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Ferroelectricity can reduce the subthreshold swing (SS) of metal-oxide-semiconductor field-effect transistors (MOSFETs) to below the room-temperature Boltzmann limit of ~60 mV/dec and provides an important strategy to achieve a steeper SS. Surprisingly, by carefully tuning the polarization switching dynamics of BiFeO3 ferroelectric capacitors the SS of a commercial power MOSFET can even be tuned to zero or a negative value, i.e., the drain current increases with a constant or decreasing gate voltage. In particular, in addition to the positive SS of lower than 60 mV/dec, the zero and negative SS can be established with a drain current spanning for over seven orders of magnitude. These intriguing phenomena are explained by the ferroelectric polarization switching dynamics, which change the charge redistributions and accordingly affect the voltage drops across the ferroelectric capacitor and MOSFET. This study provides deep insights into understanding the steep SS in ferroelectric MOSFETs, which could be promising for designing advanced MOSFETs with an ultralow and tunable SS. In ferroelectric MOSFETs, the reduced subthreshold swing (SS) below Boltzmann limit has attracted great attention due to its potential in decreasing power consumption. Here, through tuning the ferroelectric switching dynamics of BiFeO3 ferroelectric capacitor, the SS of a commercial MOSFET connected with the ferroelectric capacitor is significantly reduced to be zero over seven decades of the drain current. Interestingly, the SS can even be further tuned to be negative, i.e., the drain current increases with decreasing gate voltage. The intriguing strategy to control SS from positive to negative is promising for designing advanced MOSFETs with ultralow and tunable SS. Transistors: A swing in the right direction Ferroelectric materials offer a way to control transistor operation. Metal-oxide-semiconductor field-effect transistors (MOSFETs) use an electric field, created by applying a voltage to one terminal, called the gate, to control the electrical current between two other terminals, the source and the drain. An important operating parameter for MOSFETs is the subthreshold swing, which relates the change in gate voltage to the change in current flow. A lower subthreshold swing means lower power consumption. Xiaoguang Li and Yuewei Yin and their colleagues from the University of Science and Technology of China, Hefei, showed that adding ferroelectric BiFeO3 to a commercial MOSFET and tuning its dynamics reduced the swing to zero and even made it negative, meaning the drain current increases with decreasing gate voltage. This unexpected result could be promising for designing advanced low-power consumption MOSFETs. [ABSTRACT FROM AUTHOR]

Superhydrophobic metallic surfaces with mechanical stability as well as self-cleaning and anticorrosion functions are highly desirable because of their promising applications in various aspects. Large apparent water contact angles (≥150°) on metal surfaces are usually realized by high surface roughness and low surface energy. However, rough nanoscale features and low-energy coatings are prone to wear, causing degradation of the local wetting property during service. Herein, we develop a low-cost and scalable fabrication methodology to prepare composite superhydrophobic surfaces (water contact angle ∼154.7± 2.3° and sliding angle ∼1.2 ± 0.2°) by integrating a micropatterned amorphous alloy frame with functionalized nanoparticles. Amorphous interconnected microwalls provide augmented resistance against abrasion, whereas spray-coated nanomaterials residing within the frame impart water repellency. Metallic surfaces can withstand abrasion against sandpaper for 40 m under a local pressure of 120 kPa, before losing their perfect superhydrophobic performances. The composite surfaces also maintain its water repellency after mechanical bending, knife scratching, water impact jetting, ultraviolet (UV) irradiation, and acid immersion. We envisage that the design strategies here provide a practical route to manufacture water-repellent surfaces with metallic glass in harsh nautical applications. [ABSTRACT FROM AUTHOR]

Freshly, consumers gave full awareness about the diet ingredients, namely fats and sugar, and their consequences. Fat replacers “mimetics” are, therefore, recently utilized in many foodstuffs to imitate the technological and sensorial functions of lipids without unhealthy side effects. Meanwhile, the shortage of structural knowledge on the technological aspect, functional properties, applications, challenges, and stability features of fat replacers-based on animal proteins (FR-AP) significantly impedes the advancement of functional and sustainable constituents. This review summarizes the use of protein microparticles, nanofibers, microgels, and oleogels as fat replacers in dairy products and dairy alternatives. We also highlighted the advantages and limitations of FR-AP to be a platform for further industrial applications and valorization. However, although the current evidence is promising, further large-scale studies are still needed instead of the pilot ones. The mechanism through which health benefits and their bioavailability are granted is also rare. Therefore, we have compiled research results from recent studies with future needs. [ABSTRACT FROM AUTHOR]

Ferroelectricity can reduce the subthreshold swing (SS) of metal-oxide-semiconductor field-effect transistors (MOSFETs) to below the room-temperature Boltzmann limit of ~60 mV/dec and provides an important strategy to achieve a steeper SS. Surprisingly, by carefully tuning the polarization switching dynamics of BiFeO3 ferroelectric capacitors the SS of a commercial power MOSFET can even be tuned to zero or a negative value, i.e., the drain current increases with a constant or decreasing gate voltage. In particular, in addition to the positive SS of lower than 60 mV/dec, the zero and negative SS can be established with a drain current spanning for over seven orders of magnitude. These intriguing phenomena are explained by the ferroelectric polarization switching dynamics, which change the charge redistributions and accordingly affect the voltage drops across the ferroelectric capacitor and MOSFET. This study provides deep insights into understanding the steep SS in ferroelectric MOSFETs, which could be promising for designing advanced MOSFETs with an ultralow and tunable SS.In ferroelectric MOSFETs, the reduced subthreshold swing (SS) below Boltzmann limit has attracted great attention due to its potential in decreasing power consumption. Here, through tuning the ferroelectric switching dynamics of BiFeO3 ferroelectric capacitor, the SS of a commercial MOSFET connected with the ferroelectric capacitor is significantly reduced to be zero over seven decades of the drain current. Interestingly, the SS can even be further tuned to be negative, i.e., the drain current increases with decreasing gate voltage. The intriguing strategy to control SS from positive to negative is promising for designing advanced MOSFETs with ultralow and tunable SS.Transistors: A swing in the right direction Ferroelectric materials offer a way to control transistor operation. Metal-oxide-semiconductor field-effect transistors (MOSFETs) use an electric field, created by applying a voltage to one terminal, called the gate, to control the electrical current between two other terminals, the source and the drain. An important operating parameter for MOSFETs is the subthreshold swing, which relates the change in gate voltage to the change in current flow. A lower subthreshold swing means lower power consumption. Xiaoguang Li and Yuewei Yin and their colleagues from the University of Science and Technology of China, Hefei, showed that adding ferroelectric BiFeO3 to a commercial MOSFET and tuning its dynamics reduced the swing to zero and even made it negative, meaning the drain current increases with decreasing gate voltage. This unexpected result could be promising for designing advanced low-power consumption MOSFETs. [ABSTRACT FROM AUTHOR]

Background: Zika virus (ZIKV) emerged as a global epidemic in 2015-2016 from Latin America with its true geographical extent remaining unclear due to widely presumed underreporting. The identification of locations with potential and unknown spread of ZIKV is a key yet understudied component for outbreak preparedness. Here, we aim to identify locations at a high risk of cryptic ZIKV spread during 2015-2016 to further the understanding of the global ZIKV epidemiology, which is critical for the mitigation of the risk of future epidemics.Methods: We developed an importation simulation model to estimate the weekly number of ZIKV infections imported in each susceptible spatial unit (i.e. location that did not report any autochthonous Zika cases during 2015-2016), integrating epidemiological, demographic, and travel data as model inputs. Thereafter, a global risk model was applied to estimate the weekly ZIKV transmissibility during 2015-2016 for each location. Finally, we assessed the risk of onward ZIKV spread following importation in each susceptible spatial unit to identify locations with a high potential for cryptic ZIKV spread during 2015-2016.Results: We have found 24 susceptible spatial units that were likely to have experienced cryptic ZIKV spread during 2015-2016, of which 10 continue to have a high risk estimate within a highly conservative scenario, namely, Luanda in Angola, Banten in Indonesia, Maharashtra in India, Lagos in Nigeria, Taiwan and Guangdong in China, Dakar in Senegal, Maputo in Mozambique, Kinshasa in Congo DRC, and Pool in Congo. Notably, among the 24 susceptible spatial units identified, some have reported their first ZIKV outbreaks since 2017, thus adding to the credibility of our results (derived using 2015-2016 data only).Conclusion: Our study has provided valuable insights into the potentially high-risk locations for cryptic ZIKV circulation during the 2015-2016 pandemic and has also laid a foundation for future studies that attempt to further narrow this key knowledge gap. Our modelling framework can be adapted to identify areas with likely unknown spread of other emerging vector-borne diseases, which has important implications for public health readiness especially in resource-limited settings. [ABSTRACT FROM AUTHOR]

Background: The emergence of a novel coronavirus (SARS-CoV-2) in Wuhan, China, at the end of 2019 has caused widespread transmission around the world. As new epicentres in Europe and America have arisen, of particular concern is the increased number of imported coronavirus disease 2019 (COVID-19) cases in Africa, where the impact of the pandemic could be more severe. We aim to estimate the number of COVID-19 cases imported from 12 major epicentres in Europe and America to each African country, as well as the probability of reaching 10,000 cases in total by the end of March, April, May, and June following viral introduction.Methods: We used the reported number of cases imported from the 12 major epicentres in Europe and America to Singapore, as well as flight data, to estimate the number of imported cases in each African country. Under the assumption that Singapore has detected all the imported cases, the estimates for Africa were thus conservative. We then propagated the uncertainty in the imported case count estimates to simulate the onward spread of the virus, until 10,000 cases are reached or the end of June, whichever is earlier. Specifically, 1,000 simulations were run separately under four different combinations of parameter values to test the sensitivity of our results.Results: We estimated Morocco, Algeria, South Africa, Egypt, Tunisia, and Nigeria as having the largest number of COVID-19 cases imported from the 12 major epicentres. Based on our 1,000 simulation runs, Morocco and Algeria's estimated probability of reaching 10,000 cases by end of March was close to 100% under all scenarios. In particular, we identified countries with less than 1,000 cases in total reported by end of June whilst the estimated probability of reaching 10,000 cases by then was higher than 50% even under the most optimistic scenario.Conclusions: Our study highlights particular countries that are likely to reach (or have reached) 10,000 cases far earlier than the reported data suggest, calling for the prioritization of resources to mitigate the further spread of the epidemic. [ABSTRACT FROM AUTHOR]

Inorganic nanomaterials exhibit superior friction-reduction and anti-wear properties in oils. In this study, 2D layered α-zirconium phosphate (α-ZrP) nanosheets intercalated with different amines have been synthesized to study their dispersion stabilities in lubricating oil and tribological applications. The intercalated amines should be sufficiently long and lipophilic to provide stabilization to α-ZrP nanosheets in mineral oil. The results of tribological tests illustrate that with the addition of well-dispersed nanosheets, the coefficient of friction (COF) and pin volume loss reduce by ~47% and 75%, respectively. The excellent dispersion stability enables the nanosheets to flow into the contact area at the beginning, and thereby protect the rubbing surface. A reduction in the van der Waals forces between the adjacent layers induced by the intercalated amines transforms the friction between adjacent layers from pin disk to sliding, leading to a decrease in the COF under hydrodynamic lubrication. The study provides a new method to enhance the tribological properties via tuning the dispersion stabilities of nanomaterials in oils. [ABSTRACT FROM AUTHOR]

Next-generation non-volatile memories with ultrafast speed, low power consumption, and high density are highly desired in the era of big data. Here, we report a high performance memristor based on a Ag/BaTiO3/Nb:SrTiO3 ferroelectric tunnel junction (FTJ) with the fastest operation speed (600 ps) and the highest number of states (32 states or 5 bits) per cell among the reported FTJs. The sub-nanosecond resistive switching maintains up to 358 K, and the write current density is as low as 4 × 103 A cm−2. The functionality of spike-timing-dependent plasticity served as a solid synaptic device is also obtained with ultrafast operation. Furthermore, it is demonstrated that a Nb:SrTiO3 electrode with a higher carrier concentration and a metal electrode with lower work function tend to improve the operation speed. These results may throw light on the way for overcoming the storage performance gap between different levels of the memory hierarchy and developing ultrafast neuromorphic computing systems. Memristor devices based on ferroelectric tunnel junctions are promising, but suffer from quite slow switching times. Here, the authors report on ultrafast switching times at and above room temperature of 600ps in Ag/BaTiO3/Nb:SrTiO3 based ferroelectric tunnel junctions. [ABSTRACT FROM AUTHOR]

Miniaturized spectrometers are attracting widespread interest due to the rising demand for portable spectroscopic applications. While the chip-scale spectrometers are widely investigated using silicon photonics technology, few research have addressed the need for a mid-infrared (MIR) integrated chip-scale spectrometer due to the lack of an effective reconfigurable photonics approach. In this paper, we present a novel solution using silicon photonics MEMS technology in the MIR region (3.6–5 µm wavelength range). We adopt a computational spectrometry scheme using the digitalized control of cascaded MEMS-tunable waveguide couplers. The MEMS waveguide couplers are operated in digital on/off mode, thus making the device immune to driving voltage fluctuations and robust for on-chip field sensing applications. Moreover, a comprehensive numerical analysis method is discussed to systematically evaluate the performance of the computational spectrometer, including its resolution and operational bandwidth. As a proof-of-concept, a chip-scale spectrometer realized by seven cascaded MEMS-actuated waveguide coupler is demonstrated. The sparse spectral reconstruction is demonstrated in the wavelength range from 3.65 to 4.1 µm and the dual-peaks reconstruction results indicate a resolution of 8 nm. Besides, response time and power consumption of the proposed device are experimentally characterized. Benefitting from good scalability, the spectral resolution can be further improved by increasing the number of waveguide coupler stages. The proposed work has the potential to realize lab-on-a-chip applications with advances in MIR silicon photonics. © 2001 Elsevier Science. All rights reserved. • A mid-infrared digitalized MEMS-enabled computational spectrometer on the SOI platform is proposed. • The proposed spectrometer features a series of individually controlled MEMS-tunable waveguide couplers operating in a digital on/off mode in a single chip. • The proposed spectrometer demonstrates a broad working bandwidth with relatively high spectral resolution. • The proposed spectrometer demonstrates low power consumption and good scalability. [ABSTRACT FROM AUTHOR]