1,5,6-Trimethoxy-2,7-dihydroxyphenanthrene from Dendrobium officinale Exhibited Antitumor Activities for HeLa Cells.

Natural products are irreplaceable reservoirs for cancer treatments. In this study, 12 phenanthrene compounds were extracted and isolated from Dendrobium officinale. Each chemical structure was identified using comprehensive NMR analysis. All compounds were evaluated for their cytotoxic activities against five tumor cell lines, i.e., HeLa, MCF-7, SK-N-AS, Capan-2 and Hep G2. Compound 5, 1,5,6-trimethoxy-2,7-dihydroxyphenanthrene, displayed the most significant cytotoxic effect against HeLa and Hep G2 cells, with an IC50 of 0.42 and 0.20 µM. For Hela cells, further experiments demonstrated that compound 5 could obviously inhibit cell migration, block cell cycle in the G0/G1 phase and induce apoptosis. Expression measurements for p53 indicated that knock down of p53 by siRNA could mitigate the apoptosis induced by compound 5. Therefore, the compound 5 is a potential candidate drug for HeLa cells in cervical cancer.

[Research of pollution-free and precision cultivation system of Chinese herbal medicines].

The issues of disordering production and non-standard pesticide application are common in the production of Chinese herbal medicines. Aimed to above problems, research groups built the pollution-free and precision cultivation system of medicinal plants. This system mainly included the precise site selection of medicinal plants based on the GIS technology, modern omics-assisted breeding, metagenomics guiding the soil complex improvement, and the precise field management based on rational application of fertilizer and comprehensive control of disease. At present, the production and distribution of medicinal plants were performed in the many poor counties of the whole nation. The breeding platform of resistant varieties was built, and certificates of new and well-bred varieties were received, in the base of genetic backgrounds of the original species of medicinal plants. The disease incidences were declined after application of these resistant varieties. Additionally, chemical pesticide consumption of medicinal plants (such as Panax ginseng, P. notoginseng, Salvia miltiorrhiza, P. quinquefolium, Schisandra chinensis, Platycodon grandiflorum and P. grandiflorus etc.) reduced by 20%-80% based on the genetic testing technologies of plant diseases and insect pests and safety evaluation of pollution-free pesticides. The application of pollution-free and precision cultivation system of Chinese herbal medicines achieve significantly social, economic and ecological benefits.

Radiation Dose and Image Quality in Pediatric Cardiac Computed Tomography: A Comparison Between Sequential and Third-Generation Dual-Source High-Pitch Spiral Techniques.

The aim of this study was to investigate whether there is a reduction in radiation dose and improvement in image quality of pediatric cardiac computed tomography scans performed using the high-pitch spiral technique on a new third-generation dual-source 2 × 192-slice scanner (group B) compared with scans performed using the sequential technique on a single-source 256-slice scanner (group A). We performed a retrospective observational study on 40 patients aged ≤18 years who underwent prospectively electrocardiogram-triggered cardiac computed tomography. Image quality was assessed by pre-defined objective indices and a four-point subjective score. Apart from a higher mean heart rate in group A (P = 0.016), there were otherwise no significant inter-group differences in patient characteristics. The median effective dose was 4.41 mSv (interquartile range 2.58-5.90 mSv) in group A and 0.52 mSv (interquartile range 0.39-0.59 mSv) in group B (P < 0.001), representing a 88 % reduction. Subjective image quality score was significantly better in group B (4 = excellent with no artifact, mode 57.1 %) than in group A (3 = good with mild artifact, mode 57.9 %) (P < 0.001). Noise index, signal-to-noise ratio and contrast-to-noise ratio between both groups were not statistically significant. New third-generation dual-source high-pitch spiral scan technique can deliver excellent image quality with low radiation dose. Our results suggest that it should be considered as a first-choice technique for performing cardiac computed tomography in the pediatric population.

MicroRNA-224 targets ERG2 and contributes to malignant progressions of meningioma.

MicroRNA-224 is overexpressed in various malignant tumors with poor prognosis, which plays a critical role in biological processes including cell proliferation, apoptosis and several developmental and physiological progressions. However, the potential association between miR-224 and clinical outcome in patients with meningiomas remains unknown. Here, we investigate miR-224 expression and biological functions in meningiomas. MiR-224 expression was measured by Northern blot analysis and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in meningioma and normal brain tissues. Kaplan-Meier analysis and Cox regression analysis were used to exam its correlation with clinicopathological features and prognostic value. The biological effects of miR-224 on the cell proliferation and apoptosis in meningioma cells were examined by MTT assay and apoptosis assay. We found the expression levels of miR-224 were significantly higher in meningioma tissues than that in normal brain, positively correlated with advanced pathological grade. Kaplan-Meier analysis indicated that meningioma patients with low miR-224 expression exhibited significantly prolonged overall and recurrence-free survival. Furthermore, we demonstrated that ERG2 was an identical candidate target gene of MiR-224 in vitro. Our results indicated that downregulation of miR-224 suppressed cell growth and resulted in the enhancement of cell apoptosis through activation of the ERG2-BAK-induced apoptosis pathway. Our findings imply the miR-224 expression could predict the overall survival and recurrence-free survival of patients with meningioma and it might be a promising therapeutic target for treating malignant meningiomas.

Decreased levels and function of circulating endothelial progenitor cells in unruptured intracranial saccular aneurysm patients.

Circulating endothelial progenitor cells (EPCs) play a critical role in maintaining endothelial integrity and keeping vascular homeostasis. Previously, we reported that EPCs were involved in repair and remodeling of aneurismal wall. In the present study, we verified this hypothesis by investigating the proliferative ability and count of EPCs in peripheral blood of patients with unruptured intracranial aneurysms (UIAs). Twenty-four patients with UIAs (UIA group) and 24 negative controls (control group) were included in this study. Peripheral blood monocytes (PBMCs) were harvested and selectively cultured. The colony-forming ability of cultured cells was analyzed and the biological functions were examined by testing the adsorption of ulex europaeus agglutinin-1 labeled by fluorescein isothiocyanate and acetylated low-density lipoprotein internalization. The migratory and adhesive ability of cultured EPCs were assessed. In vitro cultured PBMCs were identified as EPCs by examining surface markers CD34, CD133 and vascular endothelial growth factor receptor 2 using flow cytometry. EPCs from UIA group possessed significantly decreased proliferative, migratory and adhesive capacities compared with EPCs from control group. Furthermore, EPCs count in UIA group was significantly decreased. Collectively, these results indicated that the circulating EPCs of UIA patients may be involved in intracranial aneurysm repair and remodeling.

Boosting salt resistance of short antimicrobial peptides.

The efficacies of many antimicrobial peptides are greatly reduced under high salt concentrations, therefore limiting their use as pharmaceutical agents. Here, we describe a strategy to boost salt resistance and serum stability of short antimicrobial peptides by adding the nonnatural bulky amino acid ß-naphthylalanine to their termini. The activities of the short salt-sensitive tryptophan-rich peptide S1 were diminished at high salt concentrations, whereas the activities of its ß-naphthylalanine end-tagged variants were less affected.

A portable microfluidic electrochemical sensing platform for rapid detection of hazardous metal Pb2+ based on thermocapillary convection using 3D Ag-rGO-f-Ni(OH)2/NF as a signal amplifying element.

Heavy metal pollution is causing a great threat to ecological environment and public health, which needs an efficient strategy for monitoring. A portable microfluidic electrochemical sensing system was developed for the determination of heavy metal ions. Herein, the detection of Pb2+ was chosen as a model, and a microfluidic electrochemical sensing chip relying on a smartphone-based electrochemical workstation was proposed for rapid detection Pb2+ with the assistance of thermocapillary convection result from the formed temperature gradient. The 3D Ag-rGO-f-Ni(OH)2/NF composites, prepared by one-step hydrothermal method without any Ni precursor salt, were used to further amplify electrochemical signals under the synergistic effect of thermocapillary convection. The thermocapillary convection could accelerate the preconcentration process and shorten the detection time (save 300 s of preconcentration time). The fabricated system exhibited the exceptional competence for monitoring of Pb2+ range from 0.01 µg/L to 2100 µg/L with a low detection limit (LOD) of 0.00464 µg/L. Furthermore, this portable system has been successfully demonstrated for detecting Pb2+ (0.01 µg/L to 2100 µg/L) in river water (LOD = 0.00498 µg/L), fish (LOD = 0.00566 µg/L) and human serum samples (LOD = 0.00836 µg/L), and the results were consistent with inductively coupled plasma-mass spectrometry (ICP-MS). The proposed novel sensing platform provides a cost-effectiveness, rapidly responding and ease-to-use pathway for analysis of heavy metal ions in real samples and shows great potential in point-of-care testing.

Concordance analysis of cerebrospinal fluid with the tumor tissue for integrated diagnosis in gliomas based on next-generation sequencing.

Purpose: The driver mutations of gliomas have been identified in cerebrospinal fluid (CSF). Here we compared the concordance between CSF and tumor tissue for integrated diagnosis in gliomas using next-generation sequencing (NGS) to evaluate the feasibility of CSF detection in gliomas. Patients and methods: 27 paired CSF/tumor tissues of glioma patients were sequenced by a customized gene panel based on NGS. All CSF samples were collected through lumbar puncture before surgery. Integrated diagnosis was made by analysis of histology and tumor DNA molecular pathology according to the 2021 WHO classification of the central nervous system tumors. Results: A total of 24 patients had detectable circulating tumor DNA (ctDNA) and 22 had at least one somatic mutation or chromosome alteration in CSF. The ctDNA levels varied significantly across different ages, Ki-67 index, magnetic resonance imaging signal and glioma subtypes (p < 0.05). The concordance between integrated ctDNA diagnosis and the final diagnosis came up to 91.6% (Kappa, 0.800). We reclassified the clinical diagnosis of 3 patients based on the results of CSF ctDNA sequencing, and 4 patients were reassessed depending on tumor DNA. Interestingly, a rare IDH1 R132C was identified in CSF ctDNA, but not in the corresponding tumor sample. Conclusion: This study demonstrates a high concordance between integrated ctDNA diagnosis and the final diagnosis of gliomas, highlighting the practicability of NGS based detection of mutations of CSF in assisting integrated diagnosis of gliomas, especially glioblastoma.

Case Report: Cancer spectrum and genetic characteristics of a de novo germline POLD1 p.L606M variant-induced polyposis syndrome.

Germline variations in the DNA polymerase genes, POLE and POLD1, can lead to a hereditary cancer syndrome that is characterized by frequent gastrointestinal polyposis and multiple primary malignant tumors. However, because of its rare occurrence, this disorder has not been extensively studied. In this report, we present the case of a 22-year-old female patient who had been diagnosed with gastrointestinal polyposis, breast fibroadenoma, multiple primary colorectal cancers, and glioblastoma (grade IV) within a span of 4 years. Next-generation sequencing analysis revealed a germline variant in POLD1 (c.1816C>A; p.L606M). In silico analysis using protein functional predicting software, including SIFT, Polyphen, GERP++, and CADD, further confirmed the pathogenicity of POLD1 p.L606M (classified as ACMG grade Class 4). In line with polymerase deficiency, both rectal cancer and glioblastoma tissues exhibited a high tumor mutation burden, with 16.9 muts/Mb and 347.1 muts/Mb, respectively. Interestingly, the patient has no family history of cancer, and gene examination of both parents confirms that this is a de novo germline variant. Therefore, molecular screening for POLD1 may be necessary for patients with such a cancer spectrum, regardless of their family history.

Production of Diethyl Maleate via Oxidative Depolymerization of Organosolv Lignin from Wheat Stalk over the Cooperative Acidic Ionic Liquid Pair.

Lignin, the second largest component of biomass, is considered as an important alternative source of fossil reserves for the production of fuels and chemicals. Here, we developed a novel method to oxidatively degrade organosolv lignin into value-added four-carbon esters, particularly diethyl maleate (DEM), with the cooperative catalyst consisting of 1-(3-sulfobutyl) triethylammonium hydrogen sulfate ([BSTEA]HSO4) and 1-butyl-3-methylimidazolium ferric chloride ([BMIM]Fe2Cl7). Under optimized conditions (1.00 MPa initial O2 pressure, 160 °C, 5 h), the lignin aromatic ring was effectively cleaved by oxidation to form DEM with a yield of 15.85% and a selectivity of 44.25% in the presence of the synergistic catalyst of [BMIM]Fe2Cl7-[BSMIM]HSO4 (1/3, mol/mol). The structure and composition analysis of lignin residues and liquid products confirmed that the aromatic units in lignin were effectively and selectively oxidized. Furthermore, the catalytic oxidation of lignin model compounds was explored for obtaining a possible reaction pathway of oxidative cleavage of lignin aromatic units to DEM. This study provides a promising alternative method for the production of traditional petroleum-based chemicals.

Producing Lignin and Ethyl Levulinate from Wheat Stalk Using 1-(3-Sulfobutyl) Triethylammonium Hydrogen Sulfate and USY Zeolite.

The facile, green, and efficient strategy for the separation of lignin from straw and subsequent production of value-added chemicals is crucial to the current utilization of straw. Herein, up to 23.72% of lignin was isolated from wheat stalk over cheap and green 1-(3-sulfobutyl) triethylammonium hydrogen sulfate ([BSTEA]HSO4) in aqueous ethanol (Vethanol: Vwater = 4:1). The acquired lignin was verified as a p-hydroxyphenyl-guaiacyl-syringyl type, which had a narrower molecular weight distribution, better thermal stability, and higher purity compared with those of the lignin obtained using 1-methyl-3-(4-sulfobutyl)-imidazolium hydrogen sulfate and 1-(3-sulfobutyl) pyridinium hydrogen sulfate. Moreover, a carbohydrate-rich liquid containing [BSTEA]HSO4 was obtained by water removal from the waste liquid after lignin separation and further converted to ethyl levulinate (EL) by a one-pot process in the presence of inexpensive and stable USY zeolite. The yield of EL reached 30.23% at 200 °C for 60 min over the presence of 40% [BSTEA]HSO4 and 60% USY zeolite. Under optimal conditions, the yields of lignin and EL can respectively reach 83.89 and 72.28% of those catalyzed by a fresh catalyst after five cycles. In short, the above-mentioned methods present a green, economic, and efficient route for the extraction of lignin and further treatment of the liquid waste generated during the extraction process.

Glucocorticoid receptor and histone deacetylase-2 mediate dexamethasone-induced repression of MUC5AC gene expression.

Airway occlusion in obstructive airway diseases is caused in part by the overproduction of secretory mucin glycoproteins through the up-regulation of mucin (MUC) genes by inflammatory mediators. Some pharmacological agents, including the glucocorticoid dexamethasone (Dex), repress mucin concentrations in lung epithelial cancer cells. Here, we show that Dex reduces the expression of MUC5AC, a major airway mucin gene, in primary differentiated normal human bronchial epithelial (NHBE) cells in a dose-dependent and time-dependent manner, and that the Dex-induced repression is mediated by the glucocorticoid receptor (GR) and two glucocorticoid response elements (GREs) in the MUC5AC promoter. The pre-exposure of cells to RU486, a GR antagonist, and mutations in either the GRE3 or GRE5 cis-sites abolished the Dex-induced repression. Chromatin immunoprecipitation (ChIP) assays showed a rapid temporal recruitment of GR to the GRE3 and GRE5 cis-elements in the MUC5AC promoter in NHBE and in A549 cells. Immunofluorescence showed nuclear colocalization of GR and histone deacetylase-2 (HDAC2) in MUC5AC-expressing NHBE cells. ChIP also showed a rapid temporal recruitment of HDAC2 to the GRE3 and GRE5 cis-elements in the MUC5AC promoter in both cell types. The knockdown of HDAC2 by HDAC2-specific short interfering RNA prevented the Dex-induced repression of MUC5AC in NHBE and A549 cells. These data demonstrate that GR and HDAC2 are recruited to the GRE3 and GRE5 cis-sites in the MUC5AC promoter and mediate the Dex-induced cis repression of MUC5AC gene expression. A better understanding of the mechanisms whereby glucocorticoids repress MUC5AC gene expression may be useful in formulating therapeutic interventions in chronic lung diseases.

Hybridizing electron-mediated H5PMo10V2O40 with CdS/g-C3N4 for efficient photocatalytic performance of Z-scheme heterojunction in wastewater treatment.

Photocatalytic technology has been considered as a promising method to alleviate environmental pollution owing to the dual characteristics of redox. The novel V-based H5PMo10V2O40 (HPA-2) photocatalyst with Z-scheme heterostructure was constructed. The energy level of HPA-2 matches well with CdS and g-C3N4 (CN) according to Mott-Schottky and UV-Vis diffused reflectance tests, which allows the efficient separation of photogenerated electrons. The optimized CdS/HPA-2/CN showed superior ability in Rhodamine B (RhB) degradation and reduction of Cr (Ⅵ) under visible light irradiation. The maximum rate constant reached 0.092 min-1 for RhB degradation at 60 min and 0.260 min-1 for Cr (Ⅵ) reduction at 20 min, respectively. The photocatalytic mechanism was analyzed by adding scavengers. The effect of active species for RhB degradation was determined as h+ > ·O2- > ·OH, while ·O2- and e- were essential for the reduction of Cr (Ⅵ). Besides, cyclic tests exhibit excellent repeatability and stable structure of CdS/HPA-2/CN after four cycles. Meanwhile, the detailed degradation process of RhB involving de-ethylation, hydroxylation, substitution and decarboxylation was determined according to LC-MS and evaluated by Fukui function calculation. Furthermore, total organic carbon content decreased to 6.2% of the initial value. In this work, as an electron mediator, HPA-2 provides the inspiration for construction of Z-scheme heterojunction, and CdS/HPA-2/CN exhibits enormous potential in the environmental remediation by photocatalysis.

Follow-up study on ThinPrep cytology test-positive patients in tropical regions.

BACKGROUND: As shown in the statistics from the World Health Organization, it is estimated that approximately 75000 new cases of cervical cancer occur every year in China. In 2008, 33000 people died of cervical cancer in China. It is proven that most women are at risk of cervical cancer. The progression from human papillomavirus (HPV) infection to cervical cancer can be several years or decades, which offers a unique opportunity to prevent cancer. AIM: To observe the changes in ThinPrep cytology tests (TCT) and HPV infection in patients who were detected to be positive via TCT screening of cervical cancer and further explore the biopsy results. METHODS: This paper performed a follow-up study on 206 cervical cancer screening-positive patients of 12231 total cases from our previous research. We conducted an observational study on the TCT results based on the interpretation of The Bethesda System. RESULTS: Over a 5-year period, 10 cases received consistent follow-up. The proportions of cases in which glandular epithelial lesions were detected increased over the follow-up period. The differences between the years were statistically significant (P < 0.01). Over the 5 years, the proportion of patients whose squamous epithelial lesions transformed into glandular epithelial lesions increased yearly. Annual positive rates of HPV infection were: year 1, 73% (24/33); year 2, 43% (6/14); year 3, 36% (9/25); year 4, 50% (9/18); and year 5, 25% (6/24). The positive detection rate after biopsy over a 9-year period was 29%. CONCLUSION: The follow-up study for 5 years to 9 years revealed a tendency to change from squamous epithelial lesions to glandular epithelial lesions and an improvement of the disease (which had not been reported previously). The HPV test indicated a high negative conversion ratio of the viral infection. However, the follow-up cases were not found to have persistent infection of high-risk HPV. Therefore, early intervention of cervical cancer screening is necessary. Low re-examination compliance, patient education, and preventive measures should be enhanced.

Characterization of magnetic domain walls using electron magnetic chiral dichroism.

Domain walls and spin states of permalloy were investigated by electron magnetic chiral dichroism (EMCD) technique in Lorentz imaging mode using a JEM-2100F transmission electron microscope. EMCD signals from both Fe and Ni L3,2 edges were detected from the Bloch lines but not from the adjacent main wall. The magnetic polarity orientation of the circular Bloch line is opposite to that of the cross Bloch line. The orientations of Fe and Ni spins are parallel rather than antiparallel, both at the cross Bloch line and circular Bloch line.

miR-24 targets HMOX1 to regulate inflammation and neurofunction in rats with cerebral vasospasm after subarachnoid hemorrhage.

OBJECTIVE: To investigate the effects of miR-24 and HMOX1 on the inflammatory response and neurological function in rats with cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH). METHODS: Fifteen Sprague-Dawley rats were randomly assigned to the sham group (sham operation, treated with normal saline). Rat model of SAH-induced CVS was established in 90 rats, and these rats were randomly divided into the model, miR-24 NC (treated with miR-24-NC vector), miR-24 inhibitor (treated with miR-24 inhibitor vector), HMOX-NC (treated with HMOX1-NC vector), oe-HMOX1 (treated with HMOX1 overexpression vector), and miR-24 inhibitor + si-HMOX1 (treated with miR-24 inhibitor and si-HMOX1 vectors) groups. Adenoviral vectors containing the target sequences were injected into the hippocampus of the rats in the corresponding groups. Dual-luciferase reporter assay was conducted to verify the relationship between miR-24 and HMOX1. The learning and memory abilities, neurological function, cerebral edema, permeability of blood-brain barrier, myeloperoxidase activity, and levels of miR-24, HMOX1, interleukin-6, tumor necrosis factor-α, superoxide dismutase, and malondialdehyde in rats were examined. RESULTS: miR-24 could negatively regulate HMOX1 expression. SAH-induced CVS was accompanied with increased miR-24 expression and decreased HMOX1 expression. Inhibiting miR-24 expression or enhancing the expression of its down streaming target, HMOX1, could partly reverse the increased oxidation and inflammation as well as functional deficits in the rats. Moreover, the effects of miR-24 inhibitor could be reversed by inhibiting HMOX1 expression. CONCLUSION: miR-24 downregulation can promote HMOX1 expression, thereby decreasing the inflammatory response and improving the neurological function of rats with CVS after SAH.

Soluble triggering receptor expressed on myeloid cells-1 as a serum biomarker of early neurologic deterioration and prognosis in acute supratentorial intracerebral hemorrhage.

BACKGROUND: Triggering receptor expressed on myeloid cells-1 (TREM-1) participates in neuroinflammation. We intended to ascertain whether serum soluble TREM-1 (sTREM-1) could be utilized as a biomarker of inflammation, severity, early neurologic deterioration (END) and outcome after primary intracerebral hemorrhage (ICH). METHODS: Serum sTREM-1 levels were gauged in 104 ICH patients and 104 healthy controls. END was diagnosed when the National Institutes of Health Stroke Scale (NIHSS) score increased ≥ 4 points or death between admission and 24 h after admission. Patients with a modified Rankin scale score of > 2 at 3 months were considered to have poor outcome. RESULTS: As compared to controls, patients exhibited significantly elevated serum sTREM-1 levels (median: 309.0 vs 67.9 pg/ml). Serum sTREM-1 concentrations were intimately correlated with NIHSS score (r = 0.574), hematoma volume (r = 0.554), blood leukocyte count (r = 0.529) and serum C-reactive protein concentrations (r = 0.509). Serum sTREM-1 concentrations > 309.0 pg/ml independently predicted END and poor outcome with odds ratio values of 4.054 and 4.721 respectively. Serum sTREM-1 concentrations distinguished END and poor outcome with areas under receiver operating characteristic curve of 0.789 and 0.813 respectively. CONCLUSION: Serum sTREM-1 may represent a promising inflammatory biomarker for assessment of severity and prediction of END and poor outcome after ICH.

Image quality, contrast enhancement and radiation dose of ECG-triggered versus non-ECG-triggered imaging of the aorta on a single source 256-slice CT scanner.

INTRODUCTION: Computed tomography angiography of the aorta (CTAA) is the modality of choice for investigating aortic disease. Our aim was to evaluate image quality, contrast enhancement and radiation dose of electrocardiograph (ECG)-triggered and non-ECG-triggered CTAA on a 256-slice single source CT scanner. Knowledge of these will allow requesting clinician and radiologist to balance radiation risk and image quality. METHODS: We retrospectively assessed data from 126 patients who had undergone CTAA on a single-source CT scanner using ECG-triggered (group 1, n = 77) or non-ECG-triggered (group 2, n =49) protocols. Radiation doses were compared. Qualitative (4-point scale) and quantitative image quality assessments were performed. RESULTS: The mean volume CT dose index, dose length product and effective dose in group 1 were 12.4 ± 1.9 mGy, 765.8 ± 112.4 mGy x cm and 13.0 ± 1.9 mSv, respectively. These were significantly higher compared with group 2 (9.1 ± 2.6 mGy, 624.1 ± 174.8 mGy x cm and 10.6 ± 3.0 mSv, respectively) ( p < 0.001). Qualitative assessment showed image quality at the aortic root-proximal ascending aorta was significantly higher in group 1 (median = 3) than in group 2 (median = 2, p < 0.001). Quantitative assessment showed significantly better mean arterial attenuation, signal-to-noise ratio and contrast-to-noise ratio in ECG-triggered CTAA compared with non-ECG-triggered CTAA. CONCLUSION: ECG-triggered CTAA in a single-source scanner has superior image quality and vessel attenuation of aortic root/ascending aorta but a higher radiation dose of approximately 23%. Its use should be considered specifically when assessing aortic root/ascending aorta pathology.

Preparation and characterization of a self-suspending ultra-low density proppant.

A self-suspending ultra-low density proppant (UDP) was developed based on the polymerization of the unsaturated carbon double bond. Its performance was characterized by FT-IR and SEM, and the sphericity and roundness, diameter distribution, density, mechanical properties, the conductivity of the propped fracture, and mass loss of different fluids were measured. The test results indicated that the UDP no longer contained the unsaturated carbon double bond and the polymerization took place in the raw material. The fracture surface of UDP is compact and it is not easy to produce debris after compression failure. The sphericity and roundness of UDP were above 0.9, and the high sphericity and roundness provided high conductivity. The stirring speed has a great influence on the diameter of UDP, and the UDP with different sizes could be used to prop the hydraulic fracture to different widths. The average apparent density of UDP is as low as 1.044 g cm-3, and it can be suspended in the fracturing fluid for a long time. The strain in the UDP is higher than that in the ceramsite and quartz sand, but its crushing ratio is far below theirs; therefore, the conductivity of the fracture propped by UDP was higher than that of quartz sand and ceramsite. The solubility of UDP in kerosene, reservoir water, and hydrochloric acid is below 1%, indicating that the UDP is also suitable for acid fracturing with proppant. All the experimental results proved that the self-suspending ultra-low density proppant has great potential use in hydraulic fracturing and acid fracturing.

[µ-2,2'-Dimethyl-2,2'-(p-phenyl-ene)diprop-yl]bis-[chloridobis(2-methyl-2-phenyl-prop-yl)tin(IV)].

The mol-ecular structure of the title compound, [Sn(2)(C(10)H(13))(4)(C(14)H(20))Cl(2)], is a binuclear centrosymmetric complex, in which the Sn atoms are four-coordinated by three C atoms and one Cl atom in a distorted tetra-hedral geometry.