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Divalent complexes of vanadium were synthesized employing bulky silyl(aryl)amido ligands −N(SiiPr3)DIPP and −N(SitBu2Me)DIPP (DIPP = 2,6-iPr2C6H3). Solid-state structural characterization revealed that although the ligand −N(SiiPr3)DIPP supports a monomeric, bis(amido) complex of vanadium, its constitutional isomer −N(SitBu2Me)DIPP affords a homoleptic complex in which the vanadium center is sandwiched between the arene rings, an unusual binding mode for arylamido ligands. Magnetometry studies indicate that V[N(SiiPr3)DIPP]2 and V[(η5-DIPP)N(SitBu2Me)]2 have similar high-spin d3 electron configurations. However, spectroscopic methods, including electron paramagnetic resonance, nuclear magnetic resonance, infrared, and UV–visible spectroscopies, in addition to cyclic voltammetry and reactivity studies, suggest that V[N(SiiPr3)DIPP]2 is stereochemically nonrigid in solution, while V[(η5-DIPP)N(SitBu2Me)]2 is not. This nonrigidity explicitly impacts the reactivity of V[N(SiiPr3)DIPP]2, which can be used to a...

Human intestinal organoids from primary human tissues have the potential to revolutionize personalized medicine and preclinical gastrointestinal disease models. A tunable, fully defined, designer matrix, termed hyaluronan elastin‐like protein (HELP) is reported, which enables the formation, differentiation, and passaging of adult primary tissue‐derived, epithelial‐only intestinal organoids. HELP enables the encapsulation of dissociated patient‐derived cells, which then undergo proliferation and formation of enteroids, spherical structures with polarized internal lumens. After 12 rounds of passaging, enteroid growth in HELP materials is found to be statistically similar to that in animal‐derived matrices. HELP materials also support the differentiation of human enteroids into mature intestinal cell subtypes. HELP matrices allow stiffness, stress relaxation rate, and integrin‐ligand concentration to be independently and quantitatively specified, enabling fundamental studies of organoid–matrix interactions and potential patient‐specific optimization. Organoid formation in HELP materials is most robust in gels with stiffer moduli (G’ ≈ 1 kPa), slower stress relaxation rate (t 1/2 ≈ 18 h), and higher integrin ligand concentration (0.5 × 10−3–1 × 10−3 m RGD peptide). This material provides a promising in vitro model for further understanding intestinal development and disease in humans and a reproducible, biodegradable, minimal matrix with no animal‐derived products or synthetic polyethylene glycol for potential clinical translation., A tunable, designer matrix, termed hyaluronan elastin‐like protein (HELP) that enables the formation, differentiation, and passaging of adult primary tissue‐derived organoids is reported. HELP matrices allow stiffness, stress relaxation rate, and integrin‐ligand concentration to be independently and quantitatively specified, enabling fundamental studies of organoid–matrix interactions and potential patient‐specific optimization.

Invading breast cancer cells transform the mechanics of their surroundings across a panorama of time scales., Living tissues embody a unique class of hybrid materials in which active and thermal forces are inextricably linked. Mechanical characterization of tissues demands descriptors that respect this hybrid nature. In this work, we develop a microrheology-based force spectrum analysis (FSA) technique to dissect the active and passive fluctuations of the extracellular matrix (ECM) in three-dimensional (3D) cell culture models. In two different stromal models and a 3D breast cancer spheroid model, our FSA reveals emergent hybrid dynamics that involve both high-frequency stress stiffening and low-frequency fluidization of the ECM. We show that this is a general consequence of nonlinear coupling between active forces and the frequency-dependent viscoelasticity of stress-stiffening networks. In 3D breast cancer spheroids, this dual active stiffening and fluidization is tightly connected with invasion. Our results suggest a mechanism whereby breast cancer cells reconcile the seemingly contradictory requirements for both tension and malleability in the ECM during invasion.

We present a method for using dynamic light scattering in the single-scattering limit to measure the viscoelastic moduli of soft materials. This microrheology technique only requires a small sample volume of 12 μL to measure up to six decades in time of rheological behavior. We demonstrate the use of dynamic light scattering microrheology (DLSμR) on a variety of soft materials, including dilute polymer solutions, covalently-crosslinked polymer gels, and active, biological fluids. In this work, we detail the procedure for applying the technique to new materials and discuss the critical considerations for implementing the technique, including a custom analysis script for analyzing data output. We focus on the advantages of applying DLSμR to biologically relevant materials: breast cancer cells encapsulated in a collagen gel and cystic fibrosis sputum. DLSμR is an easy, efficient, and economical rheological technique that can guide the design of new polymeric materials and facilitate the understanding of the underlying physics governing behavior of naturally derived materials.

The viscoelastic behavior of a physically crosslinked gel involves a spectrum of molecular relaxation processes, which at the single-chain level involve the chain undergoing transient hand-to-hand motion through the network. We develop a self-consistent theory for describing transiently associating polymer solutions that captures these complex dynamics. A single polymer chain transiently binds to a viscoelastic background that represents the polymer network formed by surrounding polymer chains. The viscoelastic background is described in the equation of motion as a memory kernel, which is self-consistently determined based on the predicted rheological behavior from the chain itself. The solution to the memory kernel is translated into rheological predictions of the complex modulus over a wide range of frequencies to capture the time-dependent behavior of a physical gel. Using the loss tangent predictions, a phase diagram is shown for the sol-gel transition of polymers with dynamic association affinities. This theory provides a predictive, molecular-level framework for the design of associating gels and supramolecular assemblies with targeted rheological properties.

It was previously shown that Bone Morphogenetic Protein (BMP)-9 is constitutively produced and secreted by hepatic stellate cells (HSC). Upon acute liver damage, BMP-9 expression is transiently down-regulated and blocking BMP-9 under conditions of chronic damage ameliorated liver fibrogenesis in C57BL/6 mice. Thereby, BMP-9 acted as a pro-fibrogenic cytokine in the liver but without directly activating isolated HSC in vitro. Lipopolysaccharide (LPS), an endotoxin derived from the membrane of Gram-negative bacteria in the gut, is known to be essential in the pathogenesis of diverse kinds of liver diseases. The aim of the present project was therefore to investigate how high levels of BMP-9 in the context of LPS signalling might result in enhanced liver damage. For this purpose, we stimulated human liver sinusoidal endothelial cells (LSEC) with LPS and incubated primary human liver myofibroblasts (MF) with the conditioned medium of these cells. We found that LPS led to the secretion of factors from LSEC that upregulate BMP-9 expression in MF. At least one of these BMP-9 enhancing factors was defined to be IL-6. High BMP-9 in turn, especially in combination with LPS stimulation, induced the expression of certain capillarization markers in LSEC and enhanced the LPS-mediated induction of pro-inflammatory cytokines in primary human macrophages. In LSEC, pre-treatment with BMP-9 reduced the LPS-mediated activation of the NfkB pathway, whereas in macrophages, LPS partially inhibited the BMP-9/Smad-1 signaling cascade. In vivo, in mice, BMP-9 led to the enhanced presence of F4/80-positive cells in the liver and it modulated the LPS-mediated regulation of inflammatory mediators. In summary, our data point to BMP-9 being a complex and highly dynamic modulator of hepatic responses to LPS: Initial effects of LPS on LSEC led to the upregulation of BMP-9 in MF but sustained high levels of BMP-9 in turn promote pro-inflammatory reactions of macrophages. Thereby, the spatial and timely fine-tuned presence (or absence) of BMP-9 is needed for efficient wound-healing responses in the liver.

SAPRC16 is an interim update to the SAPRC series of chemical mechanisms that includes updated rate constants, a revised representation of radical chemistry, and a new speciation lumping scheme to better develop predictions of SOA precursors. In this study, the ability of the SAPRC16 chemical mechanism to simulate regional ozone episodes is tested in seven (7) major cities across the United States. The UCD-CIT 3-dimensional (3D) airshed model was configured with both SAPRC11 (base mechanism) and SAPRC16 (updated mechanism). Concentrations of ozone, hydroxyl radical (OH) and hydroperoxyl (HO2) radical predicted with both mechanisms were compared to measured values. It was generally observed that SAPRC16 predicts slightly lower ozone concentrations than SAPRC11 in NOx rich urban centers. A box model analysis shows that the SAPRC16 mechanism quenches ozone production earlier than SAPRC11 as NOx concentrations increase (yielding decreasing VOC/NOx ratios). This could be caused by more detailed HO2+RO2 reactions and RO2 isomerization reactions in SAPRC16 that compete with the HO2+NO reaction. Predictions from SAPRC11 are in better agreement with the measurements in the western United States, however SAPRC16 outperforms SAPRC11 in some eastern and southern U.S. cities. These results may also be strongly influenced by the accuracy of emissions inventories in each region. Differences in ozone concentrations predicted by SAPRC16 and SAPRC11 increased as emissions decreased suggesting that the two mechanisms will predict different outcomes from future emissions control programs. In general, the SAPRC11 mechanisms slightly over-predicts OH concentration while under-predicting HO2 radical concentration and the SAPRC16 mechanism slightly under predicts OH and under predicts HO2, sometimes by large amounts. The reasons for this behavior are unknown at this time. These features will influence the secondary organic aerosol (SOA) predictions from each mechanism since the branching between high NOx and low NOx regimes depends on calculated HO2 concentrations. Further analysis of the HO2+RO2 reactions and RO2 isomerization reactions and the reasons for the lower HO2 predictions in the updated SAPRC16 chemical mechanism should be carried out before widespread adoption of the new mechanism.

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in many polyvinylchloride medical devices and is washed out easily. Thereby critically ill infants can become exposed to DEHP concentrations significantly exceeding the recommended threshold. We suspect DEHP to play an important role in the development of intestinal failure-associated liver disease. The aim of this study was therefore to determine the direct influence of DEHP on different liver cell types.HepG2, human upcyte hepatocytes, primary murine hepatocytes, LX-2, human upcyte hepatic stellate cells, and liver organoids were cultured with DEHP (0.5-500 μmol/L) and parameters including cytotoxicity, cell-cell interactions, and expression of metabolizing enzymes were investigated.DEHP modulated the expression of xenobiotic metabolizing enzymes, reduced the formation of bile canaliculi and cell polarity, and inhibited Cyp-activity in hepatocytes. DEHP had a toxic effect on LX-2 and induced the fibrogenic activation of hepatic stellate cells. The mode of action of DEHP was different in monolayer cultures compared to 3D-liver organoids, which were more sensitive to DEHP.This study suggests that DEHP modulates expression and activity of drug-detoxifying liver enzymes in humans at a clinically relevant concentration. Furthermore, it may contribute to the development of cholestasis and fibrosis. These findings strongly support the opinion, that there is a significant potential for serious adverse effects of DEHP derived from medical devices on human health, especially in very young infants with immature livers.

The study aimed to explore the effect of Saikosaponin-d (SSd) and its underlying mechanism on cell growth inhibition as well as induction of apoptosis and cell cycle arrest in renal cell carcinoma (RCC). MTT assay and colony formation assay were employed in this study, with the results indicating that RCC cells proliferation was inhibited by SSd at different doses. Analysis by flow cytometry revealed that RCC cell proliferation inhibitory effect of SSd was achieved by inducing apoptosis and cell cycle arrest at G0/G1 phase via up-regulation of p53. As compared to the control group, SSd can significantly inhibit the growth of 769-P and 786-O cell lines and induce apoptosis and cell cycle arrest. The mechanism exploration demonstrated that inhibiting the activation of EGFR/p38 signaling pathways was the molecular basis of SSd's biological effects such as inducing apoptotic death, inhibiting cell growth as well as up-regulating p53 expression in human RCC cells. In conclusion, our data suggest that SSd may serve as a promising intervention for chemopreventive or chemotherapeutic treatment for patients with RCC.

A zirconium- and Cr(III)-containing conversion coating on Al alloy 2024-T3 was prepared in solution containing Cr2(SO4)3 and K2ZrF6. Its composition was analyzed by energy dispersive X-ray spectrometry (EDS), and its corrosion resistance was investigated using polarization curve, electrochemical impedance spectroscopy (EIS), and salt spray exposure. An artificial scratch cell was used to investigate its “self-repairing” effect by EIS and X-ray photoelectron spectroscopy (XPS). In addition to Al, the conversion coating contained Zr, Cr, O, and F. The conversion coating provided obvious corrosion protection for the Al alloy 2024-T3. The EIS measurement and corrosion morphology observation of bare samples (i.e., uncoated samples) in the artificial scratch cell confirmed that the conversion coating possessed “self-repairing” effect. XPS analysis showed that Cr(III) species, but not Zr species were transported from the conversion coating to the nearby bare area as in a scratch.

Low-coordinate organoCr(III) complexes supported by the silylamido ligand –N(SiMe3)DIPP (DIPP = 2,6-diisopropylphenyl) are ethylene polymerization catalyst precursors without the need of additional cocatalyst. The reaction of CrCl3(THF)3 with 3 or 2 equiv. of LiN(SiMe3)DIPP yields either a four-membered cyclometalated Cr complex or Cr[N(SiMe3)DIPP]2Cl, respectively, with no trace of Cr[N(SiMe3)DIPP]3. Addition of 1 equiv. of LiN(SiMe3)DIPP to Cr[N(SiMe3)DIPP]2Cl also leads to the four-membered metallacycle, which upon heating transforms to a new six-membered Cr metallacycle, likely via a σ-bond metathesis step. Cr[N(SiMe3)DIPP]2Cl can be readily converted to bis(amido)Cr(III) vinyl and alkyl complexes Cr[N(SiMe3)DIPP]2R (R = vinyl, Bn, and Me). All of these structurally characterized low-coordinate Cr(III) complexes with a Cr–C bond initiate the polymerization of ethylene in the absence of activators or cocatalysts, producing ultra-high-molecular weight polyethylene.

Predictions of O_3, CO, total NO_y and individual NO_y species (NO, NO_2, HNO_3, PAN, alkyl nitrates and aerosol nitrate) from a fine resolution regional air quality modeling system for the South Coast Air Basin (SoCAB) and San Joaquin Valley Air Basin (SJVAB) of California are presented and evaluated for the 2008 ARCTAS-CARB campaign. The measurements of the chemical compounds from the fire plumes during the field campaign allow for the evaluation of the model's ability to simulate fire-influenced air masses as well. In general, the model successfully simulated the broad spatial distribution of chemical compounds in both air basins as well as the variation within the basins. Using inventories that reflect 2008 emissions levels, the model performed well in simulating NO_x (NO + NO_2) in SoCAB. Therefore, the under prediction of O_3 over these areas is more likely caused by uncertainties with the VOC emissions, chemistry, or discrepancies in the meteorology. The model did not capture the relatively high levels of O_3, and some reactive nitrogen species that were measured off shore of the SoCAB, indicating potential missing sources or the transport from on shore to off shore was not successfully captured. In SJVAB, the model had good performance in simulating different chemical compounds in the Fresno and Arvin areas. However, enhanced concentrations of O_3, NO_x, HNO_3 and PAN near dairy farms were significantly underestimated in the model. Negative biases also exist for O_3 and HNO_3 near oil fields, suggesting larger uncertainties associated with these emission sources. While the model simulated the total NO_y mixing ratios reasonably well, the prediction for partitioning between individual compounds showed larger uncertainties in the model simulation. Although the fire emissions inventory was updated to include the latest emissions estimates and speciation profiles, our model shows limited improvement in simulating the enhancement of O_3, CO, and PAN under fire impact as compared to a previous version of the modeling system. Further improvements in simulating fire emissions, especially the timing and the plume injection heights, are desired in order to better simulate the impact of fires.

Background: Biliary tract cancers (BTCs) have a poor prognosis. BTCs are characterized by a prominent desmoplastic reaction which possibly contributes to the aggressive phenotype of this tumor. The desmoplastic reaction includes excessive production and deposition of extracellular matrix proteins such as periostin, secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1, as well as accumulation of α-smooth muscle actin-positive cancer-associated fibroblasts and immune cells, secreting growth factors and cytokines including transforming growth factor (TGF)-β. In the present study, we investigated the expression of SPARC in BTC as well as its possible regulation by TGF-β. Methods: Expression levels of Sparc, TGF-β1 and its receptor ALK5 were evaluated by quantitative real-time PCR in 6 biliary tract cell lines as well as 1 immortalized cholangiocyte cell line (MMNK-1). RNAs from tumor samples of 7 biliary tract cancer patients were analyzed for expression of Sparc, TGF-β type II receptor (TbRII) as well as Twist and ZO-1. MMNK-1 cells were stimulated with TGF-β for 24 h, and Sparc, ZO-1 and E-Cadherin expressions were determined. The presence of SPARC protein was analyzed by immunohistochemistry in tumor specimens from 10 patients. Results: When comparing basal Sparc transcript levels in diverse BTC cell lines to MMNK-1 cells, we found that it was strongly downregulated in all cancer cell lines. The remaining expression levels were higher in highly differentiated cell lines (CCSW1, MZChA1, MZChA2 and TFK-1) than in less differentiated and undifferentiated ones (BDC, SKChA1). Expression of Sparc in BTC patient samples showed a significant positive correlation with expression of the epithelial marker ZO-1. In contrast, the mesenchymal marker Twist and the TbRII showed a trend of negative correlation with expression of Sparc in these samples. TGF-β exposure significantly downregulated Sparc expression in MMNK-1 cholangiocytes in vitro in parallel to downregulation of epithelial markers (E-Cadherin and ZO-1). Finally, SPARC immunostaining was performed in 10 patient samples, and the correlation between absence of SPARC and survival times was analyzed. Conclusions: These data imply that a decrease in SPARC expression is correlated with dedifferentiation of BTC cells resulting in enhanced EMT being possibly mediated by TGF-β. Thereby SPARC levels might be a marker for individual prognosis of a patient, and strategies aiming at inhibition of SPARC downregulation might have potential for new future therapies.

The amido ligand -N(Si(i)Pr3)DIPP (DIPP = 2,6-diisopropylphenyl) has been used to prepare two-coordinate complexes of Cr(I), Cr(II), and Cr(III). The two-coordinate Cr(II) complex has also been used to prepare a three-coordinate Cr(III) iodide complex, which can be used to access a stable Cr(III) methyl species.

The metabolic functions of androgen receptor (AR) in normal prostate are circumvented in prostate cancer (PCa) to drive tumor growth, and the AR also can acquire new growth-promoting functions during PCa development and progression through genetic and epigenetic mechanisms. Androgen deprivation therapy (ADT, surgical or medical castration) is the standard treatment for metastatic PCa, but patients invariably relapse despite castrate androgen levels (castration-resistant PCa, CRPC). Early studies from many groups had shown that AR was highly expressed and transcriptionally active in CRPC, and indicated that steroids from the adrenal glands were contributing to this AR activity. More recent studies showed that CRPC cells had increased expression of enzymes mediating androgen synthesis from adrenal steroids, and could synthesize androgens de novo from cholesterol. Phase III clinical trials showing a survival advantage in CRPC for treatment with abiraterone (inhibitor of the enzyme CYP17A1 required for androgen synthesis that markedly reduces androgens and precursor steroids) and for enzalutamide (new AR antagonist) have now confirmed that AR activity driven by residual androgens makes a major contribution to CRPC, and led to the recent Food and Drug Administration approval of both agents. Unfortunately, patients treated with these agents for advanced CRPC generally relapse within a year and AR appears to be active in the relapsed tumors, but the molecular mechanisms mediating intrinsic or acquired resistance to these AR-targeted therapies remain to be defined. This review outlines AR functions that contribute to PCa development and progression, the roles of intratumoral androgen synthesis and AR structural alterations in driving AR activity in CRPC, mechanisms of action for abiraterone and enzalutamide, and possible mechanisms of resistance to these agents.

We evaluate predictions from the Community Multiscale Air Quality (CMAQ version 4.7.1) model against a suite of airborne and ground-based meteorological measurements, gas- and aerosol-phase inorganic measurements, and black carbon (BC) measurements over Southern California during the CalNex field campaign in May/June 2010. Ground-based measurements are from the CalNex Pasadena ground site, and airborne measurements took place onboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Navy Twin Otter and the NOAA WP-3D aircraft. BC predictions are in general agreement with observations at the Pasadena ground site and onboard the WP-3D, but are consistently overpredicted when compared to Twin Otter measurements. Adjustments to predicted inorganic mass concentrations, based on predicted aerosol size distributions and the AMS transmission efficiency, are shown to be significant. Owing to recent shipping emission reductions, the dominant source of sulfate in the L.A. Basin may now be long-range transport. Sensitivity studies suggest that severely underestimated ammonia emissions, and not the exclusion of crustal species (Ca^(2 +), K^+, and Mg^(2 +)), are the single largest contributor to measurement/model disagreement in the eastern part of the L.A. Basin. Despite overstated NO_x emissions, total nitrate concentrations are underpredicted, which suggests a missing source of HNO_3 and/or overprediction of deposition rates. Adding gas-phase NH_3 measurements and size-resolved measurements, up to 10 μm, of nitrate and various cations (e.g. Na^+, Ca^(2 +), K^+) to routine monitoring stations in the L.A. Basin would greatly facilitate interpreting day-to-day fluctuations in fine and coarse inorganic aerosol.

To explore the underlying mechanism and treatment of myocardial injury caused by hypothyroidism, we evaluated oxidative stress in serum and myocardial tissue of hypothyroid rats. The effect of levothyroxine (LT4) replacement therapy and vitamin E (VitE) supplementation on oxidative stress-induced injury and apoptosis of myocardial tissue is examined. Male Sprague-Dawley rats were divided into five groups: normal control group, propylthiouracil group (PTU group), LT4 treatment group (PTU + LT4 group), vitamin E treatment group (PTU + VitE group), and combined treatment group (PTU + LT4 + VitE group). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) expression in serum and myocardium were determined. Myocardial apoptosis index (AI) in each group was determined by TUNEL assay. SOD levels in serum were significantly increased in PTU + VitE and PTU + LT4 + Vit E groups, as compared to that in PTU and PTU + LT4 groups (P

Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients.

Epigenetic regulation requires site-specific modification of the genome and is involved in multiple physiological processes and disease etiology. Methyltransferases, which catalyze the transfer of a methyl group from S-adenosyl-l-methionine (SAM) to various substrates, are critical components of the epigenetic machinery. This group of enzymes can methylate diverse substrates including DNA, RNA, proteins, and small-molecule metabolites. Their dysregulation has also been implicated in multiple disease states such as cancer, neurological, and cardiovascular disorders. Developing potent and selective small-molecule inhibitors of methyltransferases is valuable not only for therapeutic intervention but also for investigating the roles of these enzymes in disease progression. In this chapter, we will discuss the strategies of designing and synthesizing methyltransferases inhibitors based on the SAM scaffold. Following the section of inhibitor design, we will briefly review representative assays that are available to evaluate the potency of these inhibitors along with a detailed description of the most commonly used radiometric assay.

Limonene has a strong tendency to form secondary organic aerosol (SOA) in the atmosphere and in indoor environments. Initial oxidation occurs mainly via ozone or OH radical chemistry. We studied the effect of O(3) concentrations with or without a OH radical scavenger (2-butanol) on the SOA mass and thermal characteristics using the Gothenburg Flow Reactor for Oxidation Studies at Low Temperatures and a volatility tandem differential mobility analyzer. The SOA mass using 15 ppb limonene was strongly dependent on O(3) concentrations and the presence of a scavenger. The SOA volatility in the presence of a scavenger decreased with increasing levels of O(3), whereas without a scavenger, there was no significant change. A chemical kinetic model was developed to simulate the observations using vapor pressure estimates for compounds that potentially contributed to SOA. The model showed that the product distribution was affected by changes in both OH and ozone concentrations, which partly explained the observed changes in volatility, but was strongly dependent on accurate vapor pressure estimation methods. The model-experiment comparison indicated a need to consider organic peroxides as important SOA constituents. The experimental findings could be explained by secondary condensed-phase ozone chemistry, which competes with OH radicals for the oxidation of primary unsaturated products.

An instrumented DC-8 aircraft was employed to perform airborne observations in rural and urban environs of California during the summer 2008 NASA ARCTAS-CARB campaign. The fortuitous occurrence of large wildfire episodes in Northern California allowed for studies of fire emissions, their composition, and their interactions with rural and urban air. Relative to CO, emissions of HCN were shown to vary non-linearly with fire characteristics while those of CH 3 CN were nearly unchanged, making the latter a superior quantitative tracer of biomass combustion. Although some fire plumes over California contained little NO x and virtually no O 3 enhancement, others contained ample VOCs and sufficient NO x , largely from urban influences, to result in significant ozone formation. The highest observed O 3 mixing ratios (170 ppb) were also in fire-influenced urban air masses. Attempts to simulate these interactions using CMAQ, a high-resolution state of the art air quality model, were only minimally successful and indicated several shortcomings in simulating fire emission influences on urban smog formation. A variety of secondary oxidation products (e.g. O 3 , PAN, HCHO) were substantially underestimated in fire-influenced air masses. Available data involving fire plumes and anthropogenic pollution interactions are presently quite sparse and additional observational and mechanistic studies are needed.

Two new zinc(II) complexes, [ZnBr2L1] (I) and [ZnBr2L2] (II), where L1 is 2-[(2-isopropylaminoethylimino)methyl]-5-methoxyphenol and L2 is N,N-dimethyl-N′-(1-pyridin-2-yl-ethylidene)ethane-1,2-diamine, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Zn(II) atom is coordinated by one phenolic O and one imino N atoms of L1 and two Br atoms, forming a tetrahedral coordination geometry. In complex II, the Zn(II) atom is in a trigonal bipyramidal coordination geometry with the equatorial plane formed by the imino N atom of L2 and two Br atoms and with the two axial positions occupied by one pyridine N and one amino N atoms of L2. In the crystal structure of I, the mononuclear zinc complex molecules are linked through intermolecular N-H…O and N-H…Br hydrogen bonds, forming chains running along the y axis. The chains are further linked via intermolecular C-H…Br hydrogen bonds. In the crystal structure of II, the mononuclear zinc complex molecules are linked through intermolecular C-H…Br hydrogen bonds, forming a 3D network.

An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment. Therefore, additional study is required to evaluate the full regulatory implications of upgrading air quality models to SAPRC07.

Chronic high surface ozone (O3) levels and the increasing sulfur oxides (SOx = SO2+SO4) ambient concentrations over South Coast (SC) and other areas of California (CA) are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SOx levels (up to ~0.7 ppb of SO2 and ~1.3 ppb of SO4) is observed above ~6 km, but they did not affect CA surface air quality. The elevated SOx observed at 1–4 km is estimated to enhance surface SOx over SC by ~0.25 ppb (upper limit) on ~24 June. The near-surface SOx levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SOx emission inventories (EIs) from the California Air Resources Board (CARB) and the US Environmental Protection Agency (EPA) are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI) by EPA, but generally underestimates surface SC SOx by about a factor of two. Adjoint sensitivity analysis indicated that SO2 levels at 00:00 UTC (17:00 local time) at six SC surface sites were influenced by previous day maritime emissions over the ocean, the terrestrial emissions over nearby urban areas, and by transported SO2 from the north through both terrestrial and maritime areas. Overall maritime emissions contribute 10–70% of SO2 and 20–60% fine SO4 on-shore and over the most terrestrial areas, with contributions decreasing with in-land distance from the coast. Maritime emissions also modify the photochemical environment, shifting O3 production over coastal SC to more VOC-limited conditions. These suggest an important role for shipping emission controls in reducing fine particle and O3 concentrations in SC.

Little information is available on the effects of urease inhibitor, N-(n-butyl)thiophosphoric triamide (NBPT), and nitrification inhibitor, dicyandiamide (DCD), on nitrous oxide (N2O) emissions from fluvo-aquic soil in the North China Plain. A field experiment was conducted at the Fengqiu State Key Agro-Ecological Experimental Station, Henan Province, China, to study the influence of urea added with NBPT, DCD, and combination of both NBPT and DCD on N2O emissions during the maize growing season in 2009. Two peaks of N2O fluxes occurred during the maize growing season: the small one following irrigation and the big one after nitrogen (N) fertilizer application. There was a significant positive relationship between ln [N2O flux] and soil moisture during the maize growing season excluding the 11-day datasets after N fertilizer application, indicating that N2O flux was affected by soil moisture. Mean N2O flux was the highest in the control with urea alone, while the application of urea together with NBPT, DCD, and NBPT + DCD significantly lowered the mean N2O flux. Total N2O emission in the NBPT + DCD, DCD, NBPT, and urea alone treatments during the experimental period was 0.41, 0.47, 0.48, and 0.77 kg N2O–N ha−1, respectively. Application of urea with NBPT, DCD, and NBPT + DCD reduced N2O emission by 37.7%, 39.0%, and 46.8%, respectively, over urea alone. Based on our findings, the combination of DCD and NBPT together with urea may reduce N2O emission and improve the maize yield from fluvo-aquic soil in the North China Plain.

Multi-scale tracer and full-chemistry simulations with the STEM atmospheric chemistry model are used to analyze the effects of transported background ozone (O3) from the eastern Pacific on California air quality during the ARCTAS-CARB experiment conducted in June, 2008. Previous work has focused on the importance of long-range transport of O3 to North America air quality in springtime. However during this summer experiment the long-range transport of O3 is also shown to be important. Simulated and observed O3 transport patterns from the coast to inland northern California are shown to vary based on meteorological conditions and the O3 profiles over the oceans, which are strongly episodically affected by Asian inflows. Analysis of the correlations of O3 at various altitudes above the coastal site at Trinidad Head and at a downwind surface site in northern California, show that under long-range transport events, high O3 air-masses (O3>60 ppb) at altitudes between about 2 and 4 km can be transported inland and can significantly influence surface O3 20–30 h later. These results show the importance of characterizing the vertical structure of the lateral boundary conditions (LBC) needed in air quality simulations. The importance of the LBC on O3 prediction during this period is further studied through a series of sensitivity studies using different forms of LBC. It is shown that the use of the LBC downscaled from RAQMS global model that assimilated MLS and OMI data improves the model performance. We also show that the predictions can be further improved through the use of LBC based on NASA DC-8 airborne observations during the ARCTAS-CARB experiment. These results indicate the need to develop observational strategies to provide information on the three-dimensional nature of pollutant distributions, in order to improve our capability to predict pollution levels and to better quantify the influence of these Asian inflows on the US west coast air quality.

Cholesterol (total cholesterol, TC) as the part of the fat plays an important role in maintaining the integrity of cell membrane and generating certain of steroids as well as fat-soluble vitamins. Therefore, low levels of cholesterol in patients with sepsis maybe have adverse effects [1, 2]. Some studies have showed that high-density lipoprotein (HDL), apolipoprotein A-I (apoA-I) seem to be associated with the risk of infection by neutralizing the lipopolysaccharide(LPS) which was the most critical initiation factor in septic shock [3, 4].

The compression behavior of dense krypton plasmas over a wide pressure-temperature range have been investigated by the self-consistent fluid variational theory. The ionization degree and equation of state of dense krypton have been calculated in the range of temperature of 4–50 kK and density of 0.01–10 g/cm3. A region of thermodynamic instability is found that is related plasma phase transition. The calculated shock adiabat and principal Hugoniot of liquid krypton are in good agreement with available experimental data when the ionization energy corrections are taken into account. The results provide a guide for dynamical experiments aimed at studying the compression properties of liquid krypton at very density and fill a gap in research the properties of the inert gases.

Most structural materials existing in nature take the form of a composite. After centuries of evolution, these materials have gained highly optimized microstructures and performance. In this work, a natural biocomposite, chafer cuticle, was observed with SEM, and it was found that the insect cuticle has a laminated structure with chitin fiber and protein matrix. Special helicoidal layups of chitin fibers were found with the chitin fiber being of nanometer scale. The relationship between the nanometer scale of the chitin fiber and the fracture strength of the cuticle was analyzed. The results show that the nanometer scale of the chitin fiber is profitable to maintain and improve the fracture strength of the biocomposite.

Aerobic granular sludge is a promising biotechnology for wastewater treatment system. In this report, aerobic granular sludge was successfully cultivated in a sequential batch shaking reactor in which horizontal circular flow could be formed by shaking. In this way, granulation and aeration could be simultaneously achieved. In comparison with sequential batch airlift reactor, more homogeneous circular flow was formed in the sequential batch shaking reactor. The aerobic granules obtained in the reactor were smooth, 1.2 mm in average diameter, and had a settling velocity of 50-52 m h(-1). In addition, an increase in the hydrophobicity of the cell surface of granules indicated that granulation could be related to the change in cell hydrophobicity. Finally, microbial observation showed that rod-shape and coccoid bacteria were the dominant species in mature granules. Results of this study have important implications on the mechanism of the granulation process and further practical application.

Leakage performance of BCPMOS (Buried channel PMOS) is investigated by experimentally varying the LDD implant conditions. An anomalous leakage increase with Boron LDD implant is observed for a small geometry (narrow and short) PMOS. Experimental results indicate that the increase of leakage current for narrow and short channel PMOS can be explained by boron piling up at the edge of STI isolation and from source/drain towards the middle of channel. Further confirmation of boron piling up is proven by the surface channel NMOS threshold voltage. Based on the leakage sensitivity, BCPMOS LDD is optimized to reduce leakage current for the small geometry transistors.

The recent discovery of metallic-like superconductivity in bulk MgB2 material [1] opened a new class of possible applications in current transport, magnetic field devices and electronic devices. Fabrication of thin films in situ is essential in order to explore the device applications of this material, and in spite of a few reports [2] , [3] , [4] , this still remains a challenge. The main reasons for this are the high vapour pressure of Mg even at low temperatures, and the high susceptibility of Mg to oxidation. A number of c-axis oriented MgB2 films were grown on Al2O3-R cut, and the stoichiometry of the films was measured by ICP as a function of deposition pressure and laser fluence. It was found that the relative concentration of Mg on the substrate varies considerably with pressure and laser fluence. A relative concentration of around 53 at% Mg, which is necessary in order to form stoichiometric MgB2 phase, can be obtain only in a narrow range of deposition pressures and laser fluences. The films obtain under these conditions were characterised by X-ray diffraction and magnetic moment in applied fields up to 9T.

Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a multiterawatt pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%-90%) current to a short circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. In this paper, primary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 14.4-26.4 mm, and consisting of 132∼276 tungsten wires with 5∼10 μm in diameter. Multiple diagnostics were fielded to determine the characteristics of x-ray radiations and to obtain self-emitting images of imploding plasmas. X-ray power up to 80 TW with ∼3 ns FWMH is achieved by using nested wire arrays. The total x-ray energy exceeds 500 kJ and the peak radiation temperature is about 150 eV. Typical velocity of imploding plasmas goes around 3∼5×107 cm/s and the radial convergence ratio is between 10 and 20.

Methane emission from flooded rice fields is a net product of CH 4 production and oxidation. The ability of paddy soils to oxidize CH 4 produced endogenously is an important natural feature for mitigating CH 4 emission to the atmosphere. We conducted a series of studies on CH 4 oxidation by two fresh paddy soils (Wuxi soil and Yingtan soil). The soils were amended with NH 4 Cl at rates equivalent to 0, 10 and 50 μg N g −1 soil, respectively, and incubated over five consecutive periods at elevated CH 4 concentrations of ∼500, ∼1000, ∼1500 or ∼2000 μl l −1 in the headspace, respectively, at 25°C. NH 4 Cl addition inhibited the rates of CH 4 oxidation by the paddy soils at all initial CH 4 concentrations during the first incubation. The inhibitory effect was strengthened with increasing NH 4 Cl addition and alleviated with increasing initial CH 4 concentration, i.e. there was an interaction of NH 4 Cl and initial CH 4 concentration on the inhibitory effect. If the initial CH 4 concentration was sufficiently high (above ∼2000 μl l −1 for Wuxi soil and ∼1000 μl l −1 for Yingtan soil), the initial inhibitory effect was alleviated and then eliminated during subsequent incubations. Eventually, NH 4 Cl addition stimulated the CH 4 oxidation rate. If the initial CH 4 concentration was not sufficiently high (less than 500 μl l −1 in the headspace for both soils), the inhibitory effect was maintained during subsequent incubations. Considering the fact that the CH 4 concentration in paddy soils when they are flooded is generally higher than ∼2000 μl l −1 , we conclude that the initial effect of NH 4 Cl addition on CH 4 oxidation in paddy soils is temporary.

The viewing-angle dependence of TFTLCD color characteristics have been studied for a number of wide-viewing angle technologies. Different color characteristics were obtained for each LC mode. For particular viewing directions relative to the LC director the color shifts can be understood as changes in the relative retardation of different ray components.

Synthesis of SIGN thin films on mirror-polished Si(100) substrates has been achieved by performing a bias-assisted hot filament chemical vapor deposition. High purity nitrogen, methane, and hydrogen were used as reactant gases. Incorporated Si element in the films totally came from the Si surface of the substrate. Scanning electron microscopy showed two categories of morphologies of the films according to the introduction of hydrogen. Energy-dispersive X-ray analysis and Auger electron spectroscopy depth profiling were used to measure the chemical composition of the samples. With no hydrogen applied, the film was found to be a nitride layer over the Si substrate with some nanosize columnal silicon-containing C-N crystals embedded. With hydrogen added, the film was uniformly composed of smaller SiCN particles. On both conditions, the overall carbon content was rather limited. X-ray photoelectron spectroscopy revealed the chemical environment of C, N, and Si atoms in the samples. The effect of methane flow ratio and substrate temperature were investigated on the conditions without hydrogen flow. The effects of hydrogen flow ratio on the films were also studied. (C) 1999 Elsevier Science S.A. All rights reserved.

High-speed countercurrent chromatography (CCC) was applied to the separation of strychnine and brucine from crude extract of Strychnos nux-vomica L. using a two-phase solvent system composed of chloroform/0.07 M sodium phosphate, 0.04 M citric buffer (pH 5.08) (1:1, v/v). Fractionated components were identified with authentic pure compounds on TLC and also analyzed by HPLC, IR and FTMS. The results showed that from 40 g of the seed powder, 48.2 mg of strychnine was purified at 99.9% purity (83.3% recovery) while 18.1 mg of brucine fraction was obtained after rechromatographed by preparative TLC improving the purity to 91.2%.

The properties of polymer materials are strongly dependent on their final structure and morphology. A control of nucleation from a homogenous solution or solid phase is one of the key factors in the determination of the final structure. The second essential stage is the systematic control of the growth process during the order formation. In electrically conducting polymers, the property (conductivity) is similarly affected by the structure and morphology. We have investigated the phase separation processes of poly(3-dodecylthiophene) (PDDT) from a homogeneous melt state. An order-disorder transition (ODT) was observed during a slow cooling process. Schlieren textures were developed as shear stress was applied. In PDDT-blends, the phase separation was followed in-situ with light scattering experiments and the early stages of the phase separation were defined as the linear protion in spinodal decompositon. This formation of bicontinuous pathways was confirmed with conductivity measurements. The homogeneity of polyaniline solutions was studied by thermal analysis and it was shown that m-cresol associates strongest with doped complex. This synergism supports the good solvent concept for m-cresol. Further on, the aggregation was followed by CD-spectroscopy as the used dopant was chiral. All the above results offer reasonable hope for a kinetic control of the order formation in conducting polymers.