Preservation with 8-bromo-cyclic GMP improves pulmonary function after prolonged ischemia

BACKGROUND: Cyclic guanosine monophosphate (cGMP) is a potent second messenger for the nitric oxide pathway in the pulmonary vasculature. Increased cytosolic cGMP levels elicit pulmonary vasodilatation resulting in decreased pulmonary vascular resistance and maximized pulmonary function after ischemia-reperfusion injury. We hypothesized that the addition of a membrane-permeable cGMP analogue (8-bromo-cGMP) to a Euro-Collins (EC) preservation solution would ameliorate pulmonary reperfusion injury better than prostaglandin E1 injection alone after prolonged hypothermic ischemia. METHODS: All lungs from New Zealand White rabbits (weight, 3 to 3.5 kg) were harvested en bloc, flushed with EC solution, and reperfused with whole blood for 30 minutes. Group 1 lungs (immediate control) were immediately reperfused. Group 2 lungs (control) were stored inflated at 4 degrees C for 18 hours before reperfusion. Groups 3 and 4 lungs were flushed with EC solution containing 200 micromol/L 8-bromo-cGMP and stored at 4 degrees C for 18 and 30 hours, respectively. Fresh, nonrecirculated venous blood was used to determine single-pass pulmonary venous-arterial oxygen gradients at 10-minute intervals. Assays for cGMP, cyclic adenosine monophosphate, nitric oxide synthase activity, and myeloperoxidase were performed on all lung tissue samples. Wet to dry weight ratios were determined after 2 weeks of passive desiccation. RESULTS: Oxygenation (venous-arterial oxygen gradient), pulmonary artery pressure, pulmonary vascular resistance, and edema formation were significantly improved in groups 3 and 4 (addition of 8-bromo-cGMP to EC plus 18 or 30 hours of hypothermic ischemia). Hypothermic storage (groups 2, 3, and 4) decreased both nitric oxide synthase activity and myeloperoxidase levels compared with immediate reperfusion (group 1). CONCLUSIONS: These results suggest that the addition of a membrane-permeable cGMP analogue to an EC pulmonary flush solution improves pulmonary function after prolonged storage compared with EC and prostaglandin (E1) preservation alone. The finding of myeloperoxidase reduced levels after hypothermic storage and subsequent reperfusion may suggest a more important role for pulmonary hemodynamic control in mitigating pulmonary reperfusion injury.     

Determination of free acetaldehyde in total blood for investigating the effect of aspartate on metabolism of alcohol in mice

The cerebral cortex of anaesthetised 2- to 12-day-old rats was superfused with artificial cerebrospinal fluid containing 100 mM acetate substituted for chloride to condition the brain for spreading depression (SD). After such superfusion, the earliest SD-like events were found at day 9 and full blown SD at day 10, whereas in the unconditioned brain the first SD occurred between days 12 and 15. Acetate conditioning of the cerebral cortex may be used to unmask neuronal and glial properties that are hidden in early stages of development.     

High Thermal Conductivity Polymer Composites Fabrication through Conventional and 3D Printing Processes: State-of-the-Art and Future Trends

The lifespan and the performance of flexible electronic devices and components are affected by the large accumulation of heat, and this problem must be addressed by thermally conductive polymer composite films. Therefore, the need for the development of high thermal conductivity nanocomposites has a strong role in various applications. In this article, the effect of different particle reinforcements such as single and hybrid form, coated and uncoated particles, and chemically treated particles on the thermal conductivity of various polymers are reviewed and the mechanism behind the improvement of the required properties are discussed. Furthermore, the role of manufacturing processes such as injection molding, compression molding, and 3D printing techniques in the production of high thermal conductivity polymer composites is detailed. Finally, the potential for future research is discussed, which can help researchers to work on the thermal properties enhancement for polymeric materials.     

POTENTIAL OF ERYTHRINA VARIEGATA ORIENTALIS LEAF POWDER FOR THE REMOVAL OF COBALT(II)

Most plant materials are freely and abundantly available and can be used for the removal of heavy metals from effluents. This study investigates the effects of equilibrium, kinetic, and thermodynamic parameters on biosorption of Co(II) ions onto the plant source Erythrina variegata orientalis leaf powder. The biosorption studies are carried out in a batch process. A significant increase in percentage removal of Co(II) is observed as pH value is increased from 2 to 5 and the percentage removal is maximum at pH = 7. The maximum sorption capacity is 8.3 mg/g in the range of variables investigated. The experimental data are well represented by Freundlich and Langmuir isotherms indicating favorable biosorption. The biosorption follows second-order kinetics. The biosorption is exothermic, irreversible, and spontaneous.     

NdFeAsO1−xFx Superconductor – Impact of Fluorine Variation on Microstructure and Transport Properties

Polycrystalline samples of NdFeAsO_1?xF_x (Nd1111) with x = 0, 0.1, 0.2, 0.3, and 0.4 were synthesized using a solid‐state method at ambient pressures. A maximum transition temperature (T_C) of 52.0 K and a J_C of 1050 A/cm² at 12 K were observed for x = 0.3 and 0.4, respectively. The transport and magnetic properties observed for each stoichiometry have remarkable correlation with their corresponding structural and microstructural aspects. Moreover, the superconducting properties exhibited in this material, processed at a relatively low temperature of 1000°C, are competitive as compared to the existing reports wherein high pressures/temperatures are inevitable.     

Micromechanical modeling of hybrid composites

The main aim of this work is to study the effective elastic modulus of hybrid composites through micromechanical modeling. The micromechanical framework based on the generalized method of cells has been employed for this study. The predictions based on the present model are compared with an assortment of experimental and other theoretical predictions. The effect of two types; sequential mode and mixed mode of filler additions on the effective elastic modulus of the hybrid composite are studied. Moreover, the effect of other microstructural parameters such as the concentration, shape and aspect ratio of fillers in altering the hybridization effects are also investigated.     

Electrical and Dielectric Properties of Non-magnetic Al<Superscript>3+</Superscript> Substituted Ni–Zn Nano Ferrites for High Frequency Applications

The effect of Al substitution on electrical and dielectric parameters of Ni–Zn ferrite has been discussed in the present work. The phase identification, surface morphology was studied using X-ray diffractometer (XRD), scanning electron microscope (SEM), respectively. The XRD patterns confirm the single-phase formation of these ferrites. With Al³⁺, substitution lattice parameter decreases due to smaller Al³⁺ ions replacing Fe³⁺ ions. The average grain size obtained from SEM results are in the range of 390–27 nm. The DC resistivity was observed to increase with increasing Al³⁺ ions concentration due to the unavailability of Fe³⁺ ions. Dielectric constant (\(\upvarepsilon ^{\prime }\)) and dielectric loss tangent (tan δ) have been studied as a function of frequency (1 kHz–10 MHz) and temperature (50–300 °C). The observed results are explained on the basis of interfacial polarization as predicted by Maxwell and Wagner.     

Effect of Sintering Temperature on Thermoelectric Properties of p‐Bi2Te3 Alloys Produced by Gas Atomization

In this research, p‐type Bi₂Te₃–75% Sb₂Te₃ thermoelectric alloy powders were produced by gas atomization and subsequently sintered by hot pressing at different temperatures. The grain growth of the hot‐pressed samples was observed with increasing sintering temperature from 380°C to 460°C. The compressive strength increased with increasing hot‐pressing temperature due to the high relative density of bulk samples obtained at high temperatures. The effect of sintering temperature on thermoelectric (TE) properties was studied. The maximum power factor 3.48 mW/mK² was obtained for the sample hot pressed at 420°C due to the resulting high electrical conductivity and enhanced Seebeck coefficient values.     

Effect of Milling Time on the Microstructure and Thermoelectric Properties of P‐type TAGS‐90 Alloys by HEM and SPS

In this study, p‐type TAGS‐90 powders were fabricated using high‐energy milling (HEM), subsequently sintered by spark plasma sintering (SPS). And then, the effects of milling time on the microstructure, mechanical, and thermoelectric properties were investigated. The powders were quickly decreased to fine particles of ~1 μm in size and uniformly agglomerated with the increasing of milling time. XRD results indicated that all milled powders and SPSed samples showed single GeTe phase. Also, EDX results showed almost no contamination and exact composition after milling. The maximum figure of merit, ZT = 1.08, was obtained for 30‐min‐milled sample at 723 K.