EP Decrease Research Articles

Facile Construction of Inorganic Phosphorus/Boron-Layered Double Hydroxide Complexes for Highly Efficient Fire-Safety Epoxy Resin

For inorganic flame retardants, facile fabrication and high-efficiency fire safety without compromising the mechanical property of the matrix are still significant challenges. Here, nanolayered double hydroxide containing boron constructed on the surface of ammonium polyphosphate (APP) complexes (B-LDH@APP) is prepared by a simple in situ coprecipitation technology to reduce the fire hazard and improves the mechanical performances of epoxy resin (EP). The as-obtained 4B-LDH@APP/EP achieves the UL-94 V-0 rating and presents superior flame-safety performance. With respect to the 4APP/EP, the fire growth rate (FIGRA), the peak heat release rate (pHRR), and the peak smoke production rate (pSPR) of 4B-LDH@APP/EP decrease by 77.8, 57.3, and 52.6%, respectively. This is mainly attributed to the excellent synergistic flame-retardant effect among boron, LDH, and APP, which can accelerate the generation of compact charring residual with a good microstructure during combustion of B-LDH@APP/EP composites. Furthermore, B-LDH@APP slightly affects the mechanical performances of the EP matrix due to the upgraded interfacial interaction.

Effect of curing pressure on the curing behavior of an epoxy system: Curing kinetics and simulation verification

Most composites require a certain amount of pressure to cure, therefore, it is crucial to comprehend the effect of pressure on the curing reaction. Nonetheless, the majority of studies on curing reaction focus on isothermal or non-isothermal DSC measurements at ambient pressure. Using a high-pressure differential calorimetry scanner (Netzsch DSC 204HP), the curing process of a bisphenol A diglycidyl ether system is studied in order to evaluate the influence of curing pressure. The results indicate a competitive relationship between the effect of heating rate and pressure on the reaction rate, with the influence of heating rate being stronger. The reaction follows the autocatalytic model, and the average activation energy EP and pre-exponential factor AP decrease as the pressure increases. The obtained kinetics are used to simulate the process of forming composite laminates. When the thickness of laminates exceeds 18 mm, the maximum difference of the temperature and curing degree between ambient pressure and 2 MPa pressure is 20.65 °C and 0.161, respectively, indicating that the simulation results of thick composites are affected by whether the curing pressure is considered in kinetics.

Study on the thermal properties and insulation resistance of epoxy resin modified by hexagonal boron nitride

Abstract To study the effect of doping hexagonal boron nitride (h-BN) on the thermal properties and insulation resistance of epoxy resin (EP) and the mechanism of this effect, h-BN/epoxy composites with h-BN content of 0, 10, 20, 30, and 40 phr were prepared. Meanwhile, the corresponding molecular dynamics model of h-BN/epoxy composites was established, and the thermal conductivity, volume resistivity, glass transition temperature, and microstructure parameters of h-BN/epoxy composites were obtained. When the h-BN content is 40 phr, the thermal conductivity of h-BN/epoxy composite is increased by 138% compared to pure EP, and the glass transition temperature is increased by 76 K. At the same time, doping h-BN will reduce the insulation performance of EP. However, the lowest volume resistivity of h-BN/epoxy composite is still 1.43 × 1015 Ω·cm, and the EP composite still has good insulation performance. The fraction free volume and mean square displacement of EP decrease with the doping of h-BN, which indicates that h-BN can hinder the movement of molecular segments of EP, which is the reason for the increase in glass transition temperature.

Insights into the Discovery of Novel Neuroprotective Agents: A Comparative Study between Sulfanylcinnamic Acid Derivatives and Related Phenolic Analogues.

Exogenous antioxidants may be beneficial therapeutic tools to tackle the oxidative damage in neurodegenerative diseases by regulation of the redox state that is critical for cell viability and organ function. Inspired by natural plant polyphenols, a series of cinnamic acid-based thiophenolic and phenolic compounds were synthesized and their antioxidant and neuroprotective properties were studied. In general, our results showed that the replacement of the hydroxyl group (OH) by a sulfhydryl group (SH) increased the radical scavenging activity and enhanced the reaction rate with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) and galvinoxyl radical (GO•). These results correlated well with the lower oxidation potential (Ep) values of thiophenols. However, a lower peroxyl radical (ROO•) scavenging activity was observed for thiophenols in oxygen radical absorbance capacity (ORAC-FL) assay. Furthermore, the introduction of 5-methoxy and 5-phenyl groups in the aromatic ring of 4-thioferulic acid (TFA) 2 and ferulic acid (FA) 1 did not significantly improve their antioxidant activity, despite the slight decrease of Ep observed for compounds 5, 6, and 9. Concerning cinnamic acid amides, the antioxidant profile was similar to the parent compounds. None of the compounds under study presented significant cytotoxic effects in human differentiated neuroblastoma cells. Thiophenolic amide 3 stands out as the most promising thiophenol-based antioxidant, showing cellular neuroprotective effects against oxidative stress inducers (hydrogen peroxide and iron).

Synthesis of a novel graphene conjugated covalent organic framework nanohybrid for enhancing the flame retardancy and mechanical properties of epoxy resins through synergistic effect

A novel graphene conjugated covalent organic framework (AGO@COF) nanohybrid was synthesized by solvothermal method and used to enhance the flame retardancy and mechanical performances of epoxy resins (EP) through synergistic effect firstly. It is deduced from thermogravimetric analysis and cone calorimeter results that the obtained AGO@COF nanohybrid improves the flame retardancy of EP significantly. The time to peak heat release rate of EP increases by 17 s, the peak heat release rate and total heat release of EP decrease by 43.6 and 24.3% due to incorporation of 2 wt% AGO@COF. It is referred from thermogravimetric analysis-fourier transform infrared spectrometry results that the release of toxic gases and combustible volatiles during pyrolysis is also suppressed. As for mechanical performance of EP nanocomposites, the storage modulus of EP/2 wt% AGO@COF (34.66 GPa) in the glassy state increases by 23.8% compared with the neat epoxy (28.00 GPa). The possible mechanism for enhanced flame retardant and mechanical performances is proposed according to the test results. This work has opened up a new application for AGO@COF nanohybrid in the field of flame-retardant polymers.

Effect of A cation size on structural, magnetic and electrical properties of K2NiF4-type oxide LaSrFeO4

K2NiF4-type oxides La0.8R0.2SrFeO4 (R=La, Nd, Gd, Dy) have been synthesized by Pechini method and their structures were established by Rietveld refinements of the XRD data in the space group I4/mmm. Analysis of cell parameters shows that the decrease in the c from La to Dy compound is much larger than that in a. All the samples show antiferromagnetic behavior with increase in value of Θ with decreasing average <La/R/Sr> site radius. For all compounds, semiconducting behavior persists in the whole temperature range and can be expressed by two conduction mechanisms – Arrhenius model and polaron hopping model. The results suggests that the transport properties are dominated by the adiabatic small polaron hopping mechanism. Both activation energy (Ea) and polaron hopping energy (Ep) decrease with decreasing average ionic radius of rare earth ion at A-site.

Phase formation, glass forming ability, mechanical and thermal properties of Cu50Zr50−x Al x (0⩽x⩽11.0) glass forming alloys

Phase formation, glass forming ability, mechanical and thermal properties of Cu50Zr50−x Al x (0⩽x⩽11.0) glass forming alloys were systematically investigated. The results show that Cu50Zr47Al3 alloy has the best glass forming ability (GFA), lowest fragility index (m) and highest fracture strength. There are B2 CuZr and B19′ CuZr phases for Cu50Zr50−x Al x (0⩽x⩽5.0) alloys. B2 CuZr phase disappears and two new phases (Cu10Zr7 and CuZr2) appear when 5.0<Al<8.0. Another new AlCu2Zr phase can be clearly observed when Al ⩾8.0. The glass transition temperature (T g), the sensitivity of the T g to the heating rate (B), the activation energy for T g (E g) and the m value all increase with increasing Al content. The supercooled liquid region (ΔT x) is larger for Cu50Zr50−x Al x (x⩽5.0) than for Cu50Zr50−x Al x (x>5.0). Cu50Zr50−x Al x (0⩽x⩽4.0) alloys are off-eutectic compositions while near-eutectic compositions for Cu50Zr50−x Al x (5.0⩽x⩽11.0) alloys. The E g, E x, and E p decrease with increasing sensitive factor (β) for the studied Cu-based alloys characterized in the room-temperature brittleness. The dependence of the phase formation and GFA on the Al content is discussed.

Pan evaporation modelling and changing attribution analysis on the Tibetan Plateau (1970–2012)

AbstractPan evaporation (Ep) is an important indicator of water and energy and the decline of Ep has been reported in many regions over the last decades. The climate and Ep are dependent on each other. In this study, the temporal trends of Ep and main Ep drivers, namely mean air temperature (Ta), wind speed (u), global solar radiation (Rs), net long‐wave radiation(Rnl) and vapour pressure deficit (D) from 1970 to 2012, were calculated on the basis of 26 meteorological stations on the Tibetan Plateau. The arithmetic average of Ep from 26 stations decreased with the rate of −11.91 mm a−2; the trends of Rs, Rnl, Ta, u and D were −1.434 w m−2 decade−1, 0.2511 w m−2 decade−1, 0.3590°C decade−1, −0.2376 m s−1 decade−1 and 9.523 Pa decade−1, respectively. The diffuse irradiance is an essential parameter to model Ep and quantify the contribution of climatic factors to changing Ep. 60 724 observations of Rs and diffuse solar irradiance (Rd) from seven of the 26 stations were used to develop the correlation between the diffuse fraction (Rd/Rs), and the clearness index (Rs/Ro). On the basis of the estimation of the diffuse component of Rs and climatic data, we modified the PenPan model to estimate Chinese micro‐pan evaporation (Ep) and assess the attribution of Ep dynamics using partial derivatives. The results showed that there was a good agreement between the observed and calculated daily Ep values. The observed decrease in Ep was mostly due to declining wind speed (−13.7 mm a−2) with some contributions from decreasing solar irradiance (−3.1 mm a−2); and the increase of temperature had a large positive effect (4.55 mm a−2) in total whilst the increase of Rnl had insignificant effect (0.35 mm a−2) on Ep rates. The change of Ep is the net result of all the climatic variables. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Decrease in evaporation over the Indian monsoon region: implication on regional hydrological cycle

Using surface observations from 58 widely distributed stations over India, a highly significant (99.9 %) decreasing trend of pan evaporation (Epan) of 9.24 mm/a/a is calculated for 1971 to 2010. This constitutes a ~10 % reduction of Epan over the last four decades. While Epan is decreasing during the wet summer monsoon season (JJAS), as well as during the dry rest of the year, the rate of decrease during the dry season is much larger than that during the wet season. Apart from increasing solar dimming, surface winds are also persistently decreasing over the Indian sub-continent at the rate of −0.02 m/s/a resulting in ~40 % reduction over the last four decades. Based on PenPan model, it is shown that both the above factors contribute significantly to the decreasing trend in Epan. On a continental scale, annual mean potential evaporation (Ep) is larger than rainfall (P or Ep-P > 0, moisture divergence) indicating that India is water-limited. However, during wet monsoon P > Ep (or Ep-P < 0, moisture convergence) indicating that India is energy-limited during this season. Long term data shows that annually Ep-P follows a significant decreasing trend indicating that water limitation is decreasing with time. This is largely due to stronger decreasing trend of Ep-P during the dry season compared to weaker increasing trend of Ep-P during the wet monsoon season. The scatter plot of Ep-P versus Ep also conveys that the decrease in Ep leads to increase in moisture convergence in wet season and decrease in moisture divergence in dry season.

Influence of a Poro-Mechanical Modeling of the Intra-Luminal Thrombus and the Anisotropy of the Arterial Wall on the Prediction of the Abdominal Aortic Aneurysm Rupture

In order to improve the prediction of the Abdominal Aortic Aneurysm (AAA) rupture, a more comprehensive modeling is proposed, considering the porous nature of the Intra-Luminal Thrombus (ILT), the hyperelastic anisotropy of the AAA wall and fluid-structure interactions. Then, numerical simulations are performed on idealized AAAs. The results permitted to recover previous in vivo measurements of the intra-thrombus blood pressure. It is shown that the maximum pressure transmitted, through the ILT, to the AAA wall is about 10% lower than the pressure in the lumen. Despite this small decrease, the maximum stress (σ 1max) within the AAA wall strongly decreases when the relative volume of ILT increases. This new modeling is compared with classical modelings (dense hyperelastic ILT or hyperelastic isotropic AAA wall) by highlighting the influence of the mechanical modeling of the AAA wall and the ILT on the wall stress and the Peterson’s modulus (E P) of the AAA. This comparison shows that the magnitude and the location of σ 1max strongly depend on these modelings and that classical modelings overestimate the above decrease of σ 1max when the relative volume of ILT increases. Finally, the evolution of σ 1max with respect to E P is investigated. It is shown that, whatever the ILT modeling, the increase of its relative volume leads to a decrease of σ 1max and an increase of E P, for the isotropic AAA wall, while both σ 1max and E P decrease, for the anisotropic AAA wall. All these results point out that the prediction of the potential risk of the AAA rupture can be strongly affected by the coupling of (i) the mechanical modelings of the AAA wall and the ILT and (ii) the distribution of the latter within the aneurysm.

Association between ferrous iron accumulation and pentachlorophenol degradation at the paddy soil–water interface in the presence of exogenous low-molecular-weight dissolved organic carbon

Fourteen low-molecular-weight organic acids (organic acids) and eight neutral monosaccharides (monosaccharides) were used to investigate the intrinsic link between ferrous iron [Fe(II)] accumulation and pentachlorophenol (PCP) degradation at the paddy soil–floodwater interface. Using logistic curve fitting, significant differences were observed between Fe(II) accumulation with organic acids and monosaccharides. These differences were attributed to large variations in the dissociation constants and the number of carbon atoms per molecule. A significant relationship was observed between the maximum capacity of Fe(II) accumulation and PCP degradation. Correlations were established between environmental variables including PCP, NaOAc-/HCl-extractable Fe(II), water soluble organic carbon (WSOC), anodic peak oxidation potential (Ep) of Fe(II) species, oxidation–reduction potential (ORP), and pH. The increase in pH combined with WSOC consumption caused a decrease in Ep, which greatly enhanced the HCl-extractable Fe(II) accumulation and subsequently contributed to PCP degradation.

Poly (amide-6-b-ethylene oxide) multilayer composite membrane for carbon dioxide separation

In this paper, block copolymer poly (amide-6-b-ethylene oxide) Pebax® MH 1657 (PEBA1657) is used to prepare multilayer polyetherimide (PEI)/polydimethylsilicone (PDMS)/PEBA1657/PDMS composite membranes according to dip-coating method. The PDMS gutter layer is mainly used for preventing the pore penetration of PEBA1657 solution and the PDMS protective layer for sealing the defects of PEBA1657 selective layer. The prepared multilayer PEI/PDMS/PEBA1657/PDMS composite membranes display high permeance and high selectivity for CO2 separation. For the nonpolar gases He, H2, O2 and N2, the gas permeance decreases with the increasing molecule size. But for the polar gases CO2, H2S and SO2, their permeance is higher than that of nonpolar gases. Due to CO2 induced plasticization effect, the pressure dependence of CO2 permeance is expressed empirically by an exponential equation. And the temperature dependence of gas permeance is correlated with different Arrhenius equation below and above the melting of PEO segments. Compared with N2, H2 and CH4, CO2 has lower value of the apparent activation energy of permeation (Ep) because of its higher inherent condensability and the special interaction with polymer chain. Due to CO2 induced plasticization effect, the diffusion activation energy (Ed) of CO2 decreases with the increase of CO2 pressure, resulting in the decrease of Ep. As for CO2/N2 gas mixture, the pressure ratio strongly influences the CO2 concentration in the permeate side, and a high pressure ratio is always desirable to obtain high CO2 concentration for flue gas.

Effect of CTBN on Properties of Oxide Graphene/Epoxy Resin Composites

The effect of liquid carboxyl terminated butadiene acrylonitrile copolymer (CTBN) on the properties of oxide graphene (OG) /epoxy resin (EP) composite has been studied. The results show that oscillations process can greatly increase the tensile strength, shear strength and hardness of the composites, for the compatibility between the EP and the OG can be greatly improved after oscillations. Infra-red analysis shows that CTBN reacts with EP to form ester group. The tensile strength of the EP decrease, and the elongation at break increase, as more and more CTBN added. The tensile strength of the OG/EP composite is 14.37 MPa, while that of CTBN/OG/EP (15/0.001/100) composite is 4.84 MPa.

Projected 21st century decrease in marine productivity: a multi-model analysis

Abstract. Changes in marine net primary productivity (PP) and export of particulate organic carbon (EP) are projected over the 21st century with four global coupled carbon cycle-climate models. These include representations of marine ecosystems and the carbon cycle of different structure and complexity. All four models show a decrease in global mean PP and EP between 2 and 20% by 2100 relative to preindustrial conditions, for the SRES A2 emission scenario. Two different regimes for productivity changes are consistently identified in all models. The first chain of mechanisms is dominant in the low- and mid-latitude ocean and in the North Atlantic: reduced input of macro-nutrients into the euphotic zone related to enhanced stratification, reduced mixed layer depth, and slowed circulation causes a decrease in macro-nutrient concentrations and in PP and EP. The second regime is projected for parts of the Southern Ocean: an alleviation of light and/or temperature limitation leads to an increase in PP and EP as productivity is fueled by a sustained nutrient input. A region of disagreement among the models is the Arctic, where three models project an increase in PP while one model projects a decrease. Projected changes in seasonal and interannual variability are modest in most regions. Regional model skill metrics are proposed to generate multi-model mean fields that show an improved skill in representing observation-based estimates compared to a simple multi-model average. Model results are compared to recent productivity projections with three different algorithms, usually applied to infer net primary production from satellite observations.

A prostaglandin E2 receptor subtype EP1-selective antagonist, ONO-8711, suppresses 4-nitroquinoline 1-oxide-induced rat tongue carcinogenesis

We previously reported that certain cyclooxygenase (COX) inhibitors could inhibit chemically induced tongue carcinogenesis. In the present study, we investigated the effects of prostaglandin E(2) (PGE(2)) receptor EP(1)-selective antagonist ONO-8711 on 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis to know whether an EP(1) receptor involves in oral carcinogenesis. Male Fischer 344 rats were given drinking water containing 4-NQO for 8 weeks (20 p.p.m. for the initial 2 weeks, 25 p.p.m. for 2 weeks, and then 30 p.p.m. for 4 weeks). After 4-NQO treatment, animals were given 400 or 800 p.p.m. ONO-8711 containing diets for 23 weeks. The incidence of tongue squamous cell carcinomas (SCC) in the 4-NQO-treated rats was 64%, while that in the rats given ONO-8711 after 4-NQO exposure was 29 (P<0.05) and 29% (P<0.05) in the 400 and 800 p.p.m. of ONO-8711, respectively. The multiplicity of tongue cancer was also smaller in the 4-NQO + ONO-8711 (400 p.p.m. ONO-8711, 0.35 +/- 0.61; and 800 p.p.m. ONO-8711, 0.29 +/- 0.47; P<0.05), when compared with the 4-NQO alone group (0.88 +/- 0.88). Feeding with ONO-8711 significantly reduced PGE(2) level and cell proliferation activity in the non-tumorous epithelium of the tongue. Also, treatment with ONO-8711 resulted in the decrease in EP(1) immunohistochemical expression in the tongue lesions induced by 4-NQO. The results suggest that EP(1) receptor involves in oral carcinogenesis, and that an EP1-selective antagonist ONO-8711 exerts the cancer chemopreventive effects through the suppression of EP(1) expression, PGE(2) biosynthesis and cell proliferation.

Determination of Pulmonary Capillary Wedge Pressure Using Pulsed Wave Doppler Echocardiography: Clinical Application of Range Ambiguity Phenomenon

To predict pulmonary capillary wedge pressure (PCWP) noninvasively, several Doppler combination indices have been developed. Recently, a fair correlation has been found between the time constant of isovolumic left ventricular (LV) relaxation (tau) and pulsed wave Doppler LV inflow propagation velocity (LVIPVpw) derived through the application of range ambiguity phenomenon. In the measurement of LVIPVpw, we can simultaneously measure the peak phantom E-wave velocity (Ep) from the same heartbeat. Hence, it is hypothesized that Ep/LVIPVpw is a useful index in predicting PCWP. In all, 29 patients who underwent elective cardiac catheterization for suggested coronary artery disease were included. Mean PCWP (mPCWP) obtained from right heart catheterization was compared with echocardiographic data before and 5 minutes after sublingual application of nitroglycerin (0.6 mg). Nitroglycerin caused a significant decrease in Ep and mPCWP, but not in LVIPVpw (P < .001, P < .001, and P = .687, respectively). By stepwise multiple linear regression analysis, only the Ep/LVIPVpw (beta = 0.832, P < .001) was the independent predictor of mPCWP. After nitroglycerin intake, the change in mPCWP was significantly correlated with the change in Ep/LVIPVpw (r = 0.455, P = .015). The sensitivity and specificity of Ep/LVIPVpw > 0.74 in predicting mPCWP > 15 mm Hg were 78% and 90%, respectively (area under curve 0.86). In conclusion, Ep/LVIPVpw derived from the same heartbeat provides a good estimate of mPCWP and can be used to rapidly track the change in mPCWP.

Acceleration of cisplatin ototoxicity by perilymphatic application of 4-methylthiobenzoic acid

The antitumor agent cisplatin has dose-limiting side effects such as ototoxicity. Systemical co-treatment with anti-oxidants like 4-methylthiobenzoic acid (MTBA) and sodium thiosulfate (STS) provides protection against cisplatin ototoxicity. However, systemically administered protective agents may reduce the chemotherapeutic effect of cisplatin. Local application of the protective agents could avoid this undesirable effect. In the present study, we aimed at suppressing cisplatin-induced ototoxicity in guinea pigs by administering MTBA or STS perilymphatically through cochlear perfusion. Guinea pig cochleas were perfused for 10 min with artificial perilymph (ArtP) containing cisplatin at 0.3 mg/ml, either alone, or in combination with MTBA (0.1 or 1.0 mg/ml) or STS (0.75 or 3.0 mg/ml). The compound action potential (CAP) and the summating potential (SP), evoked by 8 kHz tone bursts, and the endocochlear potential (EP; MTBA only) were measured just before and 1, 2, 3 and 4 h after perfusion. Cisplatin gradually reduced the CAP amplitude in time. Adding MTBA only accelerated this ototoxic effect. After cisplatin treatment a decline was found in the EP, irrespective of co-treatment, i.e., addition of MTBA did not accelerate the EP decrease. In contrast to MTBA, STS ameliorated the ototoxic effect of cisplatin. In conclusion, local application of anti-oxidants can ameliorate cisplatin ototoxicity but this is not a feature of all anti-oxidants.

Measurement of aortic compliance in abdominal aortic aneurysms before and after open and endoluminal repair: preliminary results.

To assess aortic wall compliance as a portent of rupture risk in patients with abdominal aortic aneurysms. In this pilot study, 38 patients (32 men; median age 78 years, range 63-95) underwent an ultrasound scan: 20 pre-repair and 24 post-repair (18 endovascular [EVR] and 6 open). Six patients from the pre-repair group were included in a post repair study after EVR. Cine loop images were analyzed offsite using wall tracking software, which measured aortic diameter changes during cardiac cycles. Brachial blood pressure was measured, and elastic modulus (Ep) and stiffness (beta) were calculated. Preop Ep and beta were determined at the neck, inflection points (IP), and mid sac levels. Postop Ep and beta were calculated in mid sac only for technical reasons. Preoperative Ep and beta were significantly higher at IP compared with neck (median Ep 24.22 versus 12.95 N/cm(2), p<0.003; median beta 16.27 versus 8.65, p<0.003). At the mid sac, Ep and beta were also significantly higher compared with neck: Ep 26.41 versus 12.95 N/cm(2), p=0.001; beta 17.94 versus 8.65, p=0.001. The values for IP and mid sac were Ep 24.22 versus 26.41 N/cm(2), p=0.64; beta 16.27 versus 17.94, p=0.64. In the postop cases (n=24), Ep and beta in successful endovascular repair (n=12) were significantly higher than in open repair, respectively: median Ep 34.31 versus 12.33 N/cm(2), p<0.001; median beta 23.18 versus 8.24, p<0.001. Patients with endoleaks or endotension (n=6) had significantly elevated Ep and beta compared with those without endoleaks (n=12): median Ep 79.79 versus 34.31 N/ cm(2), p=0.002; median beta 51.52 versus 23.18, p<0.002. Six patients scanned before and after EVR showed a decrease of Ep and beta in 3, no change in 1, and an increase in 2. An increase greater than 2 fold was noted in a patient with a gross type II endoleak. This pilot study shows that estimates of aortic wall compliance agree well with known values for wall stress distribution. EVR leaves patients with greater wall stiffness than those undergoing open repair, a situation accentuated by endoleaks. Wall compliance and stiffness measurement promises to be useful for the evaluation of success of endovascular repair.

Interleukin-1beta induces glycosaminoglycan synthesis via the prostaglandin E2 pathway in cultured human cervical fibroblasts.

The aim of this study was to identify, in cultured human cervical fibroblasts, the mechanisms by which interleukin (IL)-1beta induces the synthesis of glycosaminoglycans (GAG) and to explore the putative role of prostaglandin E(2) (PGE(2)) in this process. Exposure of the cells for 24 h to IL-1beta induced a significant (P < 0.05) dose-dependent increase in GAG synthesis. IL-1beta (1 ng/ml) induced the expression of cyclooxygenase-2 (COX-2) protein 6 h after treatment, accompanied by a 7.5-fold increase in PGE(2) production. We confirmed that NS398, a selective COX-2 inhibitor, dose-dependently blocked PGE(2) augmentation following IL-1beta treatment. AH23848, the selective EP(4) receptor antagonist, completely abolished IL-1beta-induced GAG synthesis, whereas AH6809, an EP(2) receptor antagonist, had no effect on the stimulatory effects of IL-1beta. Furthermore, we demonstrated that 6 h exposure to IL-1beta induced a notable increase in EP(4) receptor mRNA expression and a decrease in EP(1) receptor mRNA but had no effect on the expression of EP(2) and EP(3) receptor transcripts. In conclusion, these findings indicate that IL-1beta not only induced GAG synthesis by increasing COX-2 protein expression and the subsequent PGE(2) production but also enhanced the responsiveness of cervical fibroblasts to PGE(2) by selectively up-regulating EP(4) receptor mRNA expression. These results suggest that PGE(2) may regulate human cervical ripening in an autocrine/paracrine manner via EP(4) receptors.

Interaction of a new cobalt(II) complex of five-coordinated chiral porphyrin with calf thymus DNA

A new template-directed chiral porphyrin [(TPP)Co(Trp)], where TPP = tetraphenylporphyrin and Trp = 1-tryptophan, was prepared and characterized by various physico-chemical methods. Interaction of [(TPP)Co(Trp)] with calf thymus DNA was studied by u.v.–vis. spectroscopy and cyclic voltammetry. The complex [(TPP)Co(Trp)], after interaction with calf thymus DNA, shows a shift in the absorption spectrum and a large hypochromicity, indicating an intercalating binding mode. This observation was further confirmed by the electrochemical behavior of [(TPP)Co(Trp)] before and after interaction with calf thymus DNA. The complex experiences a negative shift in E1/2 and a decrease in Ep. The ratio of cathodic to anodic peak currents ipc/ipa was ∼1 for [(TPP)Co(Trp)] while for DNA bound complex ipc/ipa ≤ 1, suggesting that the calf thymus DNA moiety is bound strongly to the complex [(TPP)Co(Trp)]. Kinetic studies of the DNA-porphyrin complex reveal a psuedo-first order rate law as the plot of kobsversus calf thymus DNA is linear passing through the origin.