High K2 Research Articles

Theoretical investigation of Rayleigh surface acoustic wave propagation characteristics in c-axis-zigzag ScAlN film/silicon substrate structure

Surface acoustic wave (SAW) resonators are key components of mobile communication systems, and the development of wideband SAW resonators is especially required because next-generation mobile communication systems require high-speed data transmission using wide frequency bands. In this study, two layered structures—(i) a c-axis-tilted ScAlN bilayer film/silicon substrate and (ii) a c-axis-zigzag ScAlN film/silicon substrate—are proposed for highly coupled SAW resonators, and the electromechanical coupling coefficient K2 of the non-leaky Rayleigh-mode SAW propagating in these structures is investigated theoretically. With a proper c-axis tilt angle and thickness selection of the ScAlN film, the first-mode Rayleigh SAW in the c-axis-tilted ScAlN bilayer film/silicon substrate and c-axis-zigzag ScAlN film/silicon substrate offers high K2. The maximum K2 was 9.56%, obtained in the c-axis-zigzag ScAlN film/silicon substrate structure, which was 2.5 times the maximum K2 in the c-axis-tilted ScAlN monolayer film/silicon substrate structure; this is because the c-axis-zigzag ScAlN films increase the shear vertical component of the SAW particle displacement, most of which is concentrated in the c-axis-zigzag ScAlN film on the silicon substrate. It is also important that the second-mode SAW (Sezawa wave) in the c-axis-zigzag ScAlN film/silicon substrate structure is not excited when the K2 value of the first-mode SAW is maximized. The techniques for fabricating a c-axis-tilted ScAlN film and a c-axis-zigzag ScAlN film have been reported, and well-established micromachining technology related to silicon semiconductors offers significant advantages in the manufacturing and processing of SAW resonators. Therefore, the c-axis-zigzag ScAlN film/silicon substrate structure has significant potential for SAW device applications.

Effects of Bacillus subtilis Natto NB205 and Its Mutant NBMK308 on Egg Quality in Aging Laying Hens.

In aging laying hens, reproductive changes reduce egg quality. Bacillus subtilis natto (B. subtilis) is a versatile bacterium with high vitamin K2 content, providing health benefits for animals and humans. This study investigated the effect of B. subtilis natto NB205 and its mutant NBMK308 on egg quality in aging laying hens. Results showed that NB205 and NBMK308 supplementation significantly improved albumen height (p < 0.001), Haugh units (p < 0.05), and eggshell thickness (p < 0.001) compared to the control group. Supplementation also increased ovalbumin expression, regulated tight junction (TJ) proteins, reduced pro-inflammatory cytokine levels, and improved the health and productivity of aging laying hens by regulating key apoptosis-related genes in the magnum part of the oviduct. There were differences in the expression of vitamin K-dependent proteins (VKDPs) in the magnum between NB205 and NBMK308, but no significant differences in the improvement of egg quality. Supplementation with NB205 and NBMK308 can improve egg quality in aging laying hens.

High electro-mechanical coupling coefficient SAW device with ScAlN on diamond

In this study, Sc concentration dependence of Sc x Al1−x N/AlN/poly-crystalline diamond/Si surface acoustic wave (SAW) characteristics at high Sc from 23.8% to 44.3% was investigated by fabricating one-port SAW resonator at high frequency. 3.8 GHz one-port resonator fabricated on Sc0.43Al0.57N showed an excellent performance of electro-mechanical coupling coefficient (K 2) as high as 6.34% for 2nd mode Sezawa wave, which enables a wide bandwidth in high frequency applications. The temperature coefficient of frequency was approximately −40 to −50 ppm deg−1 for the device fabricated with Sc concentration of 42.9%. This is a smaller value compared to conventional high K2 bulk materials such as LiNbO3. As the result, a high K2 6.34% material system at a higher Sc concentration of ScAlN/AlN/PCD was found to be possible at a high phase velocity of 7000 m s−1. Combined with the extremely high-power durability of diamond based device, high-power durable wideband SAW device at high frequency can be expected.

Crystal Phase and Morphology-Controlled Synthesis of Tungsten Oxide Nanostructures for Remarkably Ultrafast Adsorption and Separation of Organic Dyes.

Simple inorganic routes for the synthesis of WO3 nanostructures with variable crystal phases, WO3·(H2O)0.5 and (NH4)0.33WO3, and their self-assembled structures as nanoplates and nanospheres, respectively, were reported. The morphologies and formation of nanoplates and nanospheres were controlled by changing the solvent amount (H2O/n-propanol) in the solvothermal reactions without any stabilizing agent or surfactant. The adsorption properties of the WO3 nanostructures were studied, and it was found that nanospheres show remarkably higher and ultrafast adsorption of methylene blue (MB) in comparison to nanoplates and commercial WO3. The adsorption isotherms, kinetics, mechanism, and reusability of (NH4)0.33WO3 nanospheres were systematically studied. The nanospheres exhibited an exceptionally high adsorption rate K2 of 17.24 g·mg-1·min-1 and the maximum adsorption capacity of 116 mg·g-1 for MB. The adsorption cycle of nanospheres was examined, and the removal efficiency of MB remained at ∼98-99% even after three regeneration cycles. In addition, (NH4)0.33WO3 nanospheres exhibited excellent selective adsorption performance toward several cationic dyes, including MB, malachite green (MG), safranin O (SO), crystal violet (CV), and separate MO, a negatively charged dye, with a separation efficiency of 99.93 and 77.31% from binary and pentanary dye mixture solutions, respectively, at neutral pH.

Combining phosphate binder therapy with vitamin K2 inhibits vascular calcification in an experimental animal model of kidney failure.

Hyperphosphataemia is strongly associated with cardiovascular disease and mortality. Recently, phosphate binders (PBs), which are used to bind intestinal phosphate, have been shown to bind vitamin K, thereby potentially aggravating vitamin K deficiency. This vitamin K binding by PBs may offset the beneficial effects of phosphate reduction in reducing vascular calcification (VC). Here we assessed whether combining PBs with vitamin K2 supplementation inhibits VC. We performed 3/4 nephrectomy in rats, after which warfarin was given for 3 weeks to induce vitamin K deficiency. Next, animals were fed a high phosphate diet in the presence of low or high vitamin K2 and were randomized to either control or one of four different PBs for 8 weeks. The primary outcome was the amount of thoracic and abdominal aorta VC measured by high-resolution micro-computed tomography (µCT). Vitamin K status was measured by plasma MK7 levels and immunohistochemically analysed in vasculature using uncarboxylated matrix Gla protein (ucMGP) specific antibodies. The combination of a high vitamin K2 diet and PB treatment significantly reduced VC as measured by µCT for both the thoracic (P = 0.026) and abdominal aorta (P = 0.023), compared with MK7 or PB treatment alone. UcMGP stain was significantly more present in the low vitamin K2-treated groups in both the thoracic (P < 0.01) and abdominal aorta (P < 0.01) as compared with high vitamin K2-treated groups. Moreover, a high vitamin K diet and PBs led to reduced vascular oxidative stress. In an animal model of kidney failure with vitamin K deficiency, neither PB therapy nor vitamin K2 supplementation alone prevented VC. However, the combination of high vitamin K2 with PB treatment significantly attenuated VC.

First Clinical Trial of a Newly Developed, Low Menaquinone-7, Fermented Soybean Natto in Warfarin-Dependent Patients.

Bacillus subtilis fermented soybeans (natto) contain high vitamin K2 levels, mostly as menaquinone-7 (MK-7), and must be avoided by warfarin-dependent patients. This is the first report which demonstrates the characteristics and clinical relevance of a low MK-7 natto for such patients. We generated a novel, mutant B. subtilis strain TTCC2051 with short-term fermentation and reduced MK-7 production, yielding 19-24% of the normal MK-7 content. After functional assessments and a preclinical trial, 10 warfarin-dependent patients underwent a clinical trial with a 7-day ingestion test of the low MK-7 natto. Functional assessments were satisfactory, and the preclinical trial showed no increases in plasma MK-7 levels after 7 days of ingestion. In the clinical trial, 20 g/day of the low MK-7 natto significantly increased plasma MK-7 levels while 10 g/day did not. However, neither dose of low MK-7 natto changed international normalized ratio of prothrombin time (PT-INR) values in either group. The low MK-7 natto neither changed PT-INR values nor precipitated adverse events if ingested with a once-daily maximum of 20 g (46 μg of MK-7). Thus, this novel food product has potential for consumption by warfarin-dependent patients.

High quality and low loss surface acoustic wave SAW resonator based on chromium-doped AlN on sapphire

This paper aims to investigate the performances of surface acoustic wave (SAW) resonators based on chromium-doped aluminum nitride (AlCrN) piezoelectric thin film on c-cut sapphire substrate. The electromechanical properties of AlCrN (mass density, elastic, dielectric and piezoelectric constants) are obtained from density functional theory calculations for different Cr-doping concentrations. Piezoelectricity is enhanced for Al1 − xCrxN with different x concentrations. Using finite element analysis, the electroacoustic parameters such as phase velocity, electromechanical coupling factor K2 of surface acoustic modes are determined for different AlCrN thickness-to-wavelength ratios and different Cr-doping concentrations. Higher order SAW modes arise at Cr concentration x = 25%. The electrical admittance and scattering parameter S21 for the fundamental SAW modes are determined. High K2, low loss and high-quality factor are found after incorporating Cr dopant. The comparison of the obtained results with the available numerical and experimental data on AlN doped with Scandium Sc has shown a considerable improvement of SAW devices characteristics, confirming that AlCrN can be adopted as a new piezoelectric material for high performances SAW devices.

Association between gut microbiota, bone metabolism, and fracture risk in postmenopausal Japanese women

IntroductionWe investigated the relationship between gut microbiota composition and osteoporosis/fracture risk in Japanese postmenopausal women using 16S rRNA gene sequencing, FRAX, bone mineral density, biochemical bone parameters, and a self-administered questionnaire. Variation in abundance of specific microbiota was found to be significantly associated with fracture risk and vitamin K levels.Gut microbiota data with respect to bone metabolism and fracture risk is limited. Vitamin K is produced by certain intestinal bacteria and has been reported to play a role in maintaining bone quality.PurposeWe investigated relationships among gut microbiota composition, bone metabolism, and fracture risk in postmenopausal Japanese women.MethodsBone mineral density (BMD) was evaluated in 38 postmenopausal women (mean age 62.9 years) using forearm dual-energy X-ray absorptiometry. We collected and analyzed serum bone turnover markers (vitamin K fraction and tartrate-resistant acid phosphatase 5b; TRACP-5b), gut microbiota profiling (16S rRNA gene sequencing), and self-administered questionnaire data, including fracture history and vitamin K intake. Vitamin K2, BMD, and TRACP-5b data were divided into high- and low-level groups using cutoff values of 0.06 ng/mL, 87.05%, and 420 mU/dL, respectively; the proportions of bacteria were analyzed. Fracture incidence and relative risk were investigated for each bacterium.ResultsThe genus Bacteroides was predominant in the high vitamin K2 group (29.73% vs 21.58%, P = 0.022). Fracture incidence was significantly higher in the low Bacteroides group, with a 5.6-times higher risk ratio of fracture history.The family Rikenellaceae was more abundant in the low BMD group and more abundant in the high TRACP-5b group (2.15% vs 0.82%, P = 0.004; 2.38% vs 1.12%, P = 0.013, respectively).ConclusionBacteroides and Rikenellaceae may be involved in bone metabolism and fracture risk. Further investigations of the underlying microbiota-related pathways in bone metabolism may reveal treatment strategies, and facilitate the prevention of osteoporosis.

Enhanced Performance of ZnO/SiO2/Al2O3 Surface Acoustic Wave Devices with Embedded Electrodes.

With the advent of the 5G era, surface acoustic wave (SAW) devices with a larger bandwidth and better temperature stability are strongly required, meanwhile the dimensions of devices are continuously scaling down. In this work, a new layout of ZnO/SiO2/Al2O3 SAW devices with embedded electrodes was developed, and with the help of the finite element method (FEM), the propagation characteristics were simulated. Through adopting embedded electrodes, a large electromechanical coupling coefficient (K2) of 6.6% for the Rayleigh mode can be achieved (5 times larger than that of the conventional ZnO/Al2O3 structure), feasible for wideband SAW devices, and a low acoustic velocity (Vp) of 2960 m/s is exhibited simultaneously, which benefits the miniaturization of SAW devices. The dramatic enhancement of K2 is mainly attributed to the more efficient excitation of SAW in piezoelectric films. Furthermore, a SiO2 overlay is added on the top of the structure to gain an excellent zero temperature coefficient of frequency (TCF). Experimentally, we successfully fabricated SAW one-port resonators based on the proposed structure and good characteristics of high K2, low Vp, and small TCF as simulated were confirmed. Our results show that the proposed structure provides a viable route to design SAW devices with a large bandwidth, small size, and robust temperature compensation for practical use.

Evolution of strong second-order magnetic anisotropy in Pt/Co/MgO trilayers by post-annealing

In this study, the first- (K1) and second-order (K2) magnetic anisotropies are investigated as a function of post-annealing temperature (Ta) in Pt/Co/MgO heterostructures. We find that both extrinsic and intrinsic mechanisms contribute to K2 with their relative contributions significantly depending on the quality of the Co/MgO interface, which is sensitively affected by the Ta value. In contrast with previous studies that mainly considered the extrinsic effects on K2, we obtain high K2 values of up to 2.04 × 106 erg/cm3 for the stack annealed at Ta = 400 °C by maximally utilizing the intrinsic effect at the Co/MgO interface, thus facilitating robust easy-cone anisotropy. We also demonstrate that the canted magnetization can be efficiently manipulated by the spin–orbit torques generated from the Pt layer, which is an important step toward the application of easy-cone states in various spintronic devices.

Theoretical analysis of high electromechanical coupling surface acoustic wave propagating on lead-free Na0.5Bi0.5TiO3–BaTiO3 single crystal

The propagation properties of surface acoustic wave (SAW) on the Na0.5Bi0.5TiO3–BaTiO3 (NBBT) substrate with different crystal cuts were theoretically analyzed by Finite Element Method (FEM). The calculated results, for the NBBT with the optimized electrode type and thickness, indicate the existence of Rayleigh and Sezawa modes with high electromechanical coupling factor K2 ~18% and ~6.8% respectively, which are considerably higher than that of the conventional lithium niobate (LiNbO3) single crystal for SAW applications. The research provides a comprehensive understanding of the SAW propagation characteristics of lead-free NBBT, and explores the promising applications of NBBT in wideband SAW devices.

Effects of vitamin K2 on the growth and expression of HDGF in transplanted tumor of human liver cancer in nude mice

Objective To investigate the effects of vitamin K2 on the growth of transplanted tumor and the expression of HDGF in human hepatocellular carcinoma in nude mice. Methods After the establishment of metastatic human hepatocellular carcinoma models, give the tumor-bearing nude mice oral vitamin K2, the nude mice were randomly divided into three groups, 8 nude mice in each group: control group, vitamin K2 low concentration group [20 mg/(kg·d)], and vitamin K2 high concentration group [45 mg/(kg·d)]. Tumor size, tumor weight were measured during administration, inhibitory rate was calculated. The expression of HDGF protein in transplanted tumor tissues was detected after different concentrations of vitamin K2. Results The inhibitory rate of control group, low vitamin K2 concentration group and high vitamin K2 concentration group was 0%, (36.13±4.38)%, (57.90±2.57)%, respectively. Compared with the control group, the vitamin K2 intervention group showed significantly reduced tumor tissue and increased inhibitory rate (t=25.460, 80.610, P<0.05). Western blotting analysis showed that the grayscale analysis values of HDGF protein expression in low vitamin K2 concentration group and high vitamin K2 concentration group were (0.634±0.030) and (0.278±0.040), which significantly inhibited the expression of HDGF protein in tumor cells of tumor-bearing nude mice, and were statistically significant compared with the control group (t=32.730, 49.520, P<0.05). Conclusion Vitamin K2 inhibited the growth of human hepatocellular carcinoma xenografts in nude mice and down-regulated the expression of HDGF in tumor cells. Key words: Vitamin K2; Nude mice beared human hepatocellular carcinoma; Hepatoma-derived growth factor

SAW RFID Devices Using Connected IDTs as an Alternative to Conventional Reflectors for Harsh Environments

Remote interrogation of surface acoustic wave identification tag (ID-tags) imposes a high signal amplitude which is related to a high coupling coefficient value ( K2 ) and low propagation losses ( α ). In this article, we propose and discuss an alternative configuration to the standard one. Here, we replaced the conventional configuration, i.e., one interdigital transducer (IDT) and several reflectors, by a series of electrically connected IDTs. The goal is to increase the amplitude of the detected signal using direct transmission between IDTs instead of the reflection from passive reflectors. This concept can, therefore, increase the interrogation scope of ID-tags made on a conventional substrate with high K2 value. Moreover, it can also be extended to suitable substrates for harsh environments, such as high-temperature environments: the materials used exhibit limited performances (low K2 value and relatively high propagation losses) and are, therefore, rarely used for identification applications. The concept was first tested and validated using the lithium niobate 128° Y-X cut substrate, which is commonly used in ID-tags. A good agreement between experimental and numerical results was obtained for the promising concept of connected IDTs. The interesting features of the structure were also validated using a langasite substrate, which is well-known to operate at very high temperatures. Performances of both substrates (lithium niobate and langasite) were tested with an in situ RF characterization up to 600 °C. Unexpected results regarding the resilience of devices based on congruent lithium niobate were obtained.

Analysis of longitudinal leaky surface acoustic wave propagation characteristics on a piezoelectric ScAlN layer/sapphire or quartz substrate

Longitudinal leaky surface acoustic wave (LLSAW) modes with a high phase velocity are suitable for high-frequency SAW filter applications. However, their attenuation is higher than that of other SAW modes, causing a small Q factor. On the other hand, a low attenuation and high coupling factor K2 in LLSAWs on a piezoelectric thin plate/high-velocity sapphire or quartz substrate have been demonstrated theoretically and experimentally. We expected that LLSAWs propagating on a highly piezoelectric ScAlN layer/sapphire or quartz substrate also have a high phase velocity, high K2 and low attenuation. In this study, the characteristics of LLSAWs on ScAlN layer/sapphire or quartz substrates were theoretically investigated. The cut angle and SAW propagation direction of quartz substrates strongly affect the attenuation of LLSAWs on the layered structure. We found that a LLSAW resonator with (0° 90° 90°) Sc0.4Al0.6N layer/X-cut 30° Y propagation quartz has a high Q factor and high K2, which is adequate for SAW filter applications.

Large piezoelectricity on Si from highly (001)-oriented PZT thick films via a CMOS-compatible sputtering/RTP process

Integration of lead zirconate titanate (PZT) ferroelectrics into CMOS-Si technology has become a perennial challenge due to the continuously shrinking thermal budget in semiconductor processing. In this work, Pb(Zr0.53Ti0.47)O3 (PZT) thick films (∼1 µm) were prepared on LaNiO3 buffered (111)Pt/Ti/SiO2/(100) Si substrates via a low temperature (350 °C) sputtering deposition followed by a rapid thermal process (RTP). This two-step fabrication process resulted in a highly (001)-oriented perovskite PZT film with a dense, fine-grain morphology and reduced strains, hence an optimal electrical performance intrinsic to the chemical composition was achieved. EDS and XPS analyses verified a desirable evolution of the chemical stoichiometry in the RTP, as well as the expected chemical bonding states of the elements in the annealed films. Moreover, prototypical piezoelectric thin film cantilevers fabricated from the PZT/LaNiO3/Pt/Ti/SiO2/(100)Si heterostructure yielded a large transverse piezoelectric coefficient (e31,f) up to 15.7 C/m2, together with a high coupling coefficient k2∼0.23 for energy conversion efficiency. The PZT films showed high e31,f coefficients (∼10 C/m2) even when the RTP annealing time was reduced down to 2 min. Such a piezoelectric performance is close to the highest ones reported in the literature from epitaxial or highly-oriented PZT films, which require a much higher thermal budget for processing. These high quality PZT films open up many possibilities for the integration of piezoelectricity into Si-based micro-electro-mechanical systems (MEMS).

Star–disc (mis-)alignment in Rho Oph and Upper Sco: insights from spatially resolved disc systems with K2 rotation periods

The discovery of close in, giant planets (hot Jupiters) with orbital angular momentum vectors misaligned with respect to the rotation axis of their host stars presents problems for planet formation theories in which planets form in discs with angular momentum vectors aligned with that of the star. Violent, high eccentricity migration mechanisms purported to elevate planetary orbits above the natal disc plane predict populations of proto-hot Jupiters which have not been observed with Kepler. Alternative theories invoking primordial star-disc misalignments have recently received more attention. Here, the relative alignment between stars and their protoplanetary discs is assessed for the first time for a sample of 20 pre-main-sequence stars. Recently published rotation periods derived from high quality, long duration, high cadence K2 light curves for members of the $\rho$ Ophiuchus and Upper Scorpius star forming regions are matched with high angular resolution observations of spatially resolved discs and projected rotational velocities to determine stellar rotation axis inclination angles which are then compared to the disc inclinations. Ten of the fifteen systems for which the stellar inclination could be estimated are consistent with star-disc alignment while five systems indicate potential misalignments between the star and its disc. The potential for chance misalignment of aligned systems due to projection effects and characteristic measurement uncertainties is also investigated. While the observed frequency of apparent star-disc misalignments could be reproduced by a simulated test population in which 100% of systems are truly aligned, the distribution of the scale of inferred misalignment angles could not.

High performance 33.7 GHz surface acoustic wave nanotransducers based on AlScN/diamond/Si layered structures

Surface acoustic wave (SAW) devices are essential devices for communication and sensing, but usually have an operation frequency limit well below 20 GHz due to the constraints of material properties and fabrication capability. By using an AlScN/diamond layered structure with a high electromechanical coupling coefficient K2 and our proposed two-step exposure electron beam lithography (EBL) process for ultra-fine patterns, we have fabricated SAW devices with resonant frequency up to 33.7 GHz in the Ka-band, the highest one ever reported for SAW devices electrically excited by interdigital transducers (IDTs). Combined with finite element analysis, we identified that series resonances are fundamental and high order Rayleigh modes, and K2 are in the range of 1.21%–2.32%, 200% higher compared to those of traditional AlN/diamond-based SAW devices. The high order modes become stronger and dominant, particularly suitable for the development of ultrahigh frequency SAW devices and applications. In addition, the proposed EBL process showed its superb capability to make ultra-fine IDTs down to the nano-scale with excellent smooth edges and uniform patterns, suitable for ultrahigh frequency SAW development.

Multilayered structures using thin plates of LiTaO3 for acoustic wave resonators with high quality factor

Multilayered substrates, including thin plates of LiTaO3 (LT) bonded to silicon (Si) or glass wafers either directly or via intermediate layers, were numerically investigated as potential materials for surface acoustic wave (SAW) resonators with high quality (Q)-factor required for the next generation of mobile communication systems. The propagation velocities and electromechanical coupling coefficients of shear horizontally (SH) polarized acoustic waves were estimated as functions of LT orientation and thicknesses of all layers in LT/Si, LT/SiO2/Si, LT/glass, LT/AlN/glass and structures with several pairs of SiO2/AlN layers between LT and the glass wafer. Optimal combinations of cut angle, LT and electrode thicknesses, as well as the number and thicknesses of intermediate layers, required for the construction of resonators with improved performance were observed for each analyzed structure. In the resonators employing LT/Si and LT/SiO2/Si structures with 30°YX - 48°YX LT cuts, high electromechanical coupling k2, reaching 11.6%, can be combined with high velocities up to 4000 m/s, zero TCF at the resonant frequency and Q-factors that are considerably higher than in the LSAW filters using regular LT substrates. To understand the loss mechanisms that limit resonator Q-factors in LT/glass, mechanical displacements that accompany wave propagation in multilayered structures were visualized. Investigation of the nature of acoustic modes and their transformations with number and thicknesses of the layers revealed that the low-velocity glass wafer can be used as a supporting substrate if an intermediate AlN layer or alternating pairs of low- and high-velocity layers, for example SiO2/AlN, are introduced between LT and the glass wafer.

Characteristics of one-port surface acoustic wave resonator fabricated on ZnO/6H-SiC layered structure

Characteristics of one-port surface acoustic wave (SAW) resonators fabricated on ZnO/6H-SiC layered structure were investigated experimentally and theoretically. Phase velocities (Vp), electromechanical coupling coefficients (K2), quality factors (Q), and temperature coefficients of frequency (TCF) of Rayleigh wave (0th mode) and first- and second-order Sezawa wave (1st and 2nd modes, respectively) for different piezoelectric film thickness-to-wavelength (hZnO/λ) ratios were systematically studied. Results demonstrated that one-port SAW resonators fabricated on the ZnO/6H-SiC layered structure were promising for high-frequency SAW applications with moderate K2 and TCF values. A high K2 of 2.44% associated with a Vp of 5182 m s−1 and a TCF of −41.8 ppm/°C was achieved at hZnO/λ = 0.41 in the 1st mode, while a large Vp of 7210 m s−1 with a K2 of 0.19% and a TCF of −36.4 ppm/°C was obtained for hZnO/λ = 0.31 in the 2nd mode. Besides, most of the parameters were reported for the first time and will be helpful for the future design and optimization of SAW devices fabricated on ZnO/6H-SiC layered structures.

Vitamin K-induced effects on body fat and weight: results from a 3-year vitamin K2 intervention study.

Vitamin K status has been linked to fat and glucose metabolism by several authors, but whether high vitamin K intake influences body weight or composition has remained unclear. Here we tested the hypothesis that increased vitamin K intake decreases body fat or fat distribution. In a randomized placebo-controlled human intervention trial, 214 postmenopausal women, 55-65 years of age, received either 180 mcg/day of vitamin K2 (menaquinone-7, MK-7) or placebo for 3 years. Osteocalcin (OC) carboxylation was used as a marker for vitamin K status, and fat distribution was assessed by dual-energy X-ray absorptiometry total body scan. In the total cohort, MK-7 supplementation increased circulating carboxylated OC (cOC) but had no effect on body composition. In those with an above-median response in OC carboxylation ('good responders'), MK-7 treatment resulted in a significant increase in total and human molecular weight adiponectin and a decrease in abdominal fat mass and in the estimated visceral adipose tissue area compared with the placebo group and the poor responders. The fact that changes in body composition measures or markers for fat or glucose metabolism were not associated with changes in uncarboxylated OC (ucOC) does not support the assumption that ucOC stimulates fat metabolism in humans. Instead, high vitamin K2 intake may support reducing body weight, abdominal and visceral fat, notably in subjects showing a strong increase in cOC. A causal relation between the changes in cOC and body fat or distribution cannot be concluded from these data.