The effect of diluent on flame structure and laminar burning speeds of JP-8/oxidizer/diluent premixed flames

Experimental studies have been performed to investigate the flame structure and laminar burning speed of JP-8/oxidizer/diluent premixed flames at high temperatures and pressures. Three different diluents including argon, helium, and a mixture of 14% CO₂ and 86% N₂ (extra diluent gases), were used. The experiments were carried out in two constant volume spherical and cylindrical vessels. Laminar burning speeds were measured using a thermodynamics model based on the pressure rise method. Temperatures from 493 to 700 K and pressures from 1 to 11.5 atm were investigated. Extra diluent gases (EDG) decrease the laminar burning speeds but do not greatly impact the stability of the flame compared to JP-8/air. Replacing nitrogen in the air with argon and helium increases the range of temperature and pressure in the experiments. Helium as a diluent also increases the temperature and pressure range of stable flame as well as the laminar burning speed. Power law correlations have been developed for laminar burning speeds of JP-8/air/EDG and JP-8/oxygen/helium mixtures at a temperature range of 493-700 K and a pressure range of 1-10 atm for lean mixtures.     

ABCG5/G8 Deficiency in Mice Reduces Dietary Triacylglycerol and Cholesterol Transport into the Lymph

The adenosine triphosphate‐binding cassette (ABC) transporter G5/G8 is critical in protecting the body from accumulating dietary plant sterols. Expressed in the liver and small intestine, it transports plant sterols into the biliary and intestinal lumens, thus promoting their excretion. The extent to which G5/G8 regulates cholesterol absorption remains unclear. G5/G8 is also implicated in reducing the absorption of dietary triacylglycerols (TAG) by unknown mechanisms. We hypothesized that G5/G8 suppresses the production of chylomicrons, and its deficiency would enhance the absorption of both dietary TAG and cholesterol. The aim of this study was to investigate the effects of G5/G8 deficiency on lipid uptake and secretion into the lymph under steady‐state conditions. Surprisingly, compared with wild‐type mice (WT) (n = 9), G5/G8 KO (n = 13) lymph fistula mice given a continuous intraduodenal infusion of [3H]‐TAG and [14C]‐cholesterol showed a significant (P < 0.05) reduction in lymphatic transport of both [³H]‐TAG and [¹⁴C]‐cholesterol, concomitant with a significant (P < 0.05) increase of [³H]‐TAG and [¹⁴C]‐cholesterol accumulated in the intestinal lumen. There was no difference in the total amount of radiolabeled lipids retained in the intestinal mucosa between the two groups. G5/G8 KO mice given a bolus of TAG showed reduced intestinal TAG secretion compared with WT, suggesting an independent role for G5/G8 in facilitating intestinal TAG transport. Our data demonstrate that G5/G8 deficiency reduces the uptake and secretion of both dietary TAG and cholesterol by the intestine, suggesting a novel role for the sterol transporter in the formation and secretion of chylomicrons.     

Preparation and Properties of Polyether Scale Inhibitor Containing Fluorescent Groups

Water soluble fluorescent monomer, 8-allyloxy-1,3,6-pyrenetrisulfonic acid trisodium salt (AP), was synthesized from 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt and allyl chloride. AP-tagged copolymer maleic anhydride (MA)–ammonium allyl polyethoxy sulfate (APES)-AP, which is a calcium phosphate inhibitor, was prepared and the structures of AP and MA-APES-AP were characterized by FTIR and ¹H-NMR. The influence of the mole ratio of MA:APES on a calcium phosphate inhibitor of MA-APES-AP was discussed. Fluorescent properties and scale inhibition performance of MA-APES-AP were also studied. The results indicate that monomer ratio has great impact on the performance of MA-APES-AP. Fluorescent intensity increases with the concentration of MA-APES-AP, with a correlation coefficient (r) of 0.9934 and MA-APES-AP limit of detection of 1.72 mg 
83; L^?1. Calcium phosphate inhibition performance test results show that calcium phosphate inhibition of MA-APES-AP reaches 98.78 percent when the dosage is 12 mg 
83; L^?1 at 80^°C.     

辣椒碱合成方法的改进

以6-溴己酸为起始原料,经Wittig反应、胺化还原反应、N-酰化反应,制备了N-[（4-羟基-3-甲氧基苯基）-甲基]-8-甲基-6-壬烯酰胺,经EI-MS、1H NMR等测试技术分析确定了目标化合物的分子结构。     

Sulfonic Acid‐Catalyzed Autoxidative Carbon‐Carbon Coupling Reaction under Elevated Partial Pressure of Oxygen

An aerobic organocatalytic oxidative C C bond formation reaction of benzylic C H bonds with various C‐nucleophiles is described. The coupling reaction proceeds by simply stirring the substrates under elevated partial pressure of oxygen in the presence of a sulfonic acid catalyst at room temperature. Elevation of the pressure enables the reaction of a broad scope of nucleophile substrates otherwise showing poor reactivity at ambient pressure. The benzylic C H bonds of xanthene, acridanes, isochromane and related heterocycles could be functionalized with nucleophiles including ketones, 1,3‐dicarbonyl compounds and aldehydes. Electron‐rich arenes could be utilized as nucleophiles at elevated temperatures. The reactions are believed to proceed via autoxidation of the benzylic C H bonds to the hydroperoxides and subsequent nucleophilic substitution catalyzed by sulfonic acids.     

Synthesis and Characterization of Privileged Monodentate Phosphoramidite Ligands and Chiral Brønsted Acids Derived from d-Mannitol

The synthesis of several novel chiral phosphoramidite ligands (L1–L8) with C₂ symmetric, pseudo C₂ symmetric secondary amines and chiral Br8;nsted acids 1a,b has been achieved. These chiral auxiliaries were obtained from commercially available d-mannitol, and secondary amines in moderate to excellent yields. Excellent diastereoselectivites of ten chiral auxiliaries were obtained. The chiral phosphoramidite ligands and chiral Br8;nsted acids were fully characterized by spectroscopic methods.     

Molecular size evaluation of linear and branched paraffins from the gasoline pool by DFT quantum chemical calculations

A good approach of the critical molecular dimensions of 35 linear and branched C5-C8 paraffins by DFT quantum chemical calculations at B3LYP/6-31G** level of theory in gas phase is described. In this context, we found that either the determined molecular width or width-height average values can be used as critical measures in the analysis for selection of molecular sieves materials, depending on their pore size and shape. The molecular width values for linear and monosubstituted paraffins are 4.2 and 5.5 Å, respectively. In the case of disubstituted paraffins, the values are 5.5 Å for 2,3-, 2,4-, 2,5- and 3,4-disubstituted and for 2,2- and 3,3-disubstituted are 6.7-7.1 Å. The values for ethyl-substituted are 6.1-6.7 Å and for trisubstituted isoparaffins are 6.7. In order to select a porous material for selective separation of isoparaffins and paraffins, the zeolite diffusivity can be correlated with the critical diameter of the paraffins according to the geometry-limited diffusion concept and the effective minimum dimensions of the molecules. The calculated values of CPK molecular volume of the titled paraffins showed a good discrimination between the number of carbons and molecular size.     

The Sulfur and Water Resistance of Modified Washcoated Zeolite-Exchanged Monolith Catalysts for SCR of NOx with Propane

The method of preparation of modified Cu-substituted zeolite DeNOx catalysts washcoated on monolith ceramics has been developed. Non-modified and modified monolith catalysts were tested in DeNOx reaction with propane. It was shown that the catalyst modified by cerium and containing titania together with H-ZSM-5 and Al₂O₃ in the washcoating layer demonstrates high level of activity, and its resistance during multiple cycles of poisoning by sulfur compounds and water at 400 and 500°C is also high.     

Base Modification Strategies to Modulate Immune Stimulation by an siRNA

Immune stimulation triggered by siRNAs is one of the major challenges in the development of safe RNAi‐based therapeutics. Within an immunostimulatory siRNA sequence, this hurdle is commonly addressed by using ribose modifications (e.g., 2′‐OMe or 2′‐F), which results in decreased cytokine production. However, as immune stimulation by siRNAs is a sequence‐dependent phenomenon, recognition of the nucleobases by the trigger receptor(s) is also likely. Here, we use the recently published crystal structures of Toll‐like receptor 8 (TLR8) bound to small‐molecule agonists to generate computational models for ribonucleotide binding by this immune receptor. Our modeling suggested that modification of either the Watson–Crick or Hoogsteen face of adenosine would disrupt nucleotide/TLR8 interactions. We employed chemical synthesis to alter either the Watson–Crick or Hoogsteen face of adenosine and evaluated the effect of these modifications in an siRNA guide strand by measuring the immunostimulatory and RNA interference properties. For the siRNA guide strand tested, we found that modifying the Watson–Crick face is generally more effective at blocking TNFα production in human peripheral blood mononuclear cells (PBMCs) than modification at the Hoogsteen edge. We also observed that modifications near the 5′‐end were more effective at blocking cytokine production than those placed at the 3′‐end. This work advances our understanding of how chemical modifications can be used to optimize siRNA performance.