The Radiation Temperature Characteristics of Sapphire under Shock Loading

A light gas gun was used to study the radiation temperature from the window material of sapphire. The luminescence characteristics were determined using a multi-wavelength pyrometer in the pressure range of 36–50 GPa. By improving the processing technology for the metal sample and assembly technology for the target, the eight-wavelength light radiation was measured from sapphire under shock pressure without phase transition. The experimental results showed that sapphire has luminous phenomenon from 36.5 GPa. The luminous intensity changes in a linear fashion, revealing the thickness of the radiating layer of shock-compressed sapphire with a constant absorption coefficient. The results indicated that the spectral distribution is a typical thermal radiation, which fits well with the grey-body spectrum. The radiation of sapphire under shock mostly came from the adiabatic shear banding, as determined by comparing the melting line of sapphire using a static high-pressure experiment and theoretical calculations with the radiation temperature. The study is an effective means to obtain the transparent material shock radiation temperature. Moreover, an effective approach is proposed to research the radiation mechanism of transparent material and the high pressure melting line

The Radiation Temperature Characteristics of Sapphire under Shock Loading

A light gas gun was used to study the radiation temperature from the window material of sapphire. The luminescence characteristics were determined using a multi-wavelength pyrometer in the pressure range of 36–50 GPa. By improving the processing technology for the metal sample and assembly technology for the target, the eight-wavelength light radiation was measured from sapphire under shock pressure without phase transition. The experimental results showed that sapphire has luminous phenomenon from 36.5 GPa. The luminous intensity changes in a linear fashion, revealing the thickness of the radiating layer of shock-compressed sapphire with a constant absorption coefficient. The results indicated that the spectral distribution is a typical thermal radiation, which fits well with the grey-body spectrum. The radiation of sapphire under shock mostly came from the adiabatic shear banding, as determined by comparing the melting line of sapphire using a static high-pressure experiment and theoretical calculations with the radiation temperature. The study is an effective means to obtain the transparent material shock radiation temperature. Moreover, an effective approach is proposed to research the radiation mechanism of transparent material and the high pressure melting line

Nitric Oxide Concentration: A New Data Set Derived From SABER Measurements

Abstract Vertical profiles of nitric oxide (NO) concentration are derived between 120 and 250 km using updated NO emission rates measured by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar (MSIS) 2.1 model is used to provide the required parameters of temperature, atomic oxygen number density, and molecule oxygen number density needed to derive the NO concentrations using a non‐local thermodynamic equilibrium (non‐LTE) model. The SABER NO concentration shows a significant correlation with solar activity with larger peak NO concentrations and higher altitude extent during solar maximum years compared to those during the solar minimum years. The SABER NO agrees well with the MSIS 2.1 NO at altitudes above 120 km for all latitudes, while the pronounced SABER‐MSIS NO discrepancy below 120 km is likely due to the temperature underestimation by MSIS 2.1. A detailed error analysis is presented and considers systematic and random errors in all the terms in the non‐LTE model used to derive the NO concentration. Random error in MSIS 2.1 temperature and atomic oxygen dominates the uncertainty in single NO profiles above 120 km. We estimated a systematic error up to ∼36% between 120 and 250 km during solar maximum years

Characteristics and origin of tuff-type tight oil in Jimusaer sag, Junggar Basin, NW China

Based on core and thin section observation, and combined with X-ray diffraction, electron probe and geochemical analysis, the characteristics and origin of tuff tight oil of the Permian Lucaogou Formation in the Jimusaer depression, Junggar Basin were examined. There are tuff, tuffite and tuffaceous dolomite interlaid in the sedimentary rocks of the Lucaogou Formation. The alkali feldspar and quartz in the tuff are rich in strontium, which, according to mineral geochemical analysis, are originated from alkaline-peralkaline magmatic rocks. The Sr isotope ratio (87Sr/86Sr) of dolomite is similar to that of mantle, which shows minerals of tuff were formed in volcanism-related hydrothermal environments. High Sr/Ba and δ13C of dolomite, and occurrence of halite under microscope suggest that the Lucaogou Formation was deposited in high salinity environment. High content of magnesium and iron ions related to volcanism and hydrotherm, and high salinity environment contributed to the precipitation of dolomite. The distribution of tight oil, organic matter abundance of source rock and reservoir physical properties show that it is the rich nutrients provided by volcanic activity that controlled the formation of high abundance source rock; tuff, tuffaceous dolomite with plenty of residual inter-granular pores and dissolved pores are favorable reservoir sections; and tuff controls the formation and distribution of tight oil. Key words: Junggar Basin, Jimusaer Depression, tuff, tight oil, geological characteristic

Assessment of Left Ventricular Contraction Patterns Using Gated SPECT MPI to Predict Cardiac Resynchronization Therapy Response

Background: The U-shaped left ventricular (LV) contraction pattern, identified by MRI or echocardiography, is associated with improved CRT response. Gated SPECT MPI can measure both myocardial viability and mechanical dyssynchrony in a single scan. The aim of this study is to examine the relationship of the LV contraction pattern and the response of CRT in patients with left bundle branch block (LBBB). Methods: Fifty-eight patients who met CRT guidelines and who had pre-CRT MPI were enrolled. Myocardial segments with tracer uptake \u3c 50% of maximum were considered as scar. The LV contraction pattern was considered as U-shaped or non-U-shaped (U-shaped has a block line in the direction of contraction propagation). CRT response was defined as an increase in left ventricular ejection fraction ≥ 5% after 6-month follow-up. Results: Twenty-eight patients (48%) had a U-shaped contraction pattern and thirty patients (52%) had a non-U-shaped contraction pattern. The U-shaped group showed a significantly higher response rate than the non-U-shaped group (90% vs. 57%; P = 0.005). By univariate and multivariate logistic regression analysis, the U-shaped pattern was an independent predictor of CRT response. Conclusion: Non-invasive gated SPECT MPI can characterize LV mechanical contraction patterns. A U-shaped contraction pattern identified is associated with improved CRT response. This may prove useful for improved patient selection for CRT

Transport of Nitric Oxide Via Lagrangian Coherent Structures Into the Top of the Polar Vortex

The energetic particle precipitation (EPP) indirect effect (IE) refers to the downward transport of reactive odd nitrogen (NOx = NO + NO2) produced by EPP (EPP-NOx) from the polar winter mesosphere and lower thermosphere to the stratosphere where it can destroy ozone. Previous studies of the EPP IE examined NOx descent averaged over the polar region, but the work presented here considers longitudinal variations. We report that the January 2009 split Arctic vortex in the stratosphere left an imprint on the distribution of NO near the mesopause, and that the magnitude of EPP-NOx descent in the upper mesosphere depends strongly on the planetary wave (PW) phase. We focus on an 11-day case study in late January immediately following the 2009 sudden stratospheric warming during which regional-scale Lagrangian coherent structures (LCSs) formed atop the strengthening mesospheric vortex. The LCSs emerged over the north Atlantic in the vicinity of the trough of a 10-day westward traveling planetary wave. Over the next week, the LCSs acted to confine NO-rich air to polar latitudes, effectively prolonging its lifetime as it descended into the top of the polar vortex. Both a whole atmosphere data assimilation model and satellite observations show that the PW trough remained coincident in space and time with the NO-rich air as both migrated westward over the Canadian Arctic. Estimates of descent rates indicate five times stronger descent inside the PW trough compared to other longitudes. This case serves to set the stage for future climatological analysis of NO transport via LCSs

Development and Validation of an Automatic Method to Detect the Latest Contracting Viable Left Ventricular Segments to Assist Guide CRT Therapy From Gated SPECT Myocardial Perfusion Imaging

Objectives: The purpose of this study is to use ECG-gated SPECT MPI to detect the latest contracting viable left ventricular (LV) segments to help guide the LV probe placement used in CRT therapy and to validate segment selection against the visual integration method by experts. Methods: For each patient, the resting ECG-gated SPECT MPI short-axis images were sampled in 3D to generate a polar map of the perfusion distribution used to determine LV myocardial viability, and to measure LV synchronicity using our phase analysis tool. In the visual integration method, two experts visually interpreted the LV viability and mechanical dyssynchrony from the short-axis images and polar maps of viability and phase, to determine the latest contracting viable segments using the 17-segment model. In the automatic method, the apical segments, septal segments, and segments with more than 50% scar were excluded as these are not candidates for CRT LV probe placement. Amongst the remaining viable segments, the segments, whose phase angles were within 10° of the latest phase angle (the most delayed contracting segment), were identified for potential CRT LV probe placement and ranked based on the phase angles of the segments. Both methods were tested in 36 pre-CRT patients who underwent ECG-gated SPECT MPI. The accuracy was determined as the percent agreement between the visual integration and automatic methods. The automatic method was performed by a second independent operator to evaluate the inter-operator processing reproducibility. Results: In all the 36 patients, the LV lead positions of the 1st choices recommended by the automatic and visual integration methods were in the same segments in 35 patients, which achieved an agreement rate of 97.2%. In the inter-operator reproducibility test, the LV lead positions of the 1st choices recommended by the two operators were in the same segments in 25 patients, and were in the adjacent segments in 7 patients, which achieved an overall agreement of 88.8%. Conclusions: An automatic method has been developed to detect the latest contracting viable LV segments to help guide the LV probe placement used in CRT therapy. The retrospective clinical study with 36 patients suggests that this method has high agreement against the visual integration method by experts and good inter-operator reproducibility. Consequently, this method is promising to be a clinical tool to recommend the CRT LV lead positions

Empagliflozin-Enhanced Antioxidant Defense Attenuates Lipotoxicity and Protects Hepatocytes by Promoting FoxO3a- and Nrf2-Mediated Nuclear Translocation via the CAMKK2/AMPK Pathway

Lipotoxicity is an important factor in the development and progression of nonalcoholic steatohepatitis. Excessive accumulation of saturated fatty acids can increase the substrates of the mitochondrial electron transport chain in hepatocytes and cause the generation of reactive oxygen species, resulting in oxidative stress, mitochondrial dysfunction, loss of mitochondrial membrane potential, impaired triphosphate (ATP) production, and fracture and fragmentation of mitochondria, which ultimately leads to hepatocellular inflammatory injuries, apoptosis, and necrosis. In this study, we systematically investigated the effects and molecular mechanisms of empagliflozin on lipotoxicity in palmitic acid-treated LO2 cell lines. We found that empagliflozin protected hepatocytes and inhibited palmitic acid-induced lipotoxicity by reducing oxidative stress, improving mitochondrial functions, and attenuating apoptosis and inflammation responses. The mechanistic study indicated that empagliflozin significantly activated adenosine 5’-monophosphate (AMP)-activated protein kinase alpha (AMPKα) through Calcium/Calmodulin dependent protein kinase kinase beta (CAMKK2) instead of liver kinase B1 (LKB1) or TGF-beta activated kinase (TAK1). The activation of empagliflozin on AMPKα not only promoted FoxO3a phosphorylation and thus forkhead box O 3a (FoxO3a) nuclear translocation, but also promoted Nrf2 nuclear translocation. Furthermore, empagliflozin significantly upregulated the expressions of antioxidant enzymes superoxide dismutase (SOD) and HO-1. In addition, empagliflozin did not attenuate lipid accumulation at all. These results indicated that empagliflozin mitigated lipotoxicity in saturated fatty acid-induced hepatocytes, likely by promoting antioxidant defense instead of attenuating lipid accumulation through enhanced FoxO3a and Nrf2 nuclear translocation dependent on the CAMKK2/AMPKα pathway. The CAMKK2/AMPKα pathway might serve as a promising target in treatment of lipotoxicity in nonalcoholic steatohepatitis