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We report on the correlated investigation between piezoelectric properties and crystalline structure of PbZr0.52Ti0.48O3 (PZT) films under different oxygen pressures in the process of pulsed laser ...

Panax vietnamensis, or Vietnamese ginseng (VG), an endemic Panax species in Vietnam, possesses a unique saponin profile and interesting biological activities. This plant is presently in danger of extinction due to over-exploitation, resulting in many preservation efforts towards the geographical acclimatization of VG. Yet, no information on the saponin content of the acclimatized VG, an important quality indicator, is available. Here, we analyzed the saponin content in the underground parts of two- to five-year-old VG plants acclimatized to Lam Dong province. Nine characteristic saponins, including notoginsenoside-R1, ginsenoside-Rg1, -Rb1, -Rd, majonoside-R1, -R2 vina-ginsenoside-R2, -R11, and pseudoginsenoside-RT4, were simultaneously determined by HPLC coupled with UV and with a charged aerosol detector (CAD). Analyzing the results illustrated that the detection of characteristic ocotillol-type saponins in VG by CAD presented a superior capacity compared with that of UV, thus implying a preferential choice of CAD for the analysis of VG. The quantitative results indicating the saponin content in the underground parts of VG showed an increasing tendency from two to five years old, with the root and the rhizome exhibiting different saponin accumulation patterns. This is the first study that reveals the preliminary success of VG acclimatization and thereby encourages the continuing efforts to develop this valuable saponin-rich plant.

Functional oxides on silicon have been the subject of in-depth research for more than 20 years. Much of this research has been focused on the quality of the integration of materials due to their intrinsic thermodynamic incompatibility, which has hindered the flourishing of the field of research. Nevertheless, growth of epitaxial transition metal oxides on silicon with a sharp interface has been achieved by elaborated kinetically controlled sequential deposition while the crystalline quality of different functional oxides has been considerably improved. In this Research Update, we focus on three applications in which epitaxial ferroelectric oxides on silicon are at the forefront, and in each of these applications, other aspects of the integration of materials play an important role. These are the fields of piezoelectric microelectromechanical system devices, electro-optical components, and catalysis. The overview is supported by a brief analysis of the synthesis processes that enable epitaxial growth of oxides on silicon. This Research Update concludes with a theoretical description of the interfaces and the possibility of manipulating their electronic structure to achieve the desired coupling between (ferroelectric) oxides and semiconductors, which opens up a remarkable perspective for many advanced applications. © 2021 Author(s).

The impact of polarization effects induced by a ferroelectric layer on the on-state performance of ferroelectric gate AlGaN/GaN HEMTs has been studied by using experiments and extensive TCAD simulations. Stress-free and high quality crystalline (111) lead-zirconate-titanate ($\mathrm{P}\mathrm{b}(\mathrm{Z}\mathrm{r}_{x}\mathrm{T}\mathrm{i}_{1-x})\mathrm{O}_{3}$ or PZT) films on top of GaN have been successfully obtained by adopting a single magnesium-oxide (MgO) monolayer as a buffer layer. By adjusting the zirconium composition (x) of PZT, solely the spontaneous polarization in PZT is varied. In addition a onedimensional electrostatic model has been derived showing the impact of the polarization in the ferroelectric gate on the 2DEG sheet density and threshold voltage ($V_{\mathrm{T}\mathrm{H}}$), which is in good agreement with TCAD simulations. The experimental data show for $x=0.20$ a minimum on-resistance $(R_{\mathrm{O}\mathrm{N}})$ of $\sim 9.7\mathrm{k}\Omega$ and for $x=0.52$ a minimal $V_{\mathrm{T}\mathrm{H}}$ of ~-3.3V. The results are important for providing a guide line to optimize ferroelectric gate AlGaN/GaN HEMTs.

Panax vietnamensis (PV), a wild Panax species discovered in Vietnam in 1973, has been increasingly overexploited due to its economic value and therapeutic uses. This resulted in the development of PV cultivation to meet the market demand. There is little information on the accumulation of saponins in PV during cultivation, but this information could serve as an indication of the appropriate harvest time. In this study we developed an HPLC-UV/ELSD method to simultaneously determine the content of 10 characteristic saponins in PV from 2&ndash, 7 years old, including G-Rb1, G-Rd, G-Rg1, G-Re, N-R1, M-R1, M-R2, V-R2, V-R11, and p-RT4. The result indicated that from 2 to 5 years, the content of saponins in PV rhizome and radix increase 3.02 and 4.2 times, respectively, whereas from 5 to 7 years, no significant changes were observed. Hence, our study suggests that after 5 years of growth could be considered as an appropriate time for PV to be harvested. Among the analyzed saponins, G-Rg1, G-Rb1, G-Rd, and especially M-R2 were the major saponins that contributed to the change of PV&rsquo, s saponin content through the years. In addition, the developed and validated HPLC method was proven to be reliable and effective for quality control of PV.

Aberrant activation of Wnt/β-catenin signaling occurs frequently in cancer. However, therapeutic targeting of this pathway is complicated by the role of Wnt in stem cell maintenance and tissue homeostasis. Here, we evaluated antibodies blocking 6 of the 10 human Wnt/Frizzled (FZD) receptors as potential therapeutics. Crystal structures revealed a common binding site for these monoclonal antibodies (mAbs) on FZD, blocking the interaction with the Wnt palmitoleic acid moiety. However, these mAbs displayed gastrointestinal toxicity or poor plasma exposure in vivo. Structure-guided engineering was used to refine the binding of each mAb for FZD receptors, resulting in antibody variants with improved in vivo tolerability and developability. Importantly, the lead variant mAb significantly inhibited tumor growth in the HPAF-II pancreatic tumor xenograft model. Taken together, our data demonstrate that anti-FZD cancer therapeutic antibodies with broad specificity can be fine-tuned to navigate in vivo exposure and tolerability while driving therapeutic efficacy.

Dissipative particle dynamics computations were used to study the interaction between two carbon nanotubes (CNTs) stabilized with a polymer in an aqueous solution. The calculated interaction forces quantitatively described the steric effects of the adsorbed polymer on CNT agglomeration. It was found that the repulsive peak depended on the orientation of the CNTs relative to each other. A general equation describing the forces between polymer-stabilized CNTs was established, and its parameters were evaluated based on the results of the simulations. The procedure can be extended to other adsorbed molecules, like surfactants or biomolecules.

The ocotillol (OCT)-type saponins have been known as a tetracyclic triterpenoid, possessing five- or six-membered epoxy ring in the side chain. Interestingly, this type saponin was mostly found in Panax vietnamensis Ha et Grushv., Araliaceae (VG), hence making VG unique from the other Panax spp. Five OCT-type saponins, majonoside R2, vina-ginsenoside R2, majonoside R1, pseudoginsenoside RT4, vina-ginsenoside R11, together with three protopanaxadiol (PPD)-type saponins and four protopanaxatriol (PPT)-type saponins from VG were evaluated for their antimelanogenic activity. All of isolates were found to be active. More importantly, the five OCT-type saponins inhibited melanin production in B16-F10 mouse melanoma cells, without showing any cytotoxicity. Besides ginsenoside Rd and ginsenoside Rg3 in PPD and notoginsenoside R1 in PPT-type saponins, majonoside R2 was the most potent melanogenesis inhibitory activity in OCT-type saponins. In this article, we highlighted antimelanogenic activity of OCT-type saponins and potential structure-activity relationship (SAR) of ginsenosides. Our results suggested that OCT-type saponins could be used as a depigmentation agent.

Epitaxial (PbMg1/3Nb2/3O3)2/3-(PbTiO3)1/3 (PMN-PT) films with different out-of-plane orientations were prepared using a CeO2/yttria stabilized ZrO2 bilayer buffer and symmetric SrRuO3 electrodes on silicon substrates by pulsed laser deposition. The orientation of the SrRuO3 bottom electrode, either (110) or (001), was controlled by the deposition conditions and the subsequent PMN-PT layer followed the orientation of the bottom electrode. The ferroelectric, dielectric and piezoelectric properties of the (SrRuO3/PMN-PT/SrRuO3) ferroelectric capacitors exhibit orientation dependence. The properties of the films are explained in terms of a model based on polarization rotation. At low applied fields domain switching dominates the polarization change. The model indicates that polarization rotation is easier in the (110) film, which is ascribed to a smaller effect of the clamping on the shearing of the pseudo-cubic unit cell compared to the (001) case.

Relaxor ferroelectric Pb0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) thin films have been epitaxially grown via pulsed laser deposition on SrRuO3/SrTiO3 single crystal with different orientations. The high recoverable energy-storage density and energy-storage efficiency in the epitaxial PLZT thin films are mainly caused by the coexistence of relaxor and antiferroelectric-like behaviors. The recoverable energy-storage density of 12.03, 12.51 and 12.74 J/cm3 and energy-storage efficiency of 86.50, 88.14 and 88.44%, respectively, for the PLZT(001), PLZT(011) and PLZT(111) thin films measured at 1000 kV/cm. The high energy density and high efficiency indicate that the relaxor epitaxial PLZT(111) thin film is a promising candidate for high pulsed power capacitors.

Pb(Zr0.52Ti0.48)O3 (PZT) films with (001) orientation were deposited on Pt(111)/Ti/SiO2/Si(100) substrates using pulsed laser deposition. Variation of the laser pulse rate during the deposition of the PZT films was found to play a key role in the control of the microstructure and to change strongly the piezoelectric response of the thin film. The film deposited at low pulse rate has a denser columnar microstructure, which improves the transverse piezoelectric coefficient (d31f) and ferroelectric remanent polarization (Pr), whereas the less densely packed columnar grains in the film deposited at high pulse rates give rise to a significantly higher longitudinal piezoelectric coefficient (d33f) value. The effect of film thickness on the ferroelectric and piezoelectric properties of the PZT films was also investigated. With increasing film thickness, the grain column diameter gradually increases, and also the average Pr and d33f values become larger. The largest piezoelectric coefficient of d33f = 408 pm V–1 was found for a 4-μm film thickness. From a series of films in the thickness range 0.5–5 μm, the z-position dependence of the piezoelectric coefficient could be deduced. A local maximum value of 600 pm V–1 was deduced in the 3.5–4.5 μm section of the thickest films. The dependence of the film properties on film thickness is attributed to the decreasing effect of the clamping constraint imposed by the substrate and the increasing spatial separation between the grains with increasing film thickness.

Dissipative Particle Dynamics (DPD) simulations were used to investigate the conformation of polyvinyl pyrrolidone (PVP) grafted on carbon nanotubes (CNT) and the physical adsorption of the PVP under shear flow. The behavior of PVP on the surface of CNTs was illustrated after the physical adsorption of PVP on the CNT reached equilibrium in an aqueous medium. It was found that PVP molecules prefer to adsorb on the CNT surface and to occupy an “island” area. To examine the structure of CNT-PVP under shear flow, equilibrium CNT-PVP particles were released into Couette and Poiseuille flows. Depending on the shear rate, the polymer could be in one of three configurations: adsorbed, shear-affected and separated. Additionally, the conformation of the polymer was influenced. Average values of the end-to-end distance and the radius of gyration were found to increase when the shear force increases.

Visible-light-induced generation of dithianyl and dioxolanyl radicals via selective hydrogen atom transfer (HAT) has been achieved. This radical relay tactic enables remote C(sp(3))—H functionalization to permit rapid access to polyol and spiroketal segments, and in turn has been exploited as a key synthetic construct in the total synthesis of the danshenspiroketallactones. The conformational stability of the danshenspiroketallactones has also been defined via experiments and DFT calculations.

Phylogenetic and metabolomic approaches have long been employed to study evolutionary relationships among plants. Nonetheless, few studies have examined the difference in metabolites within a clade and between clades of the phylogenetic tree. We attempted to relate phylogenetic studies to metabolomics using stepwise partial least squares-discriminant analysis (PLS-DA) for the genus Panax. Samples were analyzed by ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QTOFMS) to obtain metabolite profiles. Initially, conventional principal component analysis was subsequently applied to the metabolomic data to show the limitations in relating the expression of metabolites to divisions in the phylogenetic tree. Thereafter, we introduced stepwise PLS-DA with optimized scaling methods, which were properly applied according to the branches of the phylogenetic tree of the four species. Our approach highlighted metabolites of interest by elucidating the directions and degrees of metabolic alterations in each clade of the phylogenetic tree. The results revealed the relationship between metabolic changes in the genus Panax and its species' evolutionary adaptations to different climates. We believe our method will be useful to help understand the metabolite-evolution relationship.

SummaryK-Ras and H-Ras share identical effectors and have similar properties; however, the high degree of tumor-type specificity associated with K-Ras and H-Ras mutations suggests that they have unique roles in oncogenesis. Here, we report that oncogenic K-Ras, but not H-Ras, suppresses non-canonical Wnt/Ca2+ signaling, an effect that contributes strongly to its tumorigenic properties. K-Ras does this by binding to calmodulin and so reducing CaMKii activity and expression of Fzd8. Restoring Fzd8 in K-Ras mutant pancreatic cells suppresses malignancy, whereas depletion of Fzd8 in H-RasV12-transformed cells enhances their tumor initiating capacity. Interrupting K-Ras-calmodulin binding using genetic means or by treatment with an orally active protein kinase C (PKC)-activator, prostratin, represses tumorigenesis in K-Ras mutant pancreatic cancer cells. These findings provide an alternative way to selectively target this “undruggable” protein.

Panax vietnamensis Ha et Grushv., with its main constituents vina-ginsenoside R2 (VR2) and majonoside R2 (MR2), is used in traditional folk medicine in the hill tribes of Vietnam for anti-fatigue, anti-inflammatory, and life-saving purposes. In a preliminary study, VR2 and MR2 were shown to be metabolized to pseudoginsenoside RT4 (PRT4) and ocotillol by human gut microbiota. Therefore, we measured the anti-inflammatory effects of VR2, MR2, and their metabolites in lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages. Among these ginsenosides, only VR2 exhibited cytotoxicity against peritoneal macrophages. MR2, PRT4, and ocotillol inhibited LPS-stimulated transcription factor (NF)-κB activation, and expression of the proinflammatory cytokines tumor necrosis factor-α and interleukin (IL)-1. However, these ginsenosides did not inhibit peptidoglycan-induced NF-κB activation in the macrophages. These three ginsenosides also inhibited LPS-stimulated cyclooxygenase-2 and inducible NO synthase expression, and phosphorylation of NF-κB signal molecules IL-1 receptor-associated kinase 1 and tumor growth factor-β-activated kinase 1 in peritoneal macrophages. Treatment with either PRT4 or ocotillol inhibited the Alexa Fluor 488-conjugated LPS-mediated shift of macrophages, as observed by flow cytometry. They also potently inhibited the binding of LPS to TLR4 on peritoneal macrophages, both with and without transfected MyD88 siRNA. Among the tested ginsenosides, ocotillol exhibited the strongest inhibitory effect on inflammation in LPS-stimulated macrophages via the NF-κB signaling pathway. Based on these findings, orally administered VR2 and MR2 of P. vietnamensis may be metabolized to ocotillol via PRT4, and the metabolites, particularly ocotillol, may inhibit inflammation by inhibiting the binding of LPS to TLR4 on macrophages.

Epitaxial ferroelectric Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films were fabricated on silicon substrates using pulsed laser deposition. Depending on the buffer layers and perovskite oxide electrodes, epitaxial films with different orientations were grown. (110)-oriented PZT/SrRuO 3 (and PZT/LaNiO 3 ) films were obtained on YSZ-buffered Si substrates, while (001)-oriented PZT/SrRuO 3 (and PZT/LaNiO 3 ) were fabricated with an extra CeO 2 buffer layer (CeO 2 /YSZ/Si). There is no effect of the electrode material on the properties of the films. The initial remnant polarizations in the (001)-oriented films are higher than those of (110)-oriented films, but it increases to the value of the (001) films upon cycling. The longitudinal piezoelectric d 33 ,f coefficients of the (110) films are larger than those of the (001) films, whereas the transverse piezoelectric d 31 ,f coefficients in the (110)-films are less than those in the (001)-oriented films. The difference is ascribed to the lower density (connectivity between grains) of the former films.

In a preliminary experiment, majonoside R2 (MR2), isolated from Vietnamese ginseng (Panax vietnamensis Ha et Grushv.), inhibited differentiation to Th17 cells and was metabolized to ocotillol via pseudoginsenoside RT4 (PRT4) by gut microbiota. Therefore, we examined the inhibitory effects of MR2 and its metabolites PRT4 and ocotillol against Th17 cell differentiation. These ginsenosides significantly suppressed interleukin (IL)-6/tumor growth factor beta-induced differentiation of splenic CD4(+) T cells into Th17 cells and expression of IL-17 in vitro. Among these ginsenosides, ocotillol showed the highest inhibitory effect. We also examined the anti-inflammatory effect of ocotillol in mice with 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Oral administration of ocotillol significantly suppressed TNBS-induced colon shortening, macroscopic score, myeloperoxidase activity, and production of nitric oxide and prostaglandin E2. Ocotillol treatment increased TNBS-suppressed expression of tight junction proteins ZO-1, occludin, and claudin-1 in the colon. Treatment with ocotillol inhibited TNBS-induced expression of tumor necrosis factor (TNF)-α and IL-1β, as well as activation of NF-κB and MAPKs. Moreover, treatment with ocotillol inhibited TNBS- induced differentiation to Th17 cells in the lamina propria of colon, as well as expression of T-bet, RORγt, IL-17, and IL-23. Ocotillol treatment also increased Treg cell differentiation and Foxp3 and IL-10 expression. These findings suggest that orally administered MR2 may be metabolized to ocotillol in the intestine by gut microbiota and the transformed ocotillol may ameliorate inflammatory diseases such as colitis by restoring the balance of Th17/Treg cells.

Background: Steaming of ginseng is known to change its chemical composition and biological activity. This study was carried out to investigate the effect of different steaming time-scales on chemical constituents and antiproliferative activity of Vietnamese ginseng (VG). Methods: VG was steamed at 105°C for 2–20 h. Its saponin constituents and antiproliferative activity were studied. The similarity of chemical compositions between steamed samples at 105°C and 120°C were compared. Results: Most protopanaxadiol and protopanaxatriol ginsenosides lost the sugar moiety at the C-20 position with 10–14 h steaming at 105°C and changed to their less polar analogues. However, ocotillol (OCT) ginsenosides were reasonably stable to steaming process. Antiproliferative activity against A549 lung cancer cells was increased on steaming and reached its plateau after 12 h steaming. Conclusion: Steaming VG at 105°C showed a similar tendency of chemical degradation to the steaming VG at 120°C except the slower rate of reaction. Its rate was about one-third of the steaming at 120°C.

Due to its physical properties gallium-nitride (GaN) is gaining a lot of attention as an emerging semiconductor material in the field of high-power and high-frequency electronics applications. Therefore, the improvement in the performance and/or perhaps even extension in functionality of GaN based devices would be highly desirable. The integration of ferroelectric materials such as lead-zirconate-titanate (PbZrxTi1-xO3) with GaN has a strong potential to offer such an improvement. However, the large lattice mismatch between PZT and GaN makes the epitaxial growth of Pb(Zr1-xTix)O-3 on GaN a formidable challenge. This work discusses a novel strain relaxation mechanism observed when MgO is used as a buffer layer, with thicknesses down to a single unit cell, inducing epitaxial growth of high crystallinity Pb(Zr0.52Ti0.48)O-3 (PZT) thin films. The epitaxial PZT films exhibit good ferroelectric properties, showing great promise for future GaN device applications.

Chemical and pharmacological studies of Panax vietnamensis (Vietnamese ginseng; VG) have been reported since its discovery in 1973. However, the content of each saponin in different parts of VG has not been reported. In this study, 17 ginsenosides in the different underground parts of P. vietnamensis were analyzed by HPLC/evaporative light scattering detector (ELSD). Their contents in the dried rhizome, radix, and fine roots were 195, 156, and 139 mg/g, respectively, which were extremely high compared to other Panax species. The content of protopanaxatriol (PPT)-type saponins were not much different among underground parts; however, the content of protopanaxadiol (PPD)- and ocotillol (OCT)-type saponins were greatly different. It is noteworthy that the ginsenoside pattern in the fine roots is different from other underground parts. In particular, despite the content of PPD-type saponins being the highest in the fine roots, which is similar to other Panax species, the total content of saponins was the lowest in the fine roots, which is different from other Panax species. The ratios of PPT : PPD : OCT-type saponins were 1 : 1.7 : 7.8, 1 : 1.6 : 5.5, and 1 : 4.8 : 3.3 for the rhizome, radix, and fine roots, respectively. OCT-type saponins accounted for 36-75% of total saponins and contributed mostly to the difference in the total saponin content of each part.

Two novel cadinane-type sesquiterpenoids, named as malacinones A (1) and B (2), with an unprecedented tricyclic 6/6/5 ring system have been isolated from the agarwood of Aquilaria malaccensis. Their structures were elucidated by the various spectroscopic data (IR, MS, 1D, and 2D NMR) analysis and the absolute configurations were determined by the electronic circular dichroism (ECD) spectroscopic data analysis. A plausible biosynthetic pathway of malacinones A and B was proposed.

Earlier theoretical reports predicted that the usage of a piezoelectric stressor layer around the FinFET, i.e., the PiezoFET, offers a great potential for steep subthreshold slope devices. For the first time, we analyzed the practical realization of such PiezoFETs comprising a piezoelectric stressor layer, lead–zirconate–titanate (PZT), and aluminum–nitride (AlN) deposited on n-type silicon FinFETs. A high-piezoelectric response in the range of 100 pm/V has been obtained for the PZT PiezoFET evidencing the converse piezoelectric effect in the device. The piezoelectric response for the AlN device was much less (13 pm/V) as expected. Underlying device properties, such as subthreshold swing (SS) and low-field electron mobility have been significantly affected by the presence of the PZT stressor. A 20%–50% change in the mobility and a change in the SS (about 5 mV/decade) have been observed. The change can be attributed to the strain induced reduction of the interface trap density at the ${\rm Si}/{\rm SiO}_{2}$ interface. This strain is partly formed by the bias over the piezoelectric layer, which indicates the converse piezoelectric effect related tunable strain in both the silicon channel and gate oxide.

Graphical abstractDisplay Omitted Thin film PZT/LNO stacks on an encapsulated TiN electrode are studied.Promising ferroelectric behavior of these thin film layers is reported.A passive layer adjacent to the electrode is recognized and characterized.The leakage current was described by a diffusion-based model. We realized metal-ferroelectric-metal (MFM) capacitors comprising high-quality ferroelectric lead zirconate titanate (Pb(Zr0.52Ti0.48)O3 or PZT) thin films on an LaNiO3/poly-Si/titanium nitride (TiN)/SiO2 integrated on a 100mm Si wafer. Promising effective piezoelectric coefficient and remnant polarization of 53pm/V and 19.2µC/cm2, respectively, are obtained for the 100nm-PZT/20nm-LNO stack. Further analysis of the samples indicates the presence of a passive layer, possibly near the Ti/PZT interface at the top electrode. A leakage current model has been used to explain the obtained current density-electric field curves. In this model, diffusion limited transport has been assumed in which the injection is interface-controlled. Based on the capacitance and the leakage current measurements, the thickness and dielectric constant values of the passive layer are estimated to be 2.1nm and 23, respectively. The observed apparent low barrier height value of 0.32eV is attributed to ferroelectric polarization related phenomena. A good agreement between measurement and leakage current model is obtained.

Background: This study was carried out to investigate the effect of the steaming process on chemical constituents, free radical scavenging activity, and antiproliferative effect of Vietnamese ginseng. Methods: Samples of powdered Vietnamese ginseng were steamed at 120°C for various times and their extracts were subjected to chemical and biological studies. Results: Upon steaming, contents of polar ginsenosides, such as Rb1, Rc, Rd, Re, and Rg1, were rapidly decreased, whereas less polar ginsenosides such as Rg3, Rg5, Rk1, Rk3, and Rh4 were increased as reported previously. However, ocotillol type saponins, which have no glycosyl moiety at the C-20 position, were relatively stable on steaming. The radical scavenging activity was increased continuously up to 20 h of steaming. Similarly, the antiproliferative activity against A549 lung cancer cells was also increased. Conclusion: It seems that the antiproliferative activity is closely related to the contents of ginsenoside Rg3, Rg5, and Rk1.

We have investigated the growth characteristics and optical constants of thin AlN films made by thermal atomic layer deposition (ALD) from trimethylaluminum (TMA) and ammonia (NH3). We observed the nucleation, closure and growth after closure of the films using atomic force microscopy and in-situ spectroscopic ellipsometry. A fully covered surface was obtained for films with a thickness of about 2 nm. The self-limiting ALD growth was observed at temperatures of 330 and 350◦C with deposition rates of 1.5 and 2.1 Å/cycle, respectively. At 370◦C, thermal decomposition of TMA dominated the growth mechanism, resulting in a fast and non-self-limiting deposition. Low concentrations of oxygen (0.8−2.5%) and carbon (5−7.5%) incorporated into the films were measured. We found that the refractive index increased remarkably with increasing film thickness and growth temperature.

Phyllanthusurinariaplant was used in liver relating diseases in Vietnam. The study was to know more about the bioactivities of Phyllanthusurinarialeaf extracts before and after combined with Pandanustectoriousfruit extracts and Lactobacillus rhamnosusextract. This was accomplished by examining the influence of the total aqueous, chloroform and ethylacetateextracts. The biological tests were done onCandida albicans,Salmonella typhi, Pseudomonas aeruginosaand Staphylococcus aureus.Agar diffusion test was applied to determine the antimicrobial activities.Based on the inhibition zone diameter, the result showed that Phyllanthusurinariaaqueousextraction had the inhibition on the Pseudomonas aeruginosa(21.75 ± 0.96 mm)and Staphylococcus aureus(24.75 ± 0.96 mm). The activities decreased after combined with Pandanustectoriousfruit extractson Pseudomonas aeruginosa(14.75 ± 0.50 mm) and Staphylococcus aureus(14.75 ± 0.50 mm)and Lactobacillus rhamnosus(14.75 ± 0.50 mm).The total aqueous extracts fractionated with chloroform and ethylacetate still showed activities that suggested the polar and nonpolar antimicrobial compounds existed in Phyllanthusurinaria. However, the activities of these fractionated extracts in the combination showed the weaker activities than in the using only Phyllanthusurinariaextracts. Especially, there was no activity of the ethylacetate extracts in the combination with Lactobacillus rhamnosus. The study is the first report of the combination of Phyllanthusurinaria with Pandanustectorious and Lactobacillus rhamnosus PN04. Key word: Phyllanthusurinaria, Pandanustectorius, Lactobacillus rhamnosus, Antimicrobial activity.

Very good crystallinity and highly c-axis-oriented aluminum nitride (AlN) thin films are sputtered on titanium (Ti) to fabricate thin piezoelectric cantilevers. Raman spectroscopy measurements and X-ray diffraction (XRD) indicate the high quality of these AlN films. A fabrication process, fully CMOS compatible, is developed to realize slender piezoelectric microcantilevers. Actuation enhancement for the AlN piezoelectric cantilevers is achieved by coating the slender beams with a thin PECVD silicon nitride (SiN) layer. Very good linearity and high displacement, up to 19.5 nm for 200 μm long cantilevers and 4.25 nm for 100 μm long cantilevers for 1 V actuation at quasi-static mode, are obtained with a 500 nm SiN top layer. These displacement values are three times larger than our previously reported values for cantilevers without SiN layer coating. This makes these cantilevers, without the need of employing nonstandard metals such as platinum (Pt), very promising for micro/nanoactuators.

Ca2Nb3O10 (CNOns) and Ti0.87O2 (TiOns) metal oxide nanosheets (ns) are used as a buffer layer for epitaxial growth of piezoelectric capacitor stacks on Si and Pt/Ti/SiO2/Si (Pt/Si) substrates. Highly (001)- and (110)-oriented Pb(Zr0.52Ti0.48)O3 (PZT) films are achieved by utilizing CNOns and TiOns, respectively. The piezoelectric capacitors are characterized by polarization and piezoelectric hysteresis loops and by fatigue measurements. The devices fabricated with SrRuO3 top and bottom electrodes directly on nanosheets/Si have ferroelectric and piezoelectric properties well comparable with devices that use more conventional oxide buffer layers (stacks) such as YSZ, CeO2/YSZ, or SrTiO3 on Si. The devices grown on nanosheets/Pt/Si with Pt top electrodes show significantly improved polarization fatigue properties over those of similar devices grown directly on Pt/Si. The differences in properties are ascribed to differences in the crystalline structures and the density of the films. These results show a route toward the fabrication of single crystal piezoelectric thin films and devices with high quality, long-lifetime piezoelectric capacitor structures on nonperovskite and even noncrystalline substrates such as glass or polished metal surfaces.

We investigated the residual stress and Young's modulus of Pb(ZrxTi1 - x)O3 (PZT) thin films with a (110) preferred orientation and a composition x ranging from 0.2 to 0.8. The films are grown by pulsed laser deposition on silicon cantilevers aligned along the and silicon crystal directions. Changes in resonance frequency and static bending of the cantilevers are used to determine the Young's modulus and residual stress respectively. The Young's modulus was found to be in the range of 100-200 GPa. The residual stress is tensile and shows a sharp increase from about 50 to 250 MPa at a composition of x = 0.2 to 0.4. These mechanical parameters clearly depend on the cantilever orientation with respect to the silicon crystal, which we suspect to be linked to the epitaxial growth of the films. The variation in stress with composition can be explained by the difference in thermal expansion between silicon and PZT, if we assume an intrinsic stress of 200-300 MPa to be already present immediately after deposition. Strain calculated from X-ray diffraction data leads to unreasonably high residual stress values, at least one order of magnitude higher than measured by cantilever bending. © 2016 Elsevier B.V. All rights reserved.

Dissipative particle dynamics (DPD) simulations were utilized to investigate the ability of sodium dodecyl sulfate (SDS) to adsorb inside a single-walled, arm-chair carbon nanotube (SWCNT), as well as the effect of surfactant on the properties of water inside the SWCNT. The diameter of the SWCNT varied from 1 to 5 nm. The radial and axial density profiles of water inside the SWCNTs were computed and compared with published molecular dynamics results. The average residence time and diffusivity were also calculated to show the size effect on mobility of water inside the SWCNT. It was found that nanotubes with diameter smaller than 3 nm do not allow SDS molecules to enter the SWCNT space. For larger SWCNT diameter, SDS adsorbed inside and outside the nanotube. When SDS was adsorbed in the hollow part of the SWCNT, the behavior of water inside the nanotube was found to be significantly changed. Both radial and axial density profiles of water inside the SWCNT fluctuated strongly and were different from those in bulk phase. In addition, SDS molecules increased the retention of water beads inside SWCNT (d ≥ 3nm) while water diffusivity was decreased.

This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO3/Pb(Zr,Ti)3/SrRuO3, were grown epitaxially on the Si template of silicon-on-insulator substrates by pulsed laser deposition. By using an analytical model and finite element simulation, the initial bending of the cantilevers was calculated. These theoretical analyses are in good agreement with the experimental results which were determined using a white light interferometer. The dependences of the cantilever displacement, resonance frequency and quality factor on the cantilever geometry have been investigated using a laser-Doppler vibrometer. The tip displacement ranged from 0.03 to 0.42 µm V−1, whereas the resonance frequency and quality factor values changed from 1010 to 18.6 kHz and 614 to 174, respectively, for the cantilevers with lengths in the range of 100–800 µm. Furthermore, the effect of the conductive oxide electrodes on the stability of the piezoelectric displacement of the cantilevers has been studied.

Protein kinase B/Akt is a key signaling molecule that regulates cell survival, growth, and metabolism, and inhibits apoptosis. Traumatic brain injury (TBI) activates Akt, and Akt has been implicated in neuronal survival after TBI, but little is known about injury-induced Akt activation in astrocytes, cells that exhibit hypertrophic and hyperplastic responses to CNS injury. Here we have investigated the effect of mechanical strain on Akt activation in primary cultures of rat cortical astrocytes growing on deformable Silastic membranes. When astrocytes were subjected to mechanical strain (50 msec; 5-7.5 mm displacement), we observed an increase in phosphorylation of serine 473, a key indicator of Akt activation. Akt phosphorylation was increased at 3 min postinjury, was maximal from 5 to 10 min, and declined gradually thereafter. Akt activation was also dependent on the severity of the injury. Stretch-induced Akt phosphorylation was attenuated by blocking calcium influx and phosphoinositide 3-kinase (PI3K), an upstream activator of Akt. In addition, we found that ATP is rapidly released after mechanical strain and that the P2 purinergic receptor antagonist iso-pyridoxal-5'-phosphate-6-azophenyl-2',5'disulfonate (PPADS) attenuated trauma-induced Akt activation. We conclude that mechanical strain causes activation of Akt in astrocytes via stimulation of P2 receptors. This suggests that P2 receptor/Akt signaling promotes astrocyte survival and growth, and this process may play a role in the generation of reactive gliosis after TBI.

In this study, we investigated physical and electronic properties of possible two-dimensional structures formed by Si (silicon) and Ir (iridium). To this end, different plausible structures were modeled by using density functional theory and the cohesive energies calculated for the geometry of optimized structures, with the lowest equilibrium lattice constants. Among several candidate structures, we identified three mechanically (via elastic constants and Young's modulus), dynamically (via phonon calculations), and thermodynamically stable iridium silicide monolayer structures. The lowest energy structure has a chemical formula of Ir2Si4 (called r-IrSi2), with a rectangular lattice (Pmmn space group). Its cohesive energy was calculated to be −0.248 eV (per IrSi2 unit) with respect to bulk Ir and bulk Si. The band structure indicates that the Ir2Si4 monolayer exhibits metallic properties. Other stable structures have hexagonal (P-3m1) and tetragonal (P4/nmm) cell structures with 0.12 and 0.20 eV/f.u. highe...

The authors have studied and compared the initial growth and properties of AlN films deposited on Si(111) by thermal and plasma-enhanced atomic layer deposition (ALD) using trimethylaluminum and either ammonia or a N2-H2 mixture as precursors. In-situ spectroscopic ellipsometry was employed to monitor the growth and measure the refractive index of the films during the deposition. The authors found that an incubation stage only occurred for thermal ALD. The linear growth for plasma-enhanced ALD (PEALD) started instantly from the beginning due to the higher nuclei density provided by the presence of plasma. The authors observed the evolution of the refractive index of AlN during the growth, which showed a rapid increase up to a thickness of about 30 nm followed by a saturation. Below this thickness, higher refractive index values were obtained for AlN films grown by PEALD, whereas above that the refractive index was slightly higher for thermal ALD films. X-ray diffraction characterization showed a wurtzite crystalline structure with a (1010) preferential orientation obtained for all the layers with a slightly better crystallinity for films grown by PEALD.

Lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (undoped PZT) and doped PZT thin films with thickness of about 500 nm were grown on Pt/Ti/SiO2/Si substrates by pulsed laser deposition (PLD). In this study, 1.0 mol% Nb-doping (at Zr/Ti site) as donor, 1.0 mol% Fe-doping (at Zr/Ti) as acceptor and 10 mol% Ba-doping (at Pb site) as isovalence were used. The effects of the introduction of these dopants on the ferroelectric and piezoelectric properties were investigated and compared to the undoped PZT film. A noticeable improvement of the dielectric constant (e) and effective piezoelectric coefficient (d33,f) are obtained. The maximum values of these parameters vary from 1280 and 126 pm/V for undoped PZT film to 1520 and 164 pm/V for Nb-doped PZT film. The largest remnant polarization (Pr) and coercive field (Ec) are obtained for Fe-doped PZT film, equal to 22.6 µC/cm2 and 35.3 kV/cm, as compared to 17.3 µC/cm2 and 31.2 kV/cm respectively for undoped PZT film. The Ba-doping decreases the dielectric constant but enhances the breakdown field of the film, reaching 800 kV/cm while it was only 660 kV/cm for undoped PZT film. The crystalline structure of Ba-doped film has a dominating (110) orientation instead of (100) in case of undoped, Nb-, and Fe-doped PZT films. The obtained results are important for the applications of doped PZT films in piezoMEMS devices.

A length extensional mode lead zirconate titanate (PZT)-on-Si resonator is presented using 50 Ω termination with high-stopband rejection exploiting feed-through cancellation. A 250-nm-thick (100)-dominant oriented PZT thin-film deposited on top of 3 μm Si using pulsed laser deposition has been used. The resonator is presented with the length of 40 μm (half-wavelength), which corresponds to a resonance frequency of about 83 MHz. The effect of feed-through cancellation has been studied to obtain high-stopband rejection using bottom electrode patterning in the presence of a specific grounding resistance. Using this technique, the stopband rejection can be improved by more than 20 dB.

This research presents an optimization of piezoelectric membrane actuators by maximizing the actuator displacement. Membrane actuators based on epitaxial Pb(Zr,Ti)O3 thin films grown on all-oxide electrodes and buffer layers using silicon technology were fabricated. Electrode coverage was found to be an important factor in the actuation displacement of the piezoelectric membranes. The optimum electrode coverage for maximum displacement was theoretically determined to be 39%, which is in good agreement with the experimental results. Dependences of membrane displacement and optimum electrode coverage on membrane diameter and PZT-film/Si-device-layer thickness ratio have also been investigated.

Pb 0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) relaxor-ferroelectric thin films were grown on SrRuO3/SrTiO3/Si substrates by pulsed laser deposition. A large recoverable storage density (U reco) of 13.7 J/cm3 together with a high energy efficiency (η) of 88.2% under an applied electric field of 1000 kV/cm and at 1 kHz frequency was obtained in 300-nm-thick epitaxial PLZT thin films. These high values are due to the slim and asymmetric hysteresis loop when compared to the values in the reference undoped epitaxial lead zirconate titanate Pb(Zr0.52Ti0.48)O3 ferroelectric thin films (U reco = 9.2 J/cm3 and η = 56.4%) which have a high remanent polarization and a small shift in the hysteresis loop, under the same electric field.

The effects of shear and particle shape on the physical adsorption of a polymer (polyvinyl pyrrolidone, PVP) on carbon nanoparticles (CNPs) were studied with dissipative particle dynamics (DPD) methods. It was found that the conformation of the polymer during adsorption and desorption from the nanoparticle can be classified into three possible types, i.e. adsorbed, shear-affected and separated, depending on the magnitude of the shear rate in the flow. Spherical and graphene sheet-shaped particles with adsorbed PVP were manipulated in a Couette flow to determine the threshold shear rates leading to changes in the polymer adsorption state. It was found that the polymer was stably adsorbed under higher shear conditions for graphene sheets. In addition, the end-to-end distance and the radius of gyration of the polymer adsorbate was clearly related to the adsorption state, as the polymer underwent a transition from adsorbed to the separated state when the shear rate increased. The critical shear rate at which the polymer desorbed from the surface could be useful in applications where nanoparticles can be used as a molecular delivery system. The physical adsorption and desorption of the same polymer molecules on a flat surface were also investigated. The desorption of the polymer from the flat surface occurred when the shearing force was stronger than the attraction between the PVP and the surface.

The Young’s modulus of thin films can be determined by deposition on a micronsized Si cantilever and measuring the resonance frequency before and after deposition. The accuracy of the method depends strongly on the initial determination of the mechanical properties and dimensions of the cantilever. We discuss the orientation of the cantilever with respect to the Si crystal, and the inevitable undercut of the cantilever caused by process inaccuracies. By finite element modelling we show that the Young’s modulus should be used instead of the analytical plate modulus approximation for the effective Young’s modulus of Si cantilevers used in this work for both the 1 0 0 and 1 1 0 crystal orientation. Cantilever undercut can be corrected by variation of the cantilever length. As an example, the Young’s modulus of PbZr0.52Ti0.48O3 (PZT) thin films deposited by pulsed laser deposition (PLD) was determined to be 99 GPa, with 1.4 GPa standard error.

We determined the Young’s modulus of pulsed laser deposited epitaxially grown PbZr0.52Ti0.48O3 (PZT) thin films on microcantilevers by measuring the difference in cantilever resonance frequency before and after deposition. By carefully optimizing the accuracy of this technique, we were able to show that the Young’s modulus of PZT thin films deposited on silicon is dependent on the in-plane orientation, by using cantilevers oriented along the 1 1 0 and 1 0 0 silicon directions. Deposition of thin films on cantilevers affects their flexural rigidity and increases their mass, which results in a change in the resonance frequency. An analytical relation was developed to determine the effective Young’s modulus of the PZT thin films from the shift in the resonance frequency of the cantilevers, measured both before and after the deposition. In addition, the appropriate effective Young’s modulus valid for our cantilevers’ dimensions was used in the calculations that were determined by a combined analytical and finite-element (FE) simulations approach. We took extra care to eliminate the errors in the determination of the effective Young’s modulus of the PZT thin film, by accurately determining the dimensions of the cantilevers and by measuring many cantilevers of different lengths. Over-etching during the release of cantilevers from the handle wafer caused an undercut. Since this undercut cannot be avoided, the effective length was determined and used in the calculations. The Young’s modulus of PZT, deposited by pulsed laser deposition, was determined to be 103.0 GPa with a standard error of ± 1.4 GPa for the 1 1 0 crystal direction of silicon. For the 1 0 0 silicon direction, we measured 95.2 GPa with a standard error of ± 2.0 GPa.

In this thesis, the integration of lead zirconate titanate Pb(Zr,Ti)O3 (PZT) thin films into piezoelectric microelectromechanical systems (MEMS) based on silicon is studied. In these structures, all epitaxial oxide layers (thin film/electrode/buffer-layer(s)) were deposited by pulsed laser deposition (PLD). First, the orientation control of PZT thin films on silicon has been studied. We found that by using a seedlayer (~4 A) of Ru-deficient SrnRun-1O3n-2 between SRO bottom-electrode and CeO2/YSZ buffered (001)Si substrates, the orientation of PZT thin films can be switched from (110) to (001). When the conductive-oxide SRO electrodes were substituted for Pt, the accumulation of oxygen vacancies near the interface was prevented, and therefore the fatigue-free behavior was observed in the PZT/SRO capacitors up to 108 switching cycles. The effects film thickness on the microstructure and electrical properties of PZT(52/48) films have been also investigated in this chapter. In the film thickness range investigated, the microstructure and crystalline structure almost do not change with thickness. The thickness dependence of the remnant polarization and the dielectric constant is interpreted in terms of the interfacial layer at the film/electrode interface. The increased remnant polarization and dielectric constant is due to the reduction of interfacial effect in PZT films with an increase in film thickness. Moreover, the reduction of interfacial effect also leads to the decrease in coercive field. The integration of ferroelectric PZT thin films onto Si cantilever beams was investigated. The main focus of this chapter is on the development of piezo-cantilevers for optimization of the fabrication process as well as for understanding of the potential applications. As the results, using the PLD technique and MEMS micro-fabrication processes, piezoelectric PZT cantilever arrays with beam lengths ranging from 100 to 800 μm with widths ranging from 50 to 150 μm were designed and fabricated.

Supported bilayer has many advantages over conventional black lipid bilayer. A supported bilayer is highly stable and can be made with a large surface area. Membrane proteins can be incorporated in very large numbers without disruption of the bilayer, thereby allowing robust macroscopic recordings. A very important advantage is that incorporated proteins are immobile. This lack of mobility is essential for the study of conformational changes with single molecule fluorescence. We are interested in studying gating charge movement and conformational changes in voltage dependent membrane proteins such as a voltage dependent K+ channel. For this purpose, we have developed an essentially electrostatic voltage clamp system for a supported bilayer that allows measurement of intramembrane transient currents but not DC currents. The supported bilayer is formed by liposome fusion on top of a semiconductor substrate that serves as the reference electrode. Electrolyte solution is present above the bilayer where an Ag/AgCl electrode serves as the active electrode. The electrode pair is connected to conventional voltage clamp electronics that imposes the voltage and measures the current. We verified supported bilayer formation by the decrease of the total capacitance. Furthermore, we have verified that a voltage is imposed across the bilayer by using voltage dependent fluorescent membrane probes. The electrolyte/supported bilayer/electrode system is essentially linear across a voltage range of −300 to +300 mV. We have seen that direct incorporation of the voltage dependent protein KvAP into the supported bilayer modifies the kinetics of the transient currents as well as the voltage dependence of charge movement. This method opens the possibility for studies of simultaneous gating charge movement electrically and voltage dependent conformational change spectroscopically in purified membrane proteins. Support: NIH GM030376.

Crystalline Pb(Zr,Ti)O3 (PZT) thin films between metallic-oxide SrRuO3 (SRO) electrodes were prepared using pulsed laser deposition on CeO2/yttria-stabilized zirconia buffered silicon (001) substrates. Different deposition conditions for the initial layers of the bottom SRO electrode result in an orientation switch. Either (110)- or (001)-oriented SRO thin films are obtained and the PZT films deposited on the bottom electrode continued both growth directions. The ferroelectric characteristics of the SRO/PZT/SRO capacitors are found to be strongly dependent on their crystalline orientation: PZT (001)-oriented thin films showed stable, high quality ferroelectric response, while the remnant polarization of the PZT (110)-oriented thin films only show high response after multiple switching cycles.

This paper presents the novel synthesis design of a three-degree of freedom silicon piezoresistive accelerometer. The purpose of this novel synthesis design is to achieve the high performance device. The design synthesis has been performed based on considerations of mechanical and electronics sensitivities, noise and thermal effects, respectively. The mechanical sensitivity is optimized due to combination of a FEM software and a MNA one. The electronics sensitivity, noise and thermal effect can be determined by thermal, mechanical and piezoresistive coupled-field simulations. The dimension of sensor is as small as 1.5 mm2, so it is suitable for many immerging applications.

Growing evidence indicates that trophic actions of extracellular nucleotides are involved in CNS development, injury and repair. For example, upon CNS injury, ATP is released and contributes to the formation of reactive astrocytes, cells that produce molecules that can impede or promote axonal regeneration. Proliferation is one of the features of reactive astrogliosis, particularly in traumatic injury. Fibroblast growth factor (FGF)2 is also increased after injury and can stimulate astrocyte proliferation. Extracellular ATP enhances FGF2-induced proliferation in a process mediated by P2Y receptors and increased cyclin expression. However, when P2X receptors are activated, FGF2-induced proliferation is inhibited. P2 receptors are coupled to extracellular signal regulated protein kinase (ERK), and differences in the extent and duration of ERK activation by P2Y and P2X receptors may mediate the opposing effects of these receptors on FGF2-induced mitogenesis. Trauma also activates P2 receptor/ERK signalling, and stimulation of this and other protein kinase pathways by extracellular ATP increases expression of cell adhesion and extracellular matrix molecules involved in migration, glial contact formation, neuronal guidance and synapse formation. These findings support the hypothesis that purinergic signalling via protein kinase cascades plays a key role in astrocyte proliferation, glia-glia connections, and neuron-glia interactions in both normal and pathological conditions.

Piezoelectrical, ferroelectrical, and structural properties of epitaxial pseudocubic (110)pc oriented 500 nm thick PbZr1−xTixO3 thin films, prepared by pulsed laser deposition on (001) silicon substrates, were measured as a function of composition. The dependence of the measurement data on the Ti content is explained by an abrupt transition from the rhombohedral r-phase to the tetragonal (c/a) 45 phase for x ≈ 0.6, indicating a shift of the Morphotropic Phase Boundary to this value, where the effective piezoelectric coefficient e3 1 ,eff and dielectric constant e33 ,eff reach their maximum values. These findings are of great significance for Si-based piezo-micro electro mechanical systems, in particular energy harvesters. The largest value of the figure-of-merit for such devices was found for x = 0.6, FOM=24.0 GPa