump yards of Islamabad (Pakistan) were used in this study. Penetration, ductility and softening-point tests were conducted with bitumen modified with different contents of waste LDPE bag flakes; i.e., 0%, 2%, 4%, 6% and 8% to figure out the optimum modifier content (OMC). Marshall testing was performed for the determination of optimum bitumen content (OBC). Using OBC and incorporating LDPE contents as a replacement for OBC, HMA samples were tested for performance evaluation, including rutting resistance and moisture susceptibility and compared with the performance of unmodified HMA. It was observed that 4% of LDPE as a replacement for OBC in the HMA can be used as OMC and yielded better performance results than unmodified asphalt mix. Rutting resistance was improved by 20.86% and tensile strength ratio (TSR) for moisture susceptibility evaluation was above the specified limit of 80%. KEYWORDS: Waste LDPE bags, Low-cost bitumen modifier, Performance evaluation, Performance improvement, Cost comparison, Sustainable environment.

In English

Oil and oil products enters surface waters as a result of man-made disasters, caused, in particular, by military operations. In order to prevent ecological catastrophe, it is necessary to remove hydrocarbons from water surface. The paper is devoted to the development of materials for the extraction of non-polar liquids from aqueous media. Magnetic sorbents based on non-carbonized biopolymers (both plant cellulose and keratin) are proposed. Biopolymer matrices of different morphology on the level of fiber bundles were used for the composite preparation. Dependent on origin, the matrices are characterized by different morphologies at the level of fiber bundles: they are straight (cellulose obtained from wood and corn cobs), helical (cellulose of tea leaves or scaly (keratin from animal wool). Magnetite particles were inserted into biopolymer matrices after the removal of non-cellulose and non-keratin inclusions from them. The samples were investigated with SEM and FTIR techniques, magnetite was identified with XRD analysis. The most homogeneous distribution of magnetic particles, a size of which is less than 1 mm, was found for the matrix obtained from corn cobs. This composite contained the least amount of iron (0.24 mass. %), namely this sample demonstrates the best flotation. The sorbent based on cellulose from tea leaves contained 71% of iron: the particles sink almost completely. The capacity towards non-polar liquids was estimated as follows (g g–1): 1.6–8.6 (vegetable oil), 10.5–16.4 (crude oil), 9.8–14.5 (kerosene). After the removal of crude oil from water surface, no film of this liquid was visually observed. The value of chemical oxygen demand was » 0.2 mgO2 dm–3, this is less than the demand for drinking water. Moreover, the sorbent can be easy removed from water surface with magnet. As found, the sorbents can be used for removal of toxic metal ions from water. As found, magnetic particles improves sorption of Pb2+ ions but decrease Cd2+ sorption. Thus, the sorbents with small content of inorganic modifier can be used for the removal of oil and oil products from water surface. The sorbents, which demonstrate bad flotation, can be used for the recovery of inorganic ions. The advantages of biopolymer-based sorbents over known material is a simple preparation procedure that involves cheap and available feedstock. Moreover, the sorbents can be easy separated from aqueous phase with magnet.

Modification of Poly(vinyl chloride) with Bio-Based Cassia Oil to Improve Thermo-Mechanical and Antimicrobial Properties

The purpose of this study was to modify plasticised PVC to obtain a material with antimicrobial properties and selected mechanical properties. Natural cassia oil (CO) was used to modify plasticised PVC materials. The modified material was produced by extrusion. The introduced modifier had a maximum concentration of 20 phr. Rheological and mechanical properties were evaluated, and the glass transition temperature was determined. The antioxidant and antimicrobial activity of the agar diffusion method was investigated by analysing the growth inhibition zones against Enterococcus faecalis and Listeria monocytogenes. A favourable effect of the cassia oil content on the increase in antioxidant activity of the developed polymeric materials was found with an increase in the modifier content and the duration of action (30 days). The largest growth restriction zones were observed for L. monocytogenes, i.e., they showed the highest sensitivity to the modified material. The simultaneous decrease in modulus of elasticity, increase in elongation at break, and decrease in Tg indicate that the modifier has a plasticising effect on PVC. The developed material may find application as an active and/or functional material, especially as an emitter of antimicrobial agents, in the packaging used to store minimally processed food.

Modeling and optimization of asphalt content, waste palm oil clinker powder and waste rice straw ash for sustainable asphalt paving employing response surface methodology: A pilot study

Waste management is becoming increasingly important around the world, and incorporating agro-waste into the pavement industry represents a promising strategy for achieving sustainability while improving mixture properties. In this study, we optimize and determine the optimum asphalt binder content of asphalt concrete mixtures modified with waste palm oil clinker powder (WPOCP) and waste rice straw ash (WRSA) to improve their engineering properties. To optimize the interactions between three independent variables (asphalt binder, WPOCP, and WRSA content) on mixture bulk unit weight (BUW), void in the total mix (VTM), Marshall stability, and flow values, the Marshall mix design approach and response surface methodology (RSM) with a Box-Behnken design were used. WPOCP samples containing 2%, 4%, 6%, and 8% by weight of asphalt mixtures were prepared, as were WRSA samples containing 25%, 50%, 75%, and 100% by weight of filler, with asphalt binder content ranging from 4 to 6% by weight of the mix. The statistical model results show that all responses were significant, with high coefficients of correlation (R2) of 0.9840, 0.9971, 0.9920, and 0.9891 for the BUW, VTM, Marshall stability, and flow, respectively. Individual effects of the input variables and synergistic interactions between the three variables were observed to influence all of the responses. Numerical optimization produced optimum WPOCP, WRSA, and asphalt content values of 8%, 74%, and 5%, respectively. The mean error for all responses was less than 5%, indicating that predicted values agree well with experimental data and that generated models accurately reflect experimental results. Based on the findings of the study, it can be concluded that RSM is an effective method for determining the optimal asphalt binder and modifier content in asphalt mixtures. It enables the identification of the most important variables influencing the response of the asphalt mixture and enables mixture optimization for improved performance. Furthermore, incorporating WPOCP and WRSA into asphalt mixtures was found to improve both volumetric and Marshall properties, resulting in a more sustainable approach in the pavement industry.

Subcritical water hydrolysis for the obtention of bioactive peptides from a grasshopper Sphenarium purpurascens protein concentrate

The effect of adding sodium bicarbonate(SB) and citric acid(CA) in the subcritical water (SW) hydrolysis process was studied to improve peptide extraction from Sphenarium purpurascens. A complete factorial(23) design was accomplished, and the effects of the temperature, pressure and modifier concentration on the degree of hydrolysis(DH), molecular distribution, antioxidant activity and Angiotensin I-converting enzyme(ACE) inhibitory activity were evaluated. A protein concentrate was obtained and hydrolyzed, showing a DH of up to 44.56 ± 0.92% with the addition of 1 M SB at 130 °C/20 MPa; meanwhile, 38.73 ± 0.58% was observed using CA under the same conditions. The best bioactivities were found in CA treatments: IC50 of up to 4.06 ± 0.35 mg/mL for DPPH, 330 ± 0.03 µg/mL for ABTS and up to 0.148 ± 0.016 mg/mL for the ACE inhibition activity. Moreover, differential hydrolysis was found due to the presence of modifiers and process conditions, being able to modulate the hydrolysis degree and obtaining hydrolysates with different characteristics and bioactivities.

The rheological properties of high-viscosity modified reclaimed asphalt binder at multiple application temperatures

The asphalt binder of permeable asphalt concrete has high requirements and there are few studies on mixing reclaimed asphalt (RA) with high-viscosity asphalt (HVA) for recycled permeable asphalt concrete. This study aims to research the wide-temperature-range rheological properties of high-viscosity modified reclaimed asphalt binder (HVRA) which is the bituminous binder in recycled permeable asphalt concrete. First, HVRA was prepared by mixing RA and HVA, wherein RA was extracted from reclaimed asphalt pavement (RAP) and HVA was prepared in the laboratory. Then, the properties of HVRA at multiple application temperatures were analyzed by basic indexes test, dynamic shear rheological test, and bending beam rheometer test. Finally, the comprehensive performance was contrastively evaluated by radar chart. The results revealed that the properties of HVRA are excellent when the high-viscosity modifier (HVM) content is 18 % and 20 %. Additionally, the rheological properties and fatigue resistance of the HVRA showed a decreasing trend with adding RA. Among them, considering rheological properties, the optimal content of HVM in HVA is 18 % − 20 %, and the optimal proportion of RA in HVRA is 10 % − 20 %. Furthermore, the fatigue performance of HVRA is significantly enhanced when HVM content is 18 %, especially the fatigue life of HVRA with 10% RAP is 5–9 times HVA containing 12 % HVM which is regularly used as the bituminous binder.

Experimental Study on Engineering Characteristics of High-Speed Railway Subgrade Filler in Island Permafrost Regions

The high-speed railway (HSR) subgrade has a strict settlement-control standard at the mm level, but its deformation stability is significantly threatened on permafrost with poor thermal stability and in susceptible-to-thawing settlements. Therefore, the filler suitable for permafrost regions needs to be explored and determined. In this study, the frost heaves, permeabilities and static strength characteristics of three coarse fillers were experimentally investigated, and the optimal subgrade filler was determined for the certain HSR, the first HSR in permafrost regions around the world. The test fillers include pure fillers, 5% cement improved fillers and 5% cement + 3% modifier improved fillers, and the effects of curing time, modifier content and freeze–thaw cycles were analyzed. The test results show that: (1) the frost heave rate and permeability coefficient decrease with the increase of curing time and modifier content, while increasing with the freeze-thaw cycles; (2) After six freeze–thaw cycles, the cement + modifier improved filler’s frost heave rate and permeability coefficient are 0.51 and 0.00331 cm/s, a larger decrease in the frost heave rate (more than 50%) and the permeability coefficient (about one order of magnitude) than that of pure filler; (3) The cement + modifier improved filler shares the highest compressive strength under different curing times and freeze-thaw cycles. In summary, the modifier has a more significant influence on the engineering characteristics than the curing time or freeze-thaw cycles, and the cement + modifier improved filler has the best comprehensive performance. This study will provide a technical reference for the foundation-treatment and disease-prevention of HSRs in island permafrost regions.

Comparison of Marshall Stability values of the different bitumen mixes with crumb rubber

Modified bitumen with crumb rubber can enhance the bitumen’s physical properties and the mixes’ Marshall Stability values. Aside from the fact that it reduces the amount of tyre waste, the use of crumb rubber can also improve the properties of bitumen, which can help to extend the life of flexible pavements. When VG 30 bitumen is combined with crumb rubber, penetration values drop significantly. As the modifier concentration is increased, the penetration value decreases. When modified with 5CR, 10CR, and 15CR, neat bitumen’s penetration value drops to 61, 58, and 49 respectively. Marshall Compared to unmodified mixes, bitumen modified with crumb rubber has higher stability values. The stability values increase as the modifier content increases. As a result, stiffer binder results in a higher stability value of the mix, which is supported by an increase in modifier content. For every 5-15% increase in crumb rubber, an improvement of 10-25% was observed.

Rutting characteristics evaluation and prediction model development for warm mix asphalt

ABSTRACT The warm mix asphalt (WMA) technology has brought environmental sustainability into the pavement industry with its preparation at lower production temperatures than hot mix asphalt (HMA). Nevertheless, it has also raised concerns regarding the mixture’s resistance to permanent deformation as a result of its reduced aging during production. This study examines the effects of warm mix modification on the rutting potential of bituminous mixes. Two modifiers were used for WMA preparation – polyethylene wax (PEW) and waste cooking oil (WCO). Binder rutting properties were evaluated using the multiple stress creep recovery (MSCR) test. Subsequently, WMA mixtures were prepared at adequate production temperatures, and then their rutting characteristics were evaluated using the Cooper wheel tracker device. The study concluded that introducing warm mix modifiers in small amounts, approximately 1–2% by weight of bitumen, results in rutting characteristics comparable to virgin bituminous mix, whereas the characteristics deteriorate at higher modifier contents. Furthermore, a rutting prediction model based on the Weibull failure rate function (WFRF) was developed. A strong correlation was found between the measured wheel tracking data and the prediction model in all mixtures. PEW was discovered to be a superior warm mix modifier to WCO in terms of rutting resistance.

Enantioselective Human Serum Albumin Binding of Apremilast: Liquid Chromatographic, Fluorescence and Molecular Docking Study.

The interaction between human serum albumin (HSA) and apremilast (APR), a novel antipsoriatic drug, was characterized by multimodal analytical techniques including high-performance liquid chromatography (HPLC), fluorescence spectroscopy and molecular docking for the first time. Using an HSA chiral stationary phase, the APR enantiomers were well separated, indicating enantioselective binding between the protein and the analytes. The influence of chromatographic parameters-type and concentration of the organic modifier, buffer type, pH, ionic strength of the mobile phase, flow rate and column temperature-on the chromatographic responses (retention factor and selectivity) was analyzed in detail. The results revealed that the eutomer S-APR bound to the protein to a greater extent than the antipode. The classical van 't Hoff method was applied for thermodynamic analysis, which indicated that the enantioseparation was enthalpy-controlled. The stability constants of the protein-enantiomer complexes, determined by fluorescence spectroscopy, were in accordance with the elution order observed in HPLC (KR-APR-HSA = 6.45 × 103 M-1, KS-APR-HSA = 1.04 × 104 M-1), showing that, indeed, the later-eluting S-APR displayed a stronger binding with HSA. Molecular docking was applied to study and analyze the interactions between HSA and the APR enantiomers at the atomic level. It was revealed that the most favored APR binding occurred at the border between domains I and II of HSA, and secondary interactions were responsible for the different binding strengths of the enantiomers.

The Characterisation of Fracture Resistance of Asphalt Mixtures Containing Rubber Modifiers and a Wax-Based Additive

Asphalt mixture modification with rubberised material frequently results in improved characteristics and extended service life in actual application. This research characterised the synergistic consequences of rubber modifiers (crumb rubber powder (CRP) and natural rubber latex (NRL)) and wax-based admixtures (Tough Fix Hyper (TFH)) on the performance of the asphalt mixture from the fracture energy and laboratory fracture resistance perspectives. Semicircular bending (SCB) and indirect tensile strength (ITS) tests were conducted to assess the fracture properties of the asphalt mixture samples. To prepare asphalt mixture samples, the wet method was utilised. Higher CRP levels resulted in greater strength and a longer time to attain peak force for both control and mixtures containing wax admixture, as determined by SCB. The interaction between the higher CRP or NRL content and the TFH additive enhanced the fracture resistance, indicating that the components are highly compatible. The 10L + TFH additive produced the highest fraction of energy, indicating a more significant improvement than the counterpart mixes containing the CRP modifier. In addition, incorporation of the CRP and NRL increased the fracture plastic zone (FPZ), resulting in increased fracture toughness. Therefore, the gradient of fracture toughness and fracture energy in the asphalt mix depends on the rubber type, content, and TFH. Although the higher CRP, NRL, and TFH improve the fracture energy and cracking resistance, they increase the crack initiation and propagation velocities, whereby the high bitumen stiffness makes the mixture more brittle than the control mixture. Caution should be exercised when selecting the content of rubber modifier and TFH for the asphalt pavements in low-temperature service. Also, there is a direct interconnection between fracture resistance and fracture energy in the mixtures containing CRP, NRL, and TFH. Such correlations can be used as the premise of predictive micro- and macro-models to evaluate mixture performance in terms of fracture resistance.

Patient Perspectives on a Targeted Text Messaging Campaign to Encourage Screening for Diabetes: Qualitative Study.

A sizeable proportion of prediabetes and diabetes cases among adults in the United States remain undiagnosed. Patient-facing clinical decision support (CDS) tools that leverage electronic health records (EHRs) have the potential to increase diabetes screening. Given the widespread mobile phone ownership across diverse groups, text messages present a viable mode for delivering alerts directly to patients. The use of unsolicited text messages to offer hemoglobin A1c (HbA1c) screening has not yet been studied. It is imperative to gauge perceptions of "cold texts" to ensure that information and language are optimized to promote engagement with text messages that affect follow-through with health behaviors. This study aims to gauge the perceptions of and receptiveness to text messages to inform content that would facilitate engagement with text messages intended to initiate a mobile health (mHealth) intervention for targeted screening. Messages were designed to invite those not already diagnosed with diabetes to make a decision to take part in HbA1c screening and walk them through the steps required to perform the behavior based solely on an automated text exchange. In total, 6 focus groups were conducted at Wake Forest Baptist Health (WFBH) between September 2019 and February 2020. The participants were adult patients without diabetes who had completed an in-person visit at the Family and Community Medicine Clinic within the previous year. We displayed a series of text messages and asked the participants to react to the message content and suggest improvements. Content was deductively coded with respect to the Health Belief Model (HBM) and inductively coded to identify other emergent themes that could potentially impact engagement with text messages. Participants (N=36) were generally receptive to the idea of receiving a text-based alert for HbA1c screening. Plain language, personalization, and content, which highlighted perceived benefits over perceived susceptibility and perceived severity, were important to participants' understanding of and receptiveness to messages. The patient-physician relationship emerged as a recurring theme in which patients either had a desire or held an assumption that their provider would be working behind the scenes throughout each step of the process. Participants needed further clarification to understand the steps involved in following through with HbA1c screening and receiving results. Our findings suggest that patients may be receptive to text messages that alert them to a risk of having an elevated HbA1c in direct-to-patient alerts that use cold texting. Using plain and positive language, integrating elements of personalization, and defining new processes clearly were identified by participants as modifiable content elements that could act as facilitators that would help overcome barriers to engagement with these messages. A patient's relationship with their provider and the financial costs associated with texts and screening may affect receptiveness and engagement in this process.

Evidence for the Hydration of Some Organic Compounds during Reverse-Phase HPLC Analysis.

Some polar analytes (X) can reversibly form hydrates in water-containing eluents under the conditions of reversed-phase HPLC analysis, X + H2O ⇄ X × H2O. One of the methods to detect their formation is the recurrent approximation of the net retention times of such analytes, tR(C + ΔC) = atR(C) + b, where ΔC = const is the constant step in the variation of the organic modifier content of an eluent. These dependencies are linear if hydrates are not formed, but in the case of hydrate formation, they deviate from linearity under high water content. It has been shown that UV spectroscopic parameters, namely, relative optical densities: Arel = A(λ1)/A(λ2), depend on eluent composition for some organic compounds, but their variations cannot be used as indicators for hydrate formation. The coefficients that characterize the dependence of the analyte retention indices on the organic component concentration of an eluent, dRI/dC, appeared to be the most informative additional criterion for hydration. The values of these coefficients for most polar analytes are largely negative (dRI/dC < 0), whereas, for nonpolar compounds, they are largely positive (dRI/dC > 0).

Structural optimization of steel bridge deck pavement based on mixture performance and mechanical simulation

The upper layer of modified SMA mixture (SMAM) and the lower layer of epoxy asphalt mixture (EAM) is a steel bridge deck pavement (SBDP) structure with application potential, but there is a lack of systematic research on it. In this study, the pavement material and structure of SMAM + EAM were optimized using mixture performance tests and finite element analysis, which provided guidance to facilitate its promotion and application. Firstly, the pavement performance and dynamic properties of SMAMs and EAMs prepared with different binders were compared to preferably select the appropriate SBDP material. Secondly, the dynamic modulus master curves of the mixtures were established to provide material parameters for pavement structure design. Finally, the FEA method was applied to comparatively analyze the dynamic mechanical response of the pavement structure for different structures, thickness combinations, and temperatures to optimize the SBDP structure purposefully. The results demonstrated that EAM had better high-temperature rutting resistance than SMAM, while SMAM had superior moisture damage and skid resistance. The modifier contents in the asphalt binder used for SMAM and EAM were recommended to be 12 wt% and 40 wt%, respectively. From the FEA results, the SMAM + EAM structure met the performance requirements of SBDP. Compared with double-layered EAM, the deformation resistance of the SMAM + EAM structure was reduced, but it was beneficial to avoid the occurrence of crack defects and interlayer shear damage. Furthermore, the recommended pavement thickness combination was 4.5 + 3.5 cm.