Millimeter-wave spectroscopy and computational chemical studies of biologically significance and interstellar molecules

Ph.DDOCTOR OF PHILOSOPH

Innovative Technology for Self‐Powered Sensors: Triboelectric Nanogenerators

Abstract Internet of Things and wearable technology's quick development have opened up a vast market for sensor systems. However, typical sensors' external power supplies' short lifespan and expensive maintenance restrict them from being used more widely. Triboelectric nanogenerators (TENGs), a recently created mechanical energy harvesting and self‐powered sensing device, show enormous promise to get over these restrictions. TENG can be used not only to power sensors instead of conventional chemical batteries but also be utilized to actualize sensing by taking advantage of the unique characteristics of the friction layer itself. Triboelectric nanogenerators efficiently provide crucial infrastructure for a new generation of sensing devices that gather data using several self‐powered sensors in abundance. The recent progress in the development of TENGs applied in the sensor field is reviewed. First, the working mechanisms of solid‐solid TENG and solid–liquid TENG are introduced. Subsequently, the development of TENG‐based sensing systems and their application progress in self‐powered temperature sensors, self‐powered pressure sensors, self‐powered humidity sensors, self‐powered atmosphere sensors, self‐powered wireless sensors, interface wetting status monitoring, solution property monitoring, and friction condition monitoring are highlighted. Finally, current challenges and open opportunities are discussed

Evaluation of polymeric nanoparticle formulations by effective imaging and quantitation of cellular uptake for controlled delivery of doxorubicin

10.1002/smll.201402073Small11422861197-120

Current Research Trends and Perspectives on Solid-State Nanomaterials in Hydrogen Storage

Hydrogen energy, with environment amicable, renewable, efficiency, and cost-effective advantages, is the future mainstream substitution of fossil-based fuel. However, the extremely low volumetric density gives rise to the main challenge in hydrogen storage, and therefore, exploring effective storage techniques is key hurdles that need to be crossed to accomplish the sustainable hydrogen economy. Hydrogen physically or chemically stored into nanomaterials in the solid-state is a desirable prospect for effective large-scale hydrogen storage, which has exhibited great potentials for applications in both reversible onboard storage and regenerable off-board storage applications. Its attractive points include safe, compact, light, reversibility, and efficiently produce sufficient pure hydrogen fuel under the mild condition. This review comprehensively gathers the state-of-art solid-state hydrogen storage technologies using nanostructured materials, involving nanoporous carbon materials, metal-organic frameworks, covalent organic frameworks, porous aromatic frameworks, nanoporous organic polymers, and nanoscale hydrides. It describes significant advances achieved so far, and main barriers need to be surmounted to approach practical applications, as well as offers a perspective for sustainable energy research

THE MILLIMETER- AND SUBMILLIMETER-WAVE SPECTRUM OF DIETHYL ETHER (C2H5OC2H5)(C_{2}H_{5}OC_{2}H_{5})

Author Institution: Department of Physics, The Ohio State University; Department of Chemistry, National University of SingaporeAlthough most organic molecules found in interstellar clouds are unsaturated in nature, saturated and near-saturated molecules are detected in so-called ""hot-core"" sources near the sites of high-mass star formation. One such molecule of high abundance is dimethyl ether. Based on this large abundance, interstellar searches have been conducted for the next most complex ethers --- ethylmethyl ether and diethyl ether --- and tentative detections made despite the lack of data at all but the lowest frequency regions. Clearly, millimeter-wave and submillimeter-wave spectral data are necessary for the unambiguous detection of these molecules. We have recently studied the rotational-torsional spectrum of ethyl methyl ether at frequencies up to 350 GHz. In this talk, we report a new study of the rotational spectrum of diethyl ether from 75 GHz through 400 GHz recorded with the OSU ""FASSST"" spectrometer and with the MMW spectrometer (frequency range 75 to 110 GHz) located at NUS. Unlike dimethyl ether and ethylmethyl ether, the anti-anti conformer (old notation: trans-trans or TT conformer) of diethyl ether is a semi-rigid molecule, the spectrum of which can be fitted with a standard A-reduced asymmetric top Hamiltonian. Based on our results, detailed interstellar searches for this species can now be undertaken

Harnessing Croconaine Organic Photosensitizers for a Milder Surface-Mediated Transfection

Polydopamine-based materials, notably Polydopamine-polyethyleneimine (PDA-PEI), have gained considerable interest for surface-mediated transfection. However, the high laser power density required to achieve high transfection efficiency poses a significant challenge in preserving cell viability. An organic photosensitizer CRO32TMI was developed to improve the photothermal conversion capability of PDA-PEI. The modified PDA-PEI-CRO32TMI exhibited remarkable photothermal and photostability properties upon NIR irradiation, enabling it to achieve better transfection efficiency at lower laser power density as compared to the traditional solution or lipid-based transfection methods

Solar-Powered Photodegradation of Pollutant Dyes Using Silver-Embedded Porous TiO2 Nanofibers

Titanium dioxide (TiO2) nanomaterials have been ubiquitously investigated as a photocatalyst for organic contaminant treatment in wastewater due to their exemplary semiconductor properties. However, their huge band gap remains a barrier for visible light absorption, limiting their utility in practical applications. The incorporation of noble metals in the TiO2 scaffold would help mitigate the problem via plasmonic resonance enhancements. Silver (Ag) is the chosen noble metal as it is relatively cheap and has great plasmonic effects. In this study, the use of electrospun Ag-embedded TiO2 nanofibers as a photocatalyst is shown to be effective in decomposing rhodamine B and methyl orange dyes under a solar simulator in 3 h, which is more efficacious as opposed to pristine TiO2 nanofibers. This showcases the potential of a simple and economic wastewater treatment system for the removal of organic pollutants

Hierarchically Self-Assembled Supramolecular Host–Guest Delivery System for Drug Resistant Cancer Therapy

In this report, a new star-like copolymer β-CD-<i>g</i>-(PNIPAAm-<i>b</i>-POEGA)_<i>x</i>, consisting of a β-CD core, grafted with temperature-responsive poly­(<i>N</i>-isopropylacrylamide) (PNIPAAm) and biocompatible poly­(oligo­(ethylene glycol) acrylate) (POEGA) in a block copolymer of the arms, was used to deliver chemotherapeutics to drug resistant cancer cells and tumors. The first step of the self-assembly process involves the encapsulation of chemotherapeutics through host–guest inclusion complexation between the β-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded β-CD-<i>g</i>-(PNIPAAm-<i>b</i>-POEGA)_<i>x</i>/PTX inclusion complex to hierarchically self-assemble into nanosized supramolecular assemblies at 37 °C, whereas the presence of poly­(ethylene glycol) (PEG) chains in the distal end of the star-like copolymer arms impart enhanced stability to the self-assembled structure. More interestingly, this supramolecular host–guest nanocomplex promoted the enhanced cellular uptake of chemotherapeutics in MDR-1 up-regulated drug resistant cancer cells and exhibited high therapeutic efficacy for suppressing drug resistant tumor growth in an <i>in vivo</i> mouse model, due to the increased stability, improvement in aqueous solubility, enhanced cellular uptake, and partial membrane pump impairment by taking the advantage of PEGylation and supramolecular complex between this star-like copolymer and chemotherapeutics. This work signifies that temperature-sensitive PEGylated supramolecular nanocarriers with good biocompatibility are effective in combating MDR-1 mediated drug resistance in both <i>in vitro</i> and <i>in vivo</i> models, which is of significant importance for the advanced drug delivery platform designed to combat drug resistant cancer

The Efficacy of Plant-Based Ionizers in Removing Aerosol for COVID-19 Mitigation

Small-sized droplets/aerosol transmission is one of the factors responsible for the spread of COVID-19, in addition to large droplets and surface contamination (fomites). While large droplets and surface contamination can be relatively easier to deal with (i.e., using mask and proper hygiene measures), aerosol presents a different challenge due to their ability to remain airborne for a long time. This calls for mitigation solutions that can rapidly eliminate the airborne aerosol. Pre-COVID-19, air ionizers have been touted as effective tools to eliminate small particulates. In this work, we sought to evaluate the efficacy of a novel plant-based ionizer in eliminating aerosol. It was found that factors such as the ion concentration, humidity, and ventilation can drastically affect the efficacy of aerosol removal. The aerosol removal rate was quantified in terms of ACH (air changes per hour) and CADR- (clean air delivery rate-) equivalent unit, with ACH as high as 12 and CADR as high as 141 ft3/minute being achieved by a plant-based ionizer in a small isolated room. This work provides an important and timely guidance on the effective deployment of ionizers in minimizing the risk of COVID-19 spread via airborne aerosol, especially in a poorly-ventilated environment