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A novel composite material based on acrylonitrile‐butadiene‐styrene (ABS) and carbon black (CB) was proposed here. Different ratios between CB and ABS (40 : 60–60 : 40 %, w/w) were studied to obtain a substrate with improved electrochemical properties. These materials were characterized by techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Raman and Fourier transform infrared (FT‐IR) spectroscopies and scanning electron microscopy (SEM). Under the CB/ABS substrate (50 : 50 %, w/w), a lower charge transfer resistance (854 Ω) and a higher heterogeneous electron transfer constant (K0=1.551×10−3 cm s−1) were found, indicating a kinetically more favorable reaction. To improve the electroanalytical performance of the CB/ABS electrode (50 : 50 %, w/w), silver nanoparticles (AgNPs) were electrodeposited using recycled silver from photographic waste, whose presence was confirmed by SEM imaging and Raman spectra. A method using square wave anodic stripping voltammetry (SWASV) and Pb2+ as model species was developed, where a wider linear working range (4.0 to 40.0 μg L−1) and lower detection limit (0.4 μg L−1) were achieved for the modified electrode. The electrode modification process was highly reproducible (RSD=9.7 %, n=9, inter‐electrode), with precise electrochemical responses (RSD=3.6 %, n=9, intra‐electrode). The applicability was demonstrated in two seawater samples, where recovery levels between 94 and 106 %, as well as statistically similar results to those obtained by atomic absorption spectroscopy, attested to the reliability of the analysis. Furthermore, it is noteworthy that an appropriate selectivity was achieved even in the presence of other metallic species. The proposed composite material is low‐cost, robust, versatile, and can be a promising tool for additive manufacturing of electrochemical sensors. [ABSTRACT FROM AUTHOR]

This article analyses the influence of acrylic fibers shape on the flexural behavior of cement composite. The fibers differ in their cross-sectional shapes due to the spinning process (wet-spun and dry-spun). The fibers were characterized by optical microscopy, and the shape factors were calculated on the basis of their geometric characteristics. Results showed that both types of acrylic fiber remarkably improved the flexural performance of the composites. Wet-spun acrylic fibers lead to high flexural strength and toughness. It was found that by increasing the fibers' shape factor by a factor of 10%, flexural strength and toughness increase to 26% and 23%, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Nanotechnology seems to hold the key that allows construction and building materials to replicate the features of natural systems improved until perfection during millions of years. This paper reviews current knowledge about nanotechnology and nanomaterials used by the construction industry. It covers the nanoscale analysis of Portland cement hydration products, the use of nanoparticles to increase the strength and durability of cimentitious composites, the photocatalytic capacity of nanomaterials and also nanotoxicity risks. [ABSTRACT FROM AUTHOR]

Composite materials with properties aimed at the additive manufacturing of affordable electrochemical sensors have received special attention in the scientific scenario. For this reason, we proposed a new composite material based on alumina oxide (Al 2 O 3) and graphite (Gpt) dispersed in polylactic acid (PLA) biopolymer. Various proportions between the materials were studied, and a better compromise between printability and electrochemical performance was obtained using Gpt/Al 2 O 3 /PLA (30:10:60% w/w). The electrodes were manufactured using a 3D pen, a portable, user-friendly, and low-cost tool. Characterizations by Raman and infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy indicated that Gpt and Al 2 O 3 were successfully incorporated into the PLA matrix. Preliminary studies using species with well-known electrochemical behavior revealed that Al 2 O 3 positively impacts the electrochemical response of the sensor. As a proof of concept, sulfamethoxazole (SMZ), a low-cost antibiotic widely used in beekeeping practices, was selected as the target analyte, and a simple, fast, and selective method using square wave voltammetry was proposed. Using the 3D-printed Gpt/Al 2 O 3 /PLA electrode, a wider linear range (2.0 to 40.0 μmol L−1), a 6.5-fold increase in sensitivity, limits of detection (LOD = 0.4 μmol L−1) and quantification (LOQ = 1.2 μmol L−1) were achieved compared to the Al 2 O 3 -free electrode (Gpt/PLA). In addition, the proposed sensor was selective against other antibiotics commonly used in beekeeping practices. Three honey samples were analyzed after simple dilution in 0.12 mol L−1 Britton-Robinson buffer, pH 7.0 (background electrolyte), and recoveries close to 100% as well as statistically comparable results from chromatographic analysis certified the accuracy and reliability of the analysis. The proposed approach is innovative and valuable in contributing to the advancement of additive manufacturing in electrochemical sensing, especially in the on-site analysis of antibiotic species in food, a public health challenge. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A new carbon-composite material is proposed for the production of affordable sensors. • Carbon nitride provided electrocatalytic properties for the detection of amaranth. • Amaranth is determined for the first time using a 3D-printed electrochemical platform. • The proposed method can be applied to different food samples. • Results similar to those of UV–Vis spectrometry confirmed the method's accuracy. The production of sustainable materials with properties aimed at the additive manufacturing of electrochemical sensors has gained prestige in the scientific scenario. Here, a novel lab-made composite material using graphite (G) and carbon nitride (C 3 N 4) embedded into polylactic acid (PLA) biopolymer is proposed to produce 3D-printed electrodes. PLA offers printability and mechanical stability in this composition, while G and C 3 N 4 provide electrical properties and electrocatalytic sites, respectively. Characterizations by Raman and infrared spectroscopies and Energy Dispersive X-rays indicated that the G/C 3 N 4 /PLA composite was successfully obtained, while electron microscopy images revealed non-homogeneous rough surfaces. Better electrochemical properties were achieved when the G/C 3 N 4 /PLA proportion (35:5:60) was used. As a proof of concept, amaranth (AMR), a synthetic dye, was selected as an analyte, and a fast method using square wave voltammetry was developed. Utilizing the 3D-printed G/C 3 N 4 /PLA electrode, a more comprehensive linear range (0.2 to 4.2 μmol/L), a 5-fold increase in sensitivity (9.83 μmol−1 L μA), and better limits of detection (LOD = 0.06 μmol/L) and quantification (LOQ = 0.18 μmol/L) were achieved compared to the G/PLA electrode. Samples of jelly, popsicles, isotonic drinks, and food flavoring samples were analyzed, and similar results to those obtained by UV–vis spectrometry confirmed the method's reliability. Therefore, the described sensor is a simple, cost-effective alternative for assessing AMR in routine food analysis. [ABSTRACT FROM AUTHOR]

• Crack self-sensing ability of concrete beam added with SF, CB and CF is studied. • Two models for FCI-COD curve are found for deflection softening/hardening beam. • Signal noise of FCI-COD curves has been analyzed by the fractal geometry method. • Hybrid use of CB and SF is an optimization option for crack self sensing concrete. This work explores the mechanical and self monitoring performance of concrete beams containing steel fiber (SF), carbon black (CB) and carbon fiber (CF), when subjected to bending. The effect of the utilization of multiphase conductive materials on the compressive strength of the concrete and the load - deflection - fractional change in impedance (FCI) relationship of the concrete beam are investigated. The relationships between FCI and crack opening displacement (COD) and sensitivity (gauge factor) are also studied. Moreover, the quantitative analysis of signal noise in FCI-COD curves has been accomplished by the fractal geometry method. The result shows that a monotonic linearity and bi-linearity increasing relationship between FCI and COD can be observed for beams with deflection-softening (Group A and Group B specimens) and deflection-hardening (Group C specimens) behavior, respectively. The diphasic conductive admixture (SF + CB) improves the FCI-COD curve with higher sensitivity and lower noise signal compared to the monophasic conductive admixture (SF) and the triphasic conductive admixture (SF + CB + CF) specimen. [ABSTRACT FROM AUTHOR]