ObjectiveNon-alcoholic fatty liver disease (NAFLD) is the leading cause of end-stage liver diseases worldwide. Understanding NAFLD prevalence and trends over time at the global, regional and national levels is critical to understanding the NAFLD disease burden and creating more tailored prevention strategies.DesignPopulation-based observational study.SettingThe study was global, including 21 regions and 195 countries or territories.Main outcomes measureThe estimated annual percentage change for NAFLD prevalence.ResultsWorldwide, cases of NAFLD have increased from 391.2 million in 1990 to 882.1 million in 2017, with the prevalence rate increasing from 8.2% to 10.9% during the same period. The increasing trends were consistent across sexes. Case numbers were highest in East Asia, followed by South Asia, then North Africa and the Middle East. The highest prevalence of NAFLD was observed in North Africa and the Middle East, while the greatest increase was detected in Western Europe, followed by Tropical Latin America, then high-income North America.ConclusionNearly all countries or territories worldwide have experienced a significant increase in NAFLD prevalence. The greatest increase was observed in Oman. Almost all countries showed a significant increasing trend in NAFLD prevalence over the past three decades. This drastic increase is alarming and suggests that NAFLD has emerged as a new public health concern worldwide. As such, more efficient prevention strategies are urgently needed.

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Lead-free single crystal, (K, Na, Li)(Nb, Ta)O3:Mn, was successfully grown using top-seeded solution growth method. Complete matrix of dielectric, piezoelectric and elastic constants for [001]C poled single crystal was determined. The piezoelectric coefficient d33 measured by the resonance method was 545 pC/N, which is almost three times that of its ceramic counterpart. The values measured by the Berlincourt meter ( d33∗=6300.16667empC/normalN) and strain-field curve ( d33∗∗=8700.16667empm/normalV) were even higher. The differences were assumed to relate with the different extrinsic contributions of domain wall vibration and domain wall translation during the measurements by different approaches, where the intrinsic contribution (on the order of 539 pm/V) was supposed to be the same. The crystal has ultrahigh electromechanical coupling factor (k33 ~ 95%) and high ultrasound velocity, which make it promising for high frequency medical transducer applications.

Resistive switching phenomena form the basis of competing memory technologies. Among them, resistive switching, originating from oxygen vacancy migration (OVM), and ferroelectric switching offer two promising approaches. OVM in oxide films/heterostructures can exhibit high/low resistive state via conducting filament forming/deforming, while the resistive switching of ferroelectric tunnel junctions (FTJs) arises from barrier height or width variation while ferroelectric polarization reverses between asymmetric electrodes. Here the authors demonstrate a coexistence of OVM and ferroelectric induced resistive switching in a BaTiO FTJ by comparing BaTiO with SrTiO based tunnel junctions. This coexistence results in two distinguishable loops with multi-nonvolatile resistive states. The primary loop originates from the ferroelectric switching. The second loop emerges at a voltage close to the SrTiO switching voltage, showing OVM being its origin. BaTiO based devices with controlled oxygen vacancies enable us to combine the benefits of both OVM and ferroelectric tunneling to produce multistate nonvolatile memory devices.

A high quality lead-free (Li, Ta) modified (K, Na)NbO 3 single crystal and its complete set of elastic, dielectric and piezoelectric coefficients with macroscopic 4mm symmetry

Artificial synapses can boost neuromorphic computing to overcome the inherent limitations of von Neumann architecture. As a promising memristor candidate, ferroelectric tunnel junctions (FTJ) enable the authors to successfully emulate spike-timing-dependent synapses. However, the nonlinear and asymmetric synaptic weight update under repeated presynaptic stimulation hampers neuromorphic computing by favoring the runaway of synaptic weights during learning. Here, the authors demonstrate an FTJ whose conductivity varies linearly and symmetrically by judiciously combining ferroelectric domain switching and oxygen vacancy migration. The artificial neural network based on this FTJ-synapse achieves classification accuracy of 96.7% during supervised learning, which is the closest to the maximum theoretical value of 98% achieved to date. This artificial synapse also demonstrates stable unsupervised learning in a noisy environment for its well-balanced spike-timing-dependent plasticity response. The novel concept of controlling ionic migration in ferroelectric materials paves the way toward highly reliable and reproducible supervised and unsupervised learning strategies.

The complete set of material constants of single domain rhombohedral phase 0.27Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.27PbTiO3:Mn single crystal has been determined. The orientation dependence of piezoelectric, dielectric, and electromechanical properties was calculated based on these single domain data. The maximum piezoelectric and electromechanical properties were found to exist near the [001]C pseudo-cubic direction. In addition, the piezoelectric properties of [001]C poled crystals with “4R” multi-domain configuration were experimentally measured and compared with the calculated values. Only a small difference (3%) was found between experimental and theoretical values, indicating the high piezoelectric properties in the “4R” state are mainly from intrinsic contributions. The mechanical quality factors Q33 are significantly improved by the Mn-doping for the “4R” domain engineered crystals but almost no change for the single domain “1R” state. On the other hand, Q15 of both single domain and multidomain crystals were found to increase with Mn-doping, due to the internal bias induced by acceptor dopants, which clamps the domain wall motions and restricts polarization rotation.