Adsorption of NO2, SO2, H2S, and NH3 on Os-Doped WSe2 Monolayers: A First-Principles Study.

In this study, DFT calculations are used to analyze the adsorption of industrial waste gases (NO2, SO2, H2S, and NH3) on WSe2 monolayers. The adsorption energy, energy band, density of states, charge transfer, and recovery time of the adsorption structures between the target gas molecules and the Os-doped WSe2 are studied. Compared with pure WSe2 monolayer, Os surface bonding doping WSe2 (Os-modified WSe2) and Os doping with Se vacancy of WSe2 (Os-embedded WSe2) exhibit improved gas molecule adsorption ability. Among them, the adsorption energy of the Os-modified WSe2 monolayer on NO2, SO2, H2S, and NH3 is greater than that of the WSe2 monolayer. At the same time, it is proved that the Os-embedded WSe2 can be used as a gas sensor for H2S and NH3 gas molecules at a high temperature.

Adsorption and Sensing of NO2, SO2, and NH3 on a Janus MoSeTe Monolayer Decorated with Transition Metals (Fe, Co, and Ni): A First-Principles Study.

This paper reports the adsorption of toxic gases (NO2, SO2, and NH3) on a MoSeTe structure based on first principles. It was found that the gas (NO2, SO2, and NH3) adsorption on a pure MoSeTe monolayer was weak; however, the adsorption performance of these gas molecules on transition-metal-atom-supported MoSeTe monolayers (TM-MoSeTe) was better than that on pure MoSeTe monolayers. In addition, there was more charge transfer between gas molecules and TM-MoSeTe. By comparing the adsorption energy and charge transfer values, the trend of adsorption energy and charge transfer in the adsorption of NO2 and SO2 was determined to be Fe-MoSeTe > Co-MoSeTe > Ni-MoSeTe. For the adsorption of NH3, the effect trend was as follows: Co-MoSeTe > Ni-MoSeTe > Fe-MoSeTe. Finally, by comparing their response times, the better gas sensor was selected. The Ni-MoSeTe system is suitable for NO2 gas sensors, and the Fe-MoSeTe and Co-MoSeTe systems are suitable for SO2 gas sensors. The Fe-MoSeTe, Co-MoSeTe, and Ni-MoSeTe systems are all suitable for NH3 gas sensors. Janus transition-metal dichalcogenides have the potential to be used as gas-sensing and scavenging materials.

3D printed self-driven thumb-sized motors for in-situ underwater pollutant remediation.

Green fuel-driven thumb sized motors (TSM) were designed and optimized by 3D printing to explore their in-situ remediation applications in rare studied underwater area. Combined with areogel processing and specialized bacteria domestication, each tiny TSM could realize large area pollutant treatment precisely in an impressive half-automatically manner.

A highly efficient, low-toxic, wide-spectrum antibacterial coating designed for 3D printed implants with tailorable release properties.

Herein, a highly customized and broad-spectrum antibacterial implant was prepared through the combination of 3D printing technology and surface nano-modification. The antibacterial coating, which consists of the film-forming agent polyvinyl alcohol (PVA), polyethylene acid (PAA), and green-synthesized silver nanoparticles (Ag-NPs), was modified on the surface of a 3D-printed implant. The small-sized Ag-NPs (<10 nm) showed potent broad spectrum activity and good biocompatibility in relatively low concentration. Moreover, through changing the content of the Ag-NPs and the proportion of PVA and PAA, the loadings and release rate of Ag-NPs could be controlled according to actual requirements, achieving the goal of precise treatment. Animal experiments demonstrated that the implant system exhibited superior anti-infection performance, which could effectively reduce the postoperative infection risk of implant materials, consequently promoting the practical process of 3D printed implants.

Zn or O? An Atomic Level Comparison on Antibacterial Activities of Zinc Oxides.

For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D-printing-manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram-positive or gram-negative bacterial species. Zinc atoms as outermost layer (ZnO-Zn) showed a more pronounced antibacterial effect towards gram-negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO-O) showed a stronger antibacterial activity against gram-positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn(2+) concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species.

The "Pure Marriage" between 3D Printing and Well-Ordered Nanoarrays by Using PEALD Assisted Hydrothermal Surface Engineering.

For the first time, homogeneous and well-ordered functional nanoarrays were grown densely on the complex structured three-dimensional (3D) printing frameworks through a general plasma enhanced atomic layer deposition (PEALD) assisted hydrothermal surface engineering process. The entire process was free from toxic additives or harmful residues and, therefore, can meet the critical requirements of high-purity products. As a practical example, 3D customized earplugs were precisely manufactured according to the model of ear canals at the 0.1 mm level. Meanwhile, well-ordered ZnO nanoarrays, formed on the surfaces of these 3D printed earplugs, could effectively prevent the growth of five main pathogens derived from the patients with otitis media and exhibited excellent wear resistance as well. On the basis of both animal experiments and volunteers' investigations, the 3D customized earplugs showed sound insulation capabilities superior to those of traditional earplugs. Further animal experiments demonstrated the potential of as-modified implant scaffolds in practical clinical applications. This work, exemplified with earplugs and implant scaffolds, oriented the development direction of 3D printing in biomedical devices, which precisely integrated customized architecture and tailored surface performance.

Full Spectrum Visible LED Light Activated Antibacterial System Realized by Optimized Cu2O Crystals.

Assisted by three-dimensional printing technology, we proposed and demonstrated a full spectrum visible light activated antibacterial system by using a combination of 500 nm sized Cu2O crystals and light-emitting diode (LED) lamps. Further improved antibacterial ratios were achieved, for the first time, with pure Cu2O for both Gram-positive bacteria and Gram-negative bacteria among all of the six different color LED lamps. For practical antibacterial applications, we revealed that the nonwoven fabric could act as excellent carrier for Cu2O crystals and provide impressive antibacterial performance. Furthermore, integrated with our self-developed app, the poly(ethylene terephthalate) film loaded with Cu2O crystals also showed significant antibacterial property, thus making it possible to be applied in field of touch screen. The present research not only provided a healthier alternative to traditional ultraviolet-based sterilization but also opened an auto-response manner to decrease the rate of microbial contamination on billions of touch screen devices.

The first visually observable three-mode antibiotic switch and its relative 3D printing assisted applications.

The first visible three-mode switchable antibiotic nanocomposite, including "Packaged" (low toxicity and high stability), "On" (potent antibacterial activity, including drug-resistant strains) and "Off" (easy separation) modes, was synthesized to address several problems caused by antibiotic abuses. Some potential applications were discussed by using animal experiments and 3D printing separately.