On the use of an explicit chemical mechanism to dissect peroxy acetyl nitrate formation.

Peroxy acetyl nitrate (PAN) is a key component of photochemical smog and plays an important role in atmospheric chemistry. Though it has been known that PAN is produced via reactions of nitrogen oxides (NOx) with some volatile organic compounds (VOCs), it is difficult to quantify the contributions of individual precursor species. Here we use an explicit photochemical model--Master Chemical Mechanism (MCM) model--to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008. PAN production was sensitive to both NOx and VOCs. Isoprene was the predominant VOC precursor at suburb with biogenic impact, whilst anthropogenic hydrocarbons dominated at downtown. PAN production was attributable to a relatively small class of compounds including NOx, xylenes, trimethylbenzenes, trans/cis-2-butenes, toluene, and propene. MCM can advance understanding of PAN photochemistry to a species level, and provide more relevant recommendations for mitigating photochemical pollution in large cities

Mediating role of resilience in the relationships of physical activity and mindful self-awareness with peace of mind among college students

Abstract Peace of mind (PoM) is an index of mental health in Asian culture and emphasizes low arousal, happiness, harmony, and an internal state of peacefulness. While previous studies have found that mindful self-awareness can contribute to PoM, regular physical activity (PA) is also an important factor contributing to one’s PoM due to its function in promoting one's resilience. The study aims to investigate a hypothetical model that assumes PA is associated with resilience while controlling for mindful self-awareness, contributing to PoM. The PoM scale, Connor-Davidson Resilience Scale, Chinese translation of Mindful Attention Awareness Scale, and PA self-report questionnaire were used. A path analysis was applied to test the association between these variables and the mediating role of resilience. A total of 436 students from a university in Taiwan were recruited; the mean age was 20.87, with 46.3% female and 73.6% engaging in over 150 min/week of moderate PA. Gender and age negatively correlated with PA. After controlling for age and gender, there was no direct effect of physical activity on PoM; both mindful self-awareness and PA predict resilience, which in turn predicts PoM, suggesting that both cognitive (i.e., mindful self-awareness) and PA are important to cultivate resilience and thus PoM

Increase in Docetaxel-Resistance of Ovarian Carcinoma-Derived RMG-1 Cells with Enhanced Expression of Lewis Y Antigen

Epithelial carcinomas of the ovary exhibit the highest mortality rate among gynecologic malignancies. Studies found that the metabolism of glycolipids or carbohydrates is associated with acquirement of anticancer drug-resistance by cancer cells. This study was to characterize possible involvement of Lewis Y (LeY) antigen in the drug-resistance of cancer cells. We transfected the α1,2-fucosyltransferase gene into human ovarian carcinoma-derived RMG-1 cells and established RMG-1-hFUT cells with enhanced expression of LeY. We determined the effects of docetaxel on the survival of cells by MTT assaying and observed the apoptosis of cells in the presence of docetaxel by flow cytometric analysis and by transmission electron microscopy. Plasma membranes and intracellular granules in RMG-1-hFUT cells were stained with anti-LeY antibody, the intensity of the staining was higher than that in control cells. The RMG-1-hFUT cells exhibited higher resistance to docetaxel than the control cells with regard to the docetaxel concentration and time course. After treatment with 10 μg/mL docetaxel for 72 h, the control cells, but not RMG-1-hFUT, contained abundant positively stained cell debris due to disintegration of the cytoskeleton. On transmission electron microscopy, although the control cells treated with docetaxel as above showed the following morphology, i.e., absence of villi, cells shrunken in size, pyknosis, agglutinated chromatin and cell buds containing nuclei in the process of apoptosis, the RMG-1-hFUT cells showed only agglutinated chromatin and vacuoles in the cytoplasm. In summary, cells with enhanced expression of LeY were shown to acquire docetaxel-resistance, indicating the possible involvement of glycoconjugates in the drug-resistance

Deglacial biogenic opal peaks revealing enhanced Southern Ocean upwelling during the last 513 ka

Strength of Southern Ocean upwelling controls the exchange of carbon dioxide (CO2) between deep ocean reservoirs and atmosphere, as well as the communication of dissolved silicon with the euphotic zone of the Southern Ocean. The silicon supply could limit diatom opal productivity in the high-latitudes of Southern Ocean and the subsequent burial of biogenic opal in underlying sediments. Here we report a record of biogenic opal export off the Prydz Bay south of the polar front of the Southern Ocean, indicating strengthened upwelling during the past five glacial terminations. In all five terminations (Isingle bondV), opal peaks occur in line with Northern Hemisphere summer insolation intensity as well as the existing IRDs, indicating that freshwater injection associated with retreat of the Northern Hemisphere ice sheets could be the cause of enhanced upwelling in the Southern Ocean during terminations. This could in turn promote CO2 outgassing, finally accelerating the completion of the terminations. In addition, the enhanced upwelling could export the Si-rich deep water to low latitudes via Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW), potentially leading to deglacial opal peaks in subtropical North Atlantic

Accuracy of digital guided implant surgery: expert consensus on nonsurgical factors and their treatments

The standardized workflow of computer-aided static guided implant surgery includes preoperative examination, data acquisition, guide design, guide fabrication and surgery. Errors may occur at each step, leading to irreversible cumulative effects and thus impacting the accuracy of implant placement. However, clinicians tend to focus on factors causing errors in surgical operations, ignoring the possibility of irreversible errors in nonstandard guided surgery. Based on the clinical practice of domestic experts and research progress at home and abroad, this paper summarizes the sources of errors in guided implant surgery from the perspectives of preoperative inspection, data collection, guide designing and manufacturing and describes strategies to resolve errors so as to gain expert consensus. Consensus recommendation: 1. Preoperative considerations: the appropriate implant guide type should be selected according to the patient's oral condition before surgery, and a retaining screw-assisted support guide should be selected if necessary. 2. Data acquisition should be standardized as much as possible, including beam CT and extraoral scanning. CBCT performed with the patient’s head fixed and with a small field of view is recommended. For patients with metal prostheses inside the mouth, a registration marker guide should be used, and the ambient temperature and light of the external oral scanner should be reasonably controlled. 3. Optimization of computer-aided design: it is recommended to select a handle-guided planting system and a closed metal sleeve and to register images by overlapping markers. Properly designing the retaining screws, extending the support structure of the guide plate and increasing the length of the guide section are methods to feasibly reduce the incidence of surgical errors. 4. Improving computer-aided production: it is also crucial to set the best printing parameters according to different printing technologies and to choose the most appropriate postprocessing procedures

The Role of Hippocampal Estradiol Receptor-α in a Perimenopausal Affective Disorders-Like Rat Model and Attenuating of Anxiety by Electroacupuncture

Hormone replacement therapy is the principal treatment for perimenopausal affective disorders which can cause severe side effects. The present study compared the effects of electroacupuncture (EA) and estradiol treatment on perimenopausal affective disorders at the behavioral and cellular levels. In this randomized experimental in vivo study, adult female rats were divided into intact, ovariectomy, chronic unpredictable stress (CUS), and ovariectomy and CUS combination groups. After week 6, all groups were subdivided to three subgroups of control, EA, and estradiol treatment. The behavioral parameters in the open field and the elevated plus maze tests were assessed before and after treatments. Alterations of serum steroid hormones and changes of estradiol receptor-α (ER-α) immunofluorescence neurons in the hippocampus sections were evaluated. EA treatment caused more antianxiety effects than estradiol treatment in CUS group (P<0.05). Notably, estradiol and EA treatments had better significant behavioral effects when the models were not estrogen-deficient. Importantly, within each group, compared to the control group, the numbers of ER-α-positive neurons were significantly larger in EA subgroups. Therefore, EA had antianxiety effects on perimenopausal affective disorders caused by CUS but not by estrogen deficiency and upregulation of hippocampus ER-α neurons may contribute to its mechanism of action

RF thermal plasma-assisted metallothermic synthesis of ultrafine ZrB2 powders

Ultrafine ZrB2 powders were synthesized in radio-frequency atmospheric-pressure thermal plasma using ZrCl4, B, and Mg as raw materials. The metallothermic reaction was ignited by the high temperature flame when the mixed precursors were carried into thermal plasma, and then propagated with the exothermic reaction enthalpies and the external energy supplied by plasma flame. Both thermodynamic analysis and experiments were conducted. The as-prepared samples were characterized by X-ray Diffraction, Transmission Electron Microscopy, and particle size analyzer. Results showed that the obtained ZrB2 powders had particle size of about 100 nm and surface area of 30.75 m(2)/g. The laboratory production rate was about 300 g/h. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Radio-Frequency Atmospheric-Pressure Plasma Synthesis of Ultrafine ZrC Powders

A radio-frequency atmospheric-pressure plasma process has been applied to the synthesis of ultrafine ZrC powders using ZrCl4 and CH4 as precursors. Both thermodynamic analysis and experiments were conducted and the as-prepared samples were characterized by X-ray diffraction, electron microscopy, and laser scattering. Results showed that ZrC powders with particle size <100nm and surface area of 36.56M(2)/g could be obtained. The addition of excess H-2 contributed to the increase in conversion rate. The conversion rate was about 65% when the carrier gas ratio (H-2/CH4) was set at 4.0 and added axially through the injection probe