Among the various VO2 polymorphs, the layered compound, VO2(B), has been the most widely investigated lithium‐ion battery electrode material. For sodium‐ion electrodes, however, an amorphous solid ...may be more advantageous as a result of the open framework to facilitate ion insertion and the ability to tolerate volumetric changes. Herein, it is shown that the Na+ insertion properties of amorphous VO2 (a‐VO2) are superior to those of crystalline VO2(B). Amorphous VO2 exhibits a linear voltage characteristic over a 3 V range (4.0 to 1.0 V vs Na/Na+) leading to a reversible capacity as high as 400 mAh g−1 and rapid redox kinetics, which is attributed to its pseudocapacitive nature. The linear voltage characteristic over 3 V affords the opportunity of fabricating a symmetric Na‐ion battery in which the a‐VO2 material serves as both the positive electrode and the negative electrode. Such a symmetric battery offers safer operation in terms of overcharging, overdischarging, polarity reversal, high charge/discharge current abuse, and long‐term usage. The results suggest that amorphous transition metal oxides may offer advantageous attributes for rapid, safe, and energy‐dense storage.
A wide‐window pseudocapacitive behavior in amorphous VO2 is reported, which allows the construction of a new pseudocapacitive‐mechanism‐enabled symmetric battery to mitigate the slow kinetics and cycling limitations of previous phase‐transition‐mechanism‐based symmetric devices. Attractive safety superiority is illustrated in the new symmetric device, including high tolerance in overcharging, overdischarging, polarity reversal, and large‐current operation.
The recent success of immunotherapies has highlighted the power of leveraging the immune system in the fight against cancer. In order for most immune‐based therapies to succeed, T cell subsets with ...the correct tumor‐targeting specificities must be mobilized. When such specificities are lacking, providing the immune system with tumor antigen material for processing and presentation is a common strategy for stimulating antigen‐specific T cell populations. While straightforward in principle, experience has shown that manipulation of the antigen presentation process can be incredibly complex, necessitating sophisticated strategies that are difficult to translate. Herein, the design of a biomimetic nanoparticle platform is reported that can be used to directly stimulate T cells without the need for professional antigen‐presenting cells. The nanoparticles are fabricated using a cell membrane coating derived from cancer cells engineered to express a co‐stimulatory marker. Combined with the peptide epitopes naturally presented on the membrane surface, the final formulation contains the necessary signals to promote tumor antigen‐specific immune responses, priming T cells that can be used to control tumor growth. The reported approach represents an emerging strategy that can be used to develop multiantigenic, personalized cancer immunotherapies.
Cancer cells are genetically engineered to express a co‐stimulatory marker that enables them to directly present their own antigens under an immunostimulatory context. Cell‐membrane‐coated nanoparticles sourced from these modified cells elicit antitumor immunity in vivo while bypassing the need for traditional cell‐mediated antigen presentation. This approach may ultimately enable the facile design of personalized artificial antigen presentation platforms.
3D batteries continue to be of widespread interest for flexible energy storage where the 3D nanostructured cathode is the key component to achieve both high energy and power densities. While current ...work on flexible cathodes tends to emphasize the use of flexible scaffolds such as graphene and/or carbon nanotubes, this approach is often limited by poor electrical contact and structural stability. This communication presents a novel synthetic approach to form 3D array cathode for the first time, the single‐crystalline Na3(VO)2(PO4)2F (NVOPF) by using VO2 array as a seed layer. The NVOPF cathode exhibits both high‐rate capability (charge/discharge in 60 s) and long‐term durability (10,000 cycles at 50 C) for Na ion storage. Utilizing in situ X‐ray diffraction and first principles calculations, the high‐rate properties are correlated with the small volume change, 2D fast ion transport, and the array morphology. A novel all‐array flexible Na+ hybrid energy storage device based on pairing the intercalation‐type NVOPF array cathode with a cogenetic pseudocapacitive VO2 nanosheet array anode is demonstrated.
An oriented Na3(VO)2(PO4)2F nanorods array on flexible substrates is fabricated and demonstrates high‐rate capability and unprecedented long‐term durability (10,000 cycles at 50 C). Using the sodium vanadium fluorophosphates array cathode and pseudocapacitive VO2 array anode, an all‐array flexible Na‐ion hybrid device is constructed, which shows ultrafast sodium ion storage feature to 20 C with high energy density up to 215 W h kg−1.
•Levelized cost of delivery (LCOD) for electrical energy storage (EES) is proposed.•Marginal levelized cost of energy (LCOE) shows that EES can reduce the system LCOE.•LCODs for Lithium-ion and ...Vanadium redox flow battery in PV system were compared.•The EES lifetime, costs, and efficiency can affect the LCOD significantly.
With the increasing technological maturity and economies of scale for solar photovoltaic (PV) and electrical energy storage (EES), there is a potential for mass-scale deployment of both technologies in stand-alone and grid-connected power systems. The challenge arises in analyzing the economic projections on complex hybrid systems utilizing PV and EES. It is well known that PV power is of diurnal and stochastic nature, and surplus electrical energy is generally available in midday during high irradiance levels. EES does not produce energy as it is not a conventional generator source. Commonly, the cost of a generating asset or the power system is evaluated by using levelized cost of electricity (LCOE). In this paper, a new metric levelized cost of delivery (LCOD) is proposed to calculate the LCOE for the EES. A review on definitions in LCOE for PV hybrid energy systems is provided. Four years of solar irradiance data from Johannesburg and the national load data from Kenya are obtained for case studies. The proposed cost calculation methods are evaluated with two types of EES, namely Vanadium redox flow battery (VRB) and Lithium-ion (Li-ion) battery. It shows that the marginal LCOE and LCOD indices can be used to assist policymakers to consider the discount rate, the type of storage technology and sizing of components in a PV-EES hybrid system.
A synthesis methodology is demonstrated to produce MoS2 nanoparticles with an expanded atomic lamellar structure that are ideal for Faradaic‐based capacitive charge storage. While much of the work on ...MoS2 focuses on the high capacity conversion reaction, that process is prone to poor reversibility. The pseudocapacitive intercalation‐based charge storage reaction of MoS2 is investigated, which is extremely fast and highly reversible. A major challenge in the field of pseudocapacitive‐based energy storage is the development of thick electrodes from nanostructured materials that can sustain the fast inherent kinetics of the active nanocrystalline material. Here a composite electrode comprised of a poly(acrylic acid) binder, carbon fibers, and carbon black additives is utilized. These electrodes deliver a specific capacity of 90 mAh g−1 in less than 20 s and can be cycled 3000 times while retaining over 80% of the original capacity. Quantitative kinetic analysis indicates that over 80% of the charge storage in these MoS2 nanocrystals is pseudocapacitive. Asymmetric full cell devices utilizing a MoS2 nanocrystal‐based electrode and an activated carbon electrode achieve a maximum power density of 5.3 kW kg−1 (with 6 Wh kg−1 energy density) and a maximum energy density of 37 Wh kg−1 (with 74 W kg−1power density).
MoS2 nanocrystals are synthesized by the thermal sulfurization of hydrothermally prepared MoO2 nanocrystals. Composite electrodes are formulated to show high levels of pseudocapacitive charge storage in traditional slurry‐based systems. These electrodes can be charged and discharged to 50% of their theoretical capacity in just 20 s and can be reversibly cycled 3000 times with greater than 80% capacity retention.
Stretchable and conductive hydrogels have been intensively studied as wearable electronics to monitor the physiological activities of human bodies. However, it remains a challenge to fabricate robust ...hydrogels as sensors with complex 3D structures. Here, we designed a 3D printable ink from cellulose nanocrystals (CNCs), deep eutectic solvents (DESs), and ionically cross-linked polyacrylic acid (PAA). DESs composed of choline chloride and ethylene glycol served as a nonvolatile medium with high ionic conductivity. The dispersion of CNCs in a mixture of DESs, acrylic acid, and Al3+ ions formed ionogels with a reversible physical network for 3D printing. After the printing process, the ionogel was solidified by the photopolymerization of acrylic acid in the presence of Al3+ ions to form a second ionically cross-linked network. The first physical network of CNCs provides an energy-dissipating mechanism to make a strong and highly stretchable nanocomposite ionogel. When compared to hydrogels, we found that the DES/CNC nanocomposite ionogel was more stable in the air because of the low volatility of DESs. We further used the DES/CNC ink to 3D print an auxetic sensor with negative Poisson’s ratios so that the sensor provided a conformal contact with the skin during large deformation. In addition, the auxetic sensor could continuously monitor and identify different motions of the human body by the change in resistance. These results demonstrate a simple and rapid strategy to fabricate stable and sensitive strain sensors from cheap and renewable feedstock.
Purpose
The Chang Gung Research Database (CGRD), the largest multi‐institutional electronic medical records (EMR) collection in Taiwan, provides good access for researchers to efficiently use the ...standardized patient‐level data. This study evaluates the capacity and representativeness of the CGRD to promote secondary use of EMR data for clinical research with more accurate estimates.
Methods
The National Health Insurance Research Database (NHIRD) which covers over 99.9% of the Taiwanese population served as the comparator in this study. We compare the data components of the CGRD with the NHIRD, including records for health care facilities, patients, diagnoses, drugs, and procedures. Using the chi‐square test, we compared the distributions of age categories and sex of patients, and the rates of their health conditions between NHIRD and CGRD based on the year 2015.
Results
The CGRD contains more clinical information such as pathological and laboratory results than the NHIRD. The CGRD includes 6.1% of outpatients and 10.2% of hospitalized patients from the NHIRD. We found the CGRD includes more elderly outpatients (23.5% vs 12.5%) and pediatric inpatients (19.7% vs 14.4%) compared with the NHIRD. We found patients' sex distributions were similar between CGRD and NHIRD, but coverage rates of severe conditions, such as cancer, were higher than other health conditions in CGRD.
Conclusions
The CGRD could serve as the basis for accurate estimates in medical studies. However, researchers should pay special attention to selection biases since patients' characteristics from CGRD differ from those of the national database.
In this paper, we show that if we have a sequence of Hadamard triples {(Nn,Bn,Ln)} with Bn⊂{0,1,..,Nn−1} for n=1,2,..., except an extreme case, then the associated Cantor-Moran ...measureμ=μ(Nn,Bn)=δ1N1B1⁎δ1N1N2B2⁎δ1N1N2N3B3⁎...=μn⁎μ>n with support inside 0,1 always admits an exponential orthonormal basis E(Λ)={e2πiλx:λ∈Λ} for L2(μ), where Λ is obtained from suitably modifying Ln. Here, μn is the convolution of the first n Dirac measures and μ>n denotes the tail-term.
We show that the completeness of E(Λ) in general depends on the “equi-positivity” of the sequence of the pull-backed tail of the Cantor-Moran measure ν>n(⋅)=μ>n((N1...Nn)−1(⋅)). Such equi-positivity can be analyzed by the integral periodic zero set of the weak limit of {ν>n}. This result offers a new conceptual understanding of the completeness of exponential functions and it improves significantly many partial results studied by recent research, whose focus has been specifically on #Bn≤4.
Using the Bourgain's example that a sum of sine can be asymptotically small, we show that, in the extreme case, there exists some Cantor-Moran measure such that the equi-positive condition fails and the Fourier transform of the associated ν>n uniformly converges on some unbounded set.
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