Modulation of phosphatidylcholine biosynthesis by peroxisome proliferating fatty acid analogues

The modulation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) biosynthesis by sulfur-substituted fatty acid analogues has been investigated in rats. We have compared the effects of two non-β-oxidizable fatty acid analogues, 3-thiadicarboxylic acid and tetradecylthioacetic acid, which induce proliferation of peroxisomes, with those of the analogue tetradecylthiopropionic acid, which is a weak peroxisome proliferator. Repeated administration of 3-thiadicarboxylic acid for seven days resulted in increased hepatic concentrations of both PC and PE, but the PC/PE ratio was decreased. PC synthesis was increased, as evidenced by increased incorporation of [³H]choline into PC and an increased activity of cytidinetriphosphate (CTP): phosphocholine cytidylyltransferase. This was accompanied by a reduction in the pool sizes of choline and phosphocholine. TheS-adenosylmethione/S-adenosylhomocysteine ratio (AdoMet/AdoHcy) was marginally affected, indicating no increase in the rate of methylation of PE to PC. Administration of tetradecylthioacetic acid also resulted in increased hepatic phospholipid levels, increased AdoMet/AdoHcy ratios and in slightly elevated activity of CTP:phosphocholine cytidylyltransferase. The most striking effect observed after tetradecylthiopropionic acid treatment was the development of fatty liver. The activity of CTP:phosphocholine cytidylyltransferase and the incorporation of [³H]choline into PC was reduced compared to 3-thiadicarboxylic acid treatment. Although the rate of methylation of PE seemed to be increased at an elevated AdoMet/AdoHcy ratio, this resulted in only minor changes in the hepatic PC and PE levels, and the PC/PE ratio remained unchanged. Furthermore, the hepatic levels of choline and phosphocholine were reduced in these rats. The activities of the two enzymes competing for choline in the liver, choline kinase and choline dehydrogenase were changed in opposite directions, with the activity of choline kinase increasing approximately 1.5-fold. In addition, it was found that the level of homocysteine was elevated in the liver of tetradecylthiopropionic acid-treated rats. The possibility is discussed that this reflects a reduced flux of choline through the oxidative pathway in the liver. In tetradecylthiopropionic acid-treated rats, there seemed to be a coordinated regulation of the two pathways for PC biosynthesis, with an increase in the methylation of PE to PC and a reduced synthesisvia the CDPcholine pathway. The increase in PC observed in rats treated with 3-thiadicarboxylic acid and tetradecylthioacetic acid suggests that increased PC synthesis is linked to peroxisome proliferation.     

Electrochemistry of chlorogenic acid: experimental and theoretical studies

Cyclic voltammetry, chronoamperometry and rotating disk electrode voltammetry as well as quantum chemical methods, are used for electrochemical study of chlorogenic acid, as an important biological molecule. The standard formal potential, diffusion coefficient, and heterogeneous electron transfer rate constant of chlorogenic acid in aqueous solution are investigated. Acidic dissociation constant of chlorogenic acid is also obtained. Quantum mechanical calculations on oxidation of chlorogenic acid in aqueous solution, using density functional theory are presented. The change of Gibbs free energy and entropy of oxidation of chlorogenic acid are calculated using thermochemistry calculations. The calculations in aqueous solution are carried out with the use of polarizable continuum solvation method. Theoretical standard electrode potential of chlorogenic acid is achieved to be 0.580 V versus standard calomel electrode (SCE) which is in agreement with the experimental value of 0.617 V obtained experimentally in this work. The difference is consistent with the values we previously reported for other quinone derivatives.     

Laser-Induced Calcite—Aragonite Transition

High-pressure phases of CaCO₃, namely aragonite, calcite II, and possibly calcite III, were synthesized in air by exposing 10- to 20-μm-size particles of CaCO₃ (calcite I phase) to a CO₂ laser radiation at short pulse lengths (≤0.1 ms). The process, therefore, has the same effect as exposing the particles to at least several hundred megapascals pressure. Processing at higher pulse lengths resulted in the decomposition of CaCO₃ to CaO and CO₂. The extent of decomposition increased with increasing pulse length.     

New Zealand immunisation schedule history

The first formal immunisation schedule for the delivery of triple (DTP) vaccine was drawn up in November 1960. Since 1960 there have been many changes to the immunisation schedule, with a further change proposed for 1996. These changes have been in response to new vaccine development and better understanding of vaccine immunology. Further changes are certain.     

新型直流侧级联光伏逆变系统的研究与分析

新型直流侧级联的光伏逆变系统拓扑结构由多路单相全桥变换器与其连接的直流侧电容组成,直流侧电容串联能减少逆变桥电压。该拓扑结构使得MOSFET这种开关器件得到更广泛的应用。使用该拓扑结构可减小主电路的电流,同时由于使用了MOSFET,电路中的开关损耗减少了很多,因此降低了线路损耗。更为重要的是,通过对级联逆变器使用载波移相SPWM方式,降低了系统的工作频率,从而直接有效地降低了开关器件的损耗。最终通过仿真验证了该拓扑结构的有效性,研究结果表明多路直流侧级联光伏逆变系统具有较优越的谐波抑制能力,其直流电压控制简单。     

Magnetic Fe3O4@ polydopamine biopolymer: Synthesis,characterization and fabrication of promising nanocomposite

In this work, Functional Fe₃O₄@ polydopamine nanocomposite (Fe₃O₄@PDA) with magnetic response and special surface area were successfully assembled utilizing the strong coordination interactions between these two versatile materials. The morphology and size, crystal structure, specific saturation magnetization, chemical structure, and thermal properties were characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), vibration magnetometer (VSM), point of zero charge (pH_pzc), Fourier infrared (FT‐IR) and thermogravimetric analysis (TGA). The self‐polymerization of dopamine could be completed within 3 days, and Fe₃O₄ nanoparticles were embedded into PDA polymer. TGA results showed that PDA content of nanocomposite can be up to 51.7 wt% and also showed a significant decrease in the decomposition temperature of PDA from 530 to 270°C in the presence of the Fe₃O₄ nanoparticles. Through TGA analysis the coating thickness was estimated to be about 0.86 nm that it is well coincident with the measured values using TEM images and XRD analysis. At room temperature by vibrating sample magnetometer (VSM), Fe₃O₄ and Fe₃O₄@PDA exhibit superparamagnetic behavior with a saturation moment of 57.87 and 44.7 emu/g, respectively. Furthermore, PZC value reduced for Fe₃O₄@PDA compared with Fe₃O₄ nanoparticles and fell from 6.7 to 3.04. J. VINYL ADDIT. TECHNOL., 25:41–47, 2019. © 2018 Society of Plastics Engineers     

Characterization and selection of suitable grades of lactose as functional fillers for capsule filling: part 1

The purpose of this work is to characterize thermal, physical and mechanical properties of different grades of lactose and better understand the relationships between these properties and capsule filling performance. Eight grades of commercially available lactose were evaluated: Pharmatose 110?M, 125?M, 150?M, 200?M, 350?M (α-lactose monohydrate), AL (anhydrous lactose containing ～80% β-AL), DCL11 (spray dried α-lactose monohydrate containing ～15% amorphous lactose) and DCL15 (granulated α-lactose monohydrate containing ～12% β-AL). In this study, different lactose grades were characterized by thermal, solid state, physical and mechanical properties and later evaluated using principal component analysis (PCA) to assess the inter-relationships among some of these properties. The lactose grades were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), moisture sorption/desorption isotherms, particle size distribution; the flow was characterized by Carr Index (CI), critical orifice diameter (COD) and angle of friction. Plug mechanical strength was estimated from its diametric crushing strength. The first and second principal components (PC) captured 47.6% and 27.4% of variation in the physical and mechanical property data, respectively. The PCA plot grouped together 110?M, AL, DCL11 and DCL15 on the one side of plot which possessed superior properties for capsule formulation and these grades were selected for future formulation development studies (part II of this work).     

Security and key management in IoT‐based wireless sensor networks: An authentication protocol using symmetric key

Wireless sensor networks (WSN) consist of hundreds of miniature sensor nodes to sense various events in the surrounding environment and report back to the base station. Sensor networks are at the base of internet of things (IoT) and smart computing applications where a function is performed as a result of sensed event or information. However, in resource‐limited WSN authenticating a remote user is a vital security concern. Recently, researchers put forth various authentication protocols to address different security issues. Gope et al presented a protocol claiming resistance against known attacks. A thorough analysis of their protocol shows that it is vulnerable to user traceability, stolen verifier, and denial of service (DoS) attacks. In this article, an enhanced symmetric key‐based authentication protocol for IoT‐based WSN has been presented. The proposed protocol has the ability to counter user traceability, stolen verifier, and DoS attacks. Furthermore, the proposed protocol has been simulated and verified using Proverif and BAN logic. The proposed protocol has the same communication cost as the baseline protocol; however, in computation cost, it has 52.63% efficiency as compared with the baseline protocol.     

The spatial and temporal distribution of metals in an urban stream: A case study of the Don River in Toronto,Canada

Widespread growth of cities, the association of trace metals with urban runoff, and the potentially deleterious effect of metals on aquatic ecology have made it important to understand the distribution and transport of metals through surface water channel networks. The Don River in Toronto, Canada has been identified as an Area of Concern for pollution to Lake Ontario, with historically high levels of metal contamination. Sampling programs are sparse, therefore a model is needed to understand the spatial and temporal variability of metals in the river network. The objectives of the current study are to: i) describe the sampled spatial and temporal variability of metals in the Don River and ii) develop a modelling strategy to describe within flood metal transport dynamics. A model setup tool is developed that links Storm Water Management Model (SWMM) with the Environmental Fluid Dynamics Code (EFDC) to allow a seamless transition from catchment hydrology to in-stream hydraulic and chemical processes. Results show that lead pollution in the Don River is decreasing, likely as a result of policy changes and sediment dredging in the mouth of the river. However, zinc and copper pollution are increasingly problematic, with copper exceeding recommended lower guidelines, particularly during floods. Model results confirm that most of the sediment and metals are transported in relatively short bursts within longer flood durations and are stored in depositional hotspots within the Lower Don River. A better monitoring strategy is needed to understand and more accurately parametrize these processes in an urban river system.