Publications by authors named "Xueliang Yang"

32 Publications

Developmental toxicity caused by sanguinarine in zebrafish embryos via regulating oxidative stress, apoptosis and wnt pathways.

Toxicol Lett 2021 Jul 9;350:71-80. Epub 2021 Jul 9.

Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Engineering Research Center of Zebrafish Models for Human Diseases and Drug Screening of Shandong Province, Shandong Provincial Engineering Laboratory for Biological Testing Technology, 28789 Jingshidong Road, Licheng District, Jinan, 250103, Shandong Province, PR China. Electronic address:

Sanguinarine, derived from the root of Sanguinaria canadensis, have multiple biological activities, such as antimicrobial, insecticidal, antitumor, anti-inflammatory and anti-angiogenesis effect, but little is known about its toxicity on normal embryonic development. Here, we study the developmental toxicity using zebrafish model. Notably, sanguinarine caused a significant increase of the malformation rate and decrease of hatching rates and body length of zebrafish embryos. Sanguinarine also impaired the normal development of heart, liver and nerve system of zebrafish embryos. Further, the ROS level and MDA concentrations were remarkably increased, while the activity of T-SOD was decreased. In addition, obvious increase of apoptosis were observed by AO staining or TUNEL assay. Further studies showed that the oxidative stress-, apoptosis-related genes were changed, while genes of nrf2 and wnt pathways were inhibited by sangunarine. To sum up, our study will be helpful to understand the adverse effect of sanguinarine on embryonic development and the underlying molecular mechanism.
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http://dx.doi.org/10.1016/j.toxlet.2021.07.001DOI Listing
July 2021

Baseline quantitative HBcAb strongly predicts undetectable HBV DNA and RNA in chronic hepatitis B patients treated with entecavir for 10 years.

Sci Rep 2021 Jun 28;11(1):13389. Epub 2021 Jun 28.

Department of Infectious Diseases, First Affiliated Hospital of Xi'an Jiaotong University, No. 277 Yanta West Road, Xi'an City, 710061, Shaanxi Province, China.

The predictive effect of quantitative anti-hepatitis B core on double-negative HBV DNA and RNA remains unstudied. We observed dynamic changes in this measure in chronic hepatitis B patients receiving entecavir for 10 years, evaluating its predictive value for double-negative HBV DNA and RNA. Twenty-seven chronic hepatitis B patients treated with entecavir for 10 years were enrolled in this study. Liver function, quantitative anti-hepatitis B core, hepatitis B surface and e antigens, HBV DNA and RNA were measured at baseline and each follow-up. Virological response was defined as double-negative HBV DNA and RNA; serological response was defined as hepatitis B e antigen seroconversion. After antiviral therapy, quantitative anti-hepatitis B core showed an overall downward trend. Patients with virological response had significantly higher quantitative anti-hepatitis B core levels than those without virological response at baseline. Patients with serological response also had higher quantitative anti-hepatitis B core levels than those without serological response at baseline and week 24. Baseline quantitative anti-hepatitis B core level was the only independent predictor for virological and serological responses. Baseline quantitative anti-hepatitis B core level was powerfully predictive of double-negative HBV DNA and RNA in chronic hepatitis B patients receiving long-term entecavir therapy.
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http://dx.doi.org/10.1038/s41598-021-92757-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8238999PMC
June 2021

Solution processable passivated silicon nanowires.

Nanoscale 2021 Jul;13(26):11439-11445

Hebei Key Lab of Optic-Electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding 071002, China. and Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76021, Germany.

The 1D confinement of silicon in the form of a nanowire revives its newness with the emergence of new optical and electronic properties. However, the development of a production process for silicon nanowires (SiNWs) having a high quality crystalline core and exhibiting good stability in solution with effective outer-shell defect passivation is still a challenge. In this work, SiNWs are prepared from a silicon wafer using solution processing steps, and importantly outer-shell-defect passivation is achieved by in situ grafting of organic molecules based on thin films. Defect passivation and the high quality of the SiNWs are confirmed with thin films on glass and flexible plastic substrates. A dramatic enhancement in both the fluorescence lifetime and infrared photoluminescence is observed. The in situ organic passivation of SiNWs has potential application in all low-dimensional silicon devices including infrared detectors, solar cells and lithium-ion battery anodes.
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http://dx.doi.org/10.1039/d1nr02131aDOI Listing
July 2021

Schaftoside Suppresses Pentylenetetrazol-Induced Seizures in Zebrafish via Suppressing Apoptosis, Modulating Inflammation, and Oxidative Stress.

ACS Chem Neurosci 2021 Jul 15;12(13):2542-2552. Epub 2021 Jun 15.

Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), 28789 East Jingshi Road, Ji'nan 250103, Shandong Province, People's Republic of China.

The lack of disease-modifying therapeutic strategies against epileptic seizures has caused a surge in preclinical research focused on exploring and developing novel therapeutic candidates for epilepsy. Compounds from traditional Chinese medicines (TCMs) have gained much attention for a plethora of neurological diseases, including epilepsy. Herein, for the first time, we evaluated the anticonvulsive effects of schaftoside (SS), a TCM, on pentylenetetrazol (PTZ)-induced epileptic seizures in zebrafish and examined the underlying mechanisms. We observed that SS pretreatments significantly suppressed seizure-like behavior and prolonged the onset of seizures. Zebrafish larvae pretreated with SS demonstrated downregulation of expression during seizures. PTZ-induced upregulation of apoptotic cells was decreased upon pretreatment with SS. Inflammatory phenomena during seizure progression including the upregulation of interleukin 6 (), interleukin 1 beta (), and nuclear factor kappa-light-chain-enhancer of activated B cells () were downregulated upon pretreatment with SS. The PTZ-induced recruitment of immunocytes was in turn reduced upon SS pretreatment. Moreover, SS pretreatment modulated oxidative stress, as demonstrated by decreased levels of catalase () and increased levels of glutathione peroxidase-1a () and manganese superoxide dismutase (). However, pretreatment with SS modulated the PTZ-induced downregulation of the relative enzyme activity of CAT, GPx, and SOD. Hence, our findings suggest that SS pretreatment ameliorates PTZ-induced seizures, suppresses apoptosis, and downregulates the inflammatory response and oxidative stress, which potentially protect against further seizures in zebrafish.
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http://dx.doi.org/10.1021/acschemneuro.1c00314DOI Listing
July 2021

STAT3 Activation Is Associated with Interleukin-10 Expression and Survival in Primary Central Nervous System Lymphoma.

World Neurosurg 2020 Feb 25;134:e1077-e1084. Epub 2019 Nov 25.

Department of Hematology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China. Electronic address:

Background: The findings from several studies have confirmed that signal transducer and activator of transcription 3 (STAT3) is constitutively phosphorylated in primary central nervous system lymphoma (PCNSL). However, the underlying mechanism and prognostic significance of STAT3 activation have not yet been clarified.

Methods: The expression of STAT3, phosphorylated STAT3 (p-STAT3), and interleukin (IL)-10 was examined in 32 PCNSL samples using immunohistochemistry. The relationship between IL-10 expression and STAT3 phosphorylation was determined. In addition, the associations of the expression of these proteins with the clinical factors and survival were analyzed.

Results: Expression of STAT3, p-STAT3, and IL-10 was detected in 28 (87.5%), 17 (53.1%), and 25 (78.1%) samples, respectively. IL-10 expression was significantly associated with STAT3 phosphorylation in PCNSL (P = 0.033). STAT3 phosphorylation and IL-10 expression were associated with the presence of multiple brain lesions (P = 0.004 and P = 0.027, respectively), suggesting that STAT3 activation might enhance the intracranial spread of tumors in PCNSL. The 2-year overall survival and progression-free survival (PFS) rates were 67.8% and 35.5%, respectively. Kaplan-Meier survival analysis demonstrated that STAT3 phosphorylation, IL-10 expression, and multiple brain lesions were significantly associated with PFS in those with PCNSL (P = 0.009, P = 0.030, and P = 0.040, respectively). However, Cox regression analysis indicated that only STAT3 phosphorylation was significantly associated with shorter PFS (hazard ratio, 3.22; 95% confidence interval, 1.24-8.37; P = 0.016).

Conclusion: Our results have indicated that STAT3 activation is closely related to IL-10 expression and that p-STAT3 might be a novel biomarker predictive of poor survival in those with PCNSL.
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http://dx.doi.org/10.1016/j.wneu.2019.11.100DOI Listing
February 2020

Study of the distribution of hepatitis B immunoglobulin in pregnant mice using small-animal imaging technology.

J Med Virol 2019 10 22;91(10):1811-1817. Epub 2019 Jul 22.

Department of Infectious Disease, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.

Background: The safety and necessity of hepatitis B immunoglobulin (HBIG) in preventing the mother-to-child transmission of hepatitis B virus (HBV) are still controversial because of its unclear mechanism of action and the inconsistent injection programs used during gestation.

Objectives: This study aimed to show the dynamic transportation and distribution of HBIG in the maternal body and to provide evidence for its clinical efficacy in preventing mother-to-child HBV transmission.

Study Design: Pregnant mice were injected with Cy7-labeled mouse anti-human monoclonal hepatitis B surface antibodies through the tail vein. In vivo imaging technology was used to observe the dynamic transportation and distribution of HBIG in the pregnant mice.

Results: HBIG fluorescence signals were higher in the uterus than in the liver, spleen, and kidneys. Fluorescence signals in the uterine region were obviously higher at the third trimester than at early and mid pregnancy.

Conclusions: HBIG is gradually deposited in the mouse placenta during pregnancy, with the phenomenon being more significant in the third trimester.
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http://dx.doi.org/10.1002/jmv.25521DOI Listing
October 2019

Comparison of Two-Dimensional Shear Wave Elastography with Nine Serum Fibrosis Indices to Assess Liver Fibrosis in Patients with Chronic Hepatitis B: A Prospective Cohort Study.

Ultraschall Med 2019 Apr 10;40(2):237-246. Epub 2019 Jan 10.

Infectious Disease, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China.

Purpose:  To prospectively assess liver fibrosis with two-dimensional shear wave elastography (2D-SWE) in patients with chronic hepatitis B (CHB) and to compare the performance of this modality with that of serum indices using Scheuer scoring from liver biopsies as the reference standard.

Materials And Methods:  123 patients with CHB underwent 2D-SWE measurements and serological tests between April 2016 and February 2018. The 2D-SWE and serum indices in the diagnosis of liver fibrosis were assessed using receiver operating characteristic (ROC) analyses.

Results:  The areas under ROC (AUCs) for 2D-SWE, aspartate transaminase-to-platelet ratio index, fibrosis index based on the four factors, Forns score, King's score, FibroIndex, red cell distribution width-to-platelet ratio, Hepascore, type IV collagen, and hyaluronic acid were 0.851, 0.738, 0.701, 0.739, 0.734, 0.711, 0.692, 0.601, 0.640, and 0.522, respectively, in the diagnosis of substantial fibrosis, 0.975, 0.819, 0.792, 0.829, 0.818, 0.807, 0.732, 0.572, 0.676, and 0.544, respectively, in the diagnosis of severe fibrosis, and 0.972, 0.883, 0.862, 0.908, 0.889, 0.918, 0.808, 0.601, 0.807, and 0.775, respectively, in the diagnosis of cirrhosis. The AUCs of 2D-SWE in the diagnosis of substantial fibrosis, severe fibrosis, and cirrhosis were significantly higher than those of the serum indices (p < 0.05).

Conclusion:  2D-SWE is a reliable noninvasive method for the assessment of liver fibrosis in patients with CHB with better diagnostic performance than that of nine serum fibrosis indices.
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http://dx.doi.org/10.1055/a-0796-6584DOI Listing
April 2019

miR‑675 promotes colorectal cancer cell growth dependent on tumor suppressor DMTF1.

Mol Med Rep 2019 Mar 20;19(3):1481-1490. Epub 2018 Dec 20.

Department of Gastroenterology, Affiliated Hospital of Beihua University, Jilin City, Jilin 132011, P.R. China.

Colorectal cancer (CRC) has become a worldwide health concern, particularly in developing countries. Therefore, the present study focuses on the investigation of oncogenic microRNA (miR)‑675‑3p, and its role in colorectal carcinogenesis. miR‑675‑3p expression was either overexpressed or inhibited in SW480 CRC cells in order to demonstrate its positive effect on the cell proliferation, as determined by MTS and flow cytometry. Then the present study utilized a luciferase assay to demonstrate that cyclin D binding myb like transcription factor 1 (DMTF1) was modulated by miR‑675‑3p directly at its 3'untranslated region. Overexpression or inhibition of miR‑675‑3p affected the expression of DMTF1, as determined by reverse transcription‑quantitative polymerase chain reaction and western blotting. In addition, the overexpression of miR‑675‑3p promoted cell proliferation, whereas the additional introduction of DMTF1 rescued the overgrowth of the SW480 cells. These results were also confirmed in HT29 CRC cells. In summary, the results of the study demonstrated that miR‑675‑3p directly regulated the expression of DMTF1, which contributed to the further regulation of CRC cell proliferation.
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http://dx.doi.org/10.3892/mmr.2018.9780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390018PMC
March 2019

Expression and location of IL-17A, E, F and their receptors in colorectal adenocarcinoma: Comparison with benign intestinal disease.

Pathol Res Pract 2018 Apr 7;214(4):482-491. Epub 2018 Mar 7.

The Clinical Immunology Center, Beihua University, Jilin, Jilin, 132013, China; The Division of Asthma, Allergy & Lung Biology, King's College London, 5th Floor Tower Wing, Guy's Hospital, London, SE1 9RT, United Kingdom. Electronic address:

The research aimed to investigate secretion, expression and location of IL-17 relative ligands, IL-17 relative receptors, infiltrating inflammatory cells and parenchymal structural cells in colorectal cancer (CRC) compared with ulcerative colitis (UC) and benign hyperplastic polyp. 29 human intestinal tissues with CRC, 17 with UC and 7 with polyp were stained using immunohistochemistry to evaluate immunoreactivity for IL-17 family relative ligands including IL-17A, E, F and their respective relative receptors such as IL-17RA, IL-17RB and IL-17RC. At the same time the infiltration of inflammatory cells including lymphocytes, phagocytes, mast cells and neutrophils and parenchymal structural cell changes involving vascular endothelial cells and CD90 fibroblast cells were also evaluated using the same methods The immunoreactivity or positive inflammatory cells of all the sections were analyzed using professional image analysis software to determine statistical significance. The immunoreactivity for IL-17A, IL-17RA, IL-17E, IL-17RB and IL-17F showed significant decrease in CRC tissue when compared to UC (p = 0.00001. respectively). The reduction of above IL-17 relative ligands and receptors was accompanied by an obvious decrease in the number of infiltrating neutrophils and mast cells in CRC (p = 0.00001 and p = 0.007, respectively) but accompanied by a marked increase of CD31 blood vessels (p = 0.001). The immunoreactivity of IL-17A, IL-17RA, IL-17E, IL-17RB and IL-17F and the numbers of infiltrating neutrophils and mast cells showed significant decrease in CRC tissues when compared to those in polyp (p < 0.05). In contrast, the immunoreactivity of IL-17RC and the numbers of CD3 1ymphocytes were elevated in CRC when compared with those in polyp (p = 0.0001, p = 0.007, respectively). In CRC tissues, positive correlations between IL-17A, IL-17RA with CD68 macrophages were observed respectively (r = 0.621, p = 0.0001; r = 0.75, p = 0.0001). IL-17 cytokine family including ligands and their corresponding receptors were secreted and expressed by infiltrating inflammatory cells. Not only infiltrating lymphocytes but also increased blood endothelial cells were relative significantly to genesis and progression of CRC.
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http://dx.doi.org/10.1016/j.prp.2018.03.011DOI Listing
April 2018

Thymosin α1 treatment reduces hepatic inflammation and inhibits hepatocyte apoptosis in rats with acute liver failure.

Exp Ther Med 2018 Apr 7;15(4):3231-3238. Epub 2018 Feb 7.

Department of Infectious Diseases, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.

The present study aimed to evaluate whether thymosin α1 (Tα1) increases survival rates through the improvement of immunofunction and inhibition of hepatocyte apoptosis in rats with acute liver failure (ALF). A total of 25 rats were randomly divided into the control group (CG), the model group (MG) and the treatment group (TG). The CG received an intraperitoneal injection of saline (2 ml). The ALF rat model was established by the intraperitoneal injection of D-galactosamine (700 mg/kg) and lipopolysaccharide (10 µg/kg). The TG received an intraperitoneal injection of Tα1 (0.03 mg/kg) 1 h prior to and 30 min after modeling. The survival rates of the rats were recorded. An additional 63 rats were randomly divided into a CG (n=3), MG (n=30) and TG (n=30). Three rats were sacrificed at 3, 6, 9 and 12 h after establishment of the rat model to detect plasma alanine transaminase (ALT), aspartate transaminase (AST), total bilirubin (TBIL), tumor necrosis factor (TNF)-α and interleukin-10 (IL-10). Liver samples were stained with hematoxylin and eosin and TUNEL, and reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to detect B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) in liver tissue. The results indicated that the survival rate of the TG was significantly higher compared with that of the MG at 24 h (P<0.05). Plasma ALT, AST and TBIL in the MG and TG increased over time (3-12 h), with ALT, AST and TBIL observed to be significantly lower in the TG compared with the MG at each time-point (P<0.05). Hepatocellular necrosis, hemorrhage and inflammatory cell infiltration of ALF were aggravated over time (3-12 h) in the MG and TG. Notably, in the Tα1-treated rats, the hepatocytes appeared healthier with fewer apoptotic cells compared with those from the MG at the same time-points. Hepatocyte apoptotic index increased in the TG and MG, but was significantly lower in the TG compared with the MG at each time-point (P<0.05) in TUNEL assays. Plasma TNF-α and IL-10 in the MG and TG increased over time (3-12 h), with TNF-α observed to be significantly lower in the TG compared with the MG at each time-point (P<0.05), however, IL-10 was observed to be significantly higher in the TG compared with the MG at each time-point (P<0.05). Bax mRNA expression was significantly lower in the TG compared with the MG at each time-point (P<0.05), whereas Bcl-2 was significantly higher (P<0.05). In conclusion, Tα1 improved survival rates in an ALF rat model by downregulating TNF-α and upregulating IL-10, leading to the attenuation of hepatic inflammation and hepatocyte apoptosis.
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http://dx.doi.org/10.3892/etm.2018.5843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5840938PMC
April 2018

Clinical evaluation of haploidentical hematopoietic combined with human umbilical cord-derived mesenchymal stem cells in severe aplastic anemia.

Eur J Med Res 2018 Mar 1;23(1):12. Epub 2018 Mar 1.

Department of Hematology, The First Affiliated Hospital of Chinese PLA General Hospital, No. 51 Fucheng Road, Haidian District, Beijing, 100048, China.

Background: This study not only evaluated the clinical effects of treatment using haploidentical hematopoietic stem cells (haplo-HSCs) combined with human umbilical cord mesenchymal stem cells (UC-MSCs) in patients with severe aplastic anemia (SAA), but also investigated the factors related to graft versus host disease (GVHD).

Methods: Cotransplantation of haplo-HSCs and UC-MSCs was performed in 24 SAA patients. The conditioning regimens consisted of rabbit anti-human T-lymphocyte immunoglobulin (ATG), cyclophosphamide, and fludarabine with or without busulfan. GVHD was prevented using cyclosporine A, ATG, anti-CD25 monoclonal antibody, and mycophenolate material.

Results: The incidence of acute GVHD was 50%. The incidence of severe acute GVHD was not related to gender, age, donor-recipient relations, and patient/donor pair, while patient/donor pair (r = 0.541, P = 0.022) was significantly correlated with incidence of chronic GVHD. Upon follow-up for a median of 13 months, 5 of the 24 patients (20.8%) were dead. The survival rates at 3 and 6 months in all patients were 87.5% (21/24) and 83.3% (20/24), respectively.

Conclusion: Cotransplantation of haplo-HSCs combined with UC-MSCs was an effective and safe approach for the treatment of patients with SAA. The appropriate conditioning regimen and early treatment for infection also played a critical role in the success of HSCT.
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http://dx.doi.org/10.1186/s40001-018-0311-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5831581PMC
March 2018

HCBP6 upregulates human SREBP1c expression by binding to C/EBPβ-binding site in the SREBP1c promoter.

BMB Rep 2018 Jan;51(1):33-38

Department of Infectious Diseases, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China.

Sterol regulatory element-binding protein-1c (SREBP1c) plays an important role in triglyceride (TG) homeostasis. Although our previous study showed that hepatitis C virus core-binding protein 6 (HCBP6) regulates SREBP1c expression to maintain intracellular TG homeostasis, the mechanism underlying this regulation is unclear. In the present study, we found that HCBP6 increased intracellular TG levels by upregulating SREBP1c expression. HCBP6 increased SREBP1c transcription by directly binding to the SREBP1c promoter (at the -139- to +359-bp region). Moreover, we observed that HCBP6 interacted with C/EBPβ-binding site in the SREBP1c promoter both in vitro and in vivo. These results indicate that HCBP6 upregulates human SREBP1c expression by binding to the C/EBPβ-binding site in the SREBP1c promoter. [BMB Reports 2018; 51(1): 33-38].
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5796632PMC
http://dx.doi.org/10.5483/bmbrep.2018.51.1.184DOI Listing
January 2018

DKK4-knockdown enhances chemosensitivity of A549/DTX cells to docetaxel.

Acta Biochim Biophys Sin (Shanghai) 2017 Oct;49(10):899-906

Department of Thoracic Surgery, Shanxi Provincial Cancer Hospital, Taiyuan 030013, China.

Drug resistance greatly limits docetaxel efficiency in the treatment of non-small cell lung cancer (NSCLC). Dickkopf 4 (DKK4), a negative regulator of Wnt/β-catenin pathway, is believed to be involved in various human cancers; whereas the association of DKK4 with acquired docetaxel resistance in NSCLC remains unclear. In the present study, we investigated the involvement of DKK4 in the docetaxel-resistant human lung adenocarcinoma A549 (A549/DTX) cells. Our results showed that DKK4 expression was significantly increased in the A549/DTX cells compared with in the A549 cells, as well as in the culture supernatant of A549/DTX cells. DKK4 overexpression increased the resistance of A549 cells to docetaxel. DKK4-knockdown promoted inhibition of A549/DTX cell growth, and reduced the colony formation and invasion capacity of A549/DTX cells. Moreover, DKK4-knockdown promoted the pro-apoptotic effect of docetaxel characterized with caspase 3 activation and inhibition of BCL-2 expression in A549/DTX cells, which was possibly mediated by inducing the activation of c-Jun N-terminal kinase (JNK)-related signaling pathway. Thus, our results indicated that DKK4-knockdown promoted the cytotoxic and pro-apoptotic activity of A549/DTX cells, which suggests a critical role of DKK4 in docetaxel resistance of the A549 cells and provides the potential to combine docetaxel therapy with DKK4 depletion in treating NSCLC.
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http://dx.doi.org/10.1093/abbs/gmx086DOI Listing
October 2017

Pterostilbene alleviates polymicrobial sepsis-induced liver injury: Possible role of SIRT1 signaling.

Int Immunopharmacol 2017 Aug 25;49:50-59. Epub 2017 May 25.

Department of Infectious Diseases, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China. Electronic address:

Liver injury occurs frequently during sepsis. Pterostilbene (Pte), a natural dimethylated analog of resveratrol from blueberries, exerts anti-inflammatory and anti-apoptotic effects in various diseases. However, the role of Pte in sepsis-induced liver injury and its underlying mechanisms remain unknown. The current study aimed to evaluate the protective effects of Pte on sepsis-induced liver injury and its potential mechanisms. Sepsis was induced using cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were administered Pte (5, 10, 15mg/kg, i.p.) at 0.5h, 2h, and 8h after CLP induction. The pathological changes of the liver were evaluated using hematoxylin and eosin (H&E) staining. The serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL-6), myeloperoxidase (MPO), p38 mitogen-activated protein kinase (p38MAPK), Bax, and B-cell lymphoma 2 (Bcl-2) were also evaluated. Pte treatment attenuated the CLP-induced liver injury, as evidenced by the attenuated histopathologic injuries and the decreased serum aminotransferase levels. Pte reduced the serum inflammatory cytokine (TNF-α and IL-6) levels and hepatic mRNA levels of TNF-α and IL-6. Pte also reduced MPO activity and p38MAPK activation in the liver. Additionally, Pte significantly inhibited Bax expression and increased Bcl-2 expression. Moreover, Pte increased the expression of sirtuin-1 (SIRT1) and reduced the expression of acetylated forkhead box O1 (Ac-FoxO1), acetylated Ac-p53, and acetylated nuclear factor-kappa beta (Ac-NF-κB). However, SIRT1 small interfering RNA (siRNA) abolished Pte's effects on the expression levels of those protein. Notably, Pte improved the survival rate in septic mice. In conclusion, Pte alleviates sepsis-induced liver injury by reducing inflammatory response and inhibiting hepatic apoptosis, and the potential mechanism is associated with SIRT1 signaling activation.
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http://dx.doi.org/10.1016/j.intimp.2017.05.022DOI Listing
August 2017

Ab initio kinetics studies of hydrogen atom abstraction from methyl propanoate.

Phys Chem Chem Phys 2016 Feb;18(6):4594-607

Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA. and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, USA.

The kinetics of hydrogen abstraction by five radicals (H, CH3, O((3)P), OH, and HO2) from a biodiesel surrogate, methyl propanoate (MP), is theoretically investigated. We employ high-level ab initio quantum chemistry methods, coupled-cluster singles and doubles with perturbative triples correction (CCSD(T)) and multi-reference singles and doubles configuration interaction (MRSDCI) with the Davidson-Silver (DS) correction, and obtain chemically accurate reaction energetics. Overall, MRSDCI + DS predicts comparable energetics to CCSD(T) for MP + H/CH3/O/OH. The rate constants are computed using transition state theory (TST-Rice-Ramsperger-Kassel-Marcus theory) in conjunction with the separable-hindered-rotor approximation, variable reaction coordinate TST, and the multi-structure all-structure (MS-AS) approach. A simplified method, semi-multi-structure, is also employed for MP + OH/HO2, and the rate coefficients with this less expensive method are in good agreement with the results obtained with the MS-AS method. The fitted modified Arrhenius expressions are provided over a temperature range of 250 to 2000 K. The predicted rate coefficients for MP + OH agree remarkably well with experimental data over a wide temperature range. Branching ratio analysis of all the studied reactions shows that abstractions of the secondary H atoms within MP are expected to dominate the consumption of fuel at low temperatures, and the contributions of abstractions from the two methyl groups increase with temperature for all abstracting radicals.
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http://dx.doi.org/10.1039/c5cp07282dDOI Listing
February 2016

History of incomplete vaccination may associate with occurrence of hemorrhagic fever with renal syndrome with relieved clinical symptoms.

J Med Virol 2016 Jul 16;88(7):1168-72. Epub 2015 Dec 16.

Department of Infectious Diseases, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi Province, China.

Objective: This retrospective study is aimed to investigate the clinical features of the patients with history of incomplete vaccination against hemorrhagic fever with renal syndrome (HFRS).

Methods: Data of 140 cases of hospitalized patients with HFRS were collected. The patients were divided into incomplete vaccinated group (n = 10) and unvaccinated group (n = 130) according to vaccination status. Demographic, clinical, and laboratory characteristics of the two groups' patients were compared through t test, Pearson χ(2) test, and Mann-Whitney test.

Results: In comparison with the unvaccinated group, the incidence rate of vomiting and hypotensive-shock, the white blood cell (WBC) and platelet count, the level of blood urea nitrogen and albumin, total number of dialysis and hospitalization cost of patients in the incomplete vaccinated group have statistically significant differences.

Conclusion: HFRS disease may still occur in individuals with a history of HFRS incomplete vaccination although the symptoms may be mild. Effective vaccination against HFRS needs sufficient doses and booster shot of the vaccine.
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http://dx.doi.org/10.1002/jmv.24443DOI Listing
July 2016

Ab initio pressure-dependent reaction kinetics of methyl propanoate radicals.

Phys Chem Chem Phys 2015 Dec;17(46):31061-72

Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA. and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544, USA.

The unimolecular dissociation and isomerization kinetics of the three methyl propanoate (MP) radicals, CH3CH2C(=O)OĊH2 (MP-m), CH3ĊHC(=O)OCH3 (MP-α), and ĊH2CH2C(=O)OCH3 (MP-β), are theoretically investigated using high-level ab initio methods and the Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation (ME) theory. Stationary-point energies are obtained using the coupled cluster singles and doubles with perturbative triples correction (CCSD(T)), multi-reference singles and doubles configuration interaction (MRSDCI) with the Davidson-Silver (DS) correction, and multi-reference averaged coupled pair functional (MRACPF2) theories. The isomerization barriers between the three radicals are predicted to be generally lower than the corresponding bond dissociation channels, leading to a strongly coupled reaction system in subsequent kinetics studies. The phenomenological temperature- and pressure-dependent rate coefficients are computed using the RRKM/ME theory over a temperature range of 500 to 2000 K and at a pressure range of 0.01 atm to the high-pressure limit, which are then fitted to modified Arrhenius expressions. The β-scission rate coefficients of MP-α to CH3CHC(=O) and CH3O[combining dot above] are predicted to be the smallest because of its highest activation energy among all studied unimolecular reactions channels. Analysis of branching fractions shows that both MP-m and MP-α radicals mainly decompose to the bimolecular products CH3CH2Ċ(=O) and H2CO, whereas the MP-β radical primarily decomposes via cleavage of a C-C bond to form C2H4 and CH3OĊ(=O). The isomerization channels dominate at low temperatures, the branching fractions of which decrease with increasing temperature and become very minor at about 2000 K. Our accurate rate coefficients and branching fractions help to illuminate the unique combustion properties of MP.
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http://dx.doi.org/10.1039/c5cp06004dDOI Listing
December 2015

Ab Initio Unimolecular Reaction Kinetics of CH2C(═O)OCH3 and CH3C(═O)OCH2 Radicals.

J Phys Chem A 2015 Oct 13;119(42):10553-62. Epub 2015 Oct 13.

Department of Chemistry, ‡Department of Mechanical and Aerospace Engineering, §Program in Applied and Computational Mathematics, and ∥Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544, United States.

The unimolecular dissociation and isomerization kinetics of the methyl ester combustion intermediates methoxycarbonylmethyl (CH2C(═O)OCH3) and acetyloxylmethyl (CH3C(═O)OCH2) are theoretically investigated using high-level ab initio methods and the Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation (ME) theory. Potential energy surfaces (PESs) are obtained using coupled cluster singles and doubles with perturbative triples correction (CCSD(T)), multireference singles and doubles configuration interaction (MRSDCI) with the Davidson-Silver (DS) correction, and multireference averaged coupled pair functional (MRACPF2) theory. The transition states exhibit high T1 diagnostics in coupled cluster calculations, suggesting the need for a multireference correlated wave function treatment. MRSDCI+DS and MRACPF2 capture their multiconfigurational character well, yielding lower barrier heights than CCSD(T) for these reactions. The rate coefficients are computed using the RRKM/ME theory over a 500-2500 K temperature range and at a pressure range of 0.01 atm to the high-pressure limit. The temperature- and pressure-dependent rate coefficients are given in modified Arrhenius expressions. The β-scission of CH2C(═O)OCH3 is predicted to have a much higher barrier than the corresponding isomerization reaction and the β-scission of CH3C(═O)OCH2. Consequently, the rate coefficients for β-scission of CH2C(═O)OCH3 are the smallest among the three reactions and the isomerization followed by decomposition to CH3C(═O) and HCHO is the dominant reaction pathway for CH2C(═O)OCH3. Both radicals CH2C(═O)OCH3 and CH3C(═O)OCH2 are predicted to mainly decompose to CH3C(═O) + HCHO rather than to the bimolecular product CH2C(═O) + CH3O. A newly developed MA combustion mechanism, using our theoretical rate coefficients for the MA-related reactions, predicts combustion properties in good agreement with available experimental data.
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http://dx.doi.org/10.1021/acs.jpca.5b08331DOI Listing
October 2015

Ab Initio Reaction Kinetics of CH3OĊ(═O) and ĊH2OC(═O)H Radicals.

J Phys Chem B 2016 Mar 14;120(8):1590-600. Epub 2015 Oct 14.

Department of Chemistry, ‡Department of Mechanical and Aerospace Engineering, §Program in Applied and Computational Mathematics, and ∥Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544, United States.

The dissociation and isomerization kinetics of the methyl ester combustion intermediates methoxycarbonyl radical (CH3OĊ(═O)) and (formyloxy)methyl radical (ĊH2OC(═O)H) are investigated theoretically using high-level ab initio methods and Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation (ME) theory. Geometries obtained at the hybrid density functional theory (DFT) and coupled cluster singles and doubles with perturbative triples correction (CCSD(T)) levels of theory are found to be similar. We employ high-level ab initio wave function methods to refine the potential energy surface: CCSD(T), multireference singles and doubles configuration interaction (MRSDCI) with the Davidson-Silver (DS) correction, and multireference averaged coupled-pair functional (MRACPF2) theory. MRSDCI+DS and MRACPF2 capture the multiconfigurational character of transition states (TSs) and predict lower barrier heights than CCSD(T). The temperature- and pressure-dependent rate coefficients are computed using RRKM/ME theory in the temperature range 300-2500 K and a pressure range of 0.01 atm to the high-pressure limit, which are then fitted to modified Arrhenius expressions. Dissociation of CH3OĊ(═O) to ĊH3 and CO2 is predicted to be much faster than dissociating to CH3Ȯ and CO, consistent with its greater exothermicity. Isomerization between CH3OĊ(═O) and ĊH2OC(═O)H is predicted to be the slowest among the studied reactions and rarely happens even at high temperature and high pressure, suggesting the decomposition pathways of the two radicals are not strongly coupled. The predicted rate coefficients and branching fractions at finite pressures differ significantly from the corresponding high-pressure-limit results, especially at relatively high temperatures. Finally, because it is one of the most important CH3Ȯ removal mechanisms under atmospheric conditions, the reaction kinetics of CH3Ȯ + CO was also studied along the PES of CH3OĊ(═O); the resulting kinetics predictions are in remarkable agreement with experiments.
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http://dx.doi.org/10.1021/acs.jpcb.5b07959DOI Listing
March 2016

Ab Initio Kinetics of Hydrogen Abstraction from Methyl Acetate by Hydrogen, Methyl, Oxygen, Hydroxyl, and Hydroperoxy Radicals.

J Phys Chem A 2015 Jun 28;119(24):6377-90. Epub 2015 May 28.

†Department of Chemistry, ‡Department of Mechanical and Aerospace Engineering, §Program in Applied and Computational Mathematics, and ∥Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States.

The kinetics of hydrogen abstraction by five radicals (H, O((3)P), OH, CH3, and HO2) from methyl acetate (MA) is investigated theoretically in order to gain further understanding of certain aspects of the combustion chemistry of biodiesels, such as the effect of the ester moiety. We employ ab initio quantum chemistry methods, coupled cluster singles and doubles with perturbative triples correction (CCSD(T)) and multireference averaged coupled pair functional theory (MRACPF2), to predict chemically accurate reaction energetics. Overall, MRACPF2 predicts slightly higher barrier heights than CCSD(T) for MA + H/CH3/O/OH, but slightly lower barrier heights for hydrogen abstraction by HO2. Based on the obtained reaction energies, we also report high-pressure-limit rate constants using transition state theory (TST) in conjunction with the separable-hindered-rotor approximation, the variable reaction coordinate TST, and the multi-structure all-structure approach. The fitted modified Arrhenius expressions are provided over a temperature range of 250 to 2000 K. The predictions are in good agreement with available experimental results. Abstractions from both of the methyl groups in MA are expected to contribute to consumption of the fuel as they exhibit similar rate coefficients. The reactions involving the OH radical are predicted to have the highest rates among the five abstracting radicals, while those initiated by HO2 are expected to be the lowest.
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http://dx.doi.org/10.1021/acs.jpca.5b03506DOI Listing
June 2015

RETRACTED ARTICLE: Cotransplantation of human umbilical cord mesenchymal and haplo-hematopoietic stem cells in patients with severe aplastic anemia.

Cytotechnology 2016 Jan 17;68(1):177. Epub 2015 Aug 17.

Department of Hematology, the First Affiliated Hospital of Chinese PLA General Hospital, No. 51 Fucheng Road, Haidian District, Beijing, 100853, China.

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http://dx.doi.org/10.1007/s10616-014-9793-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4698271PMC
January 2016

The effect of hepatitis B virus infected embryos on pregnancy outcome.

Eur J Obstet Gynecol Reprod Biol 2014 Jan 24;172:10-4. Epub 2013 Oct 24.

Department of Infectious Diseases, the First Affiliated Hospital, Xi'an Jiaotong University, Xi'an Yanta Road No. 277, Xi'an 710061, Shaanxi Province, China.

Objective: HBV vertical transmission is the main reason for chronic HBV infection, but there is no clear conclusion about the effect of HBV infection on pregnancy outcome. This study aimed to investigate the effect of HBV-infected embryos on pregnancy outcome.

Study Design: 75 couples who received ART treatment were followed up. Among them were 25 couples (group A) with at least the husband or wife infected with HBV, and 50 couples (group B) with negative serum HBV markers of both husband and wife. The clinical pregnancy rate, early abortion rate, neonatal malformation rate, neonatal HBV infection rate, and HBV infection rate of the six-month-old infant were compared between these two groups, and Fisher's exact test was applied. HBV mRNA in abandoned embryos of the patients was detected by single-cell RT-PCR.

Results: Both the early abortion rate and the abortion rate with the mother infected HBV in group A were significantly higher than in group B (P=0.043, P=0.030 respectively). The clinical pregnancy rates of groups A and B were 36% and 44% respectively (P=0.248>0.05). The neonatal malformation rate, neonatal HBV infection rate, and HBV infection rate of six-month-old infants in group A and group B were all 0. Specific HBV mRNA fragments were detected in 6 cases of 62 cleavage embryos in group A, giving a positive rate of 9.7%. The positive rates with mother infected and father infected with HBV were 13.2% (5/38) and 5.6% (1/18) respectively.

Conclusions: HBV infection can increase the early abortion rate of pregnancy, and the reason may be related to HBV-infected embryos.
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http://dx.doi.org/10.1016/j.ejogrb.2013.10.002DOI Listing
January 2014

Recombination of allyl radicals in the high temperature fall-off regime.

J Phys Chem A 2013 Jun 4;117(23):4750-61. Epub 2013 Jun 4.

Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States.

The recombination of allyl radicals (C3H5), generated from the dissociation of 1,5-hexadiene or allyl iodide dilute in krypton, has been investigated in a diaphragmless shock tube using laser schlieren densitometry, LS, (900-1700 K, 10 ± 1, 29 ± 3, 57 ± 3, and 120 ± 4 Torr). The LS density gradient profiles were simulated and excellent agreement was found between simulations and experimental profiles. Rate coefficients for C3H5I → C3H5 + I and C3H5 + C3H5 → C6H10 were obtained and showed strong fall-off. Second order rate coefficients for allyl radical recombination were determined as k(1a,124Torr) = (2.6 ± 0.8) × 10(55)T( -12.995) exp(-8426/T), k(1a,57Torr) = (1.7 ± 0.5) × 10(60)T( -14.49) exp(-9344/T), and k(1a,30Torr) = (7.5 ± 2.3) × 10(66)T( -15.935) exp(-10192/T) cm(3) mol(-1)s(-1). The contribution of a disproportionation channel in allyl radical reactions was assessed, and the best agreement was obtained with no more than 5% disproportionation. Notably, because both the forward and back reactions of C6H10 ⇌ C3H5 + C3H5 were measured, utilizing two different precursors, the equilibrium constant of this reaction could be found, suggesting an entropy of formation of 1,5-hexadiene, 87.3 cal mol(-1 )K(-1), which is significantly smaller than that group additivity predicts, but larger than other reference literature values.
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http://dx.doi.org/10.1021/jp402484vDOI Listing
June 2013

Recombinant VAA-I from Viscum album induces apoptotic cell death of hepatocellular carcinoma SMMC7721 cells.

Molecules 2012 Sep 26;17(10):11435-46. Epub 2012 Sep 26.

Department of Hepatobiliary and Pancreatic Surgery, the First Clinical Hospital, Jilin University, Jilin, China.

Researchers have proposed that VAA-I, a specific plant lectin found in Viscum album, has therapeutic effects on cancer and autoimmune diseases. VAA-I has shown some promising treatment results in some types of tumor cell lines, especially SMMC-7721 cells (human hepatocellular carcinoma cells). However, few details are known about the mechanism and process of cell death induced by VAA-I in tumor cells. In this study, the cell morphology results showed that SMMC-7721 cells treated with VAA-I exhibited several features typical of apoptotic cell death, which was confirmed by the Caspase inhibition assay. Fluo-3-acetoxymethyl ester (AM) fluorescence imaging techniques showed that rVAA-I significantly elevated the intracellular calcium level ([Ca2+]i) in SMMC-7721 cells. These findings suggest that apoptosis may play the most important role in SMMC-7721 cell death induced by rVAA-I. Finally, in the SMMC-7721 cells treated with rVAA-I, a series of genes in the p38 mitogen-activated protein kinase (MAPK) signaling pathway were expressed differentially, and further found that PI 3-kinase pathway is involved in rVAA-I signal transduction in SMMC-7721 cells.
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http://dx.doi.org/10.3390/molecules171011435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6268905PMC
September 2012

Thermal dissociation of ethylene glycol vinyl ether.

Phys Chem Chem Phys 2011 Dec 24;13(48):21288-300. Epub 2011 Oct 24.

Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL-60439, USA.

The pyrolysis of ethylene glycol vinyl ether (EGVE), an initial product of 1,4-dioxane dissociation, was examined in a diaphragmless shock tube (DFST) using laser schlieren densitometry (LS) at 57 ± 2 and 122 ± 3 Torr over 1200-1800 K. DFST/time-of-flight mass spectrometry experiments were also performed to identify reaction products. EGVE was found to dissociate via two channels: (1) a molecular H atom transfer/C-O scission to produce C(2)H(3)OH and CH(3)CHO, and (2) a radical channel involving C-O bond fission generating ˙CH(2)CH(2)OH and ˙CH(2)CHO radicals, with the second channel being strongly dominant over the entire experimental range. A reaction mechanism was constructed for the pyrolysis of EGVE which simulates the LS profiles very well over the full experimental range. The decomposition of EGVE is clearly well into the falloff region for these conditions, and a Gorin model RRKM fit was obtained for the dominant radical channel. The results are in good agreement with the experimental data and suggest the following rate coefficient expressions: k(2,∞) = (6.71 ± 2.6) × 10(27) × T(-3.21)exp(-35512/T) s(-1); k(2)(120 Torr) = (1.23 ± 0.5) × 10(92) × T(-22.87)exp(-48 248/T) s(-1); k(2)(60 Torr) = (2.59 ± 1.0) × 10(88) × T(-21.96)exp(-46283/T) s(-1).
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http://dx.doi.org/10.1039/c1cp21073dDOI Listing
December 2011

Experimental and theoretical investigation of the self-reaction of phenyl radicals.

J Phys Chem A 2010 Aug;114(32):8240-61

Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.

A combination of experiment and theory is applied to the self-reaction kinetics of phenyl radicals. The dissociation of phenyl iodide is observed with both time-of-flight mass spectrometry, TOF-MS, and laser schlieren, LS, diagnostics coupled to a diaphragmless shock tube for temperatures ranging from 1276 to 1853 K. The LS experiments were performed at pressures of 22 +/- 2, 54 +/- 7, and 122 +/- 6 Torr, and the TOF-MS experiments were performed at pressures in the range 500-700 Torr. These observations are sensitive to both the dissociation of phenyl iodide and to the subsequent self-reaction of the phenyl radicals. The experimental observations indicate that both these reactions are more complicated than previously assumed. The phenyl iodide dissociation yields approximately 6% C(6)H(4) + HI in addition to the major and commonly assumed C(6)H(5) + I channel. The self-reaction of phenyl radicals does not proceed solely by recombination, but also through disproportionation to benzene + o-/m-/p-benzynes, with comparable rate coefficients for both. The various channels in the self-reaction of phenyl radicals are studied with ab initio transition state theory based master equation calculations. These calculations elucidate the complex nature of the C(6)H(5) self-reaction and are consistent with the experimental observations. The theoretical predictions are used as a guide in the development of a model for the phenyl iodide pyrolysis that accurately reproduces the observed laser schlieren profiles over the full range of the observations.
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http://dx.doi.org/10.1021/jp1031064DOI Listing
August 2010

The dissociation of diacetyl: a shock tube and theoretical study.

J Phys Chem A 2009 Jul;113(29):8318-26

Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.

The dissociation of diacetyl dilute in krypton has been studied in a shock tube using laser schlieren densitometry at 1200-1800 K and reaction pressures of 55 +/- 2, 120 +/- 3, and 225 +/- 5 Torr. The experimentally determined rate coefficients show falloff and an ab initio/Master Equation/VRC-TST analysis was used to determine pressure-dependent rate coefficient expressions that are in good agreement with the experimental data. From the theoretical calculations k(infinity)(T) = 5.029 x 10(19) (T/298 K)(-3.40) exp(-37665/T) s(-1) for 300 < T < 2000 K. The laser schlieren profiles were simulated using a model for methyl recombination with appropriate additions for diacetyl. From the simulations rate coefficients were determined for CH(3) + CH(3) = C(2)H(6) and CH(3) + C(4)H(6)O(2) = CH(3)CO + CH(2)CO + CH(4) (k(T) = 2.818T(4.00) exp(-5737/T) cm(3) mol(-1) s(-1)). Excellent agreement is found between the simulations and experimental profiles, and Troe type parameters have been calculated for the dissociation of diacetyl and the recombination of methyl radicals.
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http://dx.doi.org/10.1021/jp903716fDOI Listing
July 2009

Decomposition and vibrational relaxation in CH3I and self-reaction of CH3 radicals.

J Phys Chem A 2009 Jul;113(29):8307-17

Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.

Vibrational relaxation and dissociation of CH(3)I, 2-20% in krypton, have been investigated behind incident shock waves in a diaphragmless shock tube at 20, 66, 148, and 280 Torr and 630-2200 K by laser schlieren densitometry. The effective collision energy obtained from the vibrational relaxation experiments has a small, positive temperature dependence, DeltaE(down) = 63 x (T/298)(0.56) cm(-1). First-order rate coefficients for dissociation of CH(3)I show a strong pressure dependence and are close to the low-pressure limit. Restricted-rotor Gorin model RRKM calculations fit the experimental results very well with DeltaE(down) = 378 x (T/298)(0.457) cm(-1). The secondary chemistry of this reaction system is dominated by reactions of methyl radicals and the reaction of the H atom with CH(3)I. The results of the decomposition experiments are very well simulated with a model that incorporates methyl recombination and reactions of methylene. Second-order rate coefficients for ethane dissociation to two methyl radicals were derived from the experiments and yield k = (4.50 +/- 0.50) x 10(17) exp(-32709/T) cm(3) mol(-1) s(-1), in good agreement with previous measurements. Rate coefficients for H + CH(3)I were also obtained and give k = (7.50 +/- 1.0) x 10(13) exp(-601/T) cm(3) mol(-1) s(-1), in reasonable agreement with a previous experimental value.
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http://dx.doi.org/10.1021/jp903336uDOI Listing
July 2009

Vacuum ultraviolet excitation spectroscopy of the autoionizing Rydberg states of atomic sulfur in the 73 350-84 950 cm(-1) frequency range.

J Chem Phys 2008 Feb;128(8):084303

Department of Chemistry, University of California, Davis, California, 95616, USA.

The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the 1 D and 1 S states have been recorded in the 73 350-84 950 cm(-1) frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S(1 D) and S(1 S) atoms are produced by the 193 nm photodissociation of CS2. The observed PIE spectra of S(1 D) and S(1 S) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S+(4S 3/2)+e(-) ionization continuum. Velocity-mapped ion images of the S+ at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the 1 D, 1 S, or 3P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes tau of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of tau(n*) proportional to, n*3, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.
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http://dx.doi.org/10.1063/1.2829403DOI Listing
February 2008

A vacuum ultraviolet laser photoionization and pulsed field ionization study of nascent S(3P2,1,0) and S(1D2) formed in the 193.3 nm photodissociation of CS2.

J Chem Phys 2008 Jan;128(1):014305

Department of Chemistry, University of California, Davis, California 95616, USA.

The photoionization efficiency (PIE) and pulsed field ionization-photoion (PFI-PI) spectra for sulfur atoms S(3P2,1,0) and S(1D2) resulting from the 193.3 nm photodissociation of CS2 have been measured using tunable vacuum ultraviolet (vuv) laser radiation in the frequency range of 82 750-83 570 cm(-1). The PIE spectrum of S(3P2,1,0) near their ionization threshold exhibits steplike structures. On the basis of the velocity-mapped ion-imaging measurements, four strong autoionizing peaks observed in the PIE measurement in this frequency range have been identified to originate from vuv excitation of S(1D2). The PFI-PI measurement reveals over 120 previously unidentified new Rydberg lines. They have been assigned as Rydberg states [3p3(4S composite function nd3 D composite function (n=17-64)] converging to the ground ionic state S+(4S composite function) formed by vuv excitations of S(3P2,1,0). The converging limits of these Rydberg series have provided more accurate values, 82 985.43+/-0.05, 83 162.94+/-0.05, and 83 559.04+/-0.05 cm(-1) for the respective ionization energies of S(3P0), S(3P1), and S(3P2) to form S+(4S composite function). The relative intensities of the PFI-PI bands for S(3P0), S(3P1), and S(3P2) have been used to determine the branching ratios for these fine structure states, S(3P0):S(3P1):S(3P2)=1.00:1.54:3.55, produced by photodissociation of CS2 at 193.3 nm.
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http://dx.doi.org/10.1063/1.2816749DOI Listing
January 2008
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