Spatiotemporal encoding MRI in a portable low-field system.

PURPOSE: Demonstrate the potential of spatiotemporal encoding (SPEN) MRI to deliver largely undistorted 2D, 3D, and diffusion weighted images on a 110 mT portable system. METHODS: SPEN's quadratic phase modulation was used to subsample the low-bandwidth dimension of echo planar acquisitions, delivering alias-free images with an enhanced immunity to image distortions in a laboratory-built, low-field, portable MRI system lacking multiple receivers. RESULTS: Healthy brain images with different SPEN time-bandwidth products and subsampling factors were collected. These compared favorably to EPI acquisitions including topup corrections. Robust 3D and diffusion weighted SPEN images of diagnostic value were demonstrated, with 2.5 mm isotropic resolutions achieved in 3 min scans. This performance took advantage of the low specific absorption rate and relative long TEs associated with low-field MRI. CONCLUSION: SPEN MRI provides a robust and advantageous fast acquisition approach to obtain faithful 3D images and DWI data in low-cost, portable, low-field systems without parallel acceleration.

Large Polaron Condensation in a Pseudo-Bilayer Quantum Hall Composite.

There is much interest regarding the "coupled ferroelectricity and superconductivity" in the two-dimensional material, bilayer Td-MoTe2; however, the value and the type of electric polarization are unknown. The device structure and the measurement method show that the measured material is the composite of the pseudo-bilayer quantum Hall system, with a thickness of about thirty-six nanometers. The derived dielectric hysteresis loops and the calculated electronic structure reveal that the condensed large polarons are responsible for the reverse ferroelectricity and the coupled superconductivity. The maximum value of polaron-type electric polarization is ~12 nC/µm2 or 1.2 × 104 µc/cm2.

A comparison of computed tomography imaging with histopathology in the sensitivity and correlation of evaluating coronary arterial calcification.

Background: The sensitivity and correlation of coronary computed tomography angiography (CTA) as compared with histopathology are unknown in evaluating coronary arterial calcification. In this study, we retrospectively evaluated qualitatively and quantitatively the sensitivity and correlation of coronary CTA compared with histopathology in assessing coronary arterial calcification. Methods: This study was conducted on 12 randomly selected cadavers aged over 40 years at the time of death, and 53 segments of coronary arteries from these 12 cadavers were obtained from the Human Anatomy Laboratory of Tianjin Medical University. The artery segments were scanned using contrasted-enhanced dual-source computed tomography (DSCT) with an axial slice thickness of 0.6 mm. Coronary artery calcification in a coronary segment was defined as the presence of 1 or more voxels with a CT density >130 Hounsfield units. According to the arc of calcification in the cross section of the coronary artery wall, calcified plaques were divided into three categories: mild, moderate, and severe calcification. The coronary artery stenosis caused by calcified plaque was observed and calculated with multiplanar reconstruction (MPR), maximum density projection, volume rendering (VR), and cross-sectional reconstruction. After CT enhancement scanning, the coronary artery specimens were cut into 4-mm long segments and embedded in paraffin for pathological staining. Pathological classification and coronary artery stenosis measured with pathological analysis were used as comparison criteria. Results: Histopathology detected 69 Vb-type plaques, while DSCT detected 57 calcified plaques. The sensitivity of CT for detecting mild, moderate, and severe calcified plaques were 88.3% [95% confidence interval (CI): 74.1-95.6%], 100% (95% CI: 69.8-100%), and 100% (95% CI: 73.2-100%), respectively. DSCT had a significant (P<0.001) correlation with histopathology in quantifying coronary artery stenosis caused by mild, moderate, and severe calcified plaques (R2=0.9278, R2=0.9158, R2=0.7923, respectively). Compared with histopathology, DSCT overestimated coronary artery stenosis caused by mild, moderate, and severe calcified plaques (3.2%±2.0%, 4.9%±4.7%, and 14.7%±8.2%, respectively; P<0.05). Conclusions: DSCT contrast enhancement scanning can detect and characterize coronary artery calcification with a good correlation with histopathologic quantification of coronary artery stenosis caused by different types of calcified plaques, even though coronary CTA may overestimate the stenosis.

In vitro nephrotoxicity and quantitative UPLC-MS analysis of three aristololactams in Houttuynia cordata.

Three analogues of aristololactam Ⅰ (AL Ⅰ), AL AⅡ, AL FⅠ and AL BⅡ, had been isolated from Houttuynia cordata, a commonly used medicinal and edible plant with heat-removing and toxin-removing functions. Considering the significant nephrotoxicity of AL Ⅰ, this study evaluated the toxicity of these three aristololactams (ALs) on human proximal tubular epithelial cells (HK-2) by MTT assay, ROS assay, ELISA tests and cytologic morphology observation. Furthermore, the distribution of the three ALs in H. cordata were investigated by UPLC-MSn recognition and quantitation in SIM mode, so as to estimate primarily the safety of the plant. The results showed that all the three ALs in H. cordata had comparative cytotoxicity as AL I with the IC50 values from 3.88 µM to 20.63 µM, caused high levels of cellular levels of reactive oxygen species (ROS) in HK-2 cells, exhibited the potential to cause renal fibrosis by remarkably increasing the levels of transforming growth factor-ß (TGF-ß1) and fibronectin (FN), and induced fibrous changes in morphology of HK-2 cells. The contents of the three ALs varied significantly in 30 batches of H. cordata from different regions and parts. Overall, the aerial part contained much more ALs (3.20 - 108.19 µg/g) than the underground part (0.95 - 11.66 µg/g), and flowers had the highest contents. Besides, no ALs were detected in the water extract of any part of H. cordata. This work revealed that the aristololactams in H. cordata had similar in vitro nephrotoxicity as AL Ⅰ and were mainly distributed in the aerial part of the plant.

Oral subacute nephrotoxicity of aristololactam I in rats.

Aristolactams (ALs) have been recognized as one kind of metabolites of aristolochic acids (AAs), the nephrotoxic components of Aristolochiaceae plants, and are more widely distributed than AAs in herbal medicines. This study evaluated the oral subacute nephrotoxicity of aristolactam I (AL I), a representative compound of ALs. AL I was intragastrically administered to rats at 20 mg·kg-1·d-1 for 10 or 20 days, with aristolochic acid I (AA I) used as positive control at the same dose. After 10-day treatment, AL I led to a significant increase in early renal injury-related indices in urine and obvious histopathological lesions in kidneys, including degeneration of tubular epithelial cells, inflammatory cell infiltration and fibrosis. The lesions induced by AL I were significantly aggravated after 20-day exposure. However, AL I induced less histopathological damage in kidneys than AA I in both 10- and 20-day groups. Our results indicated that oral AL I caused nephrotoxicity by inducing oxidative stress, inflammation, and overactivation of the complement system as AA I did. Three detected apoptosis-associated indicators were not affected by AL I but remarkably increased by AA I. In summary, oral AL I induced evident renal damage in rats after only 10 days of treatment, and the damage was aggravated after 20 days. However, AL I was obviously less nephrotoxic than AA I via oral gavage.

A new abietane diterpene and anti-complementary constituents from Juniperus tibetica.

Anti-complementary activity-guided fractionation led to the isolation of a new abietane diterpene (1) and twenty-five known compounds (2-26) from the twigs and leaves of Juniperus tibetica. All the compounds were isolated from J. tibetica for the first time. The structure of 1 was assigned by spectroscopic data and X-ray crystallography analysis. Five lignans (2, 3, 7, 9 and 10), two flavones (19 and 22), and one coumarin (23) exhibited anti-complementary activity with CH50 values ranging from 0.3 to 3.69 mM.

Regulating the balance of Th17/Treg cells in gut-lung axis contributed to the therapeutic effect of Houttuynia cordata polysaccharides on H1N1-induced acute lung injury.

Our previous study had demonstrated that oral administration of Houttuynia cordata polysaccharides (HCP) without in vitro antiviral activity ameliorated gut and lung injuries induced by influenza A virus (IAV) in mice. However, as macromolecules, HCP was hard to be absorbed in gastrointestinal tract and had no effect on lung injury when administrated intravenously. The action mechanism of HCP was thus proposed as regulating the gut mucosal-associated lymphoid tissue (GALT). Actually, HCP treatment restored the balance of Th17/Treg cells firstly in GALT and finally in the lung. HCP reduced the expression of chemokine CCL20 in the lung and regulated the balance of Th17/Treg carrying CCR6+ (the CCL20 receptor), which was associated with specific migration of Th17/Treg cells from GALT to lung. In vitro, HCP inhibited Th17 cell differentiation through the downregulation of phospho-STAT3, whereas it promoted Treg cell differentiation by upregulating phospho-STAT5. Furthermore, its therapeutic effect was abolished in RORγt-/- or Foxp3-/- mice. These findings indicated that oral administration of macromolecular polysaccharides like HCP might ameliorate lung injury in IAV infected mice via directly regulating the balance of Th17/Treg cells in gut-lung axis. Our results provided a potential mechanism underlying the therapeutic effect of polysaccharides on pulmonary infection.

Sextuple ratiometric thermometry based on 980-nm-upconverted green fluorescence of Er3+ ions in submicron crystals.

980-nm-upconverted 530 and 550 nm Er3+ green fluorescence spectra of Er3+/Yb3+-codoped NaGd(WO4)2 submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er3+. The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method.

[Biomass Compositional Analysis Using Sparse Partial Least Squares Regression and Near Infrared Spectrum Technique].

Forest bio-fuel, a new type renewable energy, has attracted increasing attention as a promising alternative. In this study, a new method called Sparse Partial Least Squares Regression (SPLS) is used to construct the proximate analysis model to analyze the fuel characteristics of sawdust combining Near Infrared Spectrum Technique. Moisture, Ash, Volatile and Fixed Carbon percentage of 80 samples have been measured by traditional proximate analysis. Spectroscopic data were collected by Nicolet NIR spectrometer. After being filtered by wavelet transform, all of the samples are divided into training set and validation set according to sample category and producing area. SPLS, Principle Component Regression (PCR), Partial Least Squares Regression (PLS) and Least Absolute Shrinkage and Selection Operator (LASSO) are presented to construct prediction model. The result advocated that SPLS can select grouped wavelengths and improve the prediction performance. The absorption peaks of the Moisture is covered in the selected wavelengths, well other compositions have not been confirmed yet. In a word, SPLS can reduce the dimensionality of complex data sets and interpret the relationship between spectroscopic data and composition concentration, which will play an increasingly important role in the field of NIR application.