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Nature May 2022The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre...
The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre technology nodes introduces issues such as leakage currents. Two-dimensional (2D) layered semiconductors, with an atomic thickness that allows superior gate-field penetration, are of interest as channel materials for future transistors. However, the integration of high-dielectric-constant (κ) materials with 2D materials, while scaling their capacitance equivalent thickness (CET), has proved challenging. Here we explore transferrable ultrahigh-κ single-crystalline perovskite strontium-titanium-oxide membranes as a gate dielectric for 2D field-effect transistors. Our perovskite membranes exhibit a desirable sub-one-nanometre CET with a low leakage current (less than 10 amperes per square centimetre at 2.5 megavolts per centimetre). We find that the van der Waals gap between strontium-titanium-oxide dielectrics and 2D semiconductors mitigates the unfavourable fringing-induced barrier-lowering effect resulting from the use of ultrahigh-κ dielectrics. Typical short-channel transistors made of scalable molybdenum-disulfide films by chemical vapour deposition and strontium-titanium-oxide dielectrics exhibit steep subthreshold swings down to about 70 millivolts per decade and on/off current ratios up to 10, which matches the low-power specifications suggested by the latest International Roadmap for Devices and Systems.
PubMed: 35546188
DOI: 10.1038/s41586-022-04588-2 -
Science (New York, N.Y.) Jun 2020Harvesting heat from the environment into electricity has the potential to power Internet-of-things (IoT) sensors, freeing them from cables or batteries and thus making...
Harvesting heat from the environment into electricity has the potential to power Internet-of-things (IoT) sensors, freeing them from cables or batteries and thus making them especially useful for wearable devices. We demonstrate a giant positive thermopower of 17.0 millivolts per degree Kelvin in a flexible, quasi-solid-state, ionic thermoelectric material using synergistic thermodiffusion and thermogalvanic effects. The ionic thermoelectric material is a gelatin matrix modulated with ion providers (KCl, NaCl, and KNO) for thermodiffusion effect and a redox couple [Fe(CN) /Fe(CN) ] for thermogalvanic effect. A proof-of-concept wearable device consisting of 25 unipolar elements generated more than 2 volts and a peak power of 5 microwatts using body heat. This ionic gelatin shows promise for environmental heat-to-electric energy conversion using ions as energy carriers.
PubMed: 32354840
DOI: 10.1126/science.aaz5045 -
Advanced Science (Weinheim,... May 2022Although adipose-derived mesenchymal stem cells (ADMSCs) isolated from patients' fat are considered as the most important autologous stem cells for tissue repair,...
Although adipose-derived mesenchymal stem cells (ADMSCs) isolated from patients' fat are considered as the most important autologous stem cells for tissue repair, significant difficulties in the neural differentiation of ADMSCs still impede stem cell therapy for neurodegenerative diseases. Herein, a wireless-electrical stimulation method is proposed to direct the neural differentiation of ADMSCs based on the electromagnetic effect using a graphene film as a conductive scaffold. By placing a rotating magnet on the top of a culture system without any inducer, the ADMSCs cultured on graphene differentiate into functional neurons within 15 days. As a conductive biodegradable nanomaterial, graphene film acts as a wireless electrical signal generator driven by the electromagnetic induction, and millivolt-level voltage generated in situ provokes ADMSCs to differentiate into neurons, proved by morphological variation, extremely high levels of neuron-specific genes, and proteins. Most importantly, Ca intracellular influx is observed in these ADMSC-derived neurons once exposure to neurotransmitters, indicating that these cells are functional neurons. This research enhances stem cell therapy for neurodegenerative diseases using autologous ADMSCs and overcomes the lack of neural stem cells. This nanostructure-mediated physical-signal simulation method is inexpensive, safe, and localized, and has a significant impact on neural regeneration.
Topics: Adipose Tissue; Cell Differentiation; Electromagnetic Phenomena; Graphite; Humans; Mesenchymal Stem Cells; Neural Stem Cells
PubMed: 35152569
DOI: 10.1002/advs.202104424 -
Pharmaceutical Development and... Feb 2022Contact lens have been proposed as a mean of ocular drug delivery, but the conventional soaking method to load hydrophobic drugs, such as latanoprost shows low drug...
Contact lens have been proposed as a mean of ocular drug delivery, but the conventional soaking method to load hydrophobic drugs, such as latanoprost shows low drug loading and high burst release with alteration in the critical lens properties. In this paper, a novel latanoprost-loaded PEGylated solid lipid nanoparticles (LP-pSLNs) were developed to increase the latanoprost loading capacity of contact lenses (LP-pSLN-L), while also sustaining ocular drug delivery. The pSLNs were spherical in shape with an average size of 105‒132 nm (nanometer) and a zeta potential ranging from ‒29.1 to ‒26.7 mV (millivolt). The LP-pSLNs led to improved swelling, transmittance, and protein adherence of the lens compared to the non-pegylated SLNs congeners (LP-SLN-L) and conventional soaked lens (LP-SM-L). The LP-SM-L lens showed low drug loading, high burst release, and a short release duration of 24 h. The LP-SLN-L and LP-pSLN-L lenses showed high drug uptake and sustained drug release up to 120 h and 96 h, respectively. The pegylation reduced the size of nanoparticles and improved the drug loading capacity, while the release rate was high in the initial hours. The LP-pSLN-L lens was found to be safe based in histopathological studies. In animal studies, the LP-pSLN-10-L batch showed high drug concentration at all-time points up to 96 h compared to the LP-SM-L and eye drop solution. In conclusion, pSLNs improved the latanoprost loading in the contact lens and showed sustained drug release, and thus can be used as a substitute to eye drop therapy.
Topics: Animals; Contact Lenses, Hydrophilic; Drug Delivery Systems; Glaucoma; Latanoprost; Liposomes; Nanoparticles; Ophthalmic Solutions; Polyethylene Glycols
PubMed: 34704874
DOI: 10.1080/10837450.2021.1999471 -
IEEE Transactions on Neural Systems and... Jul 2019This paper presents a new method of reducing the noise in the EEG response signal recorded during repetitive transcranial magnetic stimulation (rTMS). This noise is...
This paper presents a new method of reducing the noise in the EEG response signal recorded during repetitive transcranial magnetic stimulation (rTMS). This noise is principally composed of the residual stimulus artefact and millivolt amplitude compound muscle action potentials (CMAP) recorded from the scalp muscles and precludes analysis of the cortical evoked potentials, especially during the first 20-ms post stimulus. The proposed method uses the wavelet transform with a fourth-order Daubechies mother wavelet and a novel coefficient reduction algorithm based on cortical amplitude thresholds. Four other mother wavelets as well as digital filtering have been tested, and the Coiflets 2 and 3 also found to be effective with Coiflet 3 results marginally better than Daubechies 4. The approach has been tested using data recorded from 16 normal subjects during a study of cortical sensitivity to rTMS at different cortical locations using stimulation amplitudes, frequencies, and sites typically used in clinical practice to treat major depressive disorder.
Topics: Action Potentials; Adult; Algorithms; Artifacts; Computer Simulation; Depressive Disorder, Major; Electroencephalography; Electromyography; Female; Healthy Volunteers; Humans; Male; Middle Aged; Muscle, Skeletal; Scalp; Transcranial Magnetic Stimulation; Wavelet Analysis; Young Adult
PubMed: 30951471
DOI: 10.1109/TNSRE.2019.2908951 -
Science Advances Sep 2021The biophysical characteristics of the extracellular matrix (ECM), such as a three-dimensional (3D) network and bioelectricity, have a profound influence on cell...
The biophysical characteristics of the extracellular matrix (ECM), such as a three-dimensional (3D) network and bioelectricity, have a profound influence on cell development, migration, function expression, etc. Here, inspired by these biophysical cues of ECM, we develop an electromechanical coupling bio-nanogenerator (bio-NG) composed of highly discrete piezoelectric fibers. It can generate surface piezopotential up to millivolts by cell inherent force and thus provide in situ electrical stimulation for the living cells. Besides, the unique 3D space in the bio-NGs provides an ECM-like growth microenvironment for cells. As a result, our bio-NGs effectively promote cell viability and development and, more importantly, maintain its specific functional expression. These advanced in vitro bio-NGs are expected to fill the gap between the inaccurate 2D systems and the expensive and time-consuming animal models, mimicking the complexity of the ECM and the physiological relevance of an in vivo biological system.
PubMed: 34559554
DOI: 10.1126/sciadv.abh2350 -
Science (New York, N.Y.) Oct 2020Low-grade heat (below 373 kelvin) is abundant and ubiquitous but is mostly wasted because present recovery technologies are not cost-effective. The liquid-state...
Low-grade heat (below 373 kelvin) is abundant and ubiquitous but is mostly wasted because present recovery technologies are not cost-effective. The liquid-state thermocell (LTC), an inexpensive and scalable thermoelectric device, may be commercially viable for harvesting low-grade heat energy if its Carnot-relative efficiency (η) reaches ~5%, which is a challenging metric to achieve experimentally. We used a thermosensitive crystallization and dissolution process to induce a persistent concentration gradient of redox ions, a highly enhanced Seebeck coefficient (~3.73 millivolts per kelvin), and suppressed thermal conductivity in LTCs. As a result, we achieved a high η of 11.1% for LTCs near room temperature. Our device demonstration offers promise for cost-effective low-grade heat harvesting.
PubMed: 32913001
DOI: 10.1126/science.abd6749 -
Saudi Journal of Biological Sciences Aug 2021Asthma as chronic airway disease has high prevalence in children and imbalance of Th1/Th2 is a critical mechanism in pathogenesis of the asthma. Baicalein as a cell...
Asthma as chronic airway disease has high prevalence in children and imbalance of Th1/Th2 is a critical mechanism in pathogenesis of the asthma. Baicalein as a cell protective and anti-inflammatory flavonoid may have anti-asthma effect. Therefore, for better using lung, baicalein was used in chitosan-nanoparticle as anti-asthma treatment. Baicalein was loaded and encapsulated in chitosan nanoparticle. The morphology, physical characters (particle size, zeta potential and FT-IR) were analyzed. Drug encapsulation and loading capacity, accumulative release-time were studied. After asthma model producing, the mice were treated with L-B-NP and E-B-NP. At least, MCh challenge test, Cytokines measurement and Lung Histopathology were done. Nanoparticles had average size 285 ± 25 nm with negative charge -2.5 mV. The L-B-NP decreased penh value and E-B-NP decreased inflammation. Both nanoparticles increased IL-12 and decreased IL-5. Also, L-B-NP decreased mucus secretion in bronchi. L-B-NP and E-B-NP control immune-allergo-inflammatory response of asthma. L-B-NP controlled AHR and E-B-NP controlled inflammation that can be used as controlling anti-asthma drug.
PubMed: 34354413
DOI: 10.1016/j.sjbs.2021.04.009 -
ACS Applied Materials & Interfaces Dec 2022Moisture-activated electric generators (MEGs) that harvest clean energy from atmospheric humidity offer exciting opportunities for upgraded energy conversions. However,...
Moisture-activated electric generators (MEGs) that harvest clean energy from atmospheric humidity offer exciting opportunities for upgraded energy conversions. However, it is challenging to obtain MEGs that are both easy to fabricate and of high output power, due to the requirement for particular functional materials and the cumbersome manufacturing process. Herein, a simple and general method is adopted to prepare MEGs with chemically gradient structures. As a specific example, a gradient distribution of citric acid was successfully constructed inside an A4 printer paper by asymmetric drying, which can generate a continuous voltage of tens of millivolts by ambient humidity, and even to volts (275 mV and 7.6 μA cm) under asymmetric humidity stimulation, and the maximum power density output was 2.1 μW cm. The driving force behind this energy conversion is a self-maintained ionic gradient created within the paper by the asymmetric ionization of gradient organic acids when exposed to gradient or nongradient humid air. This work broadens the class of materials and possibilities for the rapid development of MEGs, shedding new light on the revolution of generators that harvest green and sustainable energy for power generation.
PubMed: 36437545
DOI: 10.1021/acsami.2c12777 -
Nature Communications Oct 2021Exploring new materials is essential in the field of material science. Especially, searching for optimal materials with utmost atomic utilization, ideal activities and...
Exploring new materials is essential in the field of material science. Especially, searching for optimal materials with utmost atomic utilization, ideal activities and desirable stability for catalytic applications requires smart design of materials' structures. Herein, we report iridium metallene oxide: 1 T phase-iridium dioxide (IrO) by a synthetic strategy combining mechanochemistry and thermal treatment in a strong alkaline medium. This material demonstrates high activity for oxygen evolution reaction with a low overpotential of 197 millivolt in acidic electrolyte at 10 milliamperes per geometric square centimeter (mA cm). Together, it achieves high turnover frequencies of 4.2 s (3.0 s) at 1.50 V vs. reversible hydrogen electrode. Furthermore, 1T-IrO also shows little degradation after 126 hours chronopotentiometry measurement under the high current density of 250 mA cm in proton exchange membrane device. Theoretical calculations reveal that the active site of Ir in 1T-IrO provides an optimal free energy uphill in *OH formation, leading to the enhanced performance. The discovery of this 1T-metallene oxide material will provide new opportunities for catalysis and other applications.
PubMed: 34650084
DOI: 10.1038/s41467-021-26336-2