Transport properties of natural gas through polyethylene nanocomposites at high temperature and pressure

Four titanium(IV) alkoxides, namely: Ti(IV) n-propoxide (1), Ti(IV) n-butoxide (2), Ti(IV) tert-butoxide (3), and Ti(IV) 2-ethylhexoxide (4), have been used as initiators in the bulk ring-opening polymerization (ROP) of ??-caprolactone (??-CL). The influence of the alkoxide group on the course of the ROP of ??-CL was investigated by means of ¹H-NMR and differential scanning calorimetry (DSC). The ¹H-NMR spectra confirmed that the ROP reaction of ??-CL proceeded via the widely accepted coordination-insertion mechanism for each of the four initiators. Isoconversional methods have been used to evaluate non-isothermal DSC data via the equations of Friedman, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW). The kinetic studies showed that the polymerization rate for the four initiators (1-4) was in the order of 1?>?2????4?>?3. The lowest activation energies (40?C47, 42?C44, and 49?C52?kJ/mol for the Friedman, KAS and OFW methods respectively) were found in the polymerizations using Ti(IV) n-propoxide (1), while the highest activation energies (84?C107, 77?C87, and 80?C91?kJ/mol for the Friedman, KAS and OFW methods respectively) were obtained using Ti(IV) tert-butoxide (3). Differences in the rates of polymerization and the activation energies amongst the four initiators appeared to be governed mainly by the different degrees of steric hindrance in the initiator structure. These results represent important findings regarding the steric influence of the alkoxide groups on the kinetics of the ROP of ??-CL initiated by titanium(IV) alkoxides.     

Effect of biogas technology on nutrient flows for small- and medium-scale pig farms in Vietnam

Increased demand for meat products has led to increased livestock production in Vietnam, which now risks environmental pollution from inappropriate animal manure management on livestock farms. Biogas technology is generally considered an efficient solution for such farms to produce renewable biofuel for use in the household and to reduce the pollution impact from animal waste. However, with biogas technology, farmers may reduce their use of manure for fertilising crops. This field survey investigated nutrient flows on small- and medium-scale livestock farms with and without biogas in Northern Vietnam, in order to identify existing problems and possibilities for sustainable livestock production. A field survey was conducted on 12 pig farms with biogas and 12 pig farms without biogas in Quoc Oai district, Hanoi city. In general, the non-biogas pig farms used on average 3.8 ton compost and 3.1 ton fresh solid manure ha^?1?crop^?1 for each of three crops typically grown per year on their arable land. They discharged on average 16?% of the total manure produced into the environment in liquid form through the public sewage system. On biogas pig farms, the use of fresh solid manure for crops and discharge of liquid manure was lower, as manure was used to produce biogas. However, excessive use of washing water on several of these farms resulted in very dilute slurry (solid manure:water ratio 1:11) entering the biogas digester. This lowered the retention time in the digester (below the optimum range of 35?C55?days), leading to low biogas production rates and possible accumulation of sediment. The digestate was also highly diluted and hence difficult and costly to transport and apply to crops, so it was largely (60?%) discharged to the environment. The input volume of washing water should therefore be reduced to a ratio of 1:5. For better sustainability, appropriate technologies are needed to absorb nutrients from the digestate before discharge and to recycle these nutrients to crops.     

Microstructure and physicomechanical properties of pressureless sintered multiwalled carbon nanotube/alumina nanocomposites

Multiwalled carbon nanotube (MWCNT)/alumina (Al₂O₃) nanocomposites containing CNT from 0.15 vol.% to 2.4 vol.% have been successfully fabricated by simple wet mixing of as-received commercial precursors followed by pressureless sintering. Extent of densification of nanocomposites sintered at low temperature (e.g. 1500 °C) was <90%, but increased up to ∼99% when sintered at 1700 °C and offered superior performance compared to pure Al₂O₃. Nanocomposites containing 0.3 vol.% MWCNT and sintered at 1700 °C for 2 h in Argon led to ∼23% and ∼34% improvement in hardness and fracture toughness, respectively, than monolithic Al₂O₃. In addition, the highest improvement (∼20%) in bending strength was obtained for 0.15 vol.% MWCNT/Al₂O₃ nanocomposite compared to pure Al₂O₃. Weibull analysis indicated reliability of nanocomposites increased up to 0.3 vol.% MWCNT, whereas, beyond that loading consistency was the same as obtained for pure Al₂O₃. Detailed microstructure and fractographic analysis were performed to assess structure-property relationship of present nanocomposites.     

Lipids and endothelium-dependent vasodilation—A review

Studies using both in vitro and in vivo techniques have repeatedly shown that endothelium-dependent vasodilation (EDV) is impaired in different forms of experimental as well as human hypercholesterolemia. Clearly this impaired EDV can be reversed by lowering cholesterol levels by diet or medical therapy. Competitive blocking of l-arginine, changes in nitric oxide synthase acitivity, increased release of endothelin-1, and inactivation of nitric oxide due to superoxide ions all contribute to the impairment in EDV during dyslipidemia. The oxidation of low density lipoprotein, with its compound lysophosphatidylcholine, plays a critical role in these events. However, data on the role of triglycerides and fat-rich meals regarding EDV are not so consistent as data for cholesterol, although a view that the compositions of individual fatty acids and antioxidants are of major importance is emerging. Thus, this review shows that while impaired FDV is a general feature of hypercholesterolemia, the mechanisms involved and the therapeutic opportunities available still have to be investigated. Furthermore, discrepancies regarding the role of triglycerides and fat content in food may be explained by divergent effects of different fatty acids on the endothelium.     

Copolymers of ε-caprolactam and polypropylene oxide via anionic polymerization: synthesis and properties

Copolymers with an elastic polypropylene oxide (PPO), middle block in the main chain of poly(ε-caprolactam) were synthesized via activated anionic ring opening polymerization of ε-caprolactam (CL) in the presence of a basic initiator sodium salt of CL (Na-CL) and effective bifunctional polymeric activators (PACs). By varyng the molecular weight, two types of PACs were synthesized based on carbamoyl derivatives of hydroxyl terminated PPO with isophorone diisocyanate and were blocked with CL. The formation of copolymers has been confirmed by proton nuclear magnetic resonance spectroscopy (¹H–NMR) and Fourier transform infrared spectroscopy (FT-IR). The influence of the molecular weight of the PACs, the CL/PAC ratio and polymerization conditions on the conversion, intrinsic viscosity and polymerization kinetics, was investigated. The calorimetric, wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), notched impact test and dynamic mechanical thermal analysis (DMTA) were performed to estimate the influence of the composition ratio and the type of PACs on the physical, thermal, and mechanical properties of the copolymers. The use of the synthesized PACs reduced the polymerization time to several minutes. The copolymers showed improved impact resistance up to more than two times higher than those of the polyamide 6 (PA-6) homopolymer, without significant changes in their high melting temperatures.     

Hydrothermally Stable WO3/ZrO2–Ce0.6Zr0.4O2 Catalyst for the Selective Catalytic Reduction of NO with NH3

A new catalyst WO₃/ZrO₂–Ce_0.6Zr_0.4O₂ (15 wt % WO₃/ZrO₂:Ce_0.6Zr_0.4O₂ = 50:50) has been developed for the selective catalytic reduction of NO with NH₃. The redox component Ce_0.6Zr_0.4O₂ was dispersed on the surface of acidic WO₃/ZrO₂ by the solution combustion method showing the best NO _x reduction efficiency among the catalysts prepared by various modes of mixing of the components. The catalyst has been characterized by XRD, Raman spectroscopy and NH₃-TPD. A NO _x reduction efficiency of more than 90 % was obtained between 300 and 500 °C at α = NH_3,in/NO _x,in = 1. The catalyst showed stable NO _x reduction efficiency after hydrothermal ageing at 700 °C. Sulfur poisoning promoted the NO _x reduction efficiency at high temperatures at the expense of a reduced activity at lower temperatures, but the catalyst could be fully regenerated by heating in O₂ at 650 °C.     

Calcium in Red Blood Cells—A Perilous Balance

Ca²⁺ is a universal signalling molecule involved in regulating cell cycle and fate, metabolism and structural integrity, motility and volume. Like other cells, red blood cells (RBCs) rely on Ca²⁺ dependent signalling during differentiation from precursor cells. Intracellular Ca²⁺ levels in the circulating human RBCs take part not only in controlling biophysical properties such as membrane composition, volume and rheological properties, but also physiological parameters such as metabolic activity, redox state and cell clearance. Extremely low basal permeability of the human RBC membrane to Ca²⁺ and a powerful Ca²⁺ pump maintains intracellular free Ca²⁺ levels between 30 and 60 nM, whereas blood plasma Ca²⁺ is approximately 1.8 mM. Thus, activation of Ca²⁺ uptake has an impressive impact on multiple processes in the cells rendering Ca²⁺ a master regulator in RBCs. Malfunction of Ca²⁺ transporters in human RBCs leads to excessive accumulation of Ca²⁺ within the cells. This is associated with a number of pathological states including sickle cell disease, thalassemia, phosphofructokinase deficiency and other forms of hereditary anaemia. Continuous progress in unravelling the molecular nature of Ca²⁺ transport pathways allows harnessing Ca²⁺ uptake, avoiding premature RBC clearance and thrombotic complications. This review summarizes our current knowledge of Ca²⁺ signalling in RBCs emphasizing the importance of this inorganic cation in RBC function and survival.     

Weight reduction is not a major reason for improvement in rheumatoid arthritis from lacto-vegetarian,vegan or Mediterranean diets

Objectives  

Several investigators have reported that clinical improvements of patients with rheumatoid arthritis (RA), from participating in therapeutic diet intervention studies, have been accompanied by loss of body weight. This has raised the question whether weight reduction per se can improve RA. In order to test this hypothesis, three previously conducted diet intervention studies, comprising 95 patients with RA, were pooled. Together with Age, Gender, and Disease Duration, change during the test period in body weight, characterised dichotomously as reduction or no reduction (dichoΔBody Weight), as well as Diet (dichotomously as ordinary diet or test diet), were the independent variables. Dependent variables were the difference (Δ) from baseline to conclusion of the study in five different disease outcome measures. ΔESR and ΔPain Score were both characterised numerically and dichotomously (improvement or no improvement). ΔAcute Phase Response, ΔPhysical Function, and ΔTender Joint Count were characterised dichotomously only. Multiple logistic regression was used to analyse associations between the independent and the disease outcome variables.