•A self-driving bead-based bioassay.•High temporal stability and reproducibility (<1.2%).•Free from background fluctuations with the use of reference particles.•Dose-dependent measurement of ...microorganisms, as low as 106 cfu/mL.•Detection of live microorganisms, including motile bacterium, P. aeruginosa, and nonmotile bacterium, S. aureus.
A self-driving, thermal-diffusion-based bioassay for the detection of microorganisms in a liquid medium is presented in this paper. In the bioassay, each particle functions as an individual sensing probe. Thus, the representative Brownian velocity of microparticles can be obtained by analyzing the velocity histogram of each particle. The ensemble average was used to enhance peak Brownian velocity. Relative error was reduced to 0.5% when the number of counted particles exceeded 60. The experimentally measured and theoretically derived Brownian velocities and diameters of the particles were in good agreement. The relative standard deviations of the temporal stability and reproducibility of the bioassay were maintained below 1.2%. A calibration curve was constructed and used to distinguish two mixed colloidal suspensions to provide proof that the bioassay can be used in practical applications. The particles were functionalized with antibodies to enable the real biological application of the bioassay in the capture and detection of motile Pseudomonas aeruginosa and nonmotile Staphylococcus aureus. The diffusivity values of both bacterial growth media decreased as bacterial concentration increased. Given that the viscosity of the growth media varied as bacteria proliferated, additional bacteria-free reference particles were added to the medium to provide dynamic background information. The diffusion-based bioassay presented here is easy to use, robust, and highly reliable. In contrast to most existing biosensors, it does not require an external power source and is thus ideal for use in resource-limited areas.
The nonlinear Hall effect (NLHE), the phenomenon in which a transverse voltage can be produced without a magnetic field, provides a potential alternative for rectification or frequency doubling1,2. ...However, the low-temperature detection of the NLHE limits its applications3,4. Here, we report the room-temperature NLHE in a type-II Weyl semimetal TaIrTe4, which hosts a robust NLHE due to broken inversion symmetry and large band overlapping at the Fermi level. We also observe a temperature-induced sign inversion of the NLHE in TaIrTe4. Our theoretical calculations suggest that the observed sign inversion is a result of a temperature-induced shift in the chemical potential, indicating a direct correlation of the NLHE with the electronic structure at the Fermi surface. Finally, on the basis of the observed room-temperature NLHE in TaIrTe4 we demonstrate the wireless radiofrequency (RF) rectification with zero external bias and magnetic field. This work opens a door to realizing room-temperature applications based on the NLHE in Weyl semimetals.Broken inversion symmetry in a type-II Weyl semimetal TaIrTe4 enables observation of the room-temperature nonlinear Hall effect as well as wireless radiofrequency rectification.
Abstract
The nonlinear Hall effect due to Berry curvature dipole (BCD) induces frequency doubling, which was recently observed in time-reversal-invariant materials. Here we report novel electric ...frequency doubling in the absence of BCD on a surface of the topological insulator Bi
2
Se
3
under zero magnetic field. We observe that the frequency-doubling voltage transverse to the applied ac current shows a threefold rotational symmetry, whereas it forbids BCD. One of the mechanisms compatible with the symmetry is skew scattering, arising from the inherent chirality of the topological surface state. We introduce the Berry curvature triple, a high-order moment of the Berry curvature, to explain skew scattering under the threefold rotational symmetry. Our work paves the way to obtain a giant second-order nonlinear electric effect in high mobility quantum materials, as the skew scattering surpasses other mechanisms in the clean limit.
One-photon-absorbing photosensitizers are commonly used in homogeneous photocatalysis which require the absorption of ultraviolet (UV) /visible light to populate the desired excited states with ...adequate energy and lifetime. Nevertheless, the limited penetration depth and competing absorption by organic substrates of UV/visible light calls upon exploring the utilization of longer-wavelength irradiation, such as near-infrared light (λ
> 700 nm). Despite being found applications in photodynamic therapy and bioimaging, two-photon absorption (TPA), the simultaneous absorption of two photons by one molecule, has been rarely explored in homogeneous photocatalysis. Herein, we report a group of ruthenium polypyridyl complexes possessing TPA capability that can drive a variety of organic transformations upon irradiation with 740 nm light. We demonstrate that these TPA ruthenium complexes can operate in an analogous manner as one-photon-absorbing photosensitizers for both energy-transfer and photoredox reactions, as well as function in concert with a transition metal co-catalyst for metallaphotoredox C-C coupling reactions.
Mapping the pathways that give rise to metastasis is one of the key challenges of breast cancer research. Recently, several large‐scale studies have shed light on this problem through analysis of ...gene expression profiles to identify markers correlated with metastasis. Here, we apply a protein‐network‐based approach that identifies markers not as individual genes but as subnetworks extracted from protein interaction databases. The resulting subnetworks provide novel hypotheses for pathways involved in tumor progression. Although genes with known breast cancer mutations are typically not detected through analysis of differential expression, they play a central role in the protein network by interconnecting many differentially expressed genes. We find that the subnetwork markers are more reproducible than individual marker genes selected without network information, and that they achieve higher accuracy in the classification of metastatic versus non‐metastatic tumors.
The ability to switch magnetic elements by spin‐orbit‐induced torques has recently attracted much attention for a path toward high‐performance, nonvolatile memories with low power consumption. ...Realizing efficient spin‐orbit‐based switching requires the harnessing of both new materials and novel physics to obtain high charge‐to‐spin conversion efficiencies, thus making the choice of spin source crucial. Here, the observation of spin‐orbit torque switching in bilayers consisting of a semimetallic film of 1T′‐MoTe2 adjacent to permalloy is reported. Deterministic switching is achieved without external magnetic fields at room temperature, and the switching occurs with currents one order of magnitude smaller than those typical in devices using the best‐performing heavy metals. The thickness‐dependence can be understood if the interfacial spin‐orbit contribution is considered in addition to the bulk spin Hall effect. Further threefold reduction in the switching current is demonstrated with resort to dumbbell‐shaped magnetic elements. These findings foretell exciting prospects of using MoTe2 for low‐power semimetal‐material‐based spin devices.
Realizing efficient spin‐orbit‐based switching requires the harnessing of both new materials and physics to obtain high charge‐to‐spin conversion efficiencies. The observation of spin‐orbit torque switching in bilayers consisting of a semimetallic film of 1T′‐MoTe2 adjacent to permalloy is reported. Deterministic switching is achieved without external magnetic fields at room temperature with currents one order of magnitude smaller than those using heavy metals.
Investigations of two-dimensional transition-metal chalcogenides (TMCs) have recently revealed interesting physical phenomena, including the quantum spin Hall effect
, valley polarization
and ...two-dimensional superconductivity
, suggesting potential applications for functional devices
. However, of the numerous compounds available, only a handful, such as Mo- and W-based TMCs, have been synthesized, typically via sulfurization
, selenization
and tellurization
of metals and metal compounds. Many TMCs are difficult to produce because of the high melting points of their metal and metal oxide precursors. Molten-salt-assisted methods have been used to produce ceramic powders at relatively low temperature
and this approach
was recently employed to facilitate the growth of monolayer WS
and WSe
. Here we demonstrate that molten-salt-assisted chemical vapour deposition can be broadly applied for the synthesis of a wide variety of two-dimensional (atomically thin) TMCs. We synthesized 47 compounds, including 32 binary compounds (based on the transition metals Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Pt, Pd and Fe), 13 alloys (including 11 ternary, one quaternary and one quinary), and two heterostructured compounds. We elaborate how the salt decreases the melting point of the reactants and facilitates the formation of intermediate products, increasing the overall reaction rate. Most of the synthesized materials in our library are useful, as supported by evidence of superconductivity in our monolayer NbSe
and MoTe
samples
and of high mobilities in MoS
and ReS
. Although the quality of some of the materials still requires development, our work opens up opportunities for studying the properties and potential application of a wide variety of two-dimensional TMCs.
Efficient utilization of sunlight in photocatalysis is widely recognized as a promising solution for addressing the growing energy demand and environmental issues resulting from fossil fuel ...consumption. Recently, there have been significant developments in various near‐infrared (NIR) light‐harvesting systems for artificial photosynthesis and photocatalytic environmental remediation. This review provides an overview of the most recent advancements in the utilization of NIR light through the creation of novel nanostructured materials and molecular photosensitizers, as well as modulating strategies to enhance the photocatalytic processes. A special focus is given to the emerging two‐photon excitation NIR photocatalysis. The unique features and limitations of different systems are critically evaluated. In particular, it highlights the advantages of utilizing NIR light and two‐photon excitation compared to UV–visible irradiation and one‐photon excitation. Ongoing challenges and potential solutions for the future exploration of NIR light‐responsive materials are also discussed.
This review article presents a comprehensive survey of the latest developments in near‐infrared (NIR) light harvesting strategies, with a particular focus on the emerging field of two‐photon excitation NIR photocatalysis. The emphasis is on the unique benefits offered by NIR light and two‐photon excitation when compared to UV–visible irradiation and one‐photon excitation.
A decade of systems biology Chuang, Han-Yu; Hofree, Matan; Ideker, Trey
Annual review of cell and developmental biology,
11/2010, Letnik:
26
Journal Article
Recenzirano
Odprti dostop
Systems biology provides a framework for assembling models of biological systems from systematic measurements. Since the field was first introduced a decade ago, considerable progress has been made ...in technologies for global cell measurement and in computational analyses of these data to map and model cell function. It has also greatly expanded into the translational sciences, with approaches pioneered in yeast now being applied to elucidate human development and disease. Here, we review the state of the field with a focus on four emerging applications of systems biology that are likely to be of particular importance during the decade to follow: (a) pathway-based biomarkers, (b) global genetic interaction maps, (c) systems approaches to identify disease genes, and (d) stem cell systems biology. We also cover recent advances in software tools that allow biologists to explore system-wide models and to formulate new hypotheses. The applications and methods covered in this review provide a set of prime exemplars useful to cell and developmental biologists wishing to apply systems approaches to areas of interest.
Large‐area and high‐quality 2D transition metal tellurides are synthesized by the chemical vapor deposition method. The as‐grown WTe2 maintains two different stacking sequences in the bilayer, where ...the atomic structure of the stacking boundary is revealed by scanning transmission electron microscopy. The low‐temperature transport measurements reveal a novel semimetal‐to‐insulator transition in WTe2 layers and an enhanced superconductivity in few‐layer MoTe2.
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