Multifunctional Chiral Three-Dimensional Phosphite Frameworks Showing Dielectric Anomaly and High Proton Conductivity.

Chair 3D Co(II) phosphite frameworks have been prepared by the ionothermal method. It belongs to chiral space group P3221, and the whole framework can be topologically represented as a chiral 4-connected qtz net. It shows a multistep dielectric response arising from the reorientation of Me2-DABCO in the chiral cavities. It can also serve as a pron conductor with high conductivity, 1.71 × 10-3 S cm-1, at room temperature, which is attributed to the formation of denser hydrogen-bonding networks providing efficient proton-transfer pathways.

[Application of 3D-printed navigation plate in pulsed radiofrequency therapy of dorsal root ganglion in thoracic postherpetic neuralgia].

Objective: To evaluate the accuracy, efficacy and safety of 3D-printed personalized navigation template in the treatment of thoracic postherpetic neuralgia (PHN) with dorsal root ganglion pulsed radiofrequency (DRG-PRF). Methods: A total of 63 patients with thoracic PHN from March 2019 to December 2020 in Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School were enrolled and randomly divided into study group (n=31) and control group (n=32) by random number table method. The study group received DRG-PRF treatment assisted by 3D-printed navigation template, while the control group received DRG-PRF treatment guided by conventional CT. The one-time success rate of puncture, the incidence of puncture times ≥3, the number of punctures, puncture time, visual analogue scale (VAS) score and surgical complications between the two groups were compared. Results: The one-time success rate of puncture in study group was 84.9% (79/93), which was higher than that of control group [30.2% (29/96)] (P<0.001). The incidence of puncture times ≥3, the number of punctures, puncture time in study group were 4.3% (4/93), 1 (1, 1) and 2.9 (2.8, 3.0) min, respectively, which were lower than that of the control group [21.9% (21/96), 2(1, 3), 9.0 (4.5, 12.9) min, respectively] (all P<0.01). No difference was found in VAS score at each time point before and after surgery between the two groups (all P>0.05). There was one case of pleura puncture in the control group, but no other complications such as straying into vertebral canal, hematoma, spinal cord injury, limb movement disorder, infection were found in the two groups. Conclusions: 3D-printed personalized navigation template is an effective method to guide DRG-PRF for the treatment of thoracic postherpetic neuralgia. It can significantly improve the surgical efficiency of DRG-PRF, but has no significant effect on the surgical efficacy.

In-plane quasi-single-domain BaTiO3 via interfacial symmetry engineering.

The control of the in-plane domain evolution in ferroelectric thin films is not only critical to understanding ferroelectric phenomena but also to enabling functional device fabrication. However, in-plane polarized ferroelectric thin films typically exhibit complicated multi-domain states, not desirable for optoelectronic device performance. Here we report a strategy combining interfacial symmetry engineering and anisotropic strain to design single-domain, in-plane polarized ferroelectric BaTiO3 thin films. Theoretical calculations predict the key role of the BaTiO3/PrScO3 [Formula: see text] substrate interfacial environment, where anisotropic strain, monoclinic distortions, and interfacial electrostatic potential stabilize a single-variant spontaneous polarization. A combination of scanning transmission electron microscopy, piezoresponse force microscopy, ferroelectric hysteresis loop measurements, and second harmonic generation measurements directly reveals the stabilization of the in-plane quasi-single-domain polarization state. This work offers design principles for engineering in-plane domains of ferroelectric oxide thin films, which is a prerequisite for high performance optoelectronic devices.

[Association between fresh fruit consumption and glycemic control in patients with type 2 diabetes].

Objective: To investigate the association between fresh fruit consumption and status of glycemic control, among patients with type 2 diabetes mellitus (T2DM). Methods: Using the stratified cluster sampling method, a cross-sectional study was conducted among 19 473 diabetic patients who were under the Disease Management Program related to the National Basic Public Health Service in Changshu county, Huai'an and Qinghe districts of Huai'an city from December 2013 to January 2014, under the combination of fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c) methods, the glycemic control status in T2DM patients was assessed. Multiple logistic regression method was used to explore the relationship between fresh fruit consumption and status of glycemic control among T2DM patients. Results: 62.4% of the T2DM patients reported their amount of fruits intake in the past year. Both the levels of FPG and HbA1c decreased in T2DM patients, when the frequency and amount of fresh fruit consumption were increasing. Compared with patients who did not take fresh fruits, the risk of poor glycemic control in patients with fresh fruit consumption of 1-4 times/week and ≥5 times/week decreased 20% (OR=0.80, 95%CI: 0.73-0.87) and 30% (OR=0.70, 95%CI: 0.62-0.80), respectively. Patients with fruit consumption of 50-99 g/day and ≥100 g/day had lower risk of poor glycemic control, with ORs (95%CI) as 0.71 (95%CI: 0.62-0.83) and 0.68 (95%CI: 0.59-0.78), respectively. Conclusions: The association of fresh fruit intake and glycemic control was statistically significant in patients with type 2 diabetes. With the increase of frequencies and amounts of fresh fruit consumption, the levels of FPG and HbA1c showed a decreasing trend. Our findings suggested that fresh fruit intake seemed helpful for glycemic control.

Chemically specific termination control of oxide interfaces via layer-by-layer mean inner potential engineering.

Creating oxide interfaces with precise chemical specificity at the atomic layer level is desired for the engineering of quantum phases and electronic applications, but highly challenging, owing partially to the lack of in situ tools to monitor the chemical composition and completeness of the surface layer during growth. Here we report the in situ observation of atomic layer-by-layer inner potential variations by analysing the Kikuchi lines during epitaxial growth of strontium titanate, providing a powerful real-time technique to monitor and control the chemical composition during growth. A model combining the effects of mean inner potential and step edge density (roughness) reveals the underlying mechanism of the complex and previously not well-understood reflection high-energy electron diffraction oscillations observed in the shuttered growth of oxide films. General rules are proposed to guide the synthesis of atomically and chemically sharp oxide interfaces, opening up vast opportunities for the exploration of intriguing quantum phenomena at oxide interfaces.

[Association between smoking/smoking cessation and glycemic control in male patients with type 2 diabetes].

Objective: To explore the association of smoking and smoking cessation with glycemic control in male patients with type 2 diabetes. Methods: From December 2013 to January 2014, a total of 7 763 male patients with type 2 diabetes, who received national basic public health service in Changshu county of Suzhou city, Huai'an and Qinghe districts of Huai'an city, Jiangsu province, were recruited by cluster sampling. Questionnaire survey and anthropometric measurements were conducted, and fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) levels were measured. Multiple linear regression model was used to evaluate the association of smoking and smoking cessation with glycemic control. Results: The prevalence of current smoking was 45.5% in male patients with type 2 diabetes. The levels of FPG and HbA1c increased with number of cigarettes smoked per day compared with non-smokers (P<0.001). Among patients with drug treatment, the average increase of HbA1c level in current smokers with smoking duration ≥30 years and smoking index ≥40 pack-years were 0.27% (95%CI: 0.05%-0.49%) and 0.38% (95%CI: 0.23%-0.53%), respectively. FPG and HbA1c level decreased obviously with smoking cessation years among former smokers (P<0.05). Among the patients receiving no drug treatment, no dose-response relationships were observed between smoking duration, smoking cessation years and levels of FPG and HbA1c. Conclusion: Cigarette smoking was negatively related with glycemic control in male type 2 diabetes patients, especially in patients with drug treatment. Smoking cessation may be beneficial for glycemic control. Smoking cessation should be encouraged for diabetes patients as early as possible.

Polar metals by geometric design.

Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions. Quantum physics supports this view, demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals--it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases. Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO3 perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements. We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedral--the structural signatures of perovskites--owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported, non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.

A perturbation theory study of electron vortices in electromagnetic fields: the case of infinitely long line charge and magnetic dipole.

The novel discovery of electron vortices carrying quantized orbital angular momentum motivated intensive research of their basic properties as well as applications, e.g. structural characterization of magnetic materials. In this paper, the fundamental interactions of electron vortices within infinitely long atomic-column-like electromagnetic fields are studied based on the relativistically corrected Pauli-Schrödinger equation and the perturbation theory. The relative strengths of three fundamental interactions, i.e. the electron-electric potential interaction, the electron-magnetic potential/field interaction and the spin-orbit coupling are discussed. The results suggest that the perturbation energies of the last two interactions are in an order of 10(3)-10(4) smaller than that of the first one for electron vortices. In addition, it is also found that the strengths of these interactions are strongly dependant on the spatial distributions of the electromagnetic field as well as the electron vortices.

Phase transitions, phase coexistence, and piezoelectric switching behavior in highly strained BiFeO(3) films.

Highly strained BiFeO3 films transition into a true tetragonal state at 430 °C but remain polar to much higher temperatures (∼800 °C). Piezoelectric switching is only possible up to 300 °C, i.e., at temperatures for which strain stabilizes the stripe-like coexistence of multiple polymorphs.

Artificially engineered superlattices of pnictide superconductors.

Significant progress has been achieved in fabricating high-quality bulk and thin-film iron-based superconductors. In particular, artificial layered pnictide superlattices offer the possibility of tailoring the superconducting properties and understanding the mechanism of the superconductivity itself. For high-field applications, large critical current densities (J(c)) and irreversibility fields (H(irr)) are indispensable along all crystal directions. On the other hand, the development of superconducting devices such as tunnel junctions requires multilayered heterostructures. Here we show that artificially engineered undoped Ba-122/Co-doped Ba-122 compositionally modulated superlattices produce ab-aligned nanoparticle arrays. These layer and self-assemble along c-axis-aligned defects, and combine to produce very large J(c) and H(irr) enhancements over a wide angular range. We also demonstrate a structurally modulated SrTiO3(STO)/Co-doped Ba-122 superlattice with sharp interfaces. Success in superlattice fabrication involving pnictides will aid the progress of heterostructured systems exhibiting new interfacial phenomena and device applications.

Electrical transport in ion beam created InAs nanospikes.

Ion beam irradiation has previously been demonstrated as a method for creating nanowire-like semiconductor nanostructures, but no previous studies have reported on the electrical properties of those structures. In this work we describe the creation and in situ transmission electron microscopy electrical characterization of nanoscale InAs spike structures on both InAs and InP substrates fabricated using a focused ion beam erosion method. Those InAs 'nanospikes' are found to possess internal structures with varying amounts of ion damaged and single crystalline material. Nanospike electrical behavior is analyzed with respect to model electronic structures and is similar to cases of barrier limited conduction in nanowires. The different electrical responses of each nanospike are found to be the result of variation in their structure, with the conductivity of InAs nanospikes formed on InAs substrates found to increase with the degree of nanospike core crystallinity. The conductivity of InAs nanospikes formed on InP substrates does not show a dependence on core crystallinity, and may be controlled by the other internal barriers to conduction inherent in that system.

Enhancement of ferroelectric polarization stability by interface engineering.

By using theoretical predictions based on first-principle calculations, we explore an interface engineering approach to stabilize polarization states in ferroelectric heterostructures with a thickness of just several nanometers.

Giant piezoelectricity on Si for hyperactive MEMS.

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.

Metallic and insulating oxide interfaces controlled by electronic correlations.

The formation of two-dimensional electron gases (2DEGs) at complex oxide interfaces is directly influenced by the oxide electronic properties. We investigated how local electron correlations control the 2DEG by inserting a single atomic layer of a rare-earth oxide (RO) [(R is lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), or yttrium (Y)] into an epitaxial strontium titanate oxide (SrTiO(3)) matrix using pulsed-laser deposition with atomic layer control. We find that structures with La, Pr, and Nd ions result in conducting 2DEGs at the inserted layer, whereas the structures with Sm or Y ions are insulating. Our local spectroscopic and theoretical results indicate that the interfacial conductivity is dependent on electronic correlations that decay spatially into the SrTiO(3) matrix. Such correlation effects can lead to new functionalities in designed heterostructures.

Creation of a two-dimensional electron gas at an oxide interface on silicon.

In recent years, reversible control over metal-insulator transition has been shown, at the nanoscale, in a two-dimensional electron gas (2DEG) formed at the interface between two complex oxides. These materials have thus been suggested as possible platforms for developing ultrahigh-density oxide nanoelectronics. A prerequisite for the development of these new technologies is the integration with existing semiconductor electronics platforms. Here, we demonstrate room-temperature conductivity switching of 2DEG nanowires formed at atomically sharp LaAlO(3)/SrTiO(3) (LAO/STO) heterointerfaces grown directly on (001) Silicon (Si) substrates. The room-temperature electrical transport properties of LAO/STO heterointerfaces on Si are comparable with those formed from a SrTiO(3) bulk single crystal. The ability to form reversible conducting nanostructures directly on Si wafers opens new opportunities to incorporate ultrahigh-density oxide nanoelectronic memory and logic elements into well-established Si-based platforms.

Ferroelectricity in strain-free SrTiO3 thin films.

Biaxial strain is known to induce ferroelectricity in thin films of nominally nonferroelectric materials such as SrTiO3. By a direct comparison of the strained and strain-free SrTiO3 films using dielectric, ferroelectric, Raman, nonlinear optical and nanoscale piezoelectric property measurements, we conclude that all SrTiO3 films and bulk crystals are relaxor ferroelectrics, and the role of strain is to stabilize longer-range correlation of preexisting nanopolar regions, likely originating from minute amounts of unintentional Sr deficiency in nominally stoichiometric samples. These findings highlight the sensitive role of stoichiometry when exploring strain and epitaxy-induced electronic phenomena in oxide films, heterostructures, and interfaces.

Template engineering of Co-doped BaFe2As2 single-crystal thin films.

Understanding new superconductors requires high-quality epitaxial thin films to explore intrinsic electromagnetic properties and evaluate device applications. So far, superconducting properties of ferropnictide thin films seem compromised by imperfect epitaxial growth and poor connectivity of the superconducting phase. Here we report new template engineering using single-crystal intermediate layers of (001) SrTiO(3) and BaTiO(3) grown on various perovskite substrates that enables genuine epitaxial films of Co-doped BaFe(2)As(2) with a high transition temperature (T(c,rho=0) of 21.5 K, where rho=resistivity), a small transition width (DeltaT(c)=1.3 K), a superior critical current density J(c) of 4.5 MA cm(-2) (4.2 K) and strong c-axis flux pinning. Implementing SrTiO(3) or BaTiO(3) templates to match the alkaline-earth layer in the Ba-122 with the alkaline-earth/oxygen layer in the templates opens new avenues for epitaxial growth of ferropnictides on multifunctional single-crystal substrates. Beyond superconductors, it provides a framework for growing heteroepitaxial intermetallic compounds on various substrates by matching interfacial layers between templates and thin-film overlayers.

Ferroelastic switching for nanoscale non-volatile magnetoelectric devices.

Multiferroics, where (anti-) ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetic ordering by an electric field through switching of the electric polarization. It has been shown that realization of magnetoelectric coupling in a single-phase multiferroic such as BiFeO(3) requires ferroelastic (71 degrees, 109 degrees) rather than ferroelectric (180 degrees) domain switching. However, the control of such ferroelastic switching in a single-phase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic back-switching at zero electric field, and thus the disappearance of non-volatile information storage. Guided by our phase-field simulations, here we report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO(3) islands. This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.

Strain-induced polarization rotation in epitaxial (001) BiFeO3 thin films.

Direct measurement of the remanent polarization of high quality (001)-oriented epitaxial BiFeO3 thin films shows a strong strain dependence, even larger than conventional (001)-oriented PbTiO3 films. Thermodynamic analysis reveals that a strain-induced polarization rotation mechanism is responsible for the large change in the out-of-plane polarization of (001) BiFeO3 with biaxial strain while the spontaneous polarization itself remains almost constant.

Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy.

We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.