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Alkali-activated cement (AAC) produced with metakaolin and black rice husk ash was investigated. The characteristics, physical properties, and thermal properties were investigated. Porosity assessments were carried out using synchrotron radiation X-ray tomographic microscopy (XTM). The results revealed that the concentration of NaOH solution and Na2SiO3 solution was the key parameter which affected the morphology and properties of AAC. Particle-structures and prolonged structures were formed when using NaOH as an activator. However, stacked plate-like structures were observed when using Na2SiO3 together with NaOH. The amorphous phases of N-A-S-H gel and geopolymer were formed. XTM profiles showed that the pore volume decreased with increasing NaOH solution concentration and Na2SiO3 contents. The 3D images illustrated that the pore structures were occupied by pores less than 50 µm in size. Pore connections within the range of 0–50 µm were the main parameter which controlled the thermal and physical properties. [ABSTRACT FROM AUTHOR]

Silver diamine nitrate (SDN) is expected to help control caries similar to silver diamine fluoride (SDF). The aim of this study was to determine the mineral precipitation in demineralized dentin and the cytotoxicity of SDN and SDF to dental pulp cells. Demineralized dentin specimens were prepared, and SDF, SDN, or water (control) was applied. The specimens were then remineralized in simulated body fluid for 2 weeks. The mineral precipitation in the specimens was examined using FTIR-ATR, SEM-EDX, and synchrotron radiation X-ray tomographic microscopy (SRXTM). Additionally, the cytotoxicity of SDF and SDN to human dental pulp stem cells was analyzed using an MTT assay. The increase in FTIR spectra attributable to apatite formation in demineralized dentin in the SDF group was significantly higher compared to the SDN and control groups (p < 0.05). Dentinal tubule occlusion by the precipitation of silver salts was detected in both SDF and SDN groups. The mineral density as shown in SRXTM images and cytotoxicity of both SDN and SDF groups were comparable (p > 0.05). In conclusion, SDF demonstrated superior in vitro apatite formation compared to SDN. However, the degree of mineral precipitation and cytotoxic effects of both were similar. [ABSTRACT FROM AUTHOR]

Owing to their structural advantages over bulk polymers, porous 3D substrates possess immense potential in triboelectric energy generation. This work reports the effective effort to fabricate the porous structure of polydimethylsiloxane, also known as the sponge-PDMS, by a simple template method. The sodium chloride salt from commodity product is used to create the 300 μm size of pores within the PDMS elastomeric layers, turning affects to the mechanical deformability of the triboelectric nanogenerator (TENG). The inner face of those pores is composited with the PVDF-HFP particles as a piezoelectric fillers. The presence of those fillers can be confirmed and their distribution within porous PDMS is 3D visualized by the synchrotron radiation X-ray tomography. The spatial distribution of the PVDF-HFP made it possible to fabricate the piezo-embedded macroporous TENG with high output power of 7.84 μW, giving over 2-fold enhancement, compared with the sponge-PDMS and even more when compared with the flat PDMS film under the same mechanical force. [ABSTRACT FROM AUTHOR]

There is a need to develop inexpensive, lightweight, and flexible high‐performance triboelectric nanogenerators (TENGs) from renewable resources. Here, a multifunctional cellulose filter paper (CFP)‐based TENG consisting of dielectric Ti0.8O2 nanosheets (Ti0.8O2 NSs) and conducting Ag nanoparticles (Ag NPs) is prepared by a simple dip coating method. The incorporation of dielectric Ti0.8O2 NSs onto the CFP significantly improves charge generation, while the inclusion of Ag NPs provides an electrically conductive path for charge transportation. The presence of these fillers can be deduced from XRD, SEM, EDS, X‐ray photoelectron spectroscopy, and Raman spectroscopy. Their distribution is visualized in 3D by synchrotron radiation X‐ray tomography. The present CFP‐based TENG provides an output voltage and current density of ≈42 V and ≈1 µA cm−2, respectively with the power density of ≈25 µW cm−2. It is capable of lighting up 40 light‐emitting diode bulbs and charging a 0.22 µF capacitor to 8 V in only 5 s. The developed TENG is also capable of detecting simple human motions, i.e., finger tapping, finger rubbing, and foot trampling. This work offers a facile design of low cost yet efficient paper‐based TENG by dual modification with multifunctional nanomaterials, and also demonstrates its use as a feasible power source that not only drives small electronics, but also scavenges energy from human actions. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have emerged as a promising functional filler in nanocomposites due to their unique anisotropy and resilience to harsh conditions. We report herein the use of Ti 0.91 O 2 nanosheets as a protective component against γ -irradiation to cellulose paper. The titanate nanosheets were prepared via a sequence of solid-state synthesis of lepidocrocite-type Cs 0.7 Ti 1.825 O 4 , proton exchange to H 0.7 Ti 1.825 O 4 ·H 2 O, and exfoliation with tetrabutylammonium hydroxide. The nanosheets were incorporated into the commercial cellulose filter paper by a simple dip coating up to 0.6 mg cm−2, equivalent to 10 wt% TiO 2. The nanosheets distribution was demonstrated by energy dispersive X-ray (EDX) mapping, synchrotron radiation X-ray tomographic microscopy (SRXTM), and atomic force microscopy (AFM). It is found that γ -irradiation (up to 50 kGy) destroyed the cellulose I β crystallinity of uncoated paper, but this is less pronounced in the cellulose/titanate nanosheets composite. This was also confirmed by the lack of a 235 nm-absorption characteristics of irradiation-induced decomposition product(s) in nanosheets-containing papers, which also exhibit UVA shielding property. The coated samples remained white while the uncoated ones were darkened with γ -irradiation. In addition, the nanosheets-coated papers showed dielectric permittivity, loss tangent, and AC conductivity which were invariant of the γ -dose, unlike those from the uncoated ones. Our work demonstrates the use of lead-free Ti 0.91 O 2 nanosheets as a γ -shielding component to slow down/prevent structural, optical, and electrical properties damages in cellulose paper, which could extend to other nature-derived materials. [Display omitted] • Simple dip coating of commercial filter paper into titanate nanosheets suspension. • Nanosheets loadings were confirmed by several techniques. • The nanosheets (0.6 mg cm−2, or 10 wt% TiO 2) prevent structural, optical, and electrical properties damages by γ -irradiation (up to 50 kGy). [ABSTRACT FROM AUTHOR]

This work demonstrated the influence of pore morphologies on the mechanical behavior and tribo-electrical performance of fabricated polydimethylsiloxane (PDMS) sponge. Commercial seasonings with different 3D geometric shapes were used as a sacrificial template to control the pore structure of the PDMS sponge. The result indicated that the softest PDMS sponge was molded by using a sodium chloride (NaCl) crystal template, as indicated by the lowest compressive modulus value. Then, P(VDF–HFP) was incorporated into PDMS prepolymer in order to enhance the charge generation characteristic of PDMS. Besides, the composite 3D structure was revealed using synchrotron radiation X-ray tomographic microscopy (SRXTM). Interpretation from the SRXTM result confirmed that the porous structure had different pore shapes, i.e. , an octahedral-like shape and a circular-like shape in a particular sponge. By pairing the composite PDMS sponge with an aluminum (Al) plate for the triboelectric nanogenerator (TENG), the maximum electrical outputs of ~29.9 V and ~0.56 μA for voltage and current, respectively, were detected with loading 50 wt% of P(VDF – HFP). The presented TENG was applied successfully for sensing basic human activities practically, which demonstrated potential applications in wearable electronics. • 3D-PDMS sponges were fabricated with various templates. • The composite P(VDF-HFP)/PDMS sponge generated a high triboelectric performance. • In single-electrode TENG mode, the V OC obtained ~40 V with the power of 25 mW. • The present TENG could sense simple human activities efficiently. [ABSTRACT FROM AUTHOR]