Reliable energy modules and higher-sensitivity, higher-density, lower-powered sensing systems are constantly required to develop wearable electronics and the Internet of Things technology. As an ...emerging technology, triboelectric nanogenerators have been potentially guiding the landscape of sustainable power units and energy-efficient sensors. However, the existing triboelectric series is primarily populated by polymers and rubbers, limiting triboelectric sensing plasticity to some extent owing to their stiff surface electronic structures. To enrich the current triboelectric group, we explore the triboelectric properties of the topological insulator nanofilm by Kelvin probe force microscopy and reveal its relatively positive electrification charging performance. Both the larger surface potential difference and the conductive surface states of the nanofilms synergistically improve the charge transfer behavior between the selected triboelectric media, endowing the topological insulator-based triboelectric nanogenerator with considerable output performance. Besides serving as a wearable power source, the ultra-compact device array demonstrates innovative system-level sensing capabilities, including precise monitoring of dynamic objects and real-time signal control at the human-machine interface. This work fills the blank between topological quantum matters and triboelectric nanogenerators and, more importantly, exploits the significant potential of topological insulator nanofilms for self-powered flexible/wearable electronics and scalable sensing technologies.
Improving the platinum (Pt) mass activity for the oxygen reduction reaction (ORR) requires optimization of both the specific activity and the electrochemically active surface area (ECSA). We found ...that solution-synthesized Pt/NiO core/shell nanowires can be converted into PtNi alloy nanowires through a thermal annealing process and then transformed into jagged Pt nanowires via electrochemical dealloying. The jagged nanowires exhibit an ECSA of 118 square meters per gram of Pt and a specific activity of 11.5 milliamperes per square centimeter for ORR (at 0.9 volts versus reversible hydrogen electrode), yielding a mass activity of 13.6 amperes per milligram of Pt, nearly double previously reported best values. Reactive molecular dynamics simulations suggest that highly stressed, undercoordinated rhombus-rich surface configurations of the jagged nanowires enhance ORR activity versus more relaxed surfaces.
This paper reviews various aspects of the enzymatic transesterification method to convert used cooking oil to biodiesel. The goal of this paper is to provide a thorough overview from general ...biodiesel production processes, reaction conditions, challenges, and solutions for higher biodiesel production yield through introducing various microorganisms that are capable of producing the enzymes required to convert used cooking oil into biodiesel. The characteristics, composition, and advantages of the used cooking oil, as feedstock for biodiesel, is also discussed. In addition, the existing transesterification methods including homogeneous alkali-catalyzed, homogeneous acid-catalyzed, non-catalytic reaction under super-critical conditions, and enzyme-catalyzed reactions are explained. Furthermore, the advantages of the enzymatic method over other methods, and the enzymes, which are the key elements of such reactions, are discussed. Lipases are the most promising enzymes currently known for biodiesel conversion. The physiological and physical properties of microbial lipases, the catalytic mechanisms of the enzymes, various methods of enzyme immobilization such as adsorption, covalent and affinity binding, entrapment, and the whole-cell immobilization are also reviewed. At the end, three case studies demonstrating unique and efficient enzymatic transesterification approaches are presented.
•General biodiesel production and existing transesterification processes.•The benefits and issues of using waste cooking oil as feedstock.•Various sources of microorganisms to produce enzymes, and catalytic mechanisms.•Adsorption, covalent binding, affinity, entrapment and whole-cell immobilization.•Case-studies demonstrating unique techniques of biodiesel production using enzymes.
Methylammonium lead iodide perovskite has attracted considerable recent interest for solution processable solar cells and other optoelectronic applications. The orthorhombic-to-tetragonal phase ...transition in perovskite can significantly alter its optical, electrical properties and impact the corresponding applications. Here, we report a systematic investigation of the size-dependent orthorhombic-to-tetragonal phase transition using a combined temperature-dependent optical, electrical transport and transmission electron microscopy study. Our studies of individual perovskite microplates with variable thicknesses demonstrate that the phase transition temperature decreases with reducing microplate thickness. The sudden decrease of mobility around phase transition temperature and the presence of hysteresis loops in the temperature-dependent mobility confirm that the orthorhombic-to-tetragonal phase transition is a first-order phase transition. Our findings offer significant fundamental insight on the temperature- and size-dependent structural, optical and charge transport properties of perovskite materials, and can greatly impact future exploration of novel electronic and optoelectronic devices from these materials.
By converting ambient energy into electricity, energy harvesting is capable of at least offsetting, or even replacing, the reliance of small portable electronics on traditional power supplies, such ...as batteries. Here we demonstrate a novel and simple generator with extremely low cost for efficiently harvesting mechanical energy that is typically present in the form of vibrations and random displacements/deformation. Owing to the coupling of contact charging and electrostatic induction, electric generation was achieved with a cycled process of contact and separation between two polymer films. A detailed theory is developed for understanding the proposed mechanism. The instantaneous electric power density reached as high as 31.2 mW/cm3 at a maximum open circuit voltage of 110 V. Furthermore, the generator was successfully used without electric storage as a direct power source for pulse electrodeposition (PED) of micro/nanocrystalline silver structure. The cathodic current efficiency reached up to 86.6%. Not only does this work present a new type of generator that is featured by simple fabrication, large electric output, excellent robustness, and extremely low cost, but also extends the application of energy-harvesting technology to the field of electrochemistry with further utilizations including, but not limited to, pollutant degradation, corrosion protection, and water splitting.
Radiomics, which extract large amount of quantification image features from diagnostic medical images had been widely used for prognostication, treatment response prediction and cancer detection. The ...treatment options for lung nodules depend on their diagnosis, benign or malignant. Conventionally, lung nodule diagnosis is based on invasive biopsy. Recently, radiomics features, a non-invasive method based on clinical images, have shown high potential in lesion classification, treatment outcome prediction.
Lung nodule classification using radiomics based on Computed Tomography (CT) image data was investigated and a 4-feature signature was introduced for lung nodule classification. Retrospectively, 72 patients with 75 pulmonary nodules were collected. Radiomics feature extraction was performed on non-enhanced CT images with contours which were delineated by an experienced radiation oncologist.
Among the 750 image features in each case, 76 features were found to have significant differences between benign and malignant lesions. A radiomics signature was composed of the best 4 features which included Laws_LSL_min, Laws_SLL_energy, Laws_SSL_skewness and Laws_EEL_uniformity. The accuracy using the signature in benign or malignant classification was 84% with the sensitivity of 92.85% and the specificity of 72.73%.
The classification signature based on radiomics features demonstrated very good accuracy and high potential in clinical application.
A hybrid‐fiber nanogenerator comprising a ZnO nanowire array, PVDF polymer and two electrodes is presented. Depending on the bending or spreading action of the human arm, at an angle of ∼90°, the ...hybrid fiber reaches electrical outputs of ∼0.1 V and ∼10 nA cm−2. The unique structure of the hybrid fiber may inspire future research in wearable energy‐harvesting technology.
Lithium-sulfur batteries can deliver significantly higher specific capacity than standard lithium ion batteries, and represent the next generation of energy storage devices for both electric vehicles ...and mobile devices. However, the lithium-sulfur technology today is plagued with numerous challenges, including poor sulfur conductivity, large volumetric expansion, severe polysulfide shuttling and low sulfur utilization, which prevent its wide-spread adoption in the energy storage industry. Here we report a freestanding three-dimensional （3D） graphene frame- work for highly efficient loading of sulfur particles and creating a high capacity sulfur cathode. Using a one-pot synthesis method, we show a mechanically robust graphene-sulfur composite can be prepared with the highest sulfur weight content （90% sulfur） reported to date, and can be directly used as the sulfur cathode without additional binders or conductive additives. The graphene-sulfur composite features a highly interconnected graphene network ensuring excellent conductivity and a 3D porous structure allowing efficient ion transport and accommodating large volume expansion. Additionally, the 3D graphene framework can also function as an effective encapsulation layer to retard the polysulfide shuttling effect, thus enabling a highly robust sulfur cathode. Electrochemical studies show that such composite can deliver a highest capacity of 969 mAh-g-1, a record high number achieved for all sulfur cathodes reported to date when normalized by the total mass of the entire electrode. Our studies demonstrate that the 3D graphene framework represents an attractive scaffold material for a high performance lithium sulfur battery cathode, and could enable exciting opportunities for ultra-high capacity energy storage applications.
Development of acquired resistance to lapatinib, a dual epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor, severely limits the duration ...of clinical response in advanced HER2‐driven breast cancer patients. Although the compensatory activation of the PI3K/Akt survival signal has been proposed to cause acquired lapatinib resistance, comprehensive molecular mechanisms remain required to develop more efficient strategies to circumvent this therapeutic difficulty. In this study, we found that suppression of HER2 by lapatinib still led to Akt inactivation and elevation of FOX3a protein levels, but failed to induce the expression of their downstream pro‐apoptotic effector p27kip1, a cyclin‐dependent kinase inhibitor. Elevation of miR‐221 was found to contribute to the development of acquired lapatinib resistance by targeting p27kip1 expression. Furthermore, upregulation of miR‐221 was mediated by the lapatinib‐induced Src family tyrosine kinase and subsequent NF‐κB activation. The reversal of miR‐221 upregulation and p27kip1 downregulation by a Src inhibitor, dasatinib, can overcome lapatinib resistance. Our study not only identified miRNA‐221 as a pivotal factor conferring the acquired resistance of HER2‐positive breast cancer cells to lapatinib through negatively regulating p27kip1 expression, but also suggested Src inhibition as a potential strategy to overcome lapatinib resistance.
The downregulation of p27kip1 by Src/NF‐κB axis‐induced miR‐221 expression as a novel mechanistic insight into lapatinib resistance. Targeting Src would be a promising strategy to overcome lapatinib resistance.
Scalable preparation of solution processable graphene and its bulk materials with high specific surface areas and designed porosities is essential for many practical applications. Herein, we report a ...scalable approach to produce aqueous dispersions of holey graphene oxide with abundant in-plane nanopores via a convenient mild defect-etching reaction and demonstrate that the holey graphene oxide can function as a versatile building block for the assembly of macrostructures including holey graphene hydrogels with a three-dimensional hierarchical porosity and holey graphene papers with a compact but porous layered structure. These holey graphene macrostructures exhibit significantly improved specific surface area and ion diffusion rate compared to the nonholey counterparts and can be directly used as binder-free supercapacitor electrodes with ultrahigh specific capacitances of 283 F/g and 234 F/cm3, excellent rate capabilities, and superior cycling stabilities. Our study defines a scalable pathway to solution processable holey graphene materials and will greatly impact the applications of graphene in diverse technological areas.
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