Complete Loop Research Articles

Solar disinfection of wastewater to reduce contamination of lettuce crops by Escherichia coli in reclaimed water irrigation

Low-cost disinfection methods to allow safe use of recycled wastewater for irrigation can have important beneficial implications in the developing world. This study aims to assess the efficiency of solar disinfection to reduce microbial contamination of lettuce crops when solar-treated wastewater effluents are used for irrigation. The irrigation study was designed as a complete experimental loop, including (i) the production of irrigation water through solar disinfection of real municipal wastewater treatment plant effluents (WWTPE), (ii) the watering of cultivated lettuce crops at the end of solar treatment, and (iii) the detection of microbial contamination on the irrigated crops 24 h after irrigation. Solar disinfection was performed using two types of reactors: (i) 20-L batch borosilicate glass reactors equipped with CPC to optimize solar irradiation, and (ii) 1.5-L PET bottles, i.e. the traditional SODIS recipients commonly used for disinfection of drinking water in developing communities. Both solar and H2O2-aided solar disinfection processes were tested during ≤5 h exposure of WWTPE, and Escherichia coli inactivation was analysed. A presence/absence detection method was developed to analyse lettuce leaves sampled 24 h after watering for the detection of E. coli. Results of inactivation assays show that solar disinfection processes can bring down bacterial concentrations of >103–104E. coli CFU mL−1 in real WWTPE to <2 CFU/mL (detection limit). The absence of E. coli on most lettuce samples after irrigation with solar-disinfected effluents (26 negative samples/28) confirmed an improved safety of irrigation practices due to solar treatment, while crops irrigated with raw WWTPE showed contamination.

HIV p24 as Scaffold for Presenting Conformational HIV Env Antigens

Heterologous protein scaffolds engrafted with structurally defined HIV Env epitopes recognized by broadly neutralizing monoclonal antibodies (MAbs) represent a promising strategy to elicit broad neutralizing antibodies. In such regards, a protein scaffold based on the HIV p24 CA protein is a highly attractive approach, providing also Gag epitopes for eliciting HIV non-neutralizing protective antibodies and specific CD4+ and CD8+ T cell responses. In the present study, computational techniques were employed to verify the presence of acceptor sites for conformational HIV Env epitopes and, as proof of concept, the analysis of HIV p24 CA-based scaffolds using a complete V3 loop in a MAb-bound conformation is presented. The V3-p24 epitope-scaffold proteins show the formation of capsomers made of hexamers similarly to the p24 wild type protein. Moreover, the conformational V3 loop presented on p24 scaffold is recognized by a panel of anti-V3 MAbs. The results suggest that HIV p24 CA protein has suitable acceptor sites for engrafting foreign epitopes, without disrupting the formation of capsomer hexamer structures, and that the V3 epitope does retain its antibody-bound conformation. This strongly support the feasibility of developing a scaffolding strategy based on p24 CA proteins displaying conformational minimal structural, antigenic HIV Env epitopes.

Role of Sequence and Structure of the Hendra Fusion Protein Fusion Peptide in Membrane Fusion

Viral fusion proteins are intriguing molecular machines that undergo drastic conformational changes to facilitate virus-cell membrane fusion. During fusion a hydrophobic region of the protein, termed the fusion peptide (FP), is inserted into the target host cell membrane, with subsequent conformational changes culminating in membrane merger. Class I fusion proteins contain FPs between 20 and 30 amino acids in length that are highly conserved within viral families but not between. To examine the sequence dependence of the Hendra virus (HeV) fusion (F) protein FP, the first eight amino acids were mutated first as double, then single, alanine mutants. Mutation of highly conserved glycine residues resulted in inefficient F protein expression and processing, whereas substitution of valine residues resulted in hypofusogenic F proteins despite wild-type surface expression levels. Synthetic peptides corresponding to a portion of the HeV F FP were shown to adopt an α-helical secondary structure in dodecylphosphocholine micelles and small unilamellar vesicles using circular dichroism spectroscopy. Interestingly, peptides containing point mutations that promote lower levels of cell-cell fusion within the context of the whole F protein were less α-helical and induced less membrane disorder in model membranes. These data represent the first extensive structure-function relationship of any paramyxovirus FP and demonstrate that the HeV F FP and potentially other paramyxovirus FPs likely require an α-helical structure for efficient membrane disordering and fusion.

Distributed Space-Time Coding for Full-Duplex Asynchronous Cooperative Communications

In this paper, we propose two distributed linear convolutional space-time coding (DLC-STC) schemes for full-duplex (FD) asynchronous cooperative communications. The DLC-STC Scheme 1 is for the case of the complete loop channel cancellation, which achieves the full asynchronous cooperative diversity. The DLC-STC Scheme 2 is for the case of the partial loop channel cancellation and amplifying, where some loop signals are used as the self-coding instead of treated as interference to be directly cancelled. We show this scheme can achieve full asynchronous cooperative diversity. We then evaluate the performance of the two schemes when loop channel information is not accurate and present an amplifying factor control method for the DLC-STC Scheme 2 to improve its performance with inaccurate loop channel information. Simulation results show that the DLC-STC Scheme 1 outperforms the DLC-STC Scheme 2 and the delay diversity scheme if perfect or high quality loop channel information is available at the relay, while the DLC-STC Scheme 2 achieves better performance if the loop channel information is imperfect.

Simulation of a convective loop for the Nested Thermal Envelope Design™ low-energy house

The Nested Thermal Envelope Design™ is an innovative low-energy house design that incorporates two thermal envelopes to create a core and perimeter zone. The perimeter acts as a thermal buffer zone, where heat loss from the core and solar gain in the perimeter are recovered to the core via an inter-zone heat pump. To optimize heat recovery from the perimeter and minimize temperature stratification, a complete loop is formed around the core living space, through which air may flow in a convective loop. A simplified convective loop was modelled with a commercial computational fluid dynamics software package. The results show that the convective loop distributes solar gains and reduces temperature stratification in the perimeter. The location of the heat pump in the convective loop was found to affect the heat pump’s coefficient of performance by up to 21%.

The Variable Displacement Compressor and Internal Regulation Valve Simulation

The air-conditioning system is a source of energy consumption and consequently, it has a strong influence on the fuel consumption, the engine load and the pollutant emissions. The air-conditioning system has to be accounted for in the energy balance under the hood. This system is composed of a variable displacement compressor including an internal regulation valve. In this paper, we model a complete system step by step. We build the compressor system and gradually add components so as to end up with the complete system. The simulation results shows that when the suction pressure becomes at some point smaller than the regulation pressure, the valve controls the compressor displacement and tends to reduce it in order to maintain a certain level for the suction pressure. It will be easier to observe the influence of the regulation valve on the complete refrigerant loop system.

Asymptotic study of a complete magnetic attitude control cycle providing a single-axis orientation

The angular motion of an axisymmetrical satellite equipped with the active magnetic attitude control system is examined. Attitude control system has to ensure necessary orientation of the axis of symmetry in the inertial space. It implements the following strategy: coarse reorientation of the axis of symmetry with nutation damping or “-Bdot” without initial detumbling; spinning-up about the axis of symmetry to achieve the property of a gyro; fine reorientation of the axis in the inertial space. Dynamics of the satellite is analytically studied using averaging technique on the complete control loop consisting of five algorithms. Solutions of the equations of motion are obtained in terms of quadratures for most cases or even in closed-form. The latter allowed to study the dependence of motion parameters including time-response with respect to the orbit inclination and other parameters for all algorithms.

The functional genomics of an eco‐evolutionary feedback loop: linking gene expression, trait evolution, and community dynamics

Feedbacks between ecological and evolutionary change may play important roles in community and ecosystem functioning, but a complete eco-evolutionary feedback loop has not been demonstrated at the community level, and we know little about molecular mechanisms underlying this kind of eco-evolutionary dynamics. In predator-prey (rotifer-alga) microcosms, cyclical changes in predator abundance generated fluctuating selection for a heritable prey defence trait, cell clumping. Predator population growth was affected more by prey evolution than by changes in prey abundance, and changes in predator abundance drove further prey evolution, completing the feedback loop. Within a predator-prey cycle, genes up-regulated as clumping declined were down-regulated as clumping increased, and vice-versa. Genes changing most in expression tended to be associated with defence or its cost. Expression patterns of individual genes differed greatly between consecutive cycles (often reversing direction), suggesting that a particular phenotype may be produced by several (perhaps many) different gene transcription pathways.

Optical delivery of nanospheres using arbitrary bending nanofibers

This work reports an optical delivery of about 700-nm diameter polystyrene spheres along arbitrary bending nanofibers (600 nm in diameter) including complete loop structure. Dependence of bending loss on bending radii and central angles of the nanofiber has also been investigated. The results show that, for a specific input optical power, there is a corresponding minimum bending radius for optical trapping and delivery. In other words, for a specific input optical power, when the bending radius of the nanofiber is larger than the minimum bending radius, the 700-nm diameter nanospheres can be trapped and delivered along the bending nanofiber. Vice versa, the nanospheres will be escaped from the bending nanofiber during the delivery process because of relatively large bending loss.

In situ carbon dioxide capture and fixation from a hot flue gas

The emission of CO2 globally from coal fired power plants is reportedly high, in the order of billion tons of CO2 per year. The amount would be much higher if the other types of fossil fuels used to generate electricity are accounted for. The present treatment or capture of this gas using conventional methods may require that the gas be injected underground for permanent storage. This solution depends on complicated machinery and suitable underground reservoirs but it poses the risk of accidental release of the gas due to seepage or negligence. A preferred method that is proposed in this presentation is by capturing and mineralizing carbon dioxide in situ. The method includes pressure swing adsorption in which highly temperature durable adsorbent is used. Annexed to the pressure swing system is a fixation unit that runs continuously and simultaneously to convert the captured CO2 into soda ash. The process requires only CO2. The other chemicals namely, sodium chloride and ammonia, can be regenerated and recycled. The process achieves almost a complete loop, making it highly sustainable.

Objective assessment of initial eye examination in patients presenting with mid-face injuries

s / International Journal of Surgery 10 (2012) S53–S109 S67 ABSTRACTS Results: In the subsequent 21 patients there were no delays in wound healing and no seromas. This reduction in complications was statistically significant (p1⁄40.001, Fisher's exact test). Conclusion: This completed audit loop has shown a reduction in abdominal wound complications after a change in practice of wound closure. Rates of delayed healing prior to the change in practice were comparable, and are currently better than, those in the published literature. 0517: OBJECTIVE ASSESSMENT OF INITIAL EYE EXAMINATION IN PATIENTS PRESENTING WITH MID-FACE INJURIES Kumaran Shanmugarajah , Shiraz Sabah , Ted Welman , Suzanne Westley , Ruth Skinner , Nadine Haram, Nicholas Segaren , Jonathan Collier . Chelsea And Westminster Hospital, London, UK; Barts and the

Analysis of a Small Loop Antenna With Inductive Coupling to Nearby Loops

This paper analyzes the inductive coupling that occurs when a loop antenna is near other conductive objects that form complete loops and are excited by incident low-frequency magnetic fields. The currents developed on the closed loops from the time changing magnetic fields generate their own magnetic fields that alter the voltage received by nearby open loop antennas. We will demonstrate how inductance theory can be used to model the system of loops. Using this theory, time domain circuit models are developed to find the open circuit voltage of a loop near one closed loop and for the open circuit voltage of one loop near two closed loops. We will show that the model is in good agreement with measurements that have been made in a TEM cell. One important application of this work is for electroexplosive device safety. It is necessary to ensure that if lightning strikes a facility that the electromagnetic fields generated inside do not have strong enough coupling to a detonator cable to cause initiation of explosives. We will show how the model can be used to analyze magnetic field coupling into a detonator cable attached to explosives in one typical type of work stand.

An Extended β7α7 Substrate-Binding Loop Is Essential for Efficient Catalysis by 3-Deoxy-d-manno-Octulosonate 8-Phosphate Synthase

The enzyme 3-deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase catalyzes the reaction between phosphoenolpyruvate and arabinose 5-phosphate (A5P) in the first committed step in the biosynthetic pathway for the formation of 3-deoxy-D-manno-octulosonate, an important component in the cell wall of Gram-negative bacteria. KDO8P synthase is evolutionarily related to the first enzyme of the shikimate pathway, 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAH7P) synthase, which uses erythrose 4-phosphate in place of A5P. The A5P binding site in KDO8P synthase is formed by three long loops that extend from the core catalytic (β/α)(8) barrel, β2α2, β7α7, and β8α8. The extended β7α7 loop is always present in KDO8P synthase yet is not observed for DAH7P synthase. Modeling of this loop indicated interactions between this loop and the extended β2α2 loop; both loops provide key hydrogen-bonding contacts with A5P. The two absolutely conserved residues on the β7α7 loop (Gln and Ser) were mutated to Ala in both the metal-dependent KDO8P synthase from Acidithiobacillus ferrooxidans and the metal-independent KDO8P synthase from Neisseria meningitidis. In addition, mutants were constructed for both enzymes with the extended β7α7 loop excised to match the DAH7P synthase architecture. Removal of the loop extension severely hindered efficient catalysis, dramatically increasing the K(m)(A5P) and reducing the k(cat) for both enzymes. Excision of the complete loop was far more detrimental to catalysis than the double mutations of the two conserved Gln and Ser residues. Therefore, the presence of the entire extended β7α7 loop is important for efficient catalysis by KDO8P synthase, with the loop acting to promote efficient and productive binding of A5P.

Conception and optimization of a membrane electrode assembly microbial fuel cell (MEA-MFC) for treatment of domestic wastewater

A membrane electrode assembly (MEA) for microbial fuel cells (MEA-MFC) was developed for continuous electricity production while treating domestic wastewater concurrently. It was optimized via three upgraded versions (noted α, β and γ) in terms of design (current collectors, hydrophilic separator nature) and operating conditions (hydraulic retention time, external resistance, aeration rate, recirculation). An overall rise of power by over 100% from version α to γ shows the importance of factors such as the choice of proper construction materials and prevention of short-circuits. A power of 2.5 mW was generated with a hydraulic retention time of 2.3 h when a Selemion proton exchange membrane was used as a hydrophilic separator in the MEA and 2.8 mW were attained with a reverse osmosis membrane. The MFC also showed a competitive value of internal resistance (≈40-50 Ω) as compared to the literature, especially considering its large volume (3 L). However, the operation of our system in a complete loop where the anolyte was allowed to trickle over the cathode (version γ) resulted in system failure.

Axonal Targeting of the 5‐HT1B Serotonin Receptor Relies on Structure‐Specific Constitutive Activation

By analogy to other axonal proteins, transcytotic delivery following spontaneous endocytosis from the somatodendritic membrane is expected to be essential for polarized distribution of axonal G-protein coupled receptors (GPCRs). However, possible contribution from constitutive activation, which may also result in constitutive GPCR endocytosis, is poorly known. Using two closely related but differentially distributed serotonin receptors, here we demonstrate higher constitutive activation and spontaneous endocytosis for the axonal 5-HT(1B) R, as compared to the somatodendritic 5-HT(1A) R, both in non-neuronal cells and neurons. Activation-dependent constitutive endocytosis is crucial for axonal targeting, because inverse-agonist treatment, which prevents constitutive activation, leads to atypical accumulation of newly synthesized 5-HT(1B) Rs on the somatodendritic plasma membrane. Using receptor chimeras composed of different domains from 5-HT(1A) R and 5-HT(1B) R, we show that the complete third intracellular loop of 5-HT(1B) R is necessary and sufficient for constitutive activation and efficient axonal targeting, both sensitive to inverse-agonist treatment. These results suggest that activation and targeting of 5-HT(1B) Rs are intimately interconnected in neurons.

Structure of the Adenosine A2A Receptor in Complex with ZM241385 and the Xanthines XAC and Caffeine

Methylxanthines, including caffeine and theophylline, are among the most widely consumed stimulant drugs in the world. These effects are mediated primarily via blockade of adenosine receptors. Xanthine analogs with improved properties have been developed as potential treatments for diseases such as Parkinson's disease. Here we report the structures of a thermostabilized adenosine A(2A) receptor in complex with the xanthines xanthine amine congener and caffeine, as well as the A(2A) selective inverse agonist ZM241385. The receptor is crystallized in the inactive state conformation as defined by the presence of a salt bridge known as the ionic lock. The complete third intracellular loop, responsible for G protein coupling, is visible consisting of extended helices 5and 6. The structures provide new insight into the features that define the ligand binding pocket of the adenosine receptor for ligands of diverse chemotypes as well as the cytoplasmic regions that interact with signal transduction proteins.

Multi-disciplinary constrained optimization of wind turbines

We describe procedures for the multi-disciplinary design optimization of wind turbines, where design parameters are optimized by maximizing a merit function, subjected to constraints that translate all relevant design requirements. Evaluation of merit function and constraints is performed by running simulations with a parametric high-fidelity aero-servo-elastic model; a detailed cross-sectional structural model is used for the minimum weight constrained sizing of the rotor blade. To reduce the computational cost, the multi-disciplinary optimization is performed by a multi-stage process that first alternates between an aerodynamic shape optimization step and a structural blade optimization one, and then combines the two to yield the final optimum solution. A complete design loop can be performed using the proposed algorithm using standard desktop computing hardware in one-two days. The design procedures are implemented in a computer program and demonstrated on the optimization of multi-MW horizontal axis wind turbines and on the design of an aero-elastically scaled wind tunnel model.

Structure and function of the complete internal fusion loop from Ebolavirus glycoprotein 2

Ebolavirus (Ebov), an enveloped virus of the family Filoviridae, causes hemorrhagic fever in humans and nonhuman primates. The viral glycoprotein (GP) is solely responsible for virus-host membrane fusion, but how it does so remains elusive. Fusion occurs after virions reach an endosomal compartment where GP is proteolytically primed by cathepsins. Fusion by primed GP is governed by an internal fusion loop found in GP2, the fusion subunit. This fusion loop contains a stretch of hydrophobic residues, some of which have been shown to be critical for GP-mediated infection. Here we present liposome fusion data and NMR structures for a complete (54-residue) disulfide-bonded internal fusion loop (Ebov FL) in a membrane mimetic. The Ebov FL induced rapid fusion of liposomes of varying compositions at pH values at or below 5.5. Consistently, circular dichroism experiments indicated that the α-helical content of the Ebov FL in the presence of either lipid-mimetic micelles or small liposomes increases in samples exposed to pH ≤5.5. NMR structures in dodecylphosphocholine micelles at pH 7.0 and 5.5 revealed a conformational change from a relatively flat extended loop structure at pH 7.0 to a structure with an ∼90° bend at pH 5.5. Induction of the bend at low pH reorients and compacts the hydrophobic patch at the tip of the FL. We propose that these changes facilitate disruption of lipids at the site of virus-host cell membrane contact and, hence, initiate Ebov fusion.

Divided and reunited maxillary artery: developmental and clinical considerations

We describe an anatomical variation of the right maxillary artery, discovered during dissection of a male human cadaver. The right maxillary artery bifurcates into unequal superficial (larger) and deep (smaller) divisions. Each division gives off several branches that distribute to the muscles of mastication, facial structures, and teeth. The superficial and deep divisions then reunite to form a complete loop, before giving off terminal branches in the pterygopalatine fossa. The entire arterial loop lies superficial to the branches of the mandibular nerve. This case provides further evidence for a network of vascular rings that surround soft tissue structures in the developing infratemporal fossa. Persistence of all or part of these rings determines adult anatomy. Extreme anatomical variations such as this one may complicate major procedures such as radical maxillectomy, as well as simple procedures such as inferior alveolar nerve blocks.

Detailed kinetic model describing new oligosaccharides synthesis using different β-galactosidases

The production of prebiotic galactooligosaccharides (GOS) from lactose has been widely studied whereas the synthesis of new prebiotic oligosaccharides with improved properties as those derived from lactulose is receiving an increasing interest. Understanding the mechanism of enzymatic oligosaccharides synthesis from lactulose would help to improve the quality of the products in a rational way as well as to increase the production efficiency by optimally selecting the operating conditions. A detailed kinetic model describing the enzymatic transgalactosylation reaction during lactulose hydrolysis is presented here for the first time. The model was calibrated with the experimental data obtained in batch assays with two different β-galactosidases at various temperatures and concentrations of substrate. A complete system identification loop, including model selection, robust estimation of the parameters by means of a global optimization method and computation of confidence intervals was performed. The kinetic model showed a good agreement between experimental data and predictions for lactulose conversion and provided important insights into the mechanism of formation of new oligosaccharides with potential prebiotic properties.