SSPH I, A Novel Anti-cancer Saponin, Inhibits EMT and Invasion and Migration of NSCLC by Suppressing MAPK/ERK1/2 and PI3K/AKT/mTOR Signaling Pathways.

BACKGROUND: Saponin of Schizocapsa plantaginea Hance I (SSPH I)，a bioactive saponin found in Schizocapsa plantaginea, exhibits significant anti-proliferation and antimetastasis in lung cancer. OBJECTIVE: To explore the anti-metastatic effects of SSPH I on non-small cell lung cancer (NSCLC) with emphasis on epithelial-mesenchymal transition (EMT) both in vitro and vivo. METHODS: The effects of SSPH I at the concentrations of 0, 0.875,1.75, and 3.5 µM on A549 and PC9 lung cancer cells were evaluated using colony formation assay, CCK-8 assay, transwell assay and wound-healing assay. The actin cytoskeleton reorganization of PC9 and A549 cells was detected using the FITC-phalloidin fluorescence staining assay. The proteins related to EMT (N-cadherin, E-cadherin and vimentin), p- PI3K, p- AKT, p- mTOR and p- ERK1/2 were detected by Western blotting. A mouse model of lung cancer metastasis was established by utilizing 95-D cells, and the mice were treated with SSPH I by gavage. RESULTS: The results suggested that SSPH I significantly inhibited the migration and invasion of NSCLC cells under a non-cytotoxic concentration. Furthermore, SSPH I at a non-toxic concentration of 0.875 µM inhibited F-actin cytoskeleton organization. Importantly, attenuation of EMT was observed in A549 cells with upregulation in the expression of epithelial cell marker E-cadherin and downregulation of the mesenchymal cell markers vimentin as well as Ncadherin. Mechanistic studies revealed that SSPH I inhibited MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways. CONCLUSION: SSPH I inhibited EMT, migration, and invasion of NSCLC cells by suppressing MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways, suggesting that the natural compound SSPH I could be used for inhibiting metastasis of NSCLC.

The OsSGS3-tasiRNA-OsARF3 module orchestrates abiotic-biotic stress response trade-off in rice.

Recurrent heat stress and pathogen invasion seriously threaten crop production, and abiotic stress often antagonizes biotic stress response against pathogens. However, the molecular mechanisms of trade-offs between thermotolerance and defense remain obscure. Here, we identify a rice thermo-sensitive mutant that displays a defect in floret development under high temperature with a mutation in SUPPRESSOR OF GENE SILENCING 3a (OsSGS3a). OsSGS3a interacts with its homolog OsSGS3b and modulates the biogenesis of trans-acting small interfering RNA (tasiRNA) targeting AUXIN RESPONSE FACTORS (ARFs). We find that OsSGS3a/b positively, while OsARF3a/b and OsARF3la/lb negatively modulate thermotolerance. Moreover, OsSGS3a negatively, while OsARF3a/b and OsARF3la/lb positively regulate disease resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) and the fungal pathogen Magnaporthe oryzae (M. oryzae). Taken together, our study uncovers a previously unknown trade-off mechanism that regulates distinct immunity and thermotolerance through the OsSGS3-tasiRNA-OsARF3 module, highlighting the regulation of abiotic-biotic stress response trade-off in plants.

Pitfalls of Using Imaging Technique in the Presence of Eustachian Valve or Chiari Network: Effects on Right-to-Left Shunt and Related Influencing Factors.

When patent foramen ovale (PFO) combines with the prominent Eustachian valve or Chiari network (EV/CN), contrast transthoracic echocardiography (cTTE) may miss the diagnosis of PFO. We sought to determine the characteristics of right-to-left shunt (RLS) in PFO patients with prominent EV/CN on cTTE and identify the causal factors of missed diagnosis. We consecutively enrolled 98 patients who suffered from PFO-related stroke and with prominent EV/CN. All patients were divided into the delayed and non-delayed groups according to the characteristics of RLS on cTTE. The characteristics of RLS were compared with those of 42 intrapulmonary shunt patients. The anatomical characteristics of PFO and EV/CN were analyzed in the 98 PFO patients. Upon cTTE, significantly delayed occurrence and longer duration of the RLS in the delayed group were found both at rest and during the Valsalva maneuver, similar to the intrapulmonary shunt. Multivariate logistic analysis revealed that the length of EV/CN (>19 mm) and the diameter of PFO at the left atrium aspect (<1.2 mm) were high-risk factors for missed diagnosis. In conclusion, RLS showed delayed emergence and disappearance in some of the PFO patients with prominent EV/CN. The length of EV/CN and the diameter of PFO may have been related to the missed diagnosis of PFO.

A Room-Temperature Ferroelectric Resonant Tunneling Diode.

Resonant tunneling is a quantum-mechanical effect in which electron transport is controlled by the discrete energy levels within a quantum-well (QW) structure. A ferroelectric resonant tunneling diode (RTD) exploits the switchable electric polarization state of the QW barrier to tune the device resistance. Here, the discovery of robust room-temperature ferroelectric-modulated resonant tunneling and negative differential resistance (NDR) behaviors in all-perovskite-oxide BaTiO3 /SrRuO3 /BaTiO3 QW structures is reported. The resonant current amplitude and voltage are tunable by the switchable polarization of the BaTiO3 ferroelectric with the NDR ratio modulated by ≈3 orders of magnitude and an OFF/ON resistance ratio exceeding a factor of 2 × 104 . The observed NDR effect is explained an energy bandgap between Ru-t2g and Ru-eg orbitals driven by electron-electron correlations, as follows from density functional theory calculations. This study paves the way for ferroelectric-based quantum-tunneling devices in future oxide electronics.

HDAC5 inactivates CYR61-regulated CD31/mTOR axis to prevent the occurrence of preeclampsia.

Our study was to pinpoint the significance of histone deacetylase 5 (HDAC5) affecting the pathogenesis of preeclampsia (PE) via CD31/mammalian target of rapamycin (mTOR) axis by regulating cysteine-rich angiogenic inducer 61 (CYR61). Expression of HDAC5, CYR61, and CD31/mTOR in placental tissues of patients with PE and trophoblast cells HTR-8/SVneo cells was determined first followed by their interaction analysis. Following different transfection, the significance of HDAC5 in cell functions was assayed in relation to CYR61 and CD31/mTOR. An in vivo PE mouse model was constructed for further validation. The clinical tissue and in vitro cell experimentations discovered that HDAC5 was downregulated in placental tissues of PE patients and trophoblast cells, while CYR61, CD31, mTOR, and p-mTOR displayed upregulation. After overexpression of HDAC5, trophoblast cell functions were enhanced. HDAC5 reduced the acetylation enrichment of H3K27 to inhibit the expression of CYR61. Furthermore, CYR61 promoted the activation of CD31/mTOR axis, thereby inhibiting HTR-8/SVneo cell functions. The in vivo rat model confirmed the above alterations. Taken together, HDAC5 contributes to downregulation of CYR61 through histone deacetylation, inactivating CD31/mTOR axis, which prevents the occurrence and development of PE.

Engineered Exosomes-Mediated Transfer of hsa-miR-320a Overcomes Chemoresistance in Cervical Cancer Cells via Targeting MCL1.

In cervical cancer (CC), cisplatin resistance greatly restricts the application in clinical. Here, we report that engineered exosomes-mediated transfer of hsa-miR-320a overcomes chemoresistance in cervical cancer cells via targeting Myeloid Cell Leukemia Sequence 1 (MCL1). In DDP resistant CC tissues, as well as cell lines, it was found that miR-320a expression is lower, engineered miR-320a exosomes were used to attenuate DDP resistance in Hela/DDP and Caski/DDP cells. Mechanistically, we find that MCL1, which is a target of miR-320a, overcomes DDP resistance in Hela/DDP cells and in mice. In conclusion, we report that the engineered miR-320a exosomes is proved to be effective and safe.

A Diffusive Sveir Epidemic Model with Time Delay and General Incidence.

In this paper, we consider a delayed diffusive SVEIR model with general incidence. We first establish the threshold dynamics of this model. Using a Nonstandard Finite Difference (NSFD) scheme, we then give the discretization of the continuous model. Applying Lyapunov functions, global stability of the equilibria are established. Numerical simulations are presented to validate the obtained results. The prolonged time delay can lead to the elimination of the infectiousness. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at 10.1007/s10473-021-0421-9.

Lung Ultrasound Surface Wave Elastography for Assessing Patients With Pulmonary Edema.

B-Mode ultrasound insonation of lungs that are dense with extravascular lung water (EVLW) produces characteristic reverberation artifacts termed B-lines. The number of B-lines present demonstrates reasonable correlation to the amount of EVLW. However, analysis of B-line artifacts generated by this modality is semi-quantitative relying on visual interpretation, and as a result, can be subject to inter-observer variability. The purpose of this study was to translate the use of a novel, quantitative lung ultrasound surface wave elastography technique (LUSWE) into the bedside assessment of pulmonary edema in patients admitted with acute congestive heart failure. B-mode lung ultrasound and LUSWE assessment of the lungs were performed using anterior and lateral intercostal spaces in the supine patient. 14 patients were evaluated at admission with reassessment performed 1-2 days after initiation of diuretic therapy. Each exam recorded the total lung B-lines, lung surface wave speeds (at 100, 150, and 200 Hz) and net fluid balance. The patient cohort experienced effective diuresis (average net fluid balance of negative 2.1 liters) with corresponding decrease in pulmonary edema visualized by B-mode ultrasound (average decrease of 13 B-Lines). In addition, LUSWE demonstrated a statistically significant reduction in the magnitude of wave speed from admission to follow-up. The reduction in lung surface wave speed suggests a decrease in lung stiffness (decreased elasticity) mediated by successful reduction of pulmonary edema. In summary, LUSWE is a noninvasive technique for quantifying elastic properties of superficial lung tissue that may prove useful as a diagnostic test, performed at the bedside, for the quantitative assessment of pulmonary edema.

Negative life events and self-harm among the elderly: Result from a survey of 7070 people aged≥60 in China.

PURPOSES: Negative life events have been reported as a risk factor for elderly self-harm. The aim of this study was to examine the relationship between negative life events and self-harm in a large sample of people aged 60 and older, and explore the role of some previously identified influential factors in this relationship. METHODS: Multi-stage stratified sampling method was used to select the elderly people over 60 years old in Shandong, China. Information were collected through face-to-face interviews. Univariate and multivariable logistic regression were used for initial analysis. Karlson-Holm-Breen (KHB) method was used for mediating effect analysis. RESULTS: A total of 7070 participants were included in the study, 160 reported they had a history of self-harm (2.3%), 756 reported they had negative life event experience (10.7%). After model adjustment, the association between negative life events, loneliness, economic status and self-harm was still statistically significant. Mediation analysis showed that the association is explained by loneliness (proportion of mediation 48.86%), self-rated economic status (16.13%). CONCLUSIONS: Negative life events, loneliness and economic status were associated with self-harm among the older adults. Loneliness and economic status may play an intermediary role in the relationship between negative life events and self-harm, especially loneliness. More psychological and social functions intervention strategies and prevention measures on the self-harm of the elderly should be provided for the elderly who have experienced negative life events.

Utility of Magnetic Resonance Imaging in Diagnosis of Prenatal Non-Visualization of the Fetal Gallbladder: A Case-Series Study.

BACKGROUND This study aimed to assess the utility of magnetic resonance imaging (MRI) in the diagnosis of prenatal non-visualization of the fetal gallbladder (PNVGB). MATERIAL AND METHODS The clinical data of 32 pregnant women with PNVGB who underwent MRI examination during the second and third trimester of pregnancy were collected and their outcomes were analyzed. RESULTS MRI showed that 26 patients (81.3%) had isolated PNVGB and 6 (18.8%) had additional malformations. In 26 patients with isolated PNVGB, 7 were found in the gallbladder on MRI and 4 were found on subsequent ultrasonography. One patient had termination of pregnancy (TOP) and 1 patient was lost to follow-up; the remaining 24 patients were known to deliver a healthy child. Among the 6 patients with additional malformations, 3 terminated their pregnancies due to combined severe abnormalities: 1 patient with horseshoe kidney and 1 with fetal echogenic bowel both had a healthy child, while 1 with fetal growth restriction (FGR) delivered a child who walked on tiptoe. CONCLUSIONS MRI contributes to identifying PNVGB detected or suspected by ultrasonography.

Association between Overweight, Obesity and the Prevalence of Multimorbidity among the Elderly: Evidence from a Cross-Sectional Analysis in Shandong, China.

(1) Background: Multimorbidity, defined as the occurrence of two or more chronic diseases, is a global public health problem which has a significant negative impact on individuals, families and the society. The aim of this study was to evaluate the association between overweight, obesity and the prevalence of multimorbidity among male and female older adults; (2) Methods: Cross-sectional data of the 7070 participants from China, aged 60 years and above included in 2017 the Shandong Elderly Family Health Service Survey were analyzed. Multivariate logistic regression analysis was used to examine the relationship between overweight, obesity and the prevalence of multimorbidity in males and females; (3) Results: Among the 7070 participants, of which 40.25% were males and 59.75% were females, the average age of all participants was (69.81 ± 6.45) years old. The prevalence of multimorbidity in older adults was 34.71%, and the overweight and obesity rates were 39.25% and 16.89%. Among the male elderly, the likelihood of multimorbidity was more than two times higher among the obese than the normal BMI population (OR: 2.14; 95%CI: 1.63-2.82). A less strong association was found in the overweight male older population (OR: 1.43; 95%CI: 1.18-1.74). In the females, compared with individuals with normal BMI, the risks for incident multimorbidity were high in the overweight and obese groups, with odds ratios of 1.42 (95%CI: 1.21-1.65) and 1.81 (95%CI: 1.51-2.17), respectively. (4) Conclusions: In this study, overweight and obesity had the strongest association with the prevalence of multimorbidity among Chinese older adults, and the associations were different between the male and female elderly. The prevalence of multimorbidity might be effectively prevented by controlling body mass index. Encouraging the elderly to eat the recommended amount of vegetables and fruits, walk at least 30 min a day and have enough sleep to maintain a healthy weight.

Prevalence and Associated Factors of Self-Treatment among the Elderly-A Comparative Study between Empty and Non-Empty Nesters in Shandong, China.

(1) Objectives: With an aging society in China, self-treatment now plays an important role in health care among older adults, but it can be problematic. This study aims to explore and compare the self-treatment behavior among empty and non-empty nesters. (2) Methods: Using a multi-stage stratified random cluster sampling method, a total of 4366 elderly people aged 60 and above from Shandong Province, China, were enrolled in this study. Data were collected through a structured questionnaire. Binary logistic regression was used to analyze the associated factors of self-treatment. (3) Results: The prevalence of self-treatment in empty nesters was significantly lower than that in non-empty ones (74.0% vs. 83.3%). Binary logistic regression analysis showed that higher educational level and poorer self-rated economic status were negatively associated with self-treatment in empty nesters, while unemployed and urban and rural residents' basic medical insurance were positively associated with self-treatment in non-empty ones. (4) Conclusions: The study indicated that empty nesters had lower likelihood of self-treatment than non-empty ones. Empty nesters with better socioeconomic status were more likely to use self-treatment; by contrast, non-empty nesters with relatively poorer socioeconomic status were more inclined to self-treatment. Targeted interventions should be developed to maximize the effectiveness of self-treatment and reduce health risks.

SSPH I, a Novel Anti-Cancer Saponin, Inhibits Autophagy and Induces Apoptosis via ROS Accumulation and ERK1/2 Signaling Pathway in Hepatocellular Carcinoma Cells.

INTRODUCTION: Saponin of Schizocapsa plantaginea Hance I (SSPH I), a novel bioactive phytochemical isolated from the rhizomes of Schizocapsa plantaginea, has been demonstrated to exhibit anti-cancer activity against various tumors in preclinical studies. However, the molecular mechanisms involved in the suppression of hepatocellular carcinoma (HCC) are poorly understood. The present study aimed at analyzing the effects of SSPH I on autophagy and apoptosis in vitro. METHODS: MTT and colony forming assays were used to detect cell viability and cell proliferation. Hoechst 33,258 staining and flow cytometry were used to determine apoptosis and ROS production. The apoptosis and autophagy-related protein expression levels were evaluated via Western blot assay. Characteristics of autophagy and apoptosis were observed by transmission electron microscopy. Lysosomal activity was stained with Lyso-Tracker Red and Magic Red Cathepsin B. RESULTS: The results showed that SSPH I exhibited potent anti-cancer activity and proliferation in HepG2 and BEL-7402 cells and inhibited HepG2 cells through inhibiting autophagy and promoting apoptosis. The mechanistic study indicated that the inhibition of autophagy of SSPH I was mediated by blocking autophagosome-lysosome fusion. Additionally, we found that SSPH I could mediate the activation of MAPK/ERK1/2 signaling pathway, and the use of NAC (ROS inhibitor) and U0126 (MEK1/2 inhibitor) converted the effect of SSPH I on apoptosis and autophagy in HepG2 cells. CONCLUSION: These data suggest that SSPH I induces tumor cells apoptosis and reduces autophagy in vitro by inducing ROS and activating MAPK/ERK1/2 signaling pathway, indicating that SSPH I might be a novel agent for the treatment of HCC.

The epigallocatechin gallate derivative Y6 reduces the cardiotoxicity and enhances the efficacy of daunorubicin against human hepatocellular carcinoma by inhibiting carbonyl reductase 1 expression.

ETHNOPHARMACOLOGICAL RELEVANCE: Green tea is the most ancient and popular beverage worldwide and its main constituent epigallocatechin-3-gallate (EGCG) has a potential role in the management of cancer through the modulation of cell signaling pathways. However, EGCG is frangible to oxidation and exhibits low lipid solubility and bioavailability, and we synthesized a derivative of EGCG in an attempt to overcome these limitations. AIM OF THE STUDY: The anthracycline antibiotic daunorubicin (DNR) is a potent anticancer agent. However, its severe cardiotoxic limits its clinical efficacy. Human carbonyl reductase 1 (CBR1) is one of the most effective human reductases for producing hydroxyl metabolites and thus may be involved in increasing the cardiotoxicity and decreasing the antineoplastic effect of anthracycline antibiotics. Accordingly, in this study, we investigated the co-therapeutic effect of Y6, a novel and potent adjuvant obtained by optimization of the structure of EGCG. MATERIAL AND METHODS: The cellular concentrations of DNR and its metabolite DNRol were measured by HPLC to determine the effects of EGCG and Y6 on the inhibition of DNRol formation. The cytotoxic effects of EGCG and Y6 were tested by MTT assay in order to identify non-toxic concentrations of them. To understand their antitumor and cardioprotective mechanisms, hypoxia-inducible factor-1α (HIF-1α) and CBR1 protein expression was measured via Western blotting and immunohistochemical staining while gene expression was analyzed using RT-PCR. Moreover, PI3K/AKT and MEK/ERK signaling pathways were analyzed via Western blotting. HepG2 xenograft model was used to detect the effects of EGCG and Y6 on the antitumor activity and cardiotoxicity of DNR in vivo. Finally, to obtain further insight into the interactions of Y6 and EGCG with HIF-1α and CBR1, we performed a molecular modeling. RESULTS: Y6(10 µg/ml or 55 mg/kg) decreased the expression of HIF-1α and CBR1 at both the mRNA and protein levels during combined drug therapy in vitro as well as in vivo, thereby inhibiting formation of the metabolite DNRol from DNR, with the mechanisms being related to PI3K/AKT and MEK/ERK signaling inhibition. In a human carcinoma xenograft model established with subcutaneous HepG2 cells, Y6(55 mg/kg) enhanced the antitumor effect and reduced the cardiotoxicity of DNR more effectively than EGCG(40 mg/kg). CONCLUSIONS: Y6 has the ability to inhibit CBR1 expression through the coordinate inhibition of PI3K/AKT and MEK/ERK signaling, then synergistically enhances the antitumor effect and reduces the cardiotoxicity of DNR.

The epigallocatechin gallate derivative Y6 inhibits human hepatocellular carcinoma by inhibiting angiogenesis in MAPK/ERK1/2 and PI3K/AKT/ HIF-1α/VEGF dependent pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Hypervascularity has been considered as one of the major features of many solid tumors. Green tea is one of the commonly drink resources in China, and its active component, Epigallocatechin gallate (EGCG), exhibits antiangiogenic activities in various experimental tumor models. However, EGCG has many shortages, e.g., relatively unstable, low lipid solubility, poor bioavailability, and short duration of action. AIM OF THE STUDY: To overcome the shortages of EGCG for antiangiogenic antitumor usage, our study developed a novel EGCG derivate, Y6(5,3',4',3″,4″,5″-6-0-ethyl-EGCG). The underlying mechanism was also elucidated. MATERIAL AND METHODS: we evaluated the effects of EGCG, Y6 on HCC and angiogenesis in vivo and in vitro. Moreover, to understand their antitumor mechanisms, key factors within angiogenesis-related signaling pathways (MAPK/ERK1/2, PI3K/AKT, HIF-1 VEGF) were analyzed by using western blot, immunohistochemistry (IHC), quantitative real-time quantitative PCR (RT-PCR). HepG2 xenograft model and the chorioallantoic membrane (CAM) were used to investigate the effects of Y6 and EGCG on tumors and anti-angiogenesis in vivo. Micro-vessel density (MVD) was analyzed by IHC of CD34 staining. IHC, qRT-PCR and Western blot were used to detect the expression of HIF-1α and VEGF protein in tumor tissues. The protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF in tumor tissues were detected by western blot. RESULTS: Our results demonstrated that both EGCG and Y6 displayed antiangiogenetic and antitumor effects against HCC cells in vitro and in vivo. We found that rather than equal amount of EGCG, Y6 displayed better abilities in inhibiting the growth of HCC tumor cells, as well as inhibiting the growth of neovascularization in the chick embryos and HepG2 xenograft tumors bearing-mice, based on the data obtained from MTT assay, immunohistochemistry (IHC), chick chorioallantoic membrane (CAM) assays. In the comparison of equivalent dose of EGCG, qRT-PCR data showed that Y6 induced more significant decrease of the mRNA levels of HIF-1α and VEGF in supernatant-treated SMMC-7721 cells under hypoxic condition, as well as in the in xenograft tumor tissues; whereas Y6 also significantly reduced the protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF to a greater extent than EGCG, determined by western blotting assay. CONCLUSIONS: our work suggests that the new EGCG derivate Y6 could significantly inhibit tumor growth and angiogenesis which is possibly involved with the signaling intervention of MAPK/ERK1/2 and PI3K/AKT/HIF-1α/VEGF pathways, and is supposed to be a potential therapeutic reagent for anti-angiogenesis treatment of solid tumors.

The Relationship between Self-Rated Economic Status and Falls among the Elderly in Shandong Province, China.

(1) Background: Older people are more vulnerable and likely to have falls and the consequences of these falls place a heavy burden on individuals, families and society. Many factors directly or indirectly affect the prevalence of falls. The aims of this study were to understand the prevalence and risk factors of falls among the elderly in Shandong, China; the relationship between economic level and falls was also preliminary explored. (2) Methods: Using a multi-stage stratified sampling method, 7070 elderly people aged 60 and over were selected in Shandong Province, China. General characteristics and a self-rated economic status were collected through face to face interviews. Chi-square tests, rank sum tests and two logistic regression models were performed as the main statistical methods. (3) Results: 8.59% of participants reported that they had experienced at least one fall in the past half year. There was a significant difference in experienced falls regarding gender, residence, marital status, educational level, smoking, drinking, hypertension, diabetes, coronary disease, and self-reported hearing. The worse the self-rated economic status, the higher the risk of falling, (poor and worried about livelihood, OR = 3.60, 95%; CI = 1.76-7.35). (4) Conclusions: Women, hypertension, diabetes and self-reported hearing loss were identified as the risk factors of falls in the elderly. The difference of economic level affects the falls of the elderly in rural and urban areas. More fall prevention measures should be provided for the elderly in poverty.

Effect of a Thin Fluid Layer on Surface Wave Speed Measurements: A Lung Phantom Study.

Lung ultrasound (US) surface wave elastography (SWE) is a novel technique that measures superficial lung tissue elastic properties. A thin pleural fluid layer covers a lung, but its effect on lung measurements in SWE is unknown. We modeled a lung and pleural fluid with sponges and a thin layer of US transmission gel. Sponge surface wave speeds measured from SWE were compared for sponges without and with the thin US gel layer at 3 wave excitation frequencies. The comparison showed that the sponge surface wave speed measurements were not affected by the thin gel layer.

Depth-dependent atomic valence determination by synchrotron techniques.

The properties of many materials can be strongly affected by the atomic valence of the contained individual elements, which may vary at surfaces and other interfaces. These variations can have a critical impact on material performance in applications. A non-destructive method for the determination of layer-by-layer atomic valence as a function of material thickness is presented for La0.7Sr0.3MnO3 (LSMO) thin films. The method utilizes a combination of bulk- and surface-sensitive X-ray absorption spectroscopy (XAS) detection modes; here, the modes are fluorescence yield and surface-sensitive total electron yield. The weighted-average Mn atomic valence as measured from the two modes are simultaneously fitted using a model for the layer-by-layer variation of valence based on theoretical model Hamiltonian calculations. Using this model, the Mn valence profile in LSMO thin film is extracted and the valence within each layer is determined to within an uncertainty of a few percent. The approach presented here could be used to study the layer-dependent valence in other systems or extended to different properties of materials such as magnetism.

Electrostatic potential and valence modulation in La0.7Sr0.3MnO3 thin films.

The Mn valence in thin film La0.7Sr0.3MnO3 was studied as a function of film thickness in the range of 1-16 unit cells with a combination of non-destructive bulk and surface sensitive X-ray absorption spectroscopy techniques. Using a layer-by-layer valence model, it was found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface. These results were supported by first principles calculations. The surface valence increases to up to Mn3.7+, whereas the interface valence reduces down to Mn2.5+. The change in valence from the expected bulk value is consistent with charge redistribution due to the polar discontinuity at the film-substrate interface. The comparison with theory employed here illustrates how this layer-by-layer valence evolves with film thickness and allows for a deeper understanding of the microscopic mechanisms at play in this effect. These results offer insight on how the two-dimensional electron gas is created in thin film oxide alloys and how the magnetic ordering is reduced with dimensionality.

A Lung Phantom Model to Study Pulmonary Edema Using Lung Ultrasound Surface Wave Elastography.

Lung ultrasound surface wave elastography (LUSWE) is a novel technique used to measure superficial lung tissue stiffness. A phantom study was carried out in the study described here to evaluate the application of LUSWE to assess lung water for pulmonary edema. A lung phantom model with cellulose sponge was used; various volumes of water were injected into the sponge to model lung water. Shaker-generated surface wave propagation on the sponge surface was recorded by a 10-MHz ultrasound probe at three shaker frequencies: 100, 150 and 200Hz. Surface wave speeds were calculated but did not exhibit dependence on the volume of injected water. However, the shear viscosity of the sponge increased with water content, and shear elasticity also exhibited a subtle increase. This study suggests that sponge viscoelasticity might change with the water content, which can be detected by LUSWE.