Results Of Recovery Tests Research Articles

Quantitative and Ultrasensitive Detection of Four Inflammatory Biomarkers by Gold Nanoparticle‐Based Paper Sensor

AbstractDue to the complexity and diversity of infectious diseases, diagnosis based solely on symptoms and imaging manifestations is associated with a high rate of misdiagnosis, so it is particularly important to find reliable and accurate biomarkers. Four inflammatory biomarkers (CRP, IL‐6, PCT and SAA) have different manifestations and roles in different infectious diseases and stages of infection, and the diagnosis and identification of infectious diseases can be realized through quantitative analysis of these four biomarkers simultaneously. In this study, we developed a colloidal gold nanoparticle (AuNP)‐based multiplex LFA strip using eight highly‐sensitive monoclonal antibodies that simultaneously detected CRP, IL‐6, PCT and SAA in serum within 15 min. And quantitative analysis was achieved with a portable strip reader, the LODs were 2.5 μg/mL, 25.3 pg/mL 0.87 ng/mL and 8.8 μg/mL for CRP, IL‐6, PCT and SAA, while detection ranges were 2.5–200 μg/mL, 25.3–8000 pg/mL 0.87–100 ng/mL and 8.8–200 μg/mL. Moreover, the quantitative colloidal gold assay correlated well with the results of a chemiluminescence immunoassay when testing clinical serum samples. Our developed method was reliable and accurate according to the recovery test results. Therefore, the strip can be used as an alternative method for the simultaneous monitoring of CRP, IL‐6, PCT and SAA in serum samples.

The Effect of Carbonhydrate Mouth Rinse on the Endurance Performance in Football Players

The presence of carbohydrates (CHO) in the mouth can enhance performance by stimulating the reward center of the brain. Mouth rinsing with CHO does not cause a potential side effect of gastrointestinal discomfort associated with CHO consumption. Numerous studies have demonstrated that using a carbohydrate solution via mouth rinsing can improve performance in endurance sports. However, research on football is limited, and the effectiveness of this approach in football is uncertain. This placebo-controlled and double-blind study was conducted to evaluate the impact of rinsing the mouth with a 15% CHO solution on endurance performance among football players. Twenty healthy male football players, aged between 20 and 25, participated in the study. Endurance performance was indirectly measured using the results of the Yo-Yo intermittent recovery (IR) test. Blood glucose and lactate levels of the football players were measured before and after the Yo-Yo IR test. They were given either a placebo or a 15% carbohydrate solution to rinse their mouths three times, including before warming up, before the Yo-Yo IR test, and in the middle of the test. There was no significant difference found in the levels of blood lactate, blood glucose, and VO2max values between the two groups (p> 0.05). The study concluded that rinsing the mouth with a 15% CHO solution had no significant impact on the endurance performance of football players.

The Use of COVID-19 Mobile Apps in Connecting Patients with Primary Healthcare in 30 Countries: Eurodata Study.

The COVID-19 pandemic has necessitated changes in European healthcare systems, with a significant proportion of COVID-19 cases being managed on an outpatient basis in primary healthcare (PHC). To alleviate the burden on healthcare facilities, many European countries developed contact-tracing apps and symptom checkers to identify potential cases. As the pandemic evolved, the European Union introduced the Digital COVID-19 Certificate for travel, which relies on vaccination, recent recovery, or negative test results. However, the integration between these apps and PHC has not been thoroughly explored in Europe. To describe if governmental COVID-19 apps allowed COVID-19 patients to connect with PHC through their apps in Europe and to examine how the Digital COVID-19 Certificate was obtained. Design and setting: Retrospective descriptive study in PHC in 30 European countries. An ad hoc, semi-structured questionnaire was developed to collect country-specific data on primary healthcare activity during the COVID-19 pandemic and the use of information technology tools to support medical care from 15 March 2020 to 31 August 2021. Key informants belong to the WONCA Europe network (World Organization of Family Doctors). The data were collected from relevant and reliable official sources, such as governmental websites and guidelines. Patient's first contact with health system, governmental COVID-19 app (name and function), Digital COVID-19 Certification, COVID-19 app connection with PHC. Primary care was the first point of care for suspected COVID-19 patients in 28 countries, and 24 countries developed apps to complement classical medical care. The most frequently developed app was for tracing COVID-19 cases (24 countries), followed by the Digital COVID-19 Certificate app (17 countries). Bulgaria, Italy, Serbia, North Macedonia, and Romania had interoperability between PHC and COVID-19 apps, and Poland and Romania's apps considered social needs. COVID-19 apps were widely created during the first pandemic year. Contact tracing was the most frequent function found in the registered apps. Connection with PHC was scarcely developed. In future pandemics, connections between health system levels should be guaranteed to develop and implement effective strategies for managing diseases.

A Creep Model of Steel Slag–Asphalt Mixture Based on Neural Networks

To characterize the complex creep behavior of steel slag–asphalt mixture influenced by both stress and temperature, predictive models employing Back Propagation (BP) and Long Short-Term Memory (LSTM) neural networks are described and compared in this paper. Multiple stress repeated creep recovery tests on AC-13 grade steel slag–asphalt mix samples were conducted at different temperatures. The experimental results were processed into a group of independent creep recovery test results, then divided into training and testing datasets. The K-fold cross-validation was applied to the training datasets to fine-tune the hyperparameters of the neural networks effectively. Compared with the experimental curves, both the effects of BP and LSTM models were investigated, and the broad applicability of the models was proven. The performance of the trained LSTM model was observed by a 95% confidence interval around the fit errors, thereby the creep strain intervals for the testing dataset were obtained. The results suggest that the LSTM model had enhanced prediction compared the BP model for creep deformation trends of steel slag–asphalt mixture at various temperatures. Due to the potent generalization strength of artificial intelligence technology, the LSTM model can be further expanded for forecasting road rutting deformations.

Hydrochemie podzemní vody Pražského hradu a okolí

The study examines the groundwater around Prague Castle as an example of an extreme urban environment that has been influenced by human activity since the Neolithic period. The long-term human activity, including several still-functioning drainage adits, resulted in a number of aggradation and degradation processes that have significantly impacted the groundwater regime. Furthermore, building development, particularly large-scale concrete structures, has had a notable effect on groundwater chemistry. This paper presents results of available archival chemical analyses from the area of interest (Fig. 1), along with our own groundwater chemical analyses. The results of recovery test in the anthropogenic alluvium well underneath the courtyard III of Prague Castle (Weiss et al. 2024) indicate that the transmissivity of saturated alluvium is low (8–10 m2/day). However, it is reasonable to assume a higher transmissivity for the entire area. The clayey anthropogenic alluvium near the surface likely has a much lower permeability than the underlying fractured zone of the Letná Formation made of shales (Late Ordovician). Field reconnaissance in the drainage adits indicates that groundwater flows directly from the historic alluvium (presence of bones and other organic remains) into the Ordovician strata. The existence of a clay aquitard, as mentioned by some authors (e.g. Kos 1965), between the historical alluvium and the underlying Ordovician is thus unlikely. The analysed water samples from selected objects can be classified into three distinct groups based on their pH levels: slightly acidic (precipitation water, and the well in the St. George’s Convent – V4), neutral (majority of samples), and alkaline (the environment underneath the courtyard III of Prague Castle). Slightly acidic pH level only applies to samples from precipitation or probable seepage (V4). The concentration of Cl- in the majority of the analysed groundwater samples is higher than the natural background level of around 8–10 mg/l, which indicates an anthropogenic source. The major source of these ions in the area is likely the use of NaCl to salt roads and sidewalks during the winter months, which has been a common practice for decades. The overall analysis of the studied samples identified two main hydrochemical types of water: Type A and Type B. Type A is represented by moderately alkaline water that is rich in sulphate and calcium/magnesium. Type B, on the other hand, is represented by strongly alkaline water rich in hydrogencarbonate and calcium, found mainly under the courtyard III of Prague Castle, which stands on a concrete structure. Type A is the predominant type and is typical of water originating in the pyrite-bearing shales of the Letná Formation. The high sulphate content of these waters may cause “sulphate attack” of concrete, leading to its decomposition and thus affecting the durability of building structures. This study provides valuable insights into groundwater chemistry in urban environments that can be applied to other similar sites.

Effects of heat, moisture/water, and compressive force on frequency response spectrum of super sensitive carbon nanofiber aggregates (SSCNFA)

Cement-based sensors should exhibit accurate measurements of strain with high sensitivity and reliability under various environmental conditions. The ability of such sensors to perform in adverse situations needs to be well developed and critically examined. Cement-based sensors are generally embedded in structural/non-structural concrete components for health monitoring. This paper provides an in-depth study of the performance and response of Super Sensitive Carbon Nanofiber Aggregates (SSCNFA) under challenging and adverse environmental conditions, including different temperature, moisture/water exposure, and compressive forces. The SSCNFA detects changes in temperatures, moist environments, and compressive forces through changes in the electrical impedance. In this study, the change in the total impedance of SSCNFAs are experimentally examined by alternating current (AC) measurements (20 Hz–300 kHz) under various environmental conditions. The thermal tests (21 °C–120 °C) and the impedance recovery tests examine and elaborate the phenomenon of resistance and total impedance reduction. The waterproofing test identifies the suitable polymer to prevent moisture percolating through the SSNCFA. Also, compression tests examine the stress/strain sensing through piezoresistivity in the linear elastic limit of the SSCNFA. The effects of these external conditions in the selective frequency range are measured to monitor the stability, reliability, recovery, and performance of the SSCNFA.The research reveals that the SSCNFA exhibited a linear electrical response against the temperature at higher frequencies (higher or equal to 10 kHz) with a standard deviation of less than 5 %. The SSCNFA's porous structure absorbs moisture during concrete casting. This absorbed moisture will be influenced by the environmental temperature variations and mechanical stresses during the service period of the structure. Additionally, the impedance recovery test results of uncoated SSCNFAs provide insight into the frequency response against the moisture/water and the stability of electrical response at the higher frequencies (higher or equal to 100 kHz). The waterproofing of the SSCNFA using M-coat A and M-coat B (polymers) proves to be effective, with the waterproofed SSCNFA sensor embedded in concrete exhibiting stress-sensing ability due to piezoresistivity. The electrical response of the SSCNFAs is more sensitive to temperature, moisture/water, and compressive stresses at low frequencies with higher standard deviations than at higher frequencies. Therefore, the experiments performed on SSCNFAs show that the SSCNFA embedded in a concrete structure is suitable for structural health monitoring. Furthermore, this research offers various avenues for the application of the SSCNFA as a multifunctional tool for temperature sensing and moisture detection of concrete structures due to cracks at critical locations.

Potential-induced degradation phenomena in single-encapsulation crystalline Si photovoltaic modules

This paper particularly explains potential-induced degradation (PID) of wafer-based standard p-type crystalline silicon technology. We present a single-encapsulation method that is useful for simulating PID in the laboratory to facilitate microanalyses of module-level solar cells. The PID testing is performed for the module with single-encapsulation and conventional modules. Their current–voltage characteristics and electroluminescence images are investigated before and after the PID tests. As described herein, we infer that the single-encapsulation modules generate PID almost in the same way as conventional modules do, and that the degradation trend is almost identical to that of conventional modules. Results of PID recovery tests indicate that the time necessary for PID recovery is always less than that for PID generation, irrespective of the encapsulation method.

Alanine aminotransferase electrochemical sensor based on graphene@MXene composite nanomaterials.

Graphene@MXene composite nanomaterials were utilized to construct anelectrochemical sensor for alanine aminotransferase (ALT) detection. The combination of graphene nanosheets with MXene avoids the self-stacking of MXene and graphene, and broadens the charge transfer channel. In addition, the composite nanomaterial provides increased loading sites for pyruvate oxidase. The principle of ALT detection is a two-step enzymatic reaction. L-Alanine was initially transferred to pyruvate catalyzed by ALT. The formed pyruvate was then oxidized by pyruvate oxidase, generating H2O2. Through the detection of the generated H2O2, ALT activity was measured. The linear range of the sensor to ALT was from 5 to 400 U·L-1 with a detection limit of 0.16 U·L-1 (S/N = 3). For real sample analysis, the spiked recovery test results of ALT in serum samples were between 96.89 and 103.93% with RSD < 5%, confirming the reliability of the sensor testing results and potential clinical application of the sensor.

Simultaneous determination of tipiracil, trifluridine and its metabolite 5-trifluoromethyluracil in human plasma using segmented polarity LC-MS/MS: A fully validated assay with clinical application

Trifluridine (FTD) and tipiracil (TPI) hydrochloride tablets (TAS-102) were used for the treatment of patients with metastatic rectal cancer that was resistant to conventional chemotherapy drugs. In this study, a rapid and sensitive liquid chromatography-tandem mass spectrometry method was developed and fully validated for the simultaneous determination of TPI, FTD, and the metabolite 5-trifluoromethyluracil (FTY) of FTD in human plasma. The plasma samples were prepared by protein precipitation. The chromatography separation was performed using ACE Excel 3 AQ (100 × 2.1 mm i.d., 1.7 µm, ACE, England) column protected by a security guard cartridge (4.0 × 2.0 mm i.d., 5 µm, Phenomenex, USA) with a gradient elution of 0.05% acetic acid in water and methanol at a flow rate of 0.35 mL/min. The MS/MS analysis was performed by using multiple reaction monitoring with the segmented polarity (positive for TPI: m/z 243.1→183.0, and negative for FTD: m/z 295.1→252.0 and FTY: m/z 178.9→158.9) electrospray ionization mode. The segmented polarity mode was designed to achieve two advantages: better sensitivity and simultaneous determination of the analytes with different ion polarities. The calibration ranges were as follows: 1.00–250 ng/ for TPI, 8.00–8000 ng/mL for FTD and 5.00–1250 ng/mL for FTY. The selectivity, accuracy, precision, matrix effect, recovery, carryover, dilution integrity and stability test results meet ICH acceptance criteria. The method was evaluated using the RGB model and successfully applied to a clinical study in patients with solid tumors. For TPI, FTD and FTY, the maximum plasma concentration was 137–147 ng/mL, 6160–6240 ng/mL and 724–725 ng/mL, respectively; the plasma elimination half-life was 1.69–1.78 h, 1.70 h, and 3.09–3.14 h, respectively, after an oral administration of 60 mg TAS-102.

Feasibility and Sustainable Performance of RAP Mixtures with Low-Viscosity Binder and Castor Wax–Corn Oil Rejuvenators

The utilization of Recycled Asphalt Pavement (RAP) mixtures in pavement construction is an environmentally friendly approach that promotes sustainable development by reducing energy consumption and material waste. However, the high cost of conventional rejuvenators limits the widespread use of RAP mixtures. In this study, a novel approach is proposed to enhance the performance of RAP mixtures by incorporating a combination of high-penetration asphalt binder and rejuvenators, namely Castor wax and Corn oil. The newly developed rejuvenator consists of 8.5% Castor wax oil, 3% Corn oil, 3% fatty acid amine surfactant, 0.2% additive, and 79.8% water. The test results demonstrate that the modified mixture exhibits superior properties compared with conventional RAP mixtures. The Multiple Stress Creep Recovery test results showed a 20% reduction in cumulative strain rate for the RAP mixture with the new rejuvenators compared with that for the conventional ones. Furthermore, the Tensile Strength Ratio test indicated a notable 9.47% improvement in the rejuvenated RAP mixture’s resistance to moisture-induced damage compared with the conventional mixture. Evaluation of viscoelastic behaviors revealed a slight reduction in dynamic modulus for the rejuvenated binder, but a significant improvement in elastic behavior. In terms of rutting resistance, the Hamburg wheel tracking rut depths of the rejuvenated binder were significantly lower, representing reductions of 21.83% for specific binder compositions. Additionally, the absence of the stripping phenomenon further confirmed the superior moisture resistance of the modified mixture. The rejuvenated binder exhibited a remarkable 28.55% increase in fatigue load cycles to failure compared with the reference RAP binder, demonstrating substantial resistance to fatigue cracking. These quantitative comparisons not only confirm the superior performance of the modified mixture over conventional RAP mixtures, but also highlight the potential cost savings achieved through the utilization of Castor wax and Corn oil rejuvenators.

A validated HPLC-DAD method and comparison of different extraction techniques for analysis of scopoletin in noni-based products

The growth of the production of noni-based products due to the therapeutic effects and health benefits of noni fruits has led to the necessity for quality control and authentication to maintain product quality. This study proposes high-performance liquid chromatography with diode-array detector (HPLC-DAD) analysis for qualitative and quantitative analysis of scopoletin as a quality marker in noni products. Four extraction methods were compared and evaluated in the present study to extract scopoletin from noni products. The results showed that accelerated solvent extraction (ASE) yielded the highest scopoletin in the shortest time with superior relative standard deviation (RSD) value among other extraction methods investigated in this study (maceration, ultrasound, and microwave-assisted extraction). The established method demonstrated excellent linearity (R2 0.9995) within the range of 0.5–100 ​μg/mL, with adequate sensitivity (LOD 0.29 ​μg/mL). It also exhibited satisfactory precision and accuracy, represented by intra- and inter-day RSD values of less than 2% and recovery test results of 99.88%. The optimized and validated ASE-HPLC-DAD method has also been successfully applied to assess scopoletin content in a broad range of commercially available noni products in Indonesia. This includes 11 noni capsules, 5 instant powders, 3 teas, and 1 effervescence. It provides a reliable, fast, and simple alternative method with high accuracy and precision that can be further developed for quality control assessment and authentication of noni-based products.

Restoration of physical properties on an aged crumb rubber modified bitumen adding a bio-based recycling agent

Reclaimed asphalt pavement (RAP) is a popular practice in the pavement industry due to environmental and economic benefits. But, RAP must be processed and treated before being reused in new pavements for preventing premature failures. A widely adopted strategy consists of adding recycling agents, and specifically rejuvenators, to mitigate the aging of the RAP binder. From the circular economy perspective, also crumb rubber (CR) from end-of-life tyres have been used to prepare binders with enhanced properties. The actual possibility of using the RAP derived from removed and/or reprocessed pavements containing CR particles (CR-RAP) for the formulation of new suitable mixtures is still a little-explored topic. Moreover, the available rejuvenators tailored on RAP have not yet evidence of effectiveness in producing asphalt mixtures containing CR-RAP. For this purpose, unaged, aged and rejuvenated blends with and without CR were studied through a rheological characterisation to evaluate the potential restoration of their physical properties when a bio-based recycling agent is added. The results of viscosity, frequency sweep, creep-recovery and multiple stress creep recovery (MSCR) tests have highlighted on the one hand the significant contribution of CR in reducing the accelerated aging effects of the binder, on the hand the effectiveness of the rejuvenator in restoring, more clearly at low temperatures, the rheological behaviour of the binders (above all for CRMB) similar to the unaged condition.

Self-Healing Capability and Mechanical Properties of Asphalt Mixtures Prepared With Light-Activated Polyurethane Prepolymer Modified Asphalt Binder

The objective of this study was to develop a new generation of ultraviolet (UV) light-activated self-healing polyurethane prepolymer modified asphalt binder using a reactive approach and to optimize the production parameters. Rheological tests were conducted on the prepared binder blends to evaluate the effect of the modification on rutting and fatigue cracking. The effect of the modification on asphalt mixtures was also evaluated using a self-healing experiment and various mechanical laboratory tests. The formation of urethane bond was confirmed using Fourier transformed infrared spectroscopy (FT-IR). Rheological test results of the modified binder demonstrated an increase in the high-temperature grading, while no significant effect was observed on the low-temperature grade. Self-healing testing of the asphalt mixtures showed that mixtures with 10% polymer and continuous exposure to UV light exhibited the highest crack healing rate. Loaded Wheel Tracking (LWT) results showed an improvement in rutting resistance of the mixtures prepared with polymer. In addition, Semi-Circular Bending (SCB) test results showed an improvement in the cracking resistance with 5% polymer. An increase in high-temperature grade was also observed for the extracted binders from the prepared asphalt mixtures. Multiple Stress Creep Recovery (MSCR) test results of the extracted binders showed an improvement in the elastic behavior and rutting resistance with an increase in polymer content. Furthermore, the extracted binders from aged mixtures showed an improved fatigue performance with the increase in polymer content.

Use of Hybrid Mineral Filler with High Emissivity in Asphalt Mixture for Cooling Road Pavements

Road asphalt pavements cover a high percentage of urban size and contribute to heat islands. This study proposed a new method to cool asphalt pavement by incorporating a kind of hybrid mineral filler (HMF) with high emissivity into a reference asphalt mixture prepared with limestone mineral filler (LMF). The physical, emissive, solar reflective, and rheological properties of asphalt mastic and the thermal performances of asphalt mixture were covered to investigate the possibility of the proposed strategy. From Fourier transform infrared spectrum test, it can be found that HMF was physically blended with asphalt. The emissivity results show that HMF increased the emissivity of asphalt mastic from 0.9204 to 0.9820. The asphalt mastic containing HMF had similar solar reflectance with the control one. In addition, HMF could enhance the rutting resistance of asphalt mastic according to the results of multiple stress creep recovery tests. When HMF replaced LMF, the thermal conductivity of the asphalt mixture with HMF increased by 0.26 W/(m·K) (the reference value was 1.72 W/(m·K)). The combined effect of high emissivity and thermal conductivity led to a lower surface temperature (i.e., -5.4 °C) in the tests. The results of this study demonstrate that HMF is a potential material to cool asphalt pavements.

Evaluating the Performance of Aluminum Oxide Nanoparticle-Modified Asphalt Binder and Modelling the Viscoelastic Properties by Using Artificial Neural Networks and Support Vector Machines

The effect of aluminum oxide nanoparticles (Al2O3) on the 60/70 penetration of asphalt cement (AC) was investigated in terms of the physical and rheological characteristics by using the Superpave testing procedures. Al2O3 at 3, 5, and 7% concentrations were blended with 60/70 penetration of grade AC. Conventional testing procedures were adopted regarding the physical characteristics, while dynamic shear rheometer (DSR) testing procedures were conducted to evaluate the high and low temperature failure parameters. In addition, heuristic modelling techniques, artificial neural networks (ANN), and support vector machines (SVM) were employed to predict the performance characteristics of AC by using the mechanical testing conditions. The frequency sweep test and multiple stress creep recovery (MSCR) test results revealed that the optimum composition of Al2O3 was at 5% concentration considering the high temperature performance characteristics since further addition of the Al2O3 resulted in degradation in the enhanced properties due to agglomeration of the nanoparticles in the blend. On the contrary, Al2O3 5% demonstrated the lowest viscoelastic behavior at intermediate temperatures. The higher complex modulus ( G ∗ ) and lower phase angle ( δ ) parameters indicated that the increase in stiffness due to the modification process was at the cost of losing elastic properties against fatigue cracking. Moreover, based on the statistical performance indicator, coefficient of determination (R2), it was observed that the ANN models for predicting G ∗ and δ achieved a prediction accuracy of 0.989 and 0.911 while SVM models were able to achieve 0.984 and 0.929, respectively, considering the training datasets. On the other hand, it was noted that SVM models outperformed the ANN models in terms of a smaller gap between the results obtained from the training and testing datasets. The difference between the training and testing datasets for G ∗ and δ parameters for the SVM models were 3.2% and 6.8% while for the ANN models, the differences were 11.6% and 9.5%, respectively, indicating that the ANN models were more prone to the overfitting phenomenon.

Effect of glutaraldehyde-chitosan crosslinked graphene oxide on high temperature properties of SBS modified asphalt

Composite material using glutaraldehyde (GA) cross-linked chitosan (CTS) and graphene oxide (GO-CTS-GA) was designed applying electrostatic interaction strategy under strong alkali environment. GO-CTS-GA was in turn applied to prepare styrene butadiene styrene (SBS) GO-CTS-GA/SBS composite modified asphalt (MA)_binder. The effect of GO-CTS-GA on the physical properties of SBS modified asphalt binder was investigated and its mechanism of action was analyzed. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy tests confirmed the retainment of GO flakes microscopic dimensions while compensating for the chemical structural defects and mechanical property damage of GO. The results of dynamic shear rheometer and multi-stress creep recovery tests indicated that the GO-CTS-GA/SBS-MA binder exhibited better viscosity performance and elasticity performance, rutting resistance and high temperature thermal stability. At 64 °C, the loss modulus of 0.10 % GO-CTS-GA/SBS-MA was 29.5 % and 25.2 % higher than that of SBS-MA and GO/SBS-MA, respectively. SEM and TEM analyses of the four components of asphalt binder before and after modification revealed that the change of asphaltene microscopic morphology seriously affects the stability of asphalt colloidal system. Fourier transform infra-red analysis of the MA binder revealed that the change of saturation fraction and colloidal polarity by GO-CTS-GA is responsible for the dispersion and cross-linking of SBS chain segments in the asphalt binder phase. This study provides important reference information for nanomaterials to change the macroscopic mechanical properties by modulating the microstructure, physical and chemical properties of asphalt binder at the micro and nano-scale.

Performance and mechanism evaluation of dopamine-hexamethylene diamine-iron tetraoxide composite rubber powder incorporated styrene-butadiene-styrene modified asphalt

• The microwave absorber PDA-HDA-Fe 3 O 4 was synthesized by a one-pot facile method. • PDA-HDA-Fe 3 O 4 /SBS-RP-MA realized improved viscoelasticity and rutting resistance. • PDA-HDA-Fe 3 O 4 /SBS-RP-MA had high microwave absorption. • Some functional groups of PDA-HDA dispersed agglomeration of Fe 3 O 4 in asphalt. In order to improve the mechanical properties, high temperature rheological properties, and self-healing of modified asphalt, the microwave absorber iron tetraoxide (Fe 3 O 4 ) was modified and polydopamine-hexamethylene diamine-Fe 3 O 4 (PDA-HDA-Fe 3 O 4 ) was prepared, which was compounded with rubber powder/styrene butadiene styrene modified asphalt (RP-SBS-MA). Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed that chemical composition and crystal morphology of PDA-HDA-Fe 3 O 4 remained unchanged. Scanning electron microscopy and atomic force microscopy revealed that the surface morphology of the modified Fe 3 O 4 was altered which could increase the mechanical interlocking interaction with the base asphalt. Dynamic shear rheometer test showed that at 46 °C, the storage modulus and loss modulus of 1 %PDA-HDA-Fe 3 O 4 /RP-SBS-MA were respectively 61.96 % and 69.65 % higher compared to that of RP-SBS-MA. The results of the multi-stress creep recovery test showed that at 3.2 kPa, the strain of 1 %PDA-HDA-Fe 3 O 4 /RP-SBS-MA was reduced by 54.16 % compared to that of RP-SBS-MA. Microwave heating tests analysis showed that the temperature of 1 %PDA-HDA-Fe 3 O 4 /RP-SBS-MA was 20.48 % and 2.41 % higher than those of RP-SBS-MA and 1 %Fe 3 O 4 /RP-SBS-MA, respectively. This was attributed to the improved microwave absorption capacity of the modified asphalt upon the addition of PDA-HDA-Fe 3 O 4 . These convincing results of the newly prepared PDA-HDA-Fe 3 O 4 /RP-SBS-MA could be envisioned of great promise for designing advanced functional asphalts for targeted applications.

A novel fluorescence biosensor based on double-stranded DNA branch migration-induced HCR and DNAzyme feedback circuit for sensitive detection of Pseudomonas aeruginosa (clean version)

Pseudomonas aeruginosa (P. aeruginosa) is one of the most common bacteria in nosocomial infection. Here, a novel fluorescence biosensor based on double-stranded DNA branch migration-induced hybridization chain reaction (HCR) and DNAzyme feedback circuit was constructed for sensitive detection of P. aeruginosa. The binding of P. aeruginosa with its aptamer on a DNA three-way junction structure initiated the double-stranded DNA branch migration to form two DNA “Y” junction structures. One DNA “Y” junction structure opened the fluorescence-labelled DNA hairpins and triggered the HCR. The other DNA “Y” junction structure formed a double-stranded DNAzyme and cleaved the specific ribonucleotide site, producing new triggering probes to start the next cycle of the double-stranded DNA branch migration. Ultimately, a large number of DNA “Y” junction structures were produced, which greatly promoted signal amplification. Under optimized conditions, the proposed biosensor detected a wide linearity range of 102–107 CFU mL−1, and the limit of detection was 37 CFU mL−1 (S/N = 3). The recovery test results indicated that the biosensor has promising clinical application potential. Because of the simultaneous initiation of the HCR and the DNAzyme feedback circuit through the double-stranded DNA branch migration, the constructed biosensor provided an ideal platform for pathogenic bacteria detection without protein enzymes and complex signal amplification procedures.

Highly sensitive and selective amperometric hydrazine sensor based on Au nanoparticle-decorated conducting polythiophene prepared via oxidative polymerization and photo-reduction techniques

In this study, gold nanoparticles (AuNPs) decorated polythiophene (Pth) nanocomposite modified glassy carbon electrode (GCE) has been used to fabricate an electrochemical sensor for the sensitive and selective detection of hydrazine. Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to adequately characterize the nanocomposite. The research findings revealed that AuNPs with cubic phase and diameter range 10–22 nm were monodispersed over the polymeric surface. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) investigation demonstrated that the AuNPs decorated Pth greatly improved the electrocatalytic performance compared with pure Pth modified GCE. This extraordinary electrochemical property is attributed to the synergistic coupling effect between AuNPs and Pth. The mechanistic analysis using CV voltammograms measured in varying scan rates revealed irreversible diffusion-controlled kinetics involving four-electron (4e−) transfer process of hydrazine oxidation. In amperometric (i-t) detection, the proposed sensor showed high sensitivity 0.1817 μAμMcm−2 and a low detection limit 0.77 μM (S/N = 3) over the concentration range 1–963 μM. Moreover, this proposed nanocomposite-based sensor was highly selective toward hydrazine in the presence of common interfering species, especially in high concentrations of sugars (e.g. glucose, sucrose, fructose, and galactose) and exhibited promising analytical results of recovery tests in water samples with acceptable recovery with a relative standard deviation less than 5%.

Mechanical behavior and recoverable properties of CFRP shape memory alloy composite under different prestrains

This paper explored a prestressed CFRP/SMA composite system, which can be applied to add prestress to the civil structural members. The composite system was composed of carbon fiber reinforced polymer (CFRP) sheets and the embedded shape memory alloy (SMA) wires. The prestress in CFRP sheets was formed by the recovery of SMA wires. Four groups of fully composite (Type I) specimens were fabricated to bear a unidirectional static load to investigate their tensile mechanical properties. Three groups of partial composite (Type II) specimens and five groups of SMA wire specimens were used to study their recoverability. The static test results showed that two main failure modes of the Type I specimens were observed, and the strength of the material was affected by the structural form of the composite. The recovery test results showed that the SMA wire could generate different levels of recovery stress under various amounts of prestrain, and the maximum recovery stress can reach 394.2 MPa for the SMA wire with 6% prestrain by heating it to 131℃. More importantly, the recovery stress can be introduced into the CFRP sheets. In addition, an analytical model for predicting the stress–strain relationship and material strength of the fully composite was proposed, and an improved segmented recovery stress–temperature model of the SMA wire under constraint conditions was also put forward. The results indicated that the calculated values are in good agreement with the experimental values, and the proposed model can effectively predict the mechanical and recoverable properties of the composites.