Activation of the low oxygen affinity-inducing potential of the Asn108({beta}){->}Lys mutation of Hb-Presbyterian on intramolecular {{alpha}}{{alpha}}-fumaryl cross-bridging

The Asn108ßLys mutation in hemoglobin (HbPresbyterianmutation) endows a low O₂ affinity-inducing propensity to theprotein. Introduction of a fumaryl cross-bridge between itstwo 99 lysine residues also induces a low O₂ affinity into HbA.We have now engineered an -fumaryl cross-bridge into Hb-Presbyterianto determine the synergy or additivity, if any, that can beachieved between these two low O₂ affinity-inducing structuralperturbations. Despite the presence of the additional -aminogroup of Lys108(ß) within the central cavity, the-amino group of Lys99() of deoxy Hb-Presbyterian retained highselectivity for -fumaryl cross-bridging, with an overall efficiencycomparable to that with HbA. The -fumaryl cross-linking of Hb-Presbyterianreduced its O₂ affinity much more significantly than that observedwith HbA, indicating a synergy between the two low O₂ affinity-inducingstructural perturbations. Apparently, the -fumaryl cross-bridgein Hb-Presbyterian activates part of the latent low O₂ affinity-inducingpotential of Lys108(ß) that is generally activatedin the presence of chloride. The synergy between the Asn108(ß)Lysmutation and the -fumaryl cross-bridging was conserved in thepresence of chloride, but not in the presence of DPG. Furthermore,in the presence of chloride and DPG, -fumaryl Hb-Presbyterianaccessed a low O₂ affinity T-state that is accessed by HbA,-HbA and Hb-Presbyterian only in the presence of IHP. Isoelectricfocusing analysis suggested that the -fumaryl cross-linkingof Hb-Presbyterian induces changes in the ionization behaviorof one or more of the functional groups neighboring Lys99()and Lys108(ß) [presumably His103() and/or Glu101(ß)]to compensate for the extra positive charge of Lys108(ß).Molecular modeling studies identified two potential chloridebinding sites per ß dimer within the middle of thecentral cavity of -fumaryl HbA involving residues His103(),Arg104(ß) and Asn108(ß). The affinity ofthese sites is increased in -fumaryl Hb-Presbyterian as a resultof the Asn108(ß)Lys mutation. Thus, the results ofthe present study suggest that the enhanced neutralization ofthe positive charges in the middle of the central cavity ofHb achieved by these two electrostatic modifications, one (the-fumaryl cross-bridge) acting directly and the other (the Presbyterianmutation) acting indirectly through the mediation of chlorideion binding, facilitates the - fumaryl-Hb Presbyterian to accessa low O₂ affinity T-state structure much more readily than eitherHb-Presbyterian or -fumaryl HbA.     

Determination of chirality in 5-hydroxy-4-methyl-3-heptanone,the aggregation pheromone ofSitophilus oryzae (L.) andS. zeamais Motschulsky

The chirality of the pheromone of the rice weevil,Sitophilus oryzae (L.), and the maize weevil,S. zeamais (Motschulsky), 5-hydroxy-4-methyl-3-heptanone, was determined using an acetyl lactate derivatization procedure. Maize weevils were shown to produce >98% 4S,5R. Determination was more difficult with rice weevils due to a smaller quantity of insect extract, but they were shown to produce at least 92% 4S, 5R.The attractancy of the four synthetic stereoisomers of 5-hydroxy-4-methyl-3-heptanone was tested using rice and maize weevils. As expected, both species were most strongly attracted to the 4S, 5R enantiomer. Maize weevils also showed low but significant responses (P < 0.05) to both 4R, 5R and 4S,5S. Rice weevils showed a highly significant (P < 0.01) response to 4R, 5S, although it was only about one third the response to 4S, 5R. Thus, (4S,5R)-5-hydroxy-4-methyl-3-heptanone is clearly the major component of the pheromone of bothS. zeamais andS. oryzae.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by USDA.     

Thermodynamic Insight into the Effects of Water Displacement and Rearrangement upon Ligand Modifications using Molecular Dynamics Simulations

Computational methods, namely molecular dynamics (MD) simulations in combination with inhomogeneous fluid solvation theory (IFST) were used to retrospectively investigate various cases of ligand structure modifications that led to the displacement of binding site water molecules. Our findings are that water displacement per se is energetically unfavorable in the discussed examples, and that it is merely the fine balance between change in protein–ligand interaction energy, ligand solvation free energies, and binding site solvation free energies that determine if water displacement is favorable or not. We furthermore evaluated if we can reproduce experimental binding affinities by a computational approach combining changes in solvation free energies with changes in protein–ligand interaction energies and entropies. In two of the seven cases, this estimation led to large errors, implying that accurate predictions of relative binding free energies based on solvent thermodynamics is challenging. Nevertheless, MD simulations can provide insight regarding which water molecules can be targeted for displacement.     

Exploration of Sulfur‐Containing Analogues for Imaging Vesicular Acetylcholine Transporter in the Brain

Sixteen new sulfur‐containing compounds targeting the vesicular acetylcholine transporter (VAChT) were synthesized and assessed for in vitro binding affinities. Enantiomers (?)‐(1‐(3‐hydroxy‐1,2,3,4‐tetrahydronaphthalen‐2‐yl)piperidin‐4‐yl)(4‐(methylthio)phenyl)methanone [(?)‐ 8 ] and (?)‐(4‐((2‐fluoroethyl)thio)phenyl)(1‐(3‐hydroxy‐1,2,3,4‐tetrahydronaph‐thalen‐2‐yl)piperidin‐4‐yl)methanone [(?)‐ 14 a ] displayed high binding affinities, with respective K_i values of 1.4 and 2.2 nm for human VAChT, moderate and high selectivity for human VAChT over σ₁ (≈13‐fold) and σ₂ receptors (>420‐fold). Radiosyntheses of (?)‐[¹¹C] 8 and (?)‐[¹⁸F] 14 a were achieved using conventional methods. Ex vivo autoradiography and biodistribution studies in Sprague–Dawley rats indicated that both radiotracers have the capacity to penetrate the blood–brain barrier, with high initial brain uptake at 5 min and rapid washout. The striatal region had the highest accumulation for both radiotracers. Pretreating the rats with the VAChT ligand (?)‐vesamicol decreased brain uptake for both radiotracers. Pretreating the rats with the σ₁ ligand YUN‐122 (N‐(4‐benzylcyclohexyl)‐2‐(2‐fluorophenyl)acetamide) also decreased brain uptake, suggesting these two radiotracers also bind to the σ₁ receptor in vivo. The microPET study of (?)‐[¹¹C] 8 in the brain of a non‐human primate showed high striatal accumulation that peaked quickly and washed out rapidly. Although preliminary results indicated these two sulfur‐containing radiotracers have high binding affinities for VAChT with rapid washout kinetics from the striatum, their σ₁ receptor binding properties limit their potential as radiotracers for quantifying VAChT in vivo.     

Impact of delignification on mechanical,morphological, and thermal properties of wood sawdust reinforced unsaturated polyester composites

Mechanical, morphological, and thermal properties of the raw and delignified wood sawdust (DWS) reinforced unsaturated polyester (UP) composites were evaluated. Composites were prepared using Resin Transfer molding technique by changing filler loading (5, 10, 15, and 20 wt%) for both raw and DWS reinforced UP. Mechanical (tensile and flexural), Fourier transform infrared spectroscopy (FTIR), morphological (scanning electron microscopy [SEM]) and thermal (thermogravimetric analysis [TGA]) properties were successively characterized. FTIR confirmed the removal of lignin from wood sawdust during the delignification process. The tensile strength, Young's modulus, and flexural strength values increased only up to 15% filler loading then decreased with increasing the filler. DWS reinforced composites had better mechanical properties compared to raw composites. SEM micrographs reveal that DWS reinforced composites have good compatibility with UP resin. According to TGA results, DWS reinforced composites showed enhanced thermal stability at the final decomposition stage above 400°C. J. VINYL ADDIT. TECHNOL., 24:185–191, 2018. © 2016 Society of Plastics Engineers     

Validation of the small-punch test as a technique for characterizing the mechanical properties of acrylic bone cement

This paper examines the validity of using the small-punch test technique as a means of quantifying the mechanical properties of acrylic bone cement under different test conditions. The elastic moduli calculated using the small-punch test method were compared with data measured using the international standard for acrylic bone resin, ISO 5833. Conclusions from the study indicate that the small-punch test is a reproducible miniature specimen test method that can be used to characterize the mechanical properties of retrieved acrylic bone cement as used in total joint replacement surgery. Moreover, the test conditions were found to influence the elastic modulus of acrylic bone cement. The test temperature had a greater effect on the elastic behaviour of the bone cement than the test medium.     

Accelerated Development and Toxin Tolerance of the Navel Orangeworm <Emphasis Type="Italic">Amyelois transitella</Emphasis> (Lepidoptera: Pyralidae) in the Presence of <Emphasis Type="Italic">Aspergillus flavus</Emphasis>

The navel orangeworm (Amyelois transitella) and the fungus Aspergillus flavus constitute a facultative mutualism and pest complex in tree nut and fruit orchards in California. The possibility exists that the broad detoxification capabilities of A. flavus benefit its insect associate by metabolizing toxicants, including hostplant phytochemicals and pesticides. We examined this hypothesis by conducting laboratory bioassays to assess growth rates and survivorship of pyrethroid-resistant (R347) and susceptible (CPQ) larval strains on potato dextrose agar diet containing almond meal with and without two furanocoumarins, xanthotoxin and bergapten, found in several hostplants, and with and without two insecticides, bifenthrin and spinetoram, used in almond and pistachio orchards. Additionally, fungi were incubated in liquid diets containing the test chemicals, and extracts of these diets were added to almond potato dextrose agar (PDA) diets and fed to larvae to evaluate the ability of the fungus to metabolize these chemicals. Larvae consuming furanocoumarin-containing diet experienced higher mortality than individuals on unamended diets, but adding A. flavus resulted in up to 61.7% greater survival. Aspergillus flavus in the diet increased development rate?>?two-fold when furanocoumarins were present, demonstrating fungal enhancement of diet quality. Adding extracts of liquid diets containing xanthotoxin and fungus decreased mortality compared to xanthotoxin alone. On diets containing bifenthrin and spinetoram, however, mortality increased. These results support the hypothesis that A. flavus enhances navel orangeworm performance and contributes to detoxification of xenobiotics. Among practical implications of our findings, this mutualistic association should be considered in designing chemical management strategies for these pests.     

Middleware for integration of legacy electrical equipment into smart grid infrastructure using wireless sensor networks

To improve the efficiency of electricity distribution, smart grids allow communication between their devices. Pieces of legacy equipment operating in the distribution network do not communicate using any commercial protocol, such as DNP3, IEC 61850, or Modbus. Thus, herein, a middleware is proposed to allow the integration of the legacy electrical equipment into a smart grid using wireless sensor networks (WSNs). Each piece of legacy electrical equipment is connected to a sensor node, and the WSN sink node runs a middleware to enable the integration of this device with a smart grid, according to the commercial communication protocols. The middleware model is proposed to guide users in the development of a WSN‐based system for integrating electrical equipment into a smart grid. The middleware was validated in a real environment, which is related to the concept of power metering. Experiments were performed using the software supervisory control and data acquisition and distributed test manager to validate the communication between the electrical equipment and the computer of the power substation control centre.     

Paradox lost: Natural boundary conditions in the Ritz–Galerkin method

We present a simple calculation which seems at first to yield erroneous results when natural boundary conditions are not enforced. Our example is the static deformation of a cantilever beam under uniform loading. The corresponding variational principle is established and two applications of the Rayleigh–Ritz–Galerkin method are made.

• (1) The deflection is expanded in a series of cosines. The energy is rendered stationary subject to all boundary conditions, geometric and natural (they are imposed through Lagrange multipliers). The resulting function is exactly the Fourier cosine expansion of the true deflection–which is a fourth-degree polynomial.
• (2) The deflection is again expanded in a cosine series but now the natural boundary conditions are ignored. The resulting series does not converge to the true solution.

Owing to the simplicity of the coefficients, exact summations are possible and the discrepancy is clear. The disagreement is large, and the object of the paper is to decide which method is right.     

Enhanced fuzzy logic‐based spray and wait routing protocol for delay tolerant networks

Delay tolerant networks are a class of ad hoc networks that enable data delivery even in the absence of end‐to‐end connectivity between nodes, which is the basic assumption for routing in ad hoc networks. Nodes in these networks work on store‐carry and forward paradigm. In addition, such networks make use of message replication as a strategy to increase the possibility of messages reaching their destination. As contact opportunities are usually of short duration, it is important to prioritize scheduling of messages. Message replication may also lead to buffer congestion. Hence, buffer management is an important issue that greatly affects the performance of routing protocols in delay tolerant networks. In this paper, Spray and Wait routing protocol, which is a popular controlled replication‐based protocol for delay tolerant networks, has been enhanced using a new fuzzy‐based buffer management strategy Enhanced Fuzzy Spray and Wait Routing, with the aim to achieve increased delivery ratio and reduced overhead ratio. It aggregates three important message properties namely number of replicas of a message, its size, and remaining time‐to‐live, using fuzzy logic to determine the message priority, which denotes its importance with respect to other messages stored in a node's buffer. It then intelligently selects messages to schedule when a contact opportunity occurs. Because determination of number of replicas of a message in the network is a difficult task, a new method for estimation of the same has been proposed. Simulation results show improved performance of enhanced fuzzy spray and wait routing in terms of delivery ratio and resource consumption. Copyright © 2014 John Wiley & Sons, Ltd.